#!/bin/bash
#
# factorio_manager.sh
#
# Copyright (C) 2020, Branko Majic <branko@majic.rs>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

# Treat unset variables as errors.
set -u

program="factorio_manager.sh"
version="0.4.0"

function synopsis() {
cat <<EOF
$program $version, helper tool for managing Factorio instances

Usage:
  $program [OPTIONS] launch INSTANCE
  $program [OPTIONS] info INSTANCE
  $program [OPTIONS] list

  $program [OPTIONS] create INSTANCE
  $program [OPTIONS] create-server INSTANCE
  $program [OPTIONS] rename CURRENT_NAME NEW_NAME
  $program [OPTIONS] copy SOURCE_INSTANCE DESTINATION_INSTANCE
  $program [OPTIONS] remove INSTANCE
  $program [OPTIONS] import INSTANCE SOURCE_DIRECTORY
  $program [OPTIONS] set-version INSTANCE
  $program [OPTIONS] reset-server-map INSTANCE

  $program [OPTIONS] versions
  $program [OPTIONS] install GAME_ARCHIVE

  $program [OPTIONS] list-backups INSTANCE
  $program [OPTIONS] backup INSTANCE [DESCRIPTION]
  $program [OPTIONS] restore INSTANCE BACKUP_NAME
  $program [OPTIONS] remove-backup INSTANCE BACKUP_NAME

  $program [OPTIONS] set-game-dir GAME_INSTALLATIONS_DIRECTORY
EOF
}

function short_usage() {
cat <<EOF
$(synopsis)

For more details see $program -h.
EOF
}

function usage() {
    cat <<EOF
$(synopsis)

$program is a helper tool for managing multiple Factorio instances.

Each instance is designated a dedicated directory, which contains all
of its configuration files, saves games, and mods, and is kept
separate from all other instances.

Each instance is bound to a specific game version, and the manager
fully supports working with multiple versions of Factorio. Base game
files are kept intact and can be shared by multiple instances.

Factorio Manager keeps instances in sub-directories under the
~/.factorio/ directory. Sub-directories correspond to instance
names.

The following instance names are reserved for special use by
the tool:

 - .game_installations (used for storing symlink towards directory
   containing Factorio installations)

Multiple commands are provided for managing Factorio instances. Each
command accepts its own set of positional arguments.


backup INSTANCE [DESCRIPTION]

    Creates backup of an instance. All backups will be stored as
    subdirectories under the .bak directory within the instance
    directory. An optional description can be passed-in to make it
    easier to distinguish between different backups. Hidden files
    (names starting with '.') will be omitted from the backup.

copy SOURCE_INSTANCE DESTINATION_INSTANCE

    Creates a copy of an existing instance. Requires name of an
    existing instance and name of the new instance to be passed-in as
    arguments. Command will refuse to overwrite destination instance
    if it already exists. Command will prompt user to specify desired
    version for the copy, and to choose whether the backups should be
    copied as well.

create INSTANCE

    Creates a new Factorio instance with the given name. Command will
    prompt the user to pick between locally available Factorio
    versions.

    NOTE: When launching the instance for the first time, Factorio
    will report that its configuration file is invalid, and offer to
    fix it. The reason is that the manager creates a minimal
    configuration file when creating an instance, and Factorio does
    not like this. It should be safe to allow Factorio to fix the
    configuration file (this will populate it with the necessary
    commented-out options).

create-server INSTANCE

    Creates a new Factorio server instance with the given
    name. Command will prompt the user to pick between locally
    available Factorio versions, and to provide settings for server.

import INSTANCE

    Creates a new instance out of existing files found within a
    Factorio installation directory. This command is useful when
    migrating from Factorio installations that store all data in the
    root of the game installation directory. Command will prompt the
    user to pick between locally available Factorio versions.

info INSTANCE

    Shows information about the specified instance. This includes:

        - instance name
        - game version
        - instance directory path
        - list of enabled/disabled mods
        - list of backups

    If verbose mode is enabled, mods are listed with URLs and
    description as well.

install GAME_ARCHIVE

    Installs Factorio from the provided archive into the game
    installations directory. Version is automatically detected from
    the archive. All extracted game files are set-up to be read-only
    to prevent accidentally running the game directly from its own
    directory.

launch INSTANCE

    Launches the instance with specified name. See the note for the
    "create" command.

list

    Lists available Factorio instances.

list-backups INSTANCE

    Lists available backups for the specified instance.

remove-backup INSTANCE BACKUP_NAME

    Removes the specified backup for the specified instance. User must
    confirm the action prior to any files being removed.

remove INSTANCE

    Removes the specified instance. User must confirm the action prior
    to any files being removed.

rename CURRENT_NAME NEW_NAME

    Renames an existing instnace. Requires current name of an
    instance, as well as a new name. Command will refuse to rename the
    instance if an instance with specified new name already exists.

restore INSTANCE BACKUP_NAME

    Restores the specified instance from the specified backup. User
    must confirm the action prior to any files being replaced.

set-game-dir GAME_INSTALLATIONS_DIRECTORY

    Sets the base directory where Factorio game installations can be
    found. Each sub-directory within this directory should be named
    after the version of Factorio it represents. For example:

        - ~/local/games/factorio/0.17.79/
        - ~/local/games/factorio/0.18.30/
        - ~/local/games/factorio/0.18.34/

    Directory must be either empty or it should contain at least one
    instance of Factorio installation already.

set-version INSTANCE

    Sets Factorio version for the specified instance. User is prompted
    to pick between locally available versions.

versions

    Shows locally available Factorio versions.


$program accepts the following options:

    -C
        Force colour output.
    -V
        Verbose mode. Some commands may provide more output when enabled.
    -q
        Quiet mode. Output a message only if newer packages are available.
    -d
        Enable debug mode.
    -v
        Show script licensing information.
    -h
        Show usage help.


Please report bugs and send feature requests to <branko@majic.rs>.
EOF
}

function version() {
    cat <<EOF
$program, version $version

+-----------------------------------------------------------------------+
| Copyright (C) 2020, Branko Majic <branko@majic.rs>                    |
|                                                                       |
| This program is free software: you can redistribute it and/or modify  |
| it under the terms of the GNU General Public License as published by  |
| the Free Software Foundation, either version 3 of the License, or     |
| (at your option) any later version.                                   |
|                                                                       |
| This program is distributed in the hope that it will be useful,       |
| but WITHOUT ANY WARRANTY; without even the implied warranty of        |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         |
| GNU General Public License for more details.                          |
|                                                                       |
| You should have received a copy of the GNU General Public License     |
| along with this program.  If not, see <http://www.gnu.org/licenses/>. |
+-----------------------------------------------------------------------+

EOF
}

function setup_colours() {

    # Set-up colours for message printing if we're not piping and terminal is
    # capable of outputting the colors.
    _color_terminal=$(tput colors 2>&1)
    if [[ -t 1 ]] && (( _color_terminal > 0 )) || (( force_colours == 1 )); then
        _text_black=$(tput setaf 0)
        _text_red=$(tput setaf 1)
        _text_green=$(tput setaf 2)
        _text_yellow=$(tput setaf 3)
        _text_blue=$(tput setaf 4)
        _text_purple=$(tput setaf 5)
        _text_cyan=$(tput setaf 6)
        _text_white=$(tput setaf 7)

        _text_bold=$(tput bold)
        _text_reset=$(tput sgr0)

        _bg_black=$(tput setab 0)
        _bg_red=$(tput setab 1)
        _bg_green=$(tput setab 2)
        _bg_yellow=$(tput setab 3)
        _bg_blue=$(tput setab 4)
        _bg_purple=$(tput setab 5)
        _bg_cyan=$(tput setab 6)
        _bg_white=$(tput setab 7)
    else
        _text_black=""
        _text_red=""
        _text_green=""
        _text_yellow=""
        _text_blue=""
        _text_purple=""
        _text_cyan=""
        _text_white=""

        _text_bold=""
        _text_reset=""

        # Part of the standard Majic Bash script template.
        # shellcheck disable=SC2034
        _bg_black=""
        # shellcheck disable=SC2034
        _bg_red=""
        # shellcheck disable=SC2034
        _bg_green=""
        # shellcheck disable=SC2034
        _bg_yellow=""
        # shellcheck disable=SC2034
        _bg_blue=""
        # shellcheck disable=SC2034
        _bg_purple=""
        # shellcheck disable=SC2034
        _bg_cyan=""
        # shellcheck disable=SC2034
        _bg_white=""
    fi

    # Make the colors available via an associative array as well.
    declare -g -A _text_colors=()

    _text_colors[black]="${_text_black}"
    _text_colors[blue]="${_text_blue}"
    _text_colors[cyan]="${_text_cyan}"
    _text_colors[green]="${_text_green}"
    _text_colors[purple]="${_text_purple}"
    _text_colors[red]="${_text_red}"
    _text_colors[white]="${_text_white}"
    _text_colors[yellow]="${_text_yellow}"

    _text_colors[boldblack]="${_text_bold}${_text_black}"
    _text_colors[boldblue]="${_text_bold}${_text_blue}"
    _text_colors[boldcyan]="${_text_bold}${_text_cyan}"
    _text_colors[boldgreen]="${_text_bold}${_text_green}"
    _text_colors[boldpurple]="${_text_bold}${_text_purple}"
    _text_colors[boldred]="${_text_bold}${_text_red}"
    _text_colors[boldwhite]="${_text_bold}${_text_white}"
    _text_colors[boldyellow]="${_text_bold}${_text_yellow}"
}

# Set-up functions for printing coloured messages.
function debug() {
    if [[ $debug != 0 ]]; then
        echo "${_text_bold}${_text_blue}[DEBUG]${_text_reset}" "$@"
    fi
}

function info() {
    echo "${_text_bold}${_text_white}[INFO] ${_text_reset}" "$@"
}

function success() {
    echo "${_text_bold}${_text_green}[OK]   ${_text_reset}" "$@"
}

function warning() {
    echo "${_text_bold}${_text_yellow}[WARN] ${_text_reset}" "$@"
}

function error() {
    echo "${_text_bold}${_text_red}[ERROR]${_text_reset}" "$@" >&2
}

#
# Prints text in requested color to standard output. Behaves as thin
# wrapper around the echo built-in.
#
# Two invocation variants with different arguments are
# supported. First argument is the one that will determine what the
# desired invocation is.
#
# Arguments (variant 1):
#
#   $1 (echo_options)
#     Additional options to pass-in to echo. Must be a single argument
#     with leading dash followed by echo's own options. E.g. "-ne".
#
#   $2 (color)
#     Text color to use. Supported values: black, blue, cyan, green,
#     purple, red, white, yellow.
#
#   $3 (text)
#     Text to output.
#
#
# Arguments (variant 2):
#
#   $1 (color)
#     Text color to use. Supported values: black, blue, cyan, green,
#     purple, red, white, yellow, boldblack, boldblue, boldcyan,
#     boldgreen, boldpurple, boldred, boldwhite, boldyellow.
#
#   $2 (text)
#     Text to output.
#
function colorecho() {
    local options="" color text
    local reset="$_text_reset"

    if [[ ${1-} =~ -.* ]]; then
        options="$1"
        shift
    fi

    color="$1"
    text="$2"

    if [[ -n $options ]]; then
        echo "$options" "${_text_colors[$color]}$text${reset}"
    else
        echo "${_text_colors[$color]}$text${reset}"
    fi
}

#
# Prints text in requested color to standard output using printf
# format string and arguments.. Behaves as thin wrapper around the
# printf built-in.
#
# Arguments:
#
#   $1 (color)
#     Text color to use. Supported values: black, blue, cyan, green,
#     purple, red, white, yellow.
#
#   $2 (format_string)
#     printf-compatible format string.
#
#   $3 .. $n
#      Replacement values for the the format string.
#
function colorprintf() {
    local reset="$_text_reset"

    local color="$1"
    local format="$2"
    shift 2

    # Variables within this printf are used for dynamic color and
    # formatting, and can't be used as arguments.
    # shellcheck disable=SC2059
    printf "${_text_colors[$color]}${format}${reset}" "$@"
}

#
# Presents user with a warning, asks user for confirmation to
# continue, and terminates the script is confirmation is not provided
# with designated exit code.
#
# This function can be used to request confirmation for dangerous
# actions/operations (such as removal of large number of files etc).
#
# The user must type-in YES (with capital casing) to proceed.
#
# Arguments:
#
#   $1 (prompt_text)
#     Text to prompt the user with.
#
#   $2 (abort_text)
#     Text to show to user in case the operation was aborted by user.
#
#   $3 (exit_code)
#     Exit code when terminating the proram.
#
function critical_confirmation() {
    local prompt_text="$1"
    local abort_text="$2"
    local exit_code="$3"

    echo -n "${_text_bold}${_text_yellow}[WARN] ${_text_reset}" "${prompt_text} Type YES to confirm (default is no): "
    read -r confirm

    if [[ $confirm != "YES" ]]; then
        error "$abort_text"
        exit "$ERROR_GENERAL"
    fi
}

#
# Validates that the specified value conforms to designated setting.
#
# This is a small helper function used within read_server_settings
# function to validate the settings.
#
# Arguments:
#
#   $1 (name)
#     Name of the setting. Used to show erros to the user.
#
#   $2 (value)
#     Value to validate.
#
#   $3 (type)
#
#     Value type. Currently supports the following types:
#
#       - bool (boolean)
#       - int (integer/number)
#       - str (string, essentially anything can pass this validation)
#       - list (space-separated list of strings, essentially anything
#         can pass this validation)
#       - VAL_1|...|VAL_N (choice between different values)
#
#     When using the VAL_1|...|VAL_N variant, validation is slightly
#     relaxed for string values to allow both quoted and unquoted
#     variants. For example, if type was set to true|false|"admins",
#     then both 'admin' and '"admins"' will validate successfully
#     against the type.
#
# Returns:
#
#   0 if validation has passed, 1 if validation failed, and 2 if
#   passed-in type is not supported.
#
function validate_server_setting_value() {
    local name="$1"
    local value="$2"
    local type="$3"

    declare -a possible_values

    local i

    # Assume failure.
    local result=1

    if [[ $type == "bool" ]]; then
        if [[ $value == true || $value == false ]]; then
            result=0
        else
            colorecho "red" "$name must be a boolean [true|false]."
        fi

    elif [[ $type == "int" ]]; then
        if [[ $value =~ ^[[:digit:]]+$ ]]; then
            result=0
        else
            colorecho "red" "$name must be a number."
        fi

    elif [[ $type == "str" ]]; then
        result=0

    elif [[ $type == "list" ]]; then
        # This is free-form space-delimited list.
        result=0

    elif [[ $type =~ ^.+\|.+$ ]]; then
        readarray -d "|" -t possible_values < <(echo -n "$type")

        for i in "${possible_values[@]}"; do
            # Allow strings without quotes to be specified by the user.
            [[ $value == "$i" || \"$value\" == "$i" ]] && result=0
        done

        [[ $result == 0 ]] || colorecho red "$name must be one of listed values [$type]."
    else
        error "Unsupported type associated with '$name': $type"
        result=2
    fi

    return "$result"
}

#
# Prompts user to provide settings for a server instance.
#
# Function will go over a number of questions, providing a set of
# default values, and allowing the user to edit them in-place. Once
# all questions have been answered, user is presented with summary and
# ability to revisit the settings again.
#
# The function will transform the answers to be fully usable in the
# server configuration file, making sure the parameters are properly
# escaped for use in a JSON file.
#
# Defaults are mostly identical to the ones listed under Factorio's
# default "server-settings.json" with some exceptions to options that
# may be considered invasion of privacy:
#
#   - User verification is disabled. Otherwise the central
#     authentication server will always be aware of who is playing the
#     game at the moment.
#   - Game is specifically configured to be non-public.
#
# In addition to settings from the "server-settings.json"
# configuiration file, settings also cover the server port (specified
# in the "config.ini").
#
# Arguments:
#
#   $1 (server_name)
#     Default name to use for the server.
#
# Sets:
#
#   settings_value
#     Associative array storing settings and their values. Keys are
#     equivalent to setting names in the server configuration file.
#
function read_server_settings() {

    # Read arguments.
    local server_name="$1"

    # Local helper variables.
    local key="" value="" prompt="" confirmed="" item="" possible_values i

    declare -A settings_prompt=()
    declare -A settings_description=()
    declare -A settings_type=()

    declare -a settings_order=()

    # Global variables set by the function.
    declare -g -A settings_value=()

    # Set-up listings of server settings. Each setting is described
    # with name, prompt, description, default value, and
    # type. Supported types are: bool, int, str, list (input treated
    # as space-delimited list).
    #
    # Maintain additional array with keys in order to maintain
    # order when displaying questions to users.
    key="name"
    settings_prompt["$key"]="Name"
    settings_description["$key"]="Name of the game as it will appear in the game listing"
    settings_value["$key"]="$server_name"
    settings_type["$key"]="str"
    settings_order+=("$key")

    key="description"
    settings_prompt["$key"]="Description"
    settings_description["$key"]="Description of the game that will appear in the listing"
    settings_value["$key"]=""
    settings_type["$key"]="str"
    settings_order+=("$key")

    key="tags"
    settings_prompt["$key"]="Tags"
    settings_description["$key"]="Tags for the game that will appear in the listing (space-separated)"
    settings_value["$key"]=""
    settings_type["$key"]="list"
    settings_order+=("$key")

    # Not part of "server-settings.json", but important to show and
    # prompt the user for.
    key="port"
    settings_prompt["$key"]="Port"
    settings_description["$key"]="Port on which the server should listen"
    settings_value["$key"]="34197"
    settings_type["$key"]="int"
    settings_order+=("$key")

    key="max_players"
    settings_prompt["$key"]="Maximum players"
    settings_description["$key"]="Maximum number of players allowed, admins can join even a full server. 0 means unlimited."
    settings_value["$key"]="0"
    settings_type["$key"]="int"
    settings_order+=("$key")

    key="public"
    settings_prompt["$key"]="Publicly available"
    settings_description["$key"]="Game will be published on the official Factorio matching server."
    settings_value["$key"]="false"
    settings_type["$key"]="bool"
    settings_order+=("$key")

    key="lan"
    settings_prompt["$key"]="Broadcast on LAN"
    settings_description["$key"]="Game will be broadcast on LAN."
    settings_value["$key"]="false"
    settings_type["$key"]="bool"
    settings_order+=("$key")

    key="username"
    settings_prompt["$key"]="Factorio login username"
    settings_description["$key"]="Your factorio.com login credentials. Required for games with visibility public."
    settings_value["$key"]=""
    settings_type["$key"]="str"
    settings_order+=("$key")

    key="password"
    settings_prompt["$key"]="Factorio login password"
    settings_description["$key"]="Your factorio.com login credentials. Required for games with visibility public."
    settings_value["$key"]=""
    settings_type["$key"]="str"
    settings_order+=("$key")

    key="token"
    settings_prompt["$key"]="Factorio authentication token"
    settings_description["$key"]="Authentication token. May be used instead of 'password' for factorio.com login credentials."
    settings_value["$key"]=""
    settings_type["$key"]="str"
    settings_order+=("$key")

    key="game_password"
    settings_prompt["$key"]="Server password"
    settings_description["$key"]="Server password used to authenticate users towards the server itself. Default value has been randomly generated using /dev/urandom."
    settings_value["$key"]=$(tr -dc 'A-Za-z0-9' < /dev/urandom | head -c 33)
    settings_type["$key"]="str"
    settings_order+=("$key")

    key="require_user_verification"
    settings_prompt["$key"]="Require user verification"
    settings_description["$key"]="When set to true, the server will only allow clients that have a valid Factorio.com account."
    settings_value["$key"]="false"
    settings_type["$key"]="bool"
    settings_order+=("$key")

    key="max_upload_in_kilobytes_per_second"
    settings_prompt["$key"]="Maxiumum upload in kilobytes per second"
    settings_description["$key"]="Limits the maximum upload speed from server towards the clients (for map transfers etc). 0 means unlimited."
    settings_value["$key"]="0"
    settings_type["$key"]="int"
    settings_order+=("$key")

    key="max_upload_slots"
    settings_prompt["$key"]="Maximum upload slots"
    settings_description["$key"]="Limits the number of simulataneous uploads from server towards clients. 0 means unlimited."
    settings_value["$key"]="5"
    settings_type["$key"]="int"
    settings_order+=("$key")

    key="minimum_latency_in_ticks"
    settings_prompt["$key"]="Minimum latency in ticks"
    settings_description["$key"]="Minimum tolerable latency in ticks for connecting clients. One tick is 16ms in default speed. 0 means no minimum."
    settings_value["$key"]="0"
    settings_type["$key"]="int"
    settings_order+=("$key")

    key="ignore_player_limit_for_returning_players"
    settings_prompt["$key"]="Ignore player limit for returning players"
    settings_description["$key"]="Players that played on this map already can join even when the max player limit was reached."
    settings_value["$key"]="false"
    settings_type["$key"]="bool"
    settings_order+=("$key")

    key="allow_commands"
    settings_prompt["$key"]="Allow commands"
    settings_description["$key"]="Allow execution of commands via Lua console."
    settings_value["$key"]="admins-only"
    settings_type["$key"]="true|false|\"admins-only\""
    settings_order+=("$key")

    key="autosave_interval"
    settings_prompt["$key"]="Autosave interval"
    settings_description["$key"]="Autosave interval in minutes."
    settings_value["$key"]="10"
    settings_type["$key"]="int"
    settings_order+=("$key")

    key="autosave_slots"
    settings_prompt["$key"]="Autosave slots"
    settings_description["$key"]="Number of autosave slots to use. Autosave slots are cycled through when the server autosaves."
    settings_value["$key"]="5"
    settings_type["$key"]="int"
    settings_order+=("$key")

    key="afk_autokick_interval"
    settings_prompt["$key"]="AFK auto-kick interval"
    settings_description["$key"]="How many minutes until someone is kicked when doing nothing, 0 for never."
    settings_value["$key"]="0"
    settings_type["$key"]="int"
    settings_order+=("$key")

    key="auto_pause"
    settings_prompt["$key"]="Auto-pause"
    settings_description["$key"]="Whether should the server be paused when no players are present."
    settings_value["$key"]="true"
    settings_type["$key"]="bool"
    settings_order+=("$key")

    key="only_admins_can_pause_the_game"
    settings_prompt["$key"]="Only admins can pause the game"
    settings_description["$key"]="Specify if only admins should be able to pause the game."
    settings_value["$key"]="true"
    settings_type["$key"]="bool"
    settings_order+=("$key")

    key="autosave_only_on_server"
    settings_prompt["$key"]="Autosave only on server"
    settings_description["$key"]="Whether autosaves should be saved only on server or also on all connected clients."
    settings_value["$key"]="true"
    settings_type["$key"]="bool"
    settings_order+=("$key")

    key="non_blocking_saving"
    settings_prompt["$key"]="[EXPERT] Non-blocking saving"
    settings_description["$key"]="Highly experimental feature, enable only at your own risk of losing your saves. On UNIX systems, server will fork itself to create an autosave. Autosaving on connected Windows clients will be disabled regardless of autosave_only_on_server option."
    settings_value["$key"]="false"
    settings_type["$key"]="bool"
    settings_order+=("$key")

    key="minimum_segment_size"
    settings_prompt["$key"]="[EXPERT] Minimum segment size"
    settings_description["$key"]="Long network messages are split into segments that are sent over multiple ticks. Their size depends on the number of peers currently connected. Increasing the segment size will increase upload bandwidth requirement for the server and download bandwidth requirement for clients. This setting only affects server outbound messages. Changing these settings can have a negative impact on connection stability for some clients."
    settings_value["$key"]="25"
    settings_type["$key"]="int"
    settings_order+=("$key")

    key="minimum_segment_size_peer_count"
    settings_prompt["$key"]="[EXPERT] Minimum segment size peer count"
    settings_description["$key"]="See description for minimum_segment_size"
    settings_value["$key"]="20"
    settings_type["$key"]="int"
    settings_order+=("$key")

    key="maximum_segment_size"
    settings_prompt["$key"]="[EXPERT] Maximum segment size"
    settings_description["$key"]="See description for minimum_segment_size"
    settings_value["$key"]="100"
    settings_type["$key"]="int"
    settings_order+=("$key")

    key="maximum_segment_size_peer_count"
    settings_prompt["$key"]="[EXPERT] Maxmium segment size peer count"
    settings_description["$key"]="See description for minimum_segment_size"
    settings_value["$key"]="10"
    settings_type["$key"]="int"
    settings_order+=("$key")

    # Loop until user has confirmed the settings.
    while [[ ${confirmed,,} != 'y' ]]; do
        confirmed=""

        # Display the settings.
        echo "Current settings:"
        echo
        for key in "${settings_order[@]}"; do
            colorecho -n "yellow" "${settings_prompt[$key]}: "
            echo "${settings_value[$key]}"
        done

        # Prompt user to confirm settings.
        while [[ ${confirmed,,} != 'y' && ${confirmed,,} != 'n' ]]; do
            echo
            colorecho -n "green" "Are you satisfied with current settings (y/n)? "
            read -rn1 confirmed
            echo
        done

        # Allow user to provide changed values if not satisfied with
        # settings.
        if [[ ${confirmed,,} == 'n' ]]; then
            echo

            local total_questions="${#settings_order[@]}"
            local current_question=1

            for key in "${settings_order[@]}"; do

                # Prompt based on associated value type for the setting.
                if [[ ${settings_type[$key]} == "bool" ]]; then
                    prompt="${settings_prompt[$key]} [true|false]:"
                elif [[ ${settings_type[$key]} == "int" ]]; then
                    prompt="${settings_prompt[$key]} [number]:"
                elif [[ ${settings_type[$key]} == "str" ]]; then
                    prompt="${settings_prompt[$key]} [text]:"
                elif [[ ${settings_type[$key]} == "list" ]]; then
                    prompt="${settings_prompt[$key]} [space-delimited list]:"
                else
                    prompt="${settings_prompt[$key]} [${settings_type[$key]}]:"
                fi

                # Add some coloring to the prompt.
                prompt=$(colorprintf "green" "%02d/%02d ${prompt} " "$current_question" "$total_questions")

                # Show setting description.
                colorecho "white" "${settings_description[$key]}" | fold -s

                # Keep prompting user until a valid value is provided.
                validation_result=""
                until [[ $validation_result == 0 ]]; do

                    read -r -p "$prompt" -e -i "${settings_value[$key]}" value

                    validate_server_setting_value "${settings_prompt[$key]}" "$value" "${settings_type[$key]}"
                    validation_result="$?"
                    [[ $validation_result == 2 ]] && error "Internal error, type not set correctly for setting: $key." && exit "$ERROR_GENERAL"
                done

                settings_value[$key]="$value"

                echo
                (( current_question++ ))
            done
        fi
    done

    # Prepare values so they can be used within the JSON file.
    for key in "${settings_order[@]}"; do
        debug "Raw value for $key: ${settings_value[$key]}"

        if ! validate_server_setting_value "$key (${settings_prompt[$key]})" "${settings_value[$key]}" "${settings_type[$key]}"; then
            error "Failed to validate the settings value. This is most likely an internal bug in $program."
            exit "$ERROR_GENERAL"
        fi

        if [[ ${settings_type[$key]} == "str" ]]; then
            settings_value[$key]="\"${settings_value[$key]}\""

        # Used for selecting between multiple values.
        elif [[ ${settings_type[$key]} =~ ^.+\|.+$ ]]; then
            readarray -d "|" -t possible_values < <(echo -n "${settings_type[$key]}")

            for i in "${possible_values[@]}"; do
                # Convenience for allowing strings without quotes specified by the user.
                [[ \"${settings_value[$key]}\" == "$i" ]] && settings_value[$key]="\"${settings_value[$key]}\""
            done

        # List of strings.
        elif [[ ${settings_type[$key]} == "list" ]]; then
            value=""

            for item in ${settings_value[$key]}; do
                value="$value, \"$item\""
            done

            settings_value[$key]="[${value##, }]"
        fi
        debug "Processed value for $key: ${settings_value[$key]}"
    done
}

#
# Validates paths according to internal tool rules or terminates the
# program.
#
# This function helps to reduce boilerplate and centralise some common
# checks around handling of various paths.
#
# Arguments:
#
#   $1 (path_test)
#     Test to apply against the path. Supported tests are:
#
#       game_installations_directory
#         Checks if path contains Factorio installations in
#         sub-directories.
#
#       instance_directory_new
#         Checks if path is unused and can be used for new instance.
#
#       instance_directory
#         Checks if path contains a valid instance.
#
#       backup_directory_new
#         Checks if path is usable as destination for a new backup.
#
#       backup_directory
#         Checks if path contains a valid backup.
#
#       instance_import_source
#         Checks if path is usable as source for importing an instance.
#
#       game_archive
#         Checks if file at designated path is a valid game archive.
#
#       server_instance_directory
#         Checks if path contains a valid server instance.
#
#   $2 (path)
#     Path that should be validated.
#
#   $3 (exit_code)
#     Exit code to use when terminating the program.
#
# Exits:
#
#   If the path type is unsupported, or if the specified path does not
#   conform to requirements for the specified path type.
#
function validate_path_or_terminate() {
    local path_test="$1"
    local path="$2"
    local exit_code="$3"

    if [[ $path_test == "game_installations_directory" ]]; then
        # Make sure user has set directory with game installations -
        # test both symlink and target destination.
        if [[ ! -L $game_installations_directory || ! -d $game_installations_directory ]]; then
            error "Game installations directory has not been properly set. Please run the set-game-dir command first."
            exit "$exit_code"
        fi

    elif [[ $path_test == "instance_directory_new" ]]; then
        if [[ -e $path/config.ini ]]; then
            error "Instance already exists."
            exit "$exit_code"
        fi

        if [[ -e $path ]]; then
            error "Instance directory already exists, but does not contain a valid Factorio instance: $path."
            exit "$exit_code"
        fi

    elif [[ $path_test == "instance_directory" ]]; then
        if [[ ! -d $path ]]; then
            error "Missing instance directory: $path"
            error "Perhaps you have misstyped the instance name or forgot to create one first?"
            exit "$exit_code"
        fi

        if [[ ! -f $path/instance.conf ]]; then
            error "Missing instance configuration file: $path/instance.conf"
            exit "$exit_code"
        fi

        if [[ ! -f $path/config.ini ]]; then
            error "Missing game configuration file: $path/config.ini"
            exit "$exit_code"
        fi

    elif [[ $path_test == "backup_directory_new" ]]; then
        if [[ -e $path/config.ini ]]; then
            error "Backup already exists under directory: $path"
            exit "$exit_code"
        elif [[ -e $path ]]; then
            error "Backup directory already exists, but does not contain a valid backup: $path"
            exit "$exit_code"
        fi

    elif [[ $path_test == "backup_directory" ]]; then

        if [[ ! -d $path ]]; then
            error "Specified backup not available under: $path"
            exit "$ERROR_ARGUMENTS"
        fi

        if [[ ! -f $path/instance.conf ]]; then
            error "Backup missing instance configuration file: $path/instance.conf"
            exit "$exit_code"
        fi

        if [[ ! -f $path/config.ini ]]; then
            error "Backup missing game configuration file: $path/config.ini"
            exit "$exit_code"
        fi

    elif [[ $path_test == "instance_import_source" ]]; then
        if [[ ! -f $path/bin/x64/factorio ]]; then
            error "Could not locate Factorio binary in directory under: $path/bin/x64/factorio"
            error "Factorio Manager natively supports instance imports only when all game data (savegames etc) are stored within Factorio installation directory."
            exit "$ERROR_ARGUMENTS"
        fi

    elif [[ $path_test == "game_archive" ]]; then
        if [[ ! -f $path ]]; then
            error "Supplied path does not point to a valid game archive."
            exit "$ERROR_ARGUMENTS"
        fi

        if ! tar --occurrence=1 --list --file "$game_archive" "factorio/bin/x64/factorio" > /dev/null; then
            error "Supplied path does not point to a valid game archive."
            exit "$ERROR_ARGUMENTS"
        fi

    elif [[ $path_test == "server_instance_directory" ]]; then
        if [[ ! -d $path ]]; then
            error "Missing instance directory: $path"
            error "Perhaps you have misstyped the instance name or forgot to create one first?"
            exit "$exit_code"
        fi

        if [[ ! -f $path/instance.conf ]]; then
            error "Missing instance configuration file: $path/instance.conf"
            exit "$exit_code"
        fi

        if [[ ! -f $path/config.ini ]]; then
            error "Missing game configuration file: $path/config.ini"
            exit "$exit_code"
        fi

        if [[ ! -f $path/server-settings.json ]]; then
            error "Missing server settings file: $path/server-settings.json"
            exit "$exit_code"
        fi
    else
        error "Unable to validate path '$path', unsupported test requested: '$path_test'."
        exit "$ERROR_GENERAL"
    fi
}

#
# Prompts user to pick version of Factorio.
#
# Arguments:
#
#   $1 (game_installations_directory)
#     Path to directory containing Factorio installations.
#
#   $2 (default_version, optional)
#     Default version to fill-in for the user. If not set, last
#     version in the directory (sorted alphabetically) will be used.
#
#   $3 (default_marker, optional)
#     Marker text to use for the default version. Default is "default".
#
# Returns:
#
#   0 if version was successfully selected, 1 otherwise.
#
# Sets:
#
#   game_version_selected
#
function select_factorio_version() {
    local game_installations_directory="$1"
    local default_version="${2-}"
    local default_marker="${3-default}"

    local game_versions_available=()
    local candidate
    local i default_option selected_option

    declare -g game_version_selected=""

    # Grab a list of available versions.
    for candidate in "$game_installations_directory"/*; do
        if [[ -f $candidate/bin/x64/factorio ]]; then
            game_versions_available+=( "$(basename "$candidate")" )
        fi
    done

    if [[ ${#game_versions_available[@]} == 0 ]]; then
        error "Could not find any Factorio installations under directory '$game_installations_directory'."
        error "Please unpack Factorio installations into the directory, or use set-game-dir command to specify directory with Factorio installations."
        return 1
    fi

    echo "The following versions of Factorio are locally available:"
    echo

    for i in "${!game_versions_available[@]}"; do
        (( i++ ))
        echo -n "  [$i] $(basename "${game_versions_available[$i-1]}")"

        # Highlight default version.
        if [[ -z $default_version && $i == "${#game_versions_available[@]}" ]] || \
               [[ -n $default_version && ${game_versions_available[i-1]} == "$default_version" ]]; then
            colorecho boldgreen " [$default_marker]"
            default_option="$i"
        else
            echo
        fi
    done

    echo

    while [[ -z $game_version_selected ]]; do
        read -r -e -p "Please specify what version you would like to use (enter for $default_marker): " selected_option
        [[ -z $selected_option ]] && selected_option="$default_option"

        if [[ $selected_option =~ ^[[:digit:]]+$ ]] && (( selected_option >= 1 && selected_option <= ${#game_versions_available[@]} )); then
            game_version_selected="${game_versions_available[$selected_option-1]}"
        else
            error "Invalid option selected, please try again."
            echo
        fi
    done

    return 0
}

#
# Removes all registered lock files. Lock files are registered via the
# global array variable "lock_files". This function is meant to be
# used in conjunction with trap built-in to clean-up the files on exit.
#
# Arguments (globals):
#
#   lock_files
#     Array listing all the lock files that should be removed.
#
function remove_lock_files() {
    local lock

    for lock in "${lock_files[@]}"; do
        rm -f "$lock"
    done
}
declare -a lock_files=()
trap remove_lock_files EXIT

#
# Acquires an exclusive lock via flock call using the specified file
# and file descriptor. If it is not possible to acquire a lock,
# terminates the script, and registers the lock file for removal.
#
# The function should be used in conjunction with subshell as follows:
#
# (
#     lock "$HOME/.mylock" 200
#
#     do_my_stuff_here
#
# ) 200>"$HOME/.mylock"
#
#
# Arguments:
#
# $1 (lock_file)
#   Path to lock file.
#
# $2 (fd)
#   File descriptor number to use for the lock.
#
function lock() {
    local lock_file="$1"
    local fd="$2"

    lock_files+=("$lock_file")

    # Obtain lock - Factorio uses the same mechanism, so we should
    # be able to detect the game is running in this way.
    if ! flock --exclusive --nonblock "$fd"; then
        error "Could not acquire lock via lock file '$lock_file'. Is Factorio still running?"
        exit "$ERROR_GENERAL"
    fi
}

# Define error codes.
SUCCESS=0
ERROR_ARGUMENTS=1
ERROR_CONFIGURATION=2
ERROR_GENERAL=3

# Disable debug and quiet modes by default.
debug=0
quiet=0
verbose=0
force_colours=0

# Set-up some default paths.
manager_directory="$HOME/.factorio"
game_installations_directory="$manager_directory/.game_installations"

# If no arguments were given, just show usage help.
if [[ -z ${1-} ]]; then
    setup_colours
    short_usage
    exit "$SUCCESS"
fi

# Parse the arguments
while getopts "VCqdvh" opt; do
    case "$opt" in
        V) verbose=1;;
        C) force_colours=1;;
	q) # shellcheck disable=SC2034 # part of standard Bash script template.
           quiet=1;;
	d) debug=1;;
        v) version
           exit "$SUCCESS";;
        h) usage
           exit "$SUCCESS";;
        *) usage
           exit "$ERROR_ARGUMENTS";;
    esac
done
i=$OPTIND
shift $((i-1))

setup_colours

# Make sure the manager home directory exists.
if [[ ! -e $manager_directory ]]; then
    info "Creating Factorio Manager home directory under: $manager_directory"
    mkdir -p "$manager_directory"
fi

command="$1"
shift


#==============#
# set-game-dir #
#==============#
if [[ $command == set-game-dir ]]; then

    # Read and verify additional positional arguments.
    game_installations_directory_target="${1-}"
    shift

    if [[ -z $game_installations_directory_target ]]; then
        error "Missing argument: GAME_INSTALLATIONS_DIRECTORY"
        exit "$ERROR_ARGUMENTS"
    fi

    if [[ ! -d $game_installations_directory_target ]]; then
        error "No such directory: $game_installations_directory"
        exit "$ERROR_GENERAL"
    fi

    # For directory to be usable, it must be either empty or contain
    # at least one Factorio installation.
    shopt -s nullglob
    candidates=("$game_installations_directory_target"/*)
    shopt -u nullglob

    factorio_versions_found=0
    for candidate in "${candidates[@]}"; do
        if [[ -f $candidate/bin/x64/factorio ]]; then
            (( factorio_versions_found++ ))
        fi
    done

    if [[ ${#candidates[@]} != 0 ]] && (( factorio_versions_found == 0 )); then
        error "Specified directory must be either empty or must contain at least one Factorio installation already."
        exit "$ERROR_GENERAL"
    fi

    # Update the link
    if [[ -L $game_installations_directory ]]; then
        rm "$game_installations_directory"
    fi

    if ! ln -s "$game_installations_directory_target" "$game_installations_directory"; then
        error "Could not create symlink from '$game_installations_directory_target' to '$game_installations_directory'."

        exit "$ERROR_GENERAL"
    fi


#==========#
# versions #
#==========#
elif [[ $command == versions ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    echo "Locally available Factorio versions:"
    echo

    # Find all sub-directories that are Factorio installations.
    for candidate in "$game_installations_directory"/*; do
        if [[ -d $candidate && -e $candidate/bin/x64/factorio ]]; then
            echo "  - $(basename "$candidate")"
        fi
    done
    echo


#======#
# list #
#======#
elif [[ $command == list ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    echo "Available instances:"
    echo

    # Find all sub-directories that are valid instances.
    for candidate in "$manager_directory"/*; do
        if [[ -f $candidate/instance.conf ]]; then
            # shellcheck source=/dev/null
            source "$candidate/instance.conf"
            # shellcheck disable=SC2154 # game_version is read from the configuration file
            echo "  - $(basename "$candidate") ($game_version)"
        fi
    done
    echo


#========#
# create #
#========#
elif [[ $command == create ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    instance="${1-}"
    shift

    # Calculate derived variables.
    instance_directory="$manager_directory/$instance"
    instance_config="$instance_directory/instance.conf"
    game_config="$instance_directory/config.ini"

    # Verify arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    # Make sure new instance directory can be used.
    validate_path_or_terminate "instance_directory_new" "$instance_directory" "$ERROR_ARGUMENTS"

    select_factorio_version "$game_installations_directory" || exit "$ERROR_GENERAL"

    # Set-up the instance.
    mkdir "$instance_directory"
    mkdir "$instance_directory/mods"
    echo "{}" > "$instance_directory/mods/mod-list.json"

    cat <<EOF > "$instance_config"
game_version="$game_version_selected"
EOF

    # @TODO: If we could somehow obtain stock config.ini file without
    # having to first run Factorio, that would be great. As it is, the
    # user will presented with warning about corrupt config.ini when
    # running the instance for the first time.
    cat <<EOF > "$game_config"
[path]
read-data=__PATH__executable__/../../data
write-data=${instance_directory}

[general]
locale=

[other]
check-updates=false
enable-crash-log-uploading=false

[interface]

[controls]

[sound]

[map-view]

[debug]

[multiplayer-lobby]

[graphics]
EOF

    echo
    warning "Factorio Manager has created a minimal empty configuration file for Factorio under $game_config."
    warning "Since the generated configuration file is almost empty, Factorio will complain that the file seems corrupt."
    warning "Factorio will offer to fix the corrupted configuration file by filling-in the missing information during the first startup."
    warning "It should be safe to accept this. This warning will be shown by Factorio only the first time."


#========#
# launch #
#========#
elif [[ $command == launch ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    instance="${1-}"
    shift

    # Set-up derived variables.
    instance_directory="$manager_directory/$instance"
    instance_config="$instance_directory/instance.conf"
    game_config="$instance_directory/config.ini"
    server_config="$instance_directory/server-settings.json"

    # Verify arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    # Validate that instance directory contains valid instance.
    validate_path_or_terminate "instance_directory" "$instance_directory" "$ERROR_ARGUMENTS"

    # Update instance write directory prior to launching - this is a
    # failsafe in case it got changed by hand or perhaps the value
    # comes from backups of a copied instance.
    current_write_data=$(grep "^write-data=" "$game_config")
    expected_write_data="write-data=${instance_directory}"

    if [[ $current_write_data != "$expected_write_data" ]]; then
        warning "Incorrect path specified for write-data in game configuration file: $game_config"
        warning "Current configuration is: $current_write_data"
        warning "Configuration will be replaced with: $expected_write_data"
        sed -i -e "s#^write-data=.*#$expected_write_data#" "$game_config"
    fi

    # Read launcher configuration for the instance.
    # shellcheck source=/dev/null
    source "$instance_config"

    if [[ -z $game_version ]]; then
        error "Missing game version information in $game_config."
        exit "$ERROR_CONFIGURATION"
    fi

    # Set-up paths for launching the game, and ensure they still exist
    # (versions can be removed by user).
    game_directory="${game_installations_directory}/${game_version}"
    factorio_bin="$game_directory/bin/x64/factorio"

    if [[ ! -e $factorio_bin ]]; then
        error "Could not locate Factorio binary under: $factorio_bin"
        error "Factorio $game_version installation may have been removed from game installations directory:"
        error "   $(readlink -f "$game_installations_directory")"
        exit "$ERROR_CONFIGURATION"
    fi

    # Launch instance
    if [[ -e $server_config ]]; then
        "$factorio_bin" --config "$game_config" --start-server "$instance_directory/saves/default.zip"
    else
        "$factorio_bin" --config "$game_config"
    fi


#========#
# backup #
#========#
elif [[ $command == backup ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    instance="${1-}"
    description="${2-}"
    shift 2

    # Use timestamp-based names for backups.
    timestamp=$(date +%Y-%m-%d_%H:%M:%S)

    # Set-up derived variables.
    instance_directory="$manager_directory/$instance"
    instance_config="$instance_directory/instance.conf"
    game_config="$instance_directory/config.ini"
    lock_file="$instance_directory/.lock"

    backup_destination="$instance_directory/.bak/$timestamp"
    backup_description="$backup_destination/.description"

    # Verify positional arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    # Validate that instance directory contains valid instance.
    validate_path_or_terminate "instance_directory" "$instance_directory" "$ERROR_ARGUMENTS"

    # Validate destination path for backup directory can be used.
    validate_path_or_terminate "backup_directory_new" "$backup_destination" "$ERROR_GENERAL"

    (
        # shellcheck disable=SC2094 # Lock file is not being read from.
        lock "$lock_file" 200

        # Backup the instance. Clean-up the backup destination in case of failure.
        mkdir -p "$backup_destination"
        if ! cp -a "$instance_directory"/* "$backup_destination"; then
            error "Could not create backup under: $backup_destination"
            rm -rf "$backup_destination"
            exit "$ERROR_GENERAL"
        fi

        # Store (optional) description.
        if [[ -n $description ]]; then
            echo "$description" > "$backup_description"
        fi

        success "Backup saved to: $backup_destination"

    ) 200>"$lock_file"


#==============#
# list-backups #
#==============#
elif [[ $command == list-backups ]]; then

    # Read positional arguments.
    instance="${1-}"
    shift

    # Set-up derived variables.
    instance_directory="$manager_directory/$instance"
    instance_config="$instance_directory/instance.conf"
    game_config="$instance_directory/config.ini"
    instance_backup_directory="$instance_directory/.bak"

    # Verify positional arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    # Validate that instance directory contains valid instance.
    validate_path_or_terminate "instance_directory" "$instance_directory" "$ERROR_ARGUMENTS"

    # Read current game version.
    # shellcheck source=/dev/null
    source "$instance_config"
    current_game_version="$game_version"
    unset game_version

    # Set-up list of backup directories.
    shopt -s nullglob
    # Glob expression for matching YYYY-MM-DD-hh:mm:ss format.
    backup_directories=("$instance_backup_directory"/[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]_[0-9][0-9]:[0-9][0-9]:[0-9][0-9])
    shopt -s nullglob

    # Show available backups to the user.
    if (( ${#backup_directories[@]} == 0 )); then
        echo "No backups are available for instance $(colorecho -n green "$instance")."
    else
        echo "Available backups for instance $(colorecho -n green "$instance") (current version $(colorecho -n green "$current_game_version"))."
        echo

        for backup_directory in "${backup_directories[@]}"; do

            backup_date=$(basename "$backup_directory")

            # Read instance configuration for backup.
            # shellcheck source=/dev/null
            source "$backup_directory/instance.conf"

            if [[ -f "$backup_directory/.description" ]]; then
                backup_description=$(<"$backup_directory/.description")
                echo "  - $backup_date - version $(colorecho -n green "$game_version") ($backup_description)"
            else
                echo "  - $backup_date - version $(colorecho -n green "$game_version")"
            fi

        done

        echo

    fi


#=========#
# restore #
#=========#
elif [[ $command == restore ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    instance="${1-}"
    backup_name="${2-}"
    shift 2

    # Set-up derived values.
    instance_directory="$manager_directory/$instance"
    restore_source="$instance_directory/.bak/$backup_name"
    backup_instance_config="$restore_source/instance.conf"
    lock_file="$instance_directory/.lock"

    # Verify positional arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    if [[ -z $backup_name ]]; then
        error "Missing argument: BACKUP_NAME"
        exit "$ERROR_ARGUMENTS"
    fi

    # Validate that instance directory contains valid instance.
    validate_path_or_terminate "instance_directory" "$instance_directory" "$ERROR_ARGUMENTS"

    # Validate that backup directory contains valid backup.
    validate_path_or_terminate "backup_directory" "$restore_source" "$ERROR_ARGUMENTS"

    (
        # shellcheck disable=SC2094 # Lock file is not being read from.
        lock "$lock_file" 200

        # Set-up a list of files and directories that will get removed.
        shopt -s nullglob
        entries_to_remove=("$instance_directory"/*)
        shopt -u nullglob

        # Present user with extensive warning on consequences.
        echo
        warning "You are about to replace current instance's files, including (but not limited to):"
        warning
        warning "  - configuration files"
        warning "  - blueprints"
        warning "  - savegames"
        warning "  - achievements"
        warning "  - mods"
        warning
        warning "All instance files will be replaced by files from specified backup."

        # Display backup information.
        echo
        if [[ -f "$restore_source/.description" ]]; then
            backup_description=$(<"$restore_source/.description")
            backup_info="$backup_name ($backup_description)"
        else
            backup_info="$backup_name"
        fi
        echo "Restore instance $(colorecho -n green "$instance") from backup: $(colorecho -n green "$backup_info")"
        echo

        # Show user what files will be removed.
        if [[ ${#entries_to_remove[@]} == 0 ]]; then
            echo "Instance directory is currently empty. No files will be removed."
            echo
        else
            echo "Files and directories that will be removed:"
            echo
            for entry in "${entries_to_remove[@]}"; do
                echo "  - $entry"
            done
            echo
        fi

        # Request from user to confirm the operation.
        critical_confirmation "Are you sure you want to proceed?" \
                              "Aborted restore process, no changes have been made to instance files." \
                              "$ERROR_GENERAL"

        if [[ ${#entries_to_remove[@]} != 0 ]]; then
            if ! rm -rf "${entries_to_remove[@]}"; then
                error "Failed to remove existing instance files."
                exit "$ERROR_GENERAL"
            fi
        fi

        if ! cp -a "$restore_source"/* "$instance_directory"; then
            error "Failed to restore backup from: $restore_source"
            exit "$ERROR_GENERAL"
        fi

        success "Instance restored from backup."

    ) 200>"$lock_file"


#===============#
# remove-backup #
#===============#
elif [[ $command == remove-backup ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    instance="${1-}"
    backup_name="${2-}"
    shift 2

    # Verify positional arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    if [[ -z $backup_name ]]; then
        error "Missing argument: BACKUP_NAME"
        exit "$ERROR_ARGUMENTS"
    fi

    # Set-up derived values.
    instance_directory="$manager_directory/$instance"
    removal_target="$instance_directory/.bak/$backup_name"
    backup_instance_config="$removal_target/instance.conf"
    lock_file="$instance_directory/.lock"

    # Validate that instance directory contains valid instance.
    validate_path_or_terminate "instance_directory" "$instance_directory" "$ERROR_ARGUMENTS"

    # Validate that backup directory contains valid backup.
    validate_path_or_terminate "backup_directory" "$removal_target" "$ERROR_ARGUMENTS"

    # Read backup instance configuration.
    # shellcheck source=/dev/null
    source "$backup_instance_config"

    # Present user with warning.
    echo
    if [[ -f "$removal_target/.description" ]]; then
        backup_description=$(<"$removal_target/.description")
        backup_info="$(colorecho green "$backup_name"), version $(colorecho green "$game_version") ($backup_description)"
    else
        backup_info="$(colorecho green "$backup_name"), version $(colorecho green "$game_version")"
    fi

    warning "You are about to remove an instance backup. All files belonging to specified backup will be removed."
    echo
    echo "Instance: $(colorecho -n green "$instance")"
    echo
    echo "Backup: $(colorecho -n green "$backup_info")"
    echo
    echo "Files and directories that will be removed:"
    echo
    echo " - $removal_target"
    echo

    # Request from user to confirm the operation.
    critical_confirmation "Are you sure you want to proceed?" \
                          "Aborted backup removal, no changes have been made to backup files." \
                          "$ERROR_GENERAL"

    if ! rm -rf "$removal_target"; then
        error "Failed to remove existing instance files."
        exit "$ERROR_GENERAL"
    fi

    success "Backup removed."


#=============#
# set-version #
#=============#
elif [[ $command == set-version ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    instance="${1-}"
    shift

    # Verify positional arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    # Set-up derived variables.
    instance_directory="$manager_directory/$instance"
    instance_config="$instance_directory/instance.conf"
    game_config="$instance_directory/config.ini"

    # Validate that instance directory contains valid instance.
    validate_path_or_terminate "instance_directory" "$instance_directory" "$ERROR_ARGUMENTS"

    # Load instance configuration.
    # shellcheck source=/dev/null
    source "$instance_config"

    # Display list of available Factorio versions.
    echo "Current version used for instance $(colorecho -n green "$instance") is $(colorecho -n green "$game_version")."
    echo
    select_factorio_version "$game_installations_directory" "$game_version" "current" || exit "$ERROR_GENERAL"
    echo

    # Change instance game version.
    if [[ $game_version_selected == "$game_version" ]]; then
        info "Current version has been kept."
    else
        sed -i -e "s/^game_version=.*/game_version=$game_version_selected/" "$instance_config"
        success "Version changed to: $(colorecho -n green "$game_version_selected")"
    fi


#======#
# info #
#======#
elif [[ $command == info ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    instance="${1-}"
    shift

    # Verify positional arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    # Set-up derived variables.
    instance_directory="$manager_directory/$instance"
    instance_config="$instance_directory/instance.conf"
    game_config="$instance_directory/config.ini"

    # Validate that instance directory contains valid instance.
    validate_path_or_terminate "instance_directory" "$instance_directory" "$ERROR_ARGUMENTS"

    # Load instance configuration.
    # shellcheck source=/dev/null
    source "$instance_config"

    # Basic information.
    echo "Instance name: $(colorecho -n green "$instance")"

    if [[ -e "$game_installations_directory/$game_version" ]]; then
        echo "Game version: $(colorecho -n green "$game_version")"
    else
        echo "Game version: $(colorecho -n red "$game_version [not available locally]")"
    fi

    echo "Instance path: $(colorecho -n green "$instance_directory")"
    echo

    # Mod information.
    shopt -s nullglob
    mod_files=("$instance_directory/mods"/*.zip)
    mod_list="$instance_directory/mods/mod-list.json"
    shopt -u nullglob

    if [[ ${#mod_files[@]} == 0 ]]; then
        echo "Available mods: none"

    # Listing using just regular tools.
    elif ! hash jq 2>/dev/null; then
        echo "Available mods:"
        echo

        # Determine if mod is enabled by default or not when added to
        # mods directory (and is not yet listed in the mod list file).
        if grep -i -q "^[[:blank:]]*enable-new-mods=false" "$game_config"; then
            enable_new_mods="false"
        else
            enable_new_mods="true"
        fi

        # Process every mod found.
        for mod_file in "${mod_files[@]}"; do

            if [[ -f $mod_file ]]; then
                # Extract basic information about mod from the filename.
                mod_basename=$(basename "$mod_file" .zip)
                mod_name="${mod_basename%_*}"
                mod_version="${mod_basename##*_}"

                # Determine if mod is enabled or not.

                if grep -A1 "\"name\": \"$mod_name\"" "$mod_list" | tail -n1 | grep -q '"enabled": false'; then
                    color="$_text_yellow"
                elif grep -A1 "\"name\": \"$mod_name\"" "$mod_list" | tail -n1 | grep -q '"enabled": true'; then
                    color=""
                elif [[ $enable_new_mods == "false" ]]; then
                    color="$_text_yellow"
                else
                    color=""
                fi

                # Show colored-information for the mod.
                printf "$color  - %-48s %8s $_text_reset\n" "$mod_name" "$mod_version"
                if (( verbose == 1 )); then
                    mod_info=$(unzip -Z1 "$mod_file" | grep "info\.json" | head -n1)
                    mod_description=$(unzip -p "$mod_file" "$mod_info" | grep '"description":' | sed -e 's/\r//g;s/[^"]*"description": //;s/^"//;s/"$//')
                    mod_description=$(echo -e "$mod_description" | fold -s -w 50 | sed -e 's/^/    /')
                    mod_url="https://mods.factorio.com/mod/${mod_info}"
                    echo
                    echo "    ($mod_url)"
                    echo
                    echo "$mod_description"
                    echo
                fi
            fi

        done

    # Listing using the jq utility.
    elif hash jq 2>/dev/null; then
        echo "Available mods (enabled/${_text_yellow}disabled${_text_reset}):"
        echo

        # Determine if mod is enabled by default or not when added to
        # mods directory (and is not yet listed in the mod list file).
        if grep -i -q "^[[:blank:]]*enable-new-mods=false" "$game_config"; then
            enable_new_mods="false"
        else
            enable_new_mods="true"
        fi

        # Query string used in jq tool to determine if mod is enabled
        # or not. Take note that this string should remain
        # single-quoted, and that $ expansions are actually done
        # internally in jq itself. Query accepts two vars - mod_name
        # and enable_new_mods.
        # shellcheck disable=SC2016 # The $enable_new_mods is meant to be interpreted by jq, not bash.
        jq_is_enabled_query='.mods | map(select(.name==$mod_name))[0] // {"name": "default", "enabled": $enable_new_mods} | .enabled'

        # Process every mod found.
        for mod_file in "${mod_files[@]}"; do

            if [[ -f $mod_file ]]; then

                # Extract basic information about mod from the filename.
                mod_basename=$(basename "$mod_file" .zip)
                mod_name="${mod_basename%_*}"
                mod_version="${mod_basename##*_}"

                # Determine if mod is enabled or not.
                if jq -e \
                      --arg "mod_name" "$mod_name" \
                      --argjson "enable_new_mods" "$enable_new_mods" \
                      "$jq_is_enabled_query" "$mod_list" > /dev/null; then
                    color=""
                else
                    color="$_text_yellow"
                fi

                # Show colored-information for the mod.
                printf "$color  - %-48s %8s $_text_reset\n" "$mod_name" "$mod_version"
                if (( verbose == 1 )); then
                    mod_info=$(unzip -Z1 "$mod_file" | grep "info\.json" | head -n1)
                    mod_description=$(unzip -p "$mod_file" "$mod_info" | jq -r -e '.description' | fold -s -w 50 | sed -e 's/^/    /')
                    mod_url="https://mods.factorio.com/mod/${mod_info}"
                    echo
                    echo "    ($mod_url)"
                    echo
                    echo "$mod_description"
                    echo
                fi
            fi
        done
    fi
    echo

    # Call self for displaying list of backups. Better than duplicating code.
    "$program" list-backups "$instance" | sed -e "s/^Available backups for instance.*/Available backups:/"


#========#
# remove #
#========#
elif [[ $command == remove ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    instance="${1-}"
    shift

    # Verify positional arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    # Set-up derived values.
    instance_directory="$manager_directory/$instance"
    instance_config="$instance_directory/instance.conf"
    lock_file="$instance_directory/.lock"

    # Validate that instance directory contains valid instance.
    validate_path_or_terminate "instance_directory" "$instance_directory" "$ERROR_ARGUMENTS"

    (
        # shellcheck disable=SC2094 # Lock file is not being read from.
        lock "$lock_file" 200

        # Set-up a list of files and directories that will get removed.
        shopt -s nullglob dotglob
        entries_to_remove=("$instance_directory"/*)
        shopt -u nullglob dotglob

        # Present user with extensive warning on consequences.
        echo
        warning "You are about to remove all instance's files, including (but not limited to):"
        warning
        warning "  - configuration files"
        warning "  - blueprints"
        warning "  - savegames"
        warning "  - achievements"
        warning "  - mods"
        warning "  - backups"
        warning
        warning "All instance files will be removed."
        echo

        # Show user what files will be removed.
        if [[ ${#entries_to_remove[@]} == 0 ]]; then
            echo "Instance directory is currently empty. No files will be removed."
            echo
        else
            echo "Files and directories that will be removed:"
            echo
            echo "  - $instance_directory"
            for entry in "${entries_to_remove[@]}"; do
                echo "  - $entry"
            done
            echo
        fi

        # Display instance information.
        # shellcheck source=/dev/null
        source "$instance_config"
        echo "Instance name:    $(colorecho -n green "$instance")"
        echo "Instance version: $(colorecho -n green "$game_version")"
        echo

        # Request from user to confirm the operation.
        critical_confirmation "Are you sure you want to proceed?" \
                              "Aborted instance removal, no changes have been made to instance files." \
                              "$ERROR_GENERAL"

        if [[ ${#entries_to_remove[@]} != 0 ]]; then
            if ! rm -rf "${entries_to_remove[@]}"; then
                error "Failed to remove instance files."
                exit "$ERROR_GENERAL"
            fi
        fi

        if ! rmdir "$instance_directory"; then
            error "Failed to remove instance files."
            exit "$ERROR_GENERAL"
        fi

        success "Instance removed."

    ) 200>"$lock_file"


#======#
# copy #
#======#
elif [[ $command == copy ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    source_instance="${1-}"
    destination_instance="${2-}"
    shift 2

    # Verify positional arguments.
    if [[ -z $source_instance ]]; then
        error "Missing argument: SOURCE_INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    if [[ -z $destination_instance ]]; then
        error "Missing argument: DESTINATION_INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    # Calculate derived variables.
    source_instance_directory="$manager_directory/$source_instance"
    source_instance_config="$source_instance_directory/instance.conf"
    source_lock_file="$source_instance_directory/.lock"

    destination_instance_directory="$manager_directory/$destination_instance"
    destination_instance_config="$destination_instance_directory/instance.conf"

    # Validate that source instance directory contains valid instance.
    validate_path_or_terminate "instance_directory" "$source_instance_directory" "$ERROR_ARGUMENTS"

    # Make sure destination instance directory can be used.
    validate_path_or_terminate "instance_directory_new" "$destination_instance_directory" "$ERROR_ARGUMENTS"

    (
        # shellcheck disable=SC2094 # Lock file is not being read from.
        lock "$source_lock_file" 200

        # Load source instance configuration.
        # shellcheck source=/dev/null
        source "$source_instance_config"

        # Display list of available Factorio versions.
        echo
        echo "If you wish to, you can now change version of Factorio used for destination instance, or keep the same version as for source instance."
        echo

        select_factorio_version "$game_installations_directory" "$game_version" "current" || exit "$ERROR_GENERAL"
        echo

        # Check if user wants to copy backup files as well.
        copy_backups=""

        until [[ $copy_backups == "y" || $copy_backups == "n" ]]; do
            echo
            read -rn1 -p "Would you like to copy backup files as well? (y/n)" copy_backups
            echo
            copy_backups="${copy_backups,,}"

            if [[ $copy_backups != "y" && $copy_backups != "n" ]]; then
                echo
                error "Please answer only with 'y' or 'n'."
            fi
        done

        # Set-up a list of files and directories to copy.
        entries_to_copy=("$source_instance_directory"/*)

        if [[ $copy_backups == "y" && -e "$source_instance_directory/.bak" ]]; then
             entries_to_copy+=("$source_instance_directory/.bak")
        fi

        # Create copy of source instance.
        mkdir "$destination_instance_directory"
        cp -a "${entries_to_copy[@]}" "$destination_instance_directory/"

        # Update write-data directory of destination instance,
        # including the backups.
        write_data="write-data=${destination_instance_directory}"
        find "$destination_instance_directory/" -type f -name config.ini -exec \
             sed -i -e "s#^write-data=.*#$write_data#" '{}' \;

        sed -i -e "s/^game_version=.*/game_version=$game_version_selected/" "$destination_instance_config"

        success "Created new instance $(colorecho -n green "$destination_instance") using version $(colorecho -n green "$game_version_selected") as copy of instance $(colorecho -n green "$source_instance")."

    ) 200>"$source_lock_file"


#========#
# import #
#========#
elif [[ $command == import ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    instance="${1-}"
    source_directory="${2-}"
    shift 2

    # Verify positional arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    if [[ -z $source_directory ]]; then
        error "Missing argument: SOURCE_DIRECTORY"
        exit "$ERROR_ARGUMENTS"
    fi

    # Calculate derived variables.
    instance_directory="$manager_directory/$instance"
    instance_config="$instance_directory/instance.conf"
    game_config="$instance_directory/config.ini"

    source_lock_file="$source_directory/.lock"

    # Make sure new instance directory can be used.
    validate_path_or_terminate "instance_directory_new" "$instance_directory" "$ERROR_ARGUMENTS"

    # Make sure that the import source is valid (should be Factorio
    # installation directory).
    validate_path_or_terminate "instance_import_source" "$source_directory" "$ERROR_ARGUMENTS"

    # List of entries to import from the source directory. Keep
    # separate array of keys for sorting purposes.
    declare -A import_entries=()
    declare -a import_entries_keys
    key="achievements-modded.dat"
    import_entries[$key]="contains achivement information for modded plays"
    import_entries_keys+=("$key")

    key="achievements.dat"
    import_entries[$key]="contains achievement information for vanilla plays"
    import_entries_keys+=("$key")

    key="archive"
    import_entries[$key]="contains desync reports"
    import_entries_keys+=("$key")

    key="blueprint-storage.dat"
    import_entries[$key]="contains global (non-savegame specific) blueprints"
    import_entries_keys+=("$key")

    key="config/config.ini"
    import_entries[$key]="contains game configuration, including things like shortcuts etc."
    import_entries_keys+=("$key")

    key="crop-cache.dat"
    import_entries[$key]="purpose is not known"
    import_entries_keys+=("$key")

    key="factorio-current.log"
    import_entries[$key]="contains logs from the currently running game"
    import_entries_keys+=("$key")

    key="factorio-previous.log"
    import_entries[$key]="contains logs from the previously running game"
    import_entries_keys+=("$key")

    key="mods"
    import_entries[$key]="contains mods and mod settings"
    import_entries_keys+=("$key")

    key="player-data.json"
    import_entries[$key]="contains global information about the player, such as username, login token, chat history, etc."
    import_entries_keys+=("$key")

    key="saves"
    import_entries[$key]="contains savegames"
    import_entries_keys+=("$key")

    # Display list of available Factorio versions and let user pick one.
    echo "Factorio version must  be selected manually for imported instances."
    echo
    select_factorio_version "$game_installations_directory" || exit "$ERROR_GENERAL"

    (
        # shellcheck disable=SC2094 # Lock file is not being read from.
        lock "$source_lock_file" 200

        # Create instance directory.
        mkdir "$instance_directory"

        # Copy files and directories.
        echo
        declare -a missing_import_entries=()
        for source_entry in "${import_entries_keys[@]}"; do
            source_entry_path="$source_directory/$source_entry"
            if [[ -e $source_entry_path ]]; then
                info "Importing $(colorecho -n blue "$source_entry")..."

                if ! cp -a "$source_entry_path" "$instance_directory/"; then
                    error "Could not import $source_entry from $source_entry_path (see above for errors)."
                    exit "$ERROR_GENERAL"
                fi
            else
                missing_import_entries+=("$source_entry")
            fi

            # Copy the configuration file.
        done

        echo

        cat <<EOF > "$instance_config"
game_version="$game_version_selected"
EOF

        # Fix write-data in config.ini
        write_data="write-data=${instance_directory}"
        sed -i -e "s#^write-data=.*#$write_data#" "$game_config"

        if [[ ${#missing_import_entries[@]} != 0 ]]; then
            warning "A number of files or directories were missing from the specified source."
            warning "For some of the entries this is perfectly normal, but you should verify that no critical files have been missed by mistake before switching to using this instance."
            echo
            for missing_import_entry in "${missing_import_entries[@]}"; do
                echo "$(colorecho blue "$missing_import_entry"), ${import_entries[$missing_import_entry]}"
                echo
            done
            warning "Press any key to continue."
            read -rn1
        fi

        success "Finished import of instance $(colorecho -n green "$instance")."

    ) 200>"$source_lock_file"


#===============#
# create-server #
#===============#
elif [[ $command == create-server ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    instance="${1-}"
    shift

    # Calculate derived variables.
    instance_directory="$manager_directory/$instance"
    instance_config="$instance_directory/instance.conf"
    game_config="$instance_directory/config.ini"
    server_config="$instance_directory/server-settings.json"
    saves_directory="$instance_directory/saves"
    main_save="$saves_directory/default.zip"

    # Verify arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    # Make sure new instance directory can be used.
    validate_path_or_terminate "instance_directory_new" "$instance_directory" "$ERROR_ARGUMENTS"

    select_factorio_version "$game_installations_directory" || exit "$ERROR_GENERAL"

    # Grab server settings from user.
    echo "You will now be prompted to provide settings for the server, with some pre-filled settings."
    echo "Do not change settings marked with [EXPERT] unless you know what you are doing."
    echo
    read_server_settings "$instance"

    # Set-up the instance.
    mkdir "$instance_directory"
    mkdir "$instance_directory/mods"
    echo "{}" > "$instance_directory/mods/mod-list.json"

    cat <<EOF > "$instance_config"
game_version="$game_version_selected"
EOF
    cat <<EOF > "$game_config"
[path]
read-data=__PATH__executable__/../../data
write-data=${instance_directory}

[general]
locale=

[other]
check-updates=false
enable-crash-log-uploading=false
port=${settings_value[port]}


[interface]

[controls]

[sound]

[map-view]

[debug]

[multiplayer-lobby]

[graphics]
EOF

    echo
    cat <<EOF >> "$server_config"
{
  "name": ${settings_value[name]},
  "description": ${settings_value[description]},
  "tags": ${settings_value[tags]},
  "max_players": ${settings_value[max_players]},
  "visibility":
  {
    "public": ${settings_value[public]},
    "lan": ${settings_value[lan]}
  },

  "_comment_credentials": "Your factorio.com login credentials. Required for games with visibility public",
  "username": ${settings_value[username]},
  "password": ${settings_value[password]},

  "_comment_token": "Authentication token. May be used instead of 'password' above.",
  "token": ${settings_value[token]},

  "game_password": ${settings_value[game_password]},

  "_comment_require_user_verification": "When set to true, the server will only allow clients that have a valid Factorio.com account",
  "require_user_verification": ${settings_value[require_user_verification]},

  "_comment_max_upload_in_kilobytes_per_second" : "optional, default value is 0. 0 means unlimited.",
  "max_upload_in_kilobytes_per_second": ${settings_value[max_upload_in_kilobytes_per_second]},

  "_comment_max_upload_slots" : "optional, default value is 5. 0 means unlimited.",
  "max_upload_slots": ${settings_value[max_upload_slots]},

  "_comment_minimum_latency_in_ticks": "optional one tick is 16ms in default speed, default value is 0. 0 means no minimum.",
  "minimum_latency_in_ticks": ${settings_value[minimum_latency_in_ticks]},

  "_comment_ignore_player_limit_for_returning_players": "Players that played on this map already can join even when the max player limit was reached.",
  "ignore_player_limit_for_returning_players": ${settings_value[ignore_player_limit_for_returning_players]},

  "_comment_allow_commands": "possible values are, true, false and admins-only",
  "allow_commands": ${settings_value[allow_commands]},

  "_comment_autosave_interval": "Autosave interval in minutes",
  "autosave_interval": ${settings_value[autosave_interval]},

  "_comment_autosave_slots": "server autosave slots, it is cycled through when the server autosaves.",
  "autosave_slots": ${settings_value[autosave_slots]},

  "_comment_afk_autokick_interval": "How many minutes until someone is kicked when doing nothing, 0 for never.",
  "afk_autokick_interval": ${settings_value[afk_autokick_interval]},

  "_comment_auto_pause": "Whether should the server be paused when no players are present.",
  "auto_pause": ${settings_value[auto_pause]},

  "only_admins_can_pause_the_game": ${settings_value[only_admins_can_pause_the_game]},

  "_comment_autosave_only_on_server": "Whether autosaves should be saved only on server or also on all connected clients. Default is true.",
  "autosave_only_on_server": ${settings_value[autosave_only_on_server]},

  "_comment_non_blocking_saving": "Highly experimental feature, enable only at your own risk of losing your saves. On UNIX systems, server will fork itself to create an autosave. Autosaving on connected Windows clients will be disabled regardless of autosave_only_on_server option.",
  "non_blocking_saving": ${settings_value[non_blocking_saving]},

  "_comment_segment_sizes": "Long network messages are split into segments that are sent over multiple ticks. Their size depends on the number of peers currently connected. Increasing the segment size will increase upload bandwidth requirement for the server and download bandwidth requirement for clients. This setting only affects server outbound messages. Changing these settings can have a negative impact on connection stability for some clients.",
  "minimum_segment_size": ${settings_value[minimum_segment_size]},
  "minimum_segment_size_peer_count": ${settings_value[minimum_segment_size_peer_count]},
  "maximum_segment_size": ${settings_value[maximum_segment_size]},
  "maximum_segment_size_peer_count": ${settings_value[maximum_segment_size_peer_count]}
}
EOF

    # Generate main save/map.
    info "Generating default savegame/map."
    game_directory="${game_installations_directory}/${game_version_selected}"
    factorio_bin="$game_directory/bin/x64/factorio"

    if ! "$factorio_bin" --config "$game_config" --create "$main_save"; then
        error "Failed to generate default savegame/map under: $main_save"
        exit "$ERROR_GENERAL"
    fi

    success "Created new server instance $(colorecho -n green "$instance")"


#=========#
# install #
#=========#
elif [[ $command == install ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    game_archive="${1-}"
    shift

    # Calculate derived variables.
    staging_directory="$game_installations_directory/.staging"
    game_staging_directory="$staging_directory/factorio"
    staging_factorio_bin="$game_staging_directory/bin/x64/factorio"

    # Verify arguments.
    if [[ -z $game_archive ]]; then
        error "Missing argument: GAME_ARCHIVE"
        exit "$ERROR_ARGUMENTS"
    fi

    validate_path_or_terminate "game_archive" "$game_archive" "$ERROR_ARGUMENTS"

    # Prepare staging directory.
    rm -rf "$staging_directory"
    mkdir "$staging_directory"

    # Extract the game version and verify it.
    tar --occurrence=1 --extract --file "$game_archive" --directory "$staging_directory" "factorio/bin/x64/factorio"

    game_version=$("$staging_factorio_bin" --version | grep '^Version' | sed -e 's/^Version: //;s/ .*//')

    if ! [[ $game_version =~ ^[[:digit:]]+\.[[:digit:]]+\.[[:digit:]]+$ ]]; then
        error "Could not parse version from output of command: $staging_factorio_bin --version"
        exit "$ERROR_GENERAL"
    fi

    # Check if version has already been installed.
    game_destination_directory="$game_installations_directory/$game_version"
    if [[ -e "$game_destination_directory" ]]; then
        error "Factorio $game_version already available under: $game_destination_directory"
        exit "$ERROR_GENERAL"
    fi

    # Unpack the full installation.
    info "Extracting the game installation, this might take a while."
    if ! tar --extract --file "$game_archive" --directory "$staging_directory"; then
        error "Could not extract game archive ($game_archive) to its staging directory ($staging_directory)."
        exit "$ERROR_GENERAL"
    fi

    # Move the game installation, and make it read-only.
    if ! mv "$game_staging_directory" "$game_destination_directory"; then
        error "Could not move the game from its staging directory ($game_staging_directory) to its destination directory ($game_destination_directory)."
        exit "$ERROR_GENERAL"
    fi
    if ! chmod -R u-w,g-w,o-w "$game_destination_directory"; then
        error "Could not write-protect the game directory ($game_destination_directory). Manual intervention might be required."
        exit "$ERROR_GENERAL"
    fi

    success "Successfully installed game version: $(colorecho -n green "$game_version")"


#==================#
# reset-server-map #
#==================#
elif [[ $command == reset-server-map ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    instance="${1-}"
    shift

    # Calculate derived variables.
    instance_directory="$manager_directory/$instance"
    instance_config="$instance_directory/instance.conf"
    game_config="$instance_directory/config.ini"
    server_config="$instance_directory/server-settings.json"
    main_save="$instance_directory/saves/default.zip"

    # Verify arguments.
    if [[ -z $instance ]]; then
        error "Missing argument: INSTANCE"
        exit "$ERROR_ARGUMENTS"
    fi

    # Validate that instance directory contains valid instance.
    validate_path_or_terminate "server_instance_directory" "$instance_directory" "$ERROR_ARGUMENTS"

    # Update instance write directory prior to launching - this is a
    # failsafe in case it got changed by hand or perhaps the value
    # comes from backups of a copied instance.
    current_write_data=$(grep "^write-data=" "$game_config")
    expected_write_data="write-data=${instance_directory}"

    if [[ $current_write_data != "$expected_write_data" ]]; then
        warning "Incorrect path specified for write-data in game configuration file: $game_config"
        warning "Current configuration is: $current_write_data"
        warning "Configuration will be replaced with: $expected_write_data"
        sed -i -e "s#^write-data=.*#$expected_write_data#" "$game_config"
    fi

    # Read launcher configuration for the instance.
    # shellcheck source=/dev/null
    source "$instance_config"

    if [[ -z $game_version ]]; then
        error "Missing game version information in $game_config."
        exit "$ERROR_CONFIGURATION"
    fi

    # Set-up paths for launching the game, and ensure they still exist
    # (versions can be removed by user).
    game_directory="${game_installations_directory}/${game_version}"
    factorio_bin="$game_directory/bin/x64/factorio"

    if [[ ! -e $factorio_bin ]]; then
        error "Could not locate Factorio binary under: $factorio_bin"
        error "Factorio $game_version installation may have been removed from game installations directory:"
        error "   $(readlink -f "$game_installations_directory")"
        exit "$ERROR_CONFIGURATION"
    fi

    # Request from user to confirm the destructive action.
    critical_confirmation "Resetting the server map will wipe the default save game as well." \
                          "Aborted server map reset, no changes have been made to instance files." \
                          "$ERROR_GENERAL"

    if ! rm -f "$main_save"; then
        error "Could not remove the default save game."
        exit "$ERROR_GENERAL"
    fi

    if ! "$factorio_bin" --config "$game_config" --create "$main_save"; then
        error "Failed to generate default savegame/map under: $main_save"
        exit "$ERROR_GENERAL"
    fi


#========#
# rename #
#========#
elif [[ $command == rename ]]; then

    # Make sure game installations directory has been set.
    validate_path_or_terminate "game_installations_directory" "$game_installations_directory" "$ERROR_CONFIGURATION"

    # Read positional arguments.
    current_name="${1-}"
    new_name="${2-}"
    shift 2

    # Verify positional arguments.
    if [[ -z $current_name ]]; then
        error "Missing argument: CURRENT_NAME"
        exit "$ERROR_ARGUMENTS"
    fi

    if [[ -z $new_name ]]; then
        error "Missing argument: NEW_NAME"
        exit "$ERROR_ARGUMENTS"
    fi

    if [[ $current_name == "$new_name" ]]; then
        error "New name must differ from current name."

        exit "$ERROR_ARGUMENTS"
    fi

    # Calculate derived variables.
    current_instance_directory="$manager_directory/$current_name"
    current_instance_config="$current_instance_directory/instance.conf"
    current_instance_lock_file="$current_instance_directory/.lock"
    new_instance_directory="$manager_directory/$new_name"

    # Validate that source instance directory contains valid instance.
    validate_path_or_terminate "instance_directory" "$current_instance_directory" "$ERROR_ARGUMENTS"

    # Make sure destination instance directory can be used.
    validate_path_or_terminate "instance_directory_new" "$new_instance_directory" "$ERROR_ARGUMENTS"

    (
        # shellcheck disable=SC2094 # Lock file is not being read from.
        lock "$current_instance_lock_file" 200

        # Load source instance configuration.
        # shellcheck source=/dev/null
        source "$current_instance_config"

        # Rename the instance.
        mv "$current_instance_directory" "$new_instance_directory"

        # Update write-data directory of destination instance,
        # including the backups.
        write_data="write-data=${new_instance_directory}"
        find "$new_instance_directory/" -type f -name config.ini -exec \
             sed -i -e "s#^write-data=.*#$write_data#" '{}' \;

        success "Renamed instance $(colorecho -n green "$current_name") to $(colorecho -n green "$new_name")."

    ) 200>"$current_instance_lock_file"
else
    error "Invalid command: $command"

    exit "$ERROR_ARGUMENTS"
fi