#!/bin/bash
#
# pip_check_requirements_upgrades.sh
#
# Copyright (C) 2017, 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/>.
#

program="pip_check_requirements_upgrades.sh"

function usage() {
    cat <<EOF
$program, a non-interactive utility for checking for available upgrades in
Python pip requirements files based on pip-tools

Usage: $program [OPTIONS] configuration_directory

$program a non-interactive utility for checking for available upgrades in Python
pip requirements files based on pip-tools. Utility is written specifically with
pip-tools in mind, and pip-tools must be available when running the utility.

If you are unfamiliar with pip-tools, please read its documentation first, and
make sure you fully understand how it works.

Utility accepts a single positionl argument - path to configuration
directory. Configuration directory should contain one or more sub-directories
where each sub-directory is treated as describing a separate Python virtual
environment. This allows the checks to be run for multiple virtual environments
in a modular manner.

Each sub-directory should contain one or more .in files with corresponding .txt
file. Base names must match (i.e. if you have production.in, the requirements
file must be called production.txt).

Utility iterates over each .in/.txt pair, calculates new requirements
based on the .in file, and diffs this against existing .txt file. If a
.in file does not have a corresponding .txt file, it is ignored
(making it possible to use the '-r base.in' syntax for including base
requirements etc).

Utility creates copy of existing requirements file, stripping it from all
comments, then calculates new requirements file (storing result in temporary
location as well), and runs a diff between them.

If newer pacakges are available that would satisfiy the provided .in file, a
diff is shown on standard output in addition to a warning message.

$program accepts the following options:

    -V virtualenv
        Path to virtual environment with pre-installed pip-tools. If specified,
        the virtual environment will be activated prior to running the utility.

    -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

+-----------------------------------------------------------------------+
| Copyright (C) 2017, 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
}

# 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 ]] && (( ${_color_terminal} > 0 )); then
    _text_bold=$(tput bold)
    _text_white=$(tput setaf 7)
    _text_blue=$(tput setaf 6)
    _text_green=$(tput setaf 2)
    _text_yellow=$(tput setaf 3)
    _text_red=$(tput setaf 1)
    _text_reset=$(tput sgr0)
else
    _text_bold=""
    _text_white=""
    _text_blue=""
    _text_green=""
    _text_yellow=""
    _text_red=""
    _text_reset=""
fi

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

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

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

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

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

# Define error codes.
SUCCESS=0
ERROR_ARGUMENTS=1
ERROR_CONFIG_DIR=2
ERROR_PIP_TOOLS_MISSING=3

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

# Set-up defaults.
virtualenv=""

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

# Parse the arguments
while getopts "V:qdvh" opt; do
    case "$opt" in
        V) virtualenv="$OPTARG";;
        q) quiet=1;;
        d) debug=1;;
        v) version
           exit "$SUCCESS";;
        h) usage
           exit "$SUCCESS";;
        *) usage
           exit "$ERROR_ARGUMENTS";;
    esac
done
i=$OPTIND
shift $(($i-1))


if [[ ${#@} == 0 ]]; then
    error "Must pass configuration directory."
    usage
    exit "$ERROR_ARGUMENTS"
fi

# Verify positional arguments.
config_dir="$1"
if [[ ! -d $config_dir ]]; then
    error "No such directory: $config_dir"
    exit "$ERROR_ARGUMENTS"
fi

# Make sure virtual environment exists.
if [[ -n $virtualenv && ! -f $virtualenv/bin/activate ]]; then
    error "Invalid virtual environment specified: $virtualenv"
    exit "$ERROR_ARGUMENTS"
fi

# Activate the virtual environment if it was specified.
[[ -n $virtualenv ]] && source "$virtualenv/bin/activate"

# Verify pip-compile is available.
if ! which pip-compile >/dev/null 2>&1; then
    error "Could not find command pip-compile from packagep pip-tools. Package might not be available in the virtual environment."
    exit "$ERROR_PIP_TOOLS_MISSING"
fi

# Process each environment.
for environment in "$config_dir"/*; do
    # Empty directory.
    if [[ ! -e $environment ]]; then
        error "Configuration directory is empty: $config_dir"
        exit "$ERROR_CONFIG_DIR"
    fi

    # Process each .in file.
    for req_in in "$environment"/*.in; do
        # Directory without .in files.
        if [[ ! -e $req_in ]]; then
            error "No .in files in directory, skipping: $environment"
            continue
        fi

        # Figure out if .txt file exists.
        req_txt="${req_in%.in}.txt"
        if [[ ! -f $req_txt ]]; then
            [[ $quiet == 0 ]] && info "Skipping input file with missing .txt file: $req_in"
            continue
        fi

        # Clean up the existing requirements file to contain only
        # package versioning information.
        current=$(sed -e 's/[[:blank:]]*#.*//' "$req_txt" | grep -v "^$" | sort -u)

        # Calculate up-to-date requirements.
        new=$(pip-compile --quiet --allow-unsafe --no-header --no-annotate --no-index --output-file - --upgrade "$req_in")
        result="$?"
        if [[ $result != 0 ]]; then
             error "Failed while running pip-compile command against (see error stack trace above): $req_in"
            continue
        fi

        # Clean up the new requirements to contain only package
        # versioning information.
        new=$(echo "$new" | sed -e 's/[[:blank:]]*#.*//' | grep -v "^$" | sort -u)

        debug "Current requirements:\n$(echo "$current")"
        debug "New requirements:\n$(echo "$new")"

        # Run diff, storing the output and result.
        # This is using Bash process substitution, which helps avoid
        # creating and keeping track of temporary files (since diff
        # must be fed with two input files). E.g. the <() will
        # essentially be path to a Bash-created/managed temporary
        # file.
        diff=$(diff -u <(echo "$current") <(echo "$new"))
        result="$?"

        # Show warning about available updates.
        if [[ $result == 0 ]]; then
            [[ $quiet == 0 ]] && info "No upgrades available for: $req_txt"
        else
            warning "Upgrades available for: $req_txt"
            echo
            echo "$diff"
            echo
        fi
    done
done