#!/bin/sh -e

if [ $# -lt 2 ] || [ $# -gt 3 ]; then
    cat >&2 <<EOD
usage: $0 CONFIG_FILE FROM_REV [TO_REV]

Runs a database migration from FROM_REV to TO_REV (default: current
working directory parent), using the specified CONFIG_FILE (.ini file).

Test is run using a clean Kallithea install, in a temporary virtual
environment. FROM_REV and (optional) TO_REV should be Mercurial revision
identifiers (e.g. changeset hash or a version number tag). The working
directory is not touched, but the database referenced in the config file
will be (re)created.

Only SQLite is available out of the box; for MySQL or PostgreSQL, set
the EXTRA environment variable to the required package(s), and it'll
be installed in the virtual environment. (E.g. EXTRA=MySQL-python or
EXTRA=psycopg2.)

The temporary directory is not removed, allowing follow-up examination
of the upgrade results. It is, however, created in /tmp by default,
which many Linux distributions automatically clean at regular intervals.
EOD
    exit 1
fi

config_file=$(readlink -f "$1")
from_rev=$2
to_rev=$3
source_repo=$(dirname "$(dirname "$(readlink -f "$0")")")

announce() {
    echo
    echo "$1"
    echo
}

quiet_if_ok() (
    local output
    local st
    set +e
    output=$("$@" < /dev/null 2>&1)
    st=$?
    if [ $st -ne 0 ]; then
        echo "$output" >&2
        echo "Command $@ returned exit status $st." >&2
        exit 1
    fi
)

HG() {
    "${HG:-hg}" --repository "$source_repo" "$@"
}

# If upgrading to "current revision", warn if working directory is dirty.
if [ ! "$to_rev" ] && [ "$(HG status -mard)" ]; then
    announce "Warning: Uncommitted changes in working directory will be ignored!"
fi

from_rev_hash=$(HG id --id --rev "${from_rev:-.}")
to_rev_hash=$(HG id --id --rev "${to_rev:-.}")
temp=$(readlink -f "$(mktemp --tmpdir -d 'dbmigrate-test.XXXXXX')")

cat <<EOD
Config file:    $config_file
EOD
sed -n -e 's/^sqlalchemy\.url *= */Database URL:   /p' "$config_file"
cat <<EOD
Working dir:    $temp
Repository:     $source_repo
Upgrade from:   $from_rev_hash (${from_rev:-current})
Upgrade to:     $to_rev_hash (${to_rev:-current})
Extra packages: ${EXTRA:-(none)}
EOD

mkdir "$temp/repos" # empty

# Enable caching for old pip versions (this will cache the pip upgrade)
# Newer pip versions cache automatically, and don't use this variable.
if [ ! "$PIP_DOWNLOAD_CACHE" ]; then
    export PIP_DOWNLOAD_CACHE=$HOME/.cache/pip/legacy
fi

install_kallithea() {
    local prefix=$1
    local rev=$2

    announce "Installing Kallithea $rev in $prefix..."

    "${VIRTUALENV:-virtualenv}" --quiet "$prefix-env"
    HG archive --rev "$rev" "$prefix"

    (
        cd "$prefix"
        . "$prefix-env/bin/activate"
        pip install --quiet --upgrade pip setuptools mercurial $EXTRA
        pip install --quiet -e .
    )
}

install_kallithea "$temp/from" "$from_rev_hash"
(
    cd "$temp/from"
    . "$temp/from-env/bin/activate"
    announce "Initializing database..."
    quiet_if_ok paster setup-db "$config_file" --repos="$temp/repos" --user=doe --email=doe@example.com --password=123456 --no-public-access --force-yes
    alembic -c "$config_file" current -v
)

install_kallithea "$temp/to" "$to_rev_hash"
(
    cd "$temp/to"
    . "$temp/to-env/bin/activate"

    announce "Commencing database upgrade from shown Alembic revision to head..."
    alembic -c "$config_file" current -v
    alembic -c "$config_file" upgrade head
    announce "Upgrade complete, now at the shown Alembic revision:"
    alembic -c "$config_file" current -v
)