#!/bin/sh

# extract config.sh.* files from binary packages
#
# Copyright 2016 Niko Tyni <ntyni@debian.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the same terms as Perl itself.

set -e

if [ $# = 0 ]; then
    echo "Usage: $0 <file.deb> [...]" 1>&2
    exit 1
fi

# sanity check
if [ ! -d debian/cross ]; then
    echo "This program is supposed to run in the perl Debian package source directory" 1>&2
    exit 1
fi

for deb in "$@"; do
    arch=$(dpkg-deb -W --showformat '${Architecture}' "$deb")
    if [ ! -n "$arch" ]; then
        echo "Could not get Debian architecture of $deb" 1>&2
        exit 1
    fi
    if [ ! -d "debian/cross/$arch" ]; then
        echo "Unknown architecture: $arch (mkdir debian/cross/$arch first?), skipping" 1>&2
        continue
    fi

    archlist="$archlist $arch"

    version=$(dpkg-deb -W --showformat '${Version}' "$deb")
    if [ ! -n "$version" ]; then
        echo "Could not get Debian version from $deb" 1>&2
        exit 1
    fi

    # shameless reliance on GNU tar fancy functionality
    #   note that we expand ${arch} in this shell and not the subshell
    #   so we don't have to export it
    if ! dpkg-deb --fsys-tarfile "$deb" | tar xf - --wildcards \
        '*/config.sh.static.gz' \
        '*/config.sh.debug.gz'  \
        '*/config.sh.shared.gz' \
        --to-command='sh -c "gzip -dc > debian/cross/'${arch}'/$(basename $TAR_FILENAME .gz)"'
    then
        echo "no config.sh.* files in $deb, skipping" 1>&2
        continue
    fi

    echo "# Extracted from Debian package version $version" >> debian/cross/$arch/config.sh.static

    # store debug and shared configs as contextless patches
    # the idea is to make it as easy (heh) as possible for bootstrappers
    # so they only have to craft the static one by hand
    for type in shared debug; do
        ( cd debian/cross/$arch && \
          ! diff -u0 config.sh.static config.sh.$type > config.sh.$type.patch && \
          rm config.sh.$type )
    done

    if [ -d .git ]; then
        git add debian/cross/$arch
    fi
done

if [ -d .git ]; then
    debs=$(sha1sum "$@")
    git commit -m "Refresh cross build support files for$archlist" \
               -m "Files extracted by $0 from:" \
               -m "$debs"
fi