#!/bin/sh
#
# unpack-debian-sources - unpack all Debian packages in a Debian
# repository
#
# Usage: unpack-debian-sources MIRROR SUITE [SECTION]...
#
# where MIRROR is the URL to a Debian mirror site, SUITE is the release,
# and SECTION is a section within the release. For example:
#
#   unpacke-debian-sources http://ftp.debian.org/debian etch main contrib
#
# If SECTION is missing, it defaults to "main contrib non-free"

set -e

die()
{
    echo "$@" 1>&2
    exit 1
}

fetch()
{
    wget -q -O - "$1"
}

parse_sources()
{
    awk '
        /^Directory:/ {
            if (dir && paths) print dir, paths
            dir = $2
            paths = ""
        }
        /^Files:/ { infiles = 1; next }
        infiles && /^ / { paths = paths " " $NF }
        infiles && (NF == 0 || /^[^ ]/) { infiles = 0 }
    '
}

showiferror()
{
    local temp="$(mktemp)"
    if ! "$@" > "$temp" 2>&1
    then
        cat "$temp"
        rm -f "$temp"
        exit 1
    fi
    rm -f "$temp"
}

unpack_dsc()
{
    (
    cd "$1"
    dsc="$(ls *.dsc)"
    showiferror dpkg-source -x *.dsc
    )
}

[ "$2" = "" ] && die "Usage: $0 MIRROR SUITE [SECTION]..."

mirror="$1"
suite="$2"
shift 2
sections="$@"

gpghome="$(mktemp -d)"
export GNUPGHOME="$gpghome"

for section in $sections
do
    sources="$mirror/dists/$suite/$section/source/Sources.bz2"
    sources_tmp="$(mktemp)"
    fetch "$sources" | bunzip2 > "$sources_tmp"

    num_packages=$(parse_sources < "$sources_tmp" | wc -l)

    n=0
    parse_sources < "$sources_tmp" |
    while read dir paths
    do
        n=$(expr $n + 1)
        if [ ! -d "$dir" ]
        then
            printf "$n/$num_packages: $dir\n"
            temp="$(mktemp -d)"
            for path in $paths
            do
                fetch "$mirror/$dir/$path" > "$temp/$path"
            done
            unpack_dsc "$temp"
            for path in $paths
            do
                rm "$temp/$path"
            done
            mkdir -p "$dir" # Create parent dirs
            rmdir "$dir" # Remove tail dir
            mv "$temp"/* "$dir" # Move the _single_ dir, which has the src
        fi
    done
done