#!/bin/sh
#
# deb-download-from-pool.sh - download specific packages from the pool
#
# Copyright (C) 2018  Antonio Ospite <ao2@ao2.it>
#
# 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/>.

set -e

MIRROR="${MIRROR:-https://deb.debian.org/debian}"
DEBUG_MIRROR="${DEBUG_MIRROR:-http://debug.mirrors.debian.org/debian-debug}"

usage() {
  PROG_NAME=$(basename "$0")
  cat <<EOF
usage: $PROG_NAME [--all|-h|--help] <package> [<version>]

Helper script to download specific packages from the pool directory of
a Debian mirror.


Options:
  --all               download all related packages even if currently
                      uninstalled
  -h, --help          display this usage message and exit


Notes:

Some settings can be changed via environment variables:
  SOURCE_PACKAGE
  POOL_DIRECTORY
  MIRROR
  DEBUG_MIRROR
EOF
}

download() {
  dpkg --validate-pkgname -- "$1" || { usage 1>&2; exit 1; }

  PACKAGE="$1"

  if [ "x$SOURCE_PACKAGE" = "x" ];
  then
    SOURCE_PACKAGE=$(apt-cache show "$PACKAGE" | grep Source | head -1 | cut -d ' ' -f 2)
    if [ "x$SOURCE_PACKAGE" = "x" ];
    then
      SOURCE_PACKAGE="$PACKAGE"
    fi
  fi

  if [ "x$POOL_DIRECTORY" = "x" ];
  then
    POOL_DIRECTORY=$(apt-cache showsrc "$SOURCE_PACKAGE" | grep Directory | head -1 | cut -d ' ' -f 2)
  fi

  POOL_URL="${MIRROR}/${POOL_DIRECTORY}"

  if [ "x$2" = "x" ];
  then
    echo "Available versions, pass one of these as the second argument:"
    wget -q "$POOL_URL" -O - | grep "${SOURCE_PACKAGE}_.*\\.dsc" | sed -e 's/^.*<a .*>.*_\(.*\)\.dsc<\/a>.*$/\1/g'
    exit $?
  fi

  dpkg --validate-version -- "$2" || { usage 1>&2; exit 1; }

  VERSION="$2"

  ARCH=$(dpkg-architecture -qDEB_BUILD_ARCH)
  PACKAGES=$(wget -q "$POOL_URL" -O - | \
    grep -e "${VERSION}[^_]*_${ARCH}" \
    -e "${VERSION}[^_]*_all" | \
    sed -e 's/^.* href="\([^"]*\)".*$/\1/g')

  for p in $PACKAGES;
  do
    PNAME=$(echo "$p" | cut -d '_' -f 1);
    STATUS=$(grep-status -X \( -F Architecture "$ARCH" --or -F Architecture all \) --and -X -F Package "$PNAME" -n -s Status || true)
    if [ "$STATUS" = "install ok installed" ] || [ "$DOWNLOAD_ALL" = "true" ];
    then
      wget -nv "${POOL_URL}/${p}"
    fi
  done
}


[ $# -eq 0 ] && { usage 1>&2 && exit 1; }

while [ $# -gt 0 ];
do
  case "$1" in
    --)
      shift
      break
      ;;
    -h|--help)
      usage
      exit 0
      ;;
    --all)
      DOWNLOAD_ALL="true"
      shift
      ;;
    -*)
      echo "Error: Unknown option '${1}'" 1>&2
      shift
      ;;
    *)
      break
      ;;
  esac
done

download "$@"
MIRROR=$DEBUG_MIRROR download "$@"