#!/usr/bin/env bash
#
# Copyright (c) 2014, Ray Donnelly <mingw.android@gmail.com>
#
# Usage: pacman-rec-filename-grep <pkg_or_group> <outfile> |<regex>|
#
#      <pkg_or_group>  Name of Pacman package or group to search in.
#
#      <outfile>       Filename to write to. Pass '-' to use stdout.
#
#      <regex>         Optional extended regex to fnmatch using grep.
#                       Defaults to matching all files by using '.*$'
#
# Exitcode: Only fails if less than two arguments are passed or when
#           outfile is not writable. Otherwise succeeds, even if the
#           package/group doesn't exist, where you just get an empty
#           outfile (or no output to stdout).
#
# Example: To get a list of all the .dlls in the base group, use:
#          pacman-rec-filename-grep base base-dlls.txt ".*\.dll$"

pkg_or_group=$1; shift
outfile=$1; shift
regex=$1
# Defaults to matching all filenames.
[[ -z "${regex}" ]] && regex=".*$"
debug=0

declare -a dependencies
declare -a new_dependencies

# Maybe it's a group ..
pacman -Sg $pkg_or_group > /dev/null 2>&1 && new_dependencies=($(pacman -Sg $pkg_or_group | cut -d' ' -f2))
# .. or maybe it's a package.
pacman -Qi $pkg_or_group > /dev/null 2>&1 && new_dependencies=("${pkg_or_group}")

while [[ ${#dependencies[@]} -ne ${#new_dependencies[@]} ]]; do
  [[ debug -eq 1 ]] && echo "sizes are dependencies=${#dependencies[@]} and new_dependencies=${#new_dependencies[@]}"
  dependencies=(${new_dependencies[@]})
  new_dependencies=()
  for package in ${dependencies[@]}; do
    new_dependencies+=("${package}")
    pkg_deps=$(pacman -Si ${package} 2>/dev/null | sed -n "s/^Depends On \+:\(.*\)$/\1/p")
    [[ debug -eq 1 ]] && echo "Dependencies of ${package} are ${pkg_deps}"
    for pkg_dep in $pkg_deps; do
      new_package=${pkg_dep%>=*}
      new_dependencies+=("${new_package}")
    done
  done
  [[ debug -eq 1 ]] && echo "new_dependencies (pre-sorting) ${new_dependencies[@]}"
  new_dependencies=($(printf "%s\n" "${new_dependencies[@]}" | sort -u));
  [[ debug -eq 1 ]] && echo "new_dependencies (post-sorting) ${new_dependencies[@]}"
done

# Some packages don't exist ('provides' ones such as 'sh' and also the 'no packages' identifier 'None')
# Allowing them to make it this far is a bit quicker than filtering them earlier on.
dependencies=()
for package in ${new_dependencies[@]}; do
  pacman -Qi ${package} > /dev/null 2>&1 && dependencies+=("${package}")
done
[[ debug -eq 1 ]] && echo "num recursively dependent packages is ${#dependencies[@]}"

# Now grep for the filename match.
declare -a matching_files
for package in ${dependencies[@]}; do
  matching_files+=($(pacman -Ql ${package} | cut -d' ' -f2 | grep -E "${regex}"))
done

matching_files=($(printf "%s\n" "${matching_files[@]}" | sort -u));

if [ "${outfile}" = "-" -o -z "${outfile}" ]; then
  echo ${matching_files[@]} | tr " " "\n"
else
  echo ${matching_files[@]} | tr " " "\n" > "${outfile}"
fi

exit 0