#!/bin/bash

provided=$(mktemp)

if grep -qxF 'ID=arch' /etc/os-release; then
  sources=(
    /var/lib/pacman/sync
    /mnt/archlinux/archlinux
    /mnt/archlinux
  )
  sudo pacman -Sy >/dev/null || exit $?
else
  >&2 echo 'skipping liste-verfuegbare-Versionen, because it currently does not reliably work on non-arch systems'
  exit 1
  sources=(
    http://pkgcache.eckner.net/arch/x86_64/core/core.db.tar.gz
    http://pkgcache.eckner.net/arch/x86_64/extra/extra.db.tar.gz
  )
fi

for i in "${!sources[@]}"; do
  source="${sources["${i}"]}"
  if [ -z "${source##*://*}" ]; then
    curl -Ss "${source}" \
    | bsdtar -Oxz
  else
    find "${sources["${i}"]}" -name '*.db' \
      -exec bsdtar -Oxzf {} \; \
    2>/dev/null
  fi \
  | sed -n '
    /^%\(NAME\|VERSION\)%$/ {
      N
      s/\n/ /
      p
    }
    /^%PROVIDES%$/,/^$/ {
      /^[^%]/ p
    }
  ' \
  | sed -n '
    s/^\(\S\+\)=\(\S\+\)-\(64\|32\)$/\2 \1/
    T no_provides
    p
    d
    :no_provides
    /^%NAME%/ {
      N
      s/^%NAME% \(\S\+\)\n%VERSION% \(\S\+\)-\S\+$/\2 \1/
      T
      p
    }
  ' \
  | sed '
    /^\(\S\+\) \1$/d
    s/^/'"${i}"' /
  '
done \
| sort -k3,3 -k1n,1 -k2Vr,2 \
| uniq -f2 \
| cut -d' ' -f2,3 \
>"${provided}"

printf '%s\n' "${provided}"