#!/bin/bash

home="$(dirname "${0}")"
target="${home}/repo"
repos=('core' 'extra' 'community' 'testing' 'community-testing' 'staging' 'multilib')
arches=('i686' 'x86_64')
lock='/tmp/mirrorsync.lck'
tmp="$(mktemp -d)"

extractinc=(--include={opt,{,usr/}{lib{,32},{s,}bin}}'/*')

getpkgname() {
	local tmp

	tmp=${1##*/}
	echo ${tmp%-*.pkg.tar.*}
}

generate_links() {
	for repo in ${repos[@]}; do
		for arch in ${arches[@]}; do
			repodir=${repo}/os/${arch}
			[ ! -f ${target}/$repodir/$repo.db ] && continue
			echo "$repo/$arch..."
			cached=false

			# extract old file archive
			if [ -f ${target}/${repodir}/${repo}.links.tar.gz ]; then
				mkdir -p ${tmp}/cache/${repodir}
				bsdtar -xf ${target}/${repodir}/${repo}.links.tar.gz -C ${tmp}/cache/${repodir}
				cached=true
			fi

			# create file lists
			for pkg in "$target/$repodir"/*.pkg.tar.?z; do
				[[ -f $pkg ]] || continue

				pkgname=$(getpkgname $pkg)
				tmppkgdir=${tmp}/tmp/${repodir}/${pkgname}
				mkdir -p $tmppkgdir
				if [ -f "${tmp}/cache/${repodir}/${pkgname}/links" ]; then
					# reuse the cached file
					mv ${tmp}/cache/${repodir}/${pkgname}/links ${tmppkgdir}/links
				else
					echo "$repo/$arch: $pkgname"
					mkdir -p ${tmppkgdir}/pkg
					bsdtar -xvof "$pkg" -C "$tmppkgdir/pkg" "${extractinc[@]}" 2>/dev/null
					find "$tmppkgdir/pkg" -type f -exec readelf -d {} + 2>/dev/null |
							sed -nr 's/.*Shared library: \[(.*)\]$/\1/p' | sort -u >"$tmppkgdir/links"
					rm -rf ${tmppkgdir}/pkg
					cached=false
				fi
			done

			# create new file archive
			if ! $cached; then
				# at least one package has changed, so let's rebuild the archive
				pkgdir=${target}/${repodir}
				mkdir -p $pkgdir
				bsdtar --exclude=*.tar.* -czf ${pkgdir}/${repo}.links.tar.gz -C ${tmp}/tmp/${repodir} .
			fi
		done
	done
}

trap "rm -rf '${tmp}'" EXIT
renice +10 -p $$ > /dev/null

{
	flock -n 9 || exit 42
	generate_links
} 9>"$lock"