#!/bin/bash -e

export TMPDIR="`mktemp -d --tmpdir pbs-absrepo-convert.XXXXXXXXXX`"
cleanup() {
	msg "$(gettext "Removing temporary files...")"
	echo rm -rf "$TMPDIR"
}
trap cleanup EXIT

. /usr/bin/libremessages

abort() {
	echo # force a fresh line
	error "$(gettext "Aborting...")"
	cleanup
}

##
# Usage: collect-data MODE
# MODE is either 'correct' or 'fast'
#
# Assumptions:
#  - currently in a working copy of the repo
#  - git branch "master" exists and is untouched
#  - TMPDIR is set and exists
# Effects:
#  - creates file "${TMPDIR}/commits"
#  - creates file "${TMPDIR}/find"
#  - creates file "${TMPDIR}/packages"
#  - creates file "${TMPDIR}/architectures"
##
collect-data() {
	msg "$(gettext "Collecting package data...")"
	[[ $# = 1 ]] || { usage; return 1; }
	local mode=$1

	case "$mode" in
		correct)
			git log --pretty=format:'%H' master > "${TMPDIR}/commits";;
		fast)
			echo master > "${TMPDIR}/commits";;
		*)
			usage; return 1;;
	esac

	# actual data collection ###############################################
	local count="$(wc -l < "${TMPDIR}/commits")"
	cat -n "${TMPDIR}/commits" | while read n commit; do
		printf '\rscanning commit %s (%d/%d)' "$commit" "$n" "$count" >> /dev/tty
		git ls-tree -rd --name-only "$commit"
	done | fgrep /repos/ | sort -u > "${TMPDIR}/find"
	echo # newline

	# extract some things ##################################################
	# packages
	{
		< "${TMPDIR}/find" sed -e 's|^\.||' -e 's|/.*||'
	} | sort -u > "${TMPDIR}/packages"
	# architectures
	{
	    echo master
	    < "${TMPDIR}/find" sed -e 's/.*-//' -e '/^any$/d'
	} | sort -u > "${TMPDIR}/architectures"
}

##
# Usage: convert-package SOURCE PACKAGE
# Assumptions:
#  - currently in a working copy of the repo
#  - TMPDIR is set
# Effects:
#  - creates git branch "packages/${SOURCE}/${PACKAGE}"
#  - creates file "${TMPDIR}/packages-${PACKAGE}.commits"
# Side effects:
#  - changes git working tree
#  - prints output of git commands
##
convert-package() {
	[[ $# = 2 ]] || { usage; return 1; }
	local source=$1
	local package=$2

	local branch="packages/${source}/${package}"
	local dir

	if git checkout "packages/${package}" &>/dev/null; then
		# special case (common; optimization)
		git checkout -b "$branch"
		git branch -D "packages/${package}"
		dir=trunk
	else
		# general case (uncommon)
		git checkout -b "$branch" orig
		dir="${package}/trunk"
	fi
	git filter-branch -f --prune-empty --subdirectory-filter "$dir" "$branch"

	git log --pretty=format:'%T %H' > "${TMPDIR}/packages-${package}.commits"
}

##
# Usage: convert-packages SOURCE
# Assumptions:
#  - meets assumptions of `convert-package`
#  - TMPDIR is set
#  - file "${TMPDIR}/packages" contains a newline-separated list of packages
# Effects:
#  - runs `convert-package` for every package listed in "${TMPDIR}/packages"
#  - prints status updates about what it is doing
##
convert-packages() {
	msg "$(gettext "Converting packages...")"
	[[ $# = 1 ]] || { usage; return 1; }
	local source=$1

	local count="$(wc -l < "${TMPDIR}/packages")"
	cat -n "${TMPDIR}/packages" | while read n package; do
		msg2 "$(gettext "(%d/%d) %s")" "$n" "$count" "$package"
		convert-package "$source" "$package"
	done
}

##
# Usage: convert-arch ARCH
# Assumptions:
#  - currently in a working copy of the repo
# Effects:
#  - creates git branch "${ARCH}"
#  - TMPDIR is set
#  - creates file "${TMPDIR}/missing-packages.${ARCH}"
# Side effects:
#  - changes git working tree
#  - prints output of git commands
##
convert-arch() {
	[[ $# = 1 ]] || { usage; return 1; }
	local arch=$1

	touch "${PKGDIR}/missing-packages.${arch}.tmp"

	git checkout orig
	git checkout -b "$arch"
	git filter-branch -f --tree-filter \
		"pbs-absrepo-convert--filterarch $arch" "$arch"

	sort -u \
	    < "${PKGDIR}/missing-packages.${arch}.tmp" \
	    > "${PKGDIR}/missing-packages.${arch}"
	rm -f "${PKGDIR}/missing-packages.${arch}.tmp"
}

##
# Usage: convert-arches
# Assumptions:
#  - meets assumptions of `convert-arch`
#  - file "${TMPDIR}/architectures" contains a newline-separated list of arches
#  - file "${TMPDIR}/packages-${PACKAGE}.commits" exists for every package
# Effects:
#  - runs `convert-arch` for every arch listed in "${TMPDIR}/architectures"
#  - prints status updates about what it is doing
##
convert-arches() {
	msg "$(gettext "Converting architectures...")"
	[[ $# = 0 ]] || { usage; return 1; }

	local count="$(wc -l < "${TMPDIR}/architectures")"
	cat -n "${TMPDIR}/architectures" | while read n arch; do
		msg2 "$(gettext "(%d/%d) %s")" "$n" "$count" "$arch"
		convert-arch "$arch"
	done
}

main() {
	trap abort EXIT
	[[ $# = 1 ]] || { usage; return 1; }
	local source=$1

	local cachedir="$(pbs-plumb-config get core.cachedir)"
	local sourcedir="$(pbs-plumb-config get core.sourcedir)"

	# init #################################################################
	msg "$(gettext "Creating working copy...")"
	git clone "${cachedir}/${source}.git" "${TMPDIR}/repo"
	cd "${TMPDIR}/repo"
	git checkout -b orig
	collect-data fast
	git branch -D master

	# main #################################################################

	convert-packages "$source"
	convert-arches "$source"

	# save results #########################################################
	msg "$(gettext "Copying into source directory...")"
	[[ -d "$sourcedir" ]] || mkdir -p "$sourcedir"
	git clone --mirror "${TMPDIR}/repo" "${sourcedir}/${source}.new.git"
	if [[ -d "${sourcedir}/${source}.git" ]]; then
		mv "${sourcedir}/${source}"{,.old}.git
	fi
	mv "${sourcedir}/${source}"{.new,}.git
	if [[ ! -d "${sourcedir}/${source}.old.git" ]]; then
		rm -rf "${sourcedir}/${source}".old.git
	fi
	trap cleanup EXIT
}

main "$@"