#!/bin/bash
# Copyright © 2014, 2016 Luke Shumaker <lukeshu@sbcglobal.net>
#
# This work is free. You can redistribute it and/or modify it under the
# terms of the Do What The Fuck You Want To Public License, Version 2,
# as published by Sam Hocevar. See the COPYING file for more details.

# Depends on the 'gitget' and 'libremessages' commands.  On Parabola
# GNU/Linux-libre, those are the 'gitget' and 'librelib' packages,
# respectively.
#
# For other systems, they both live at:
#     https://git.parabola.nu/packages/libretools.git/

set -o pipefail
set -e
. libremessages

usage() {
	print 'Usage %s CONFIG-FILE' "${0##*/}"
}

main() {
	if [[ $# != 1 ]]; then
		usage
		exit
	fi
	declare -g cfg_file="$1"

	local r=0
	while read -r repo; do
		handle-repo "$repo" || r=$?
	done < <(cfg-list-repos)
	return $r
}

handle-repo() {
	[[ $# == 1 ]] || panic
	local repo=$1
	local local url upstream downstreams downstream r=0
	
	# read configuration
	local="$(cfg-get "repo.$repo.local")"
	url="$(cfg-get "repo.$repo.url")" || true
	upstream="$(cfg-get "repo.$repo.upstream")" || true
	downstreams=($(cfg-get-all "repo.$repo.downstream")) || true

	# download
	if [[ -n "$upstream" ]]; then
		download "$upstream" "$local"
	fi

	# ensure that $local exists
	test -f "$local"/HEAD

	# upload
	for downstream in "${downstreams[@]}"; do
		upload "$url" "$local" "$downstream" || r=$?
	done

	return $r
}

download() {
	[[ $# == 3 ]] || panic
	local repo=$1
	local remote=$2
	local local=$3

	# download the repository
	local url
	url="$(remote "$remote" pull-url)"
	gitget -f -n "$repo" "$url" "$local"
	# download the metadata
	remote "$remote" get-meta > "$local/git-mirror.tmp"
	git config --file "$local/config" --rename-section git-mirror git-mirror-bak
	local IFS='='
	while read -r key val; do
		git config --file "$local/config" --add git-mirror."$key" "$val"
	done < "$local/git-mirror.tmp"
	rm -f "$local/git-mirror.tmp"
	git config --file "$local/config" --remove-section git-mirror-bak
}

upload() {
	[[ $# == 3 ]] || panic
	local clonable_url=$1
	local local=$2
	local remote=$3

	# push metadata
	{
		printf '%q ' set-meta "${remote#*:}"
		[[ -z "$clonable_url" ]] || printf '%q ' "mirror=$clonable_url"
		git config --file "$local/config" --get-regexp '^git-mirror[.]' -z|sed -z 's/ /=/'|xargs -0r printf '%q '
	} | account "${remote%%:*}"
	# push repository
	local repo_mode
	repo_mode=$(remote "$remote" repo-mode)
	if [[ $repo_mode == passive ]]; then
		local push_url
		push_url="$(remote "$remote" push-url)"
		cd "$local" && git push --mirror "$push_url"
	fi
}

# Spawn an 'account.type' helper.  It will read commands from stdin.
account() {
	[[ $# == 1 ]] || panic
	local account=$1

	local account_type
	account_type="$(cfg-get "account.$account.type")"

	{
		cfg --list -z|sed -zn "s=^account[.]$account[.]=config =p"|grep -z -v '^type='|xargs -r0 printf '%s\n'
		cat
	} | git mirror-"$type" "$account"
}

# `account` is awkward to use; so let's wrap it.
remote() {
	[[ $# > 1 ]] || panic
	local remote=$1

	[[ $remote = *:* ]]
	local account="${remote%%:*}"
	local path="${remote#*:}"

	printf '%q ' "$2" "$path" "${@:3}" | account "$account"
}

cfg() {
	git config --file "$cfg_file" "$@"
}

cfg-get() {
	[[ $# == 1 ]] || panic
	cfg --get-all "$1"
}

cfg-get-all() {
	[[ $# == 1 ]] || panic
	cfg --get-all "$1"
}

cfg-list-repos() {
	[[ $# == 0 ]] || panic
	cfg --name-only --get-regexp '^repo[.].*[.].*$' -z|sed -z -e 's|^repo[.]||' -e 's|[.][^.]*$||'|sort -zu|xargs -r0 printf '%s\n'
}

main "$@"