#!/usr/bin/env 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 -euE
. libremessages

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

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

	while read -r repo; do
		handle-repo "$repo"
	done < <(cfg-list-repos)
}

handle-repo() {
	[[ $# == 1 ]] || panic
	local repo=$1
	local local upstream downstreams downstream

	# read configuration
	local="$(cfg-get "repo.$repo.local")"
	upstream="$(cfg-get "repo.$repo.upstream")" || true
	downstreams=($(cfg-get-all "repo.$repo.downstream")) || true

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

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

	# upload
	for downstream in "${downstreams[@]}"; do
		upload "$repo" "$local" "$downstream"
	done
}

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

	local IFS='&'
	local remote=${_remote%%#*}
	local params=(${_remote#"$remote"})

	msg 'Downloading %s <- %s' "$repo" "${remote%%#*}"

	# download the repository
	local url
	url="$(remote "$remote" pull-url)"
	gitget -f -n "$repo" bare "$url" "$local"

	# download the metadata
	get-meta "$remote" > "$local/git-mirror.tmp"
	git config --file "$local/config" --rename-section git-mirror git-mirror-bak 2>/dev/null || true
	local IFS='='
	while read -r key val; do
		git config --file "$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 2>/dev/null || true
}

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

	msg 'Uploading %s -> %s' "$repo" "${remote%%#*}"

	# push metadata
	local meta
	mapfile meta < <(git config --file "$local/config" --list|sed -n 's/^git-mirror[.]//p')
	meta=("${meta[@]%$'\n'}")
	set-meta "$remote" "${meta[@]}"

	# push repository
	local repo_mode
	repo_mode=$(remote "$remote" repo-mode)
	if [[ $repo_mode == passive ]]; then
		msg2 "Pushing repo %s" "$repo"
		local push_url
		push_url="$(remote "$remote" push-url)"
		cd "$local" && git push --mirror "$push_url"
	fi
)

get-meta() (
	[[ $# = 1 ]] || panic
	local IFS remote _params params
	IFS='#' read remote _params <<<"$1"
	IFS='&' read -a params <<<"$_params"

	remote "$remote" get-meta
	[[ ${#params[@]} = 0 ]] || printf '%s\n' "${params[@]}"
)

set-meta() {
	[[ $# -ge 1 ]] || panic
	local IFS remote _params params
	IFS='#' read remote _params <<<"$1"
	IFS='&' read -a params <<<"$_params"
	local args=("${@:2}")

	remote "$remote" set-meta "${args[@]}" "${params[@]}"
}

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

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

	{
		cfg --list|sed -n "s=^account[.]$account[.]==p"|grep -v '^type='|xargs -r printf 'config %q\n'
		cat
	} | git mirror-"$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() {
	[[ $# == 0 ]] || panic
	cfg --name-only -z --get-regexp '^repo[.].*[.].*$' |sed -z -e 's|^repo[.]||' -e 's|[.][^.]*$||'|sort -zu|xargs -r0 printf '%s\n'
}

main "$@"