#!/bin/bash
set -e

# config options
declare -A keep
REMOTE="origin"
BASE_BRANCH="main"
PACKAGE_BASE_URL=
PACKAGE_RELATIVE_URL="../../rpm"
DATE="$(date "+%s %z")"
PACKAGES_KEEP=

# command line only
packages_from=
single=
verbose=0
cfg_file=

###################

# constant needed to aid quoting
nl=$'\n'

declare -A packages
declare -A new
declare -A drop
declare -A revs
gitmodules_rev=

helpandquit()
{
	cat <<-EOF
		Usage: $0 [OPTIONS] [<module> ...]
		OPTIONS:
		  --packages-from=FILE   read list of packges to sync from FILE
		  --single   create single commit for all changes
		  -h         help screen
	EOF
	exit 0
}

show_status()
{
	git for-each-ref 'refs/pq/*'
	exit 0
}

clear_queue()
{
	while read -r ref; do
		git update-ref -d "$ref"
	done < <(git for-each-ref 'refs/pq/*' --format '%(refname)')
	exit 0
}

isnew()
{
	local p="${1:?}"
	[ -n "${new[$p]}" ]
}

todrop()
{
	local p="${1:?}"
	[ -n "${drop[$p]}" ]
}

log_info()
{
	[ "$verbose" -gt 0 ] || return 0
	echo "$@"
}

makedict()
{
	local dict="$1"
	shift
	mapfile -t a < <("$@")
	for k in "${a[@]}"; do
		eval "$dict"["$k"]=1
	done
}

getopttmp=$(getopt -o hc:v --long help,single,branch:,config:,date:,remote:,status,verbose,clear,packages-from: -n "${0##*/}" -- "$@")
eval set -- "$getopttmp"

while true ; do
        case "$1" in
                -h|--help) helpandquit; shift ;;
		-v|--verbose) verbose=$((++verbose)); shift ;;
                -c|--config) cfg_file="$2"; shift 2 ;;
                --single) single=1; shift ;;
                --packages-from) packages_from="$2"; shift 2 ;;
                --remote) REMOTE="$2"; shift 2 ;;
                --branch) BASE_BRANCH="$2"; shift 2 ;;
		--status) show_status; exit 0 ;;
		--clear) clear_queue; exit 0 ;;
                --date) DATE="$2"; shift 2 ;;
                --) shift ; break ;;
                *) echo "Internal error!" ; exit 1 ;;
        esac
done

modules=("$@")

PACKAGE_BASE_URL="$(git config --get remote."$REMOTE".url)"

# shellcheck disable=SC1090
. "${cfg_file:-.settings}"

for p in $PACKAGES_KEEP; do
	keep["$p"]=1
done

if [ "${DATE:0:1}" = '@' ]; then
	DATE="$(stat -c %Y "${DATE:1}") +0100"
fi

export GIT_AUTHOR_NAME="Auto"
export GIT_AUTHOR_EMAIL="auto@suse.de"
export GIT_AUTHOR_DATE="$DATE"
export GIT_COMMITTER_NAME="Auto"
export GIT_COMMITTER_EMAIL="auto@suse.de"
export GIT_COMMITTER_DATE="$DATE"

tmpfile=$(mktemp updatemodules.XXXXXX)
tmpfile2=$(mktemp updatemodules.XXXXXX)
cleanup()
{
	rm -f "$tmpfile" "$tmpfile2"
}
trap cleanup EXIT

# read all submodules
while read -r m t cid p; do
	if [ "$t" = blob ] && [ "$p" = ".gitmodules" ]; then
		gitmodules_rev="$cid"
	fi
	[ "$t" = "commit" ]  || continue
	revs["$p"]="$cid"
done < <(git cat-file -p "$REMOTE/$BASE_BRANCH^{tree}")

if [ -n "$packages_from" ]; then
	while read -r p; do
		packages["$p"]=1
		[ -n "${revs[$p]}" ] || new["$p"]=1
	done < "$packages_from"
	for m in "${!revs[@]}"; do
		[ -n "${packages[$m]}" -o -n "${keep[$m]}" ] || drop["$m"]=1
	done
fi

[ -z "${new[*]}" ] || log_info "new: ${!new[*]}"
[ -z "${drop[*]}" ] || log_info "drop: ${!drop[*]}"

if [ "${#modules[@]}" = 0 ]; then
       modules=("${!revs[@]}" "${!new[@]}")
fi

# push queue
declare -A pq
makedict pq git for-each-ref 'refs/pq/*' --format '%(refname)'

for r in "${!pq[@]}"; do
	m="${r##*/}"
	if [ -z "${revs[$m]}" ] && ! isnew "$m" && ! todrop "$m"; then
		log_info "remove stale update entry for $m"
		git update-ref -d "$r"
	fi
done

# check remotes for updates
declare -A commits
treetext=$(git cat-file -p "$REMOTE/$BASE_BRANCH^{tree}")
git cat-file -p "$REMOTE/$BASE_BRANCH":.gitmodules > "$tmpfile"
cat "$tmpfile" > "$tmpfile2"
for m in "${modules[@]}"; do
	if isnew "$m"; then
		path="$m"
		url="$PACKAGE_RELATIVE_URL/$m"
		smbranch=
		git config -f "$tmpfile" --add "submodule.$m.path" "$path"
		git config -f "$tmpfile" --add "submodule.$m.url" "$url"
	else
		path="$(git config -f "$tmpfile" --get "submodule.$m.path")"
		url="$(git config -f "$tmpfile" --get "submodule.$m.url")"
		smbranch="$(git config -f "$tmpfile" --get "submodule.$m.branch" || :)"
	fi
	if [ -z "$path" ] || [ -z "$url" ]; then
		echo "$m unknown" >&2
		continue
	fi
	if [ "${url:0:3}" = '../' ]; then
		url="$PACKAGE_BASE_URL/$url"
	fi

	cid=
	if ! todrop "$m"; then
		read -r cid _d < <(GIT_ASKPASS=/bin/true git ls-remote "$url" "${smbranch:-HEAD}" 2>/dev/null) || true
		if [ -z "$cid" ]; then
			echo "Warning: $path not in pool, ignored" >&2
			continue
		fi
	fi

	# create a new commit for this package
	if [ "${revs[$path]}" != "$cid" ]; then
		log_info "Needs update: $path@${revs[$path]:-NEW} -> ${cid:-DROP}"
		if isnew "$m"; then
			newtreetext="$treetext${nl}160000 commit $cid	$m"
		elif todrop "$m"; then
			newtreetext="${treetext/160000 commit ${revs[$path]}	$path$nl/}"
			git config -f "$tmpfile" --remove-section "submodule.$m"
		else
			newtreetext="${treetext/${revs[$path]}	$path/$cid	$path}"
		fi
		if isnew "$m" || todrop "$m"; then
			nh=$(git hash-object -w --path .gitmodules "$tmpfile")
			newtreetext="${newtreetext/$gitmodules_rev	.gitmodules/$nh	.gitmodules}"
		fi

		if [ "$single" = 1 ]; then
			if isnew "$m" || todrop "$m"; then
				gitmodules_rev="$nh"
			fi
			treetext="$newtreetext"
			# fall through
		else
			newtree=$(echo "$newtreetext" | git mktree)
			msg="Update $m"
			isnew "$m" && msg="Add $m"
			todrop "$m" && msg="Remove $m"
			newcid="$(git commit-tree -p "$REMOTE/$BASE_BRANCH" -m "$msg" "$newtree")"
			commits["$m"]="$newcid"
			cat "$tmpfile2" > "$tmpfile"
			continue
		fi
		# fall through
	fi
	if [ -n "${pq[refs/pq/$m]}" ]; then
		log_info "remove pq for $m"
		git update-ref -d "refs/pq/$m"
	fi
done

if [ "$single" = 1 ]; then
	newtree="$(echo "$treetext" | git mktree)"
	newcid="$(git commit-tree -p "$REMOTE/$BASE_BRANCH" -m "Update all" "$newtree")"
	commits["all"]="$newcid"
elif [ -n "${pq[refs/pq/all]}" ]; then
	log_info "remove pq for single commit"
	git update-ref -d "refs/pq/all"
fi

for m in "${!commits[@]}"; do
	ref="refs/pq/$m"
	if [ -n "${pq[$ref]}" ]; then
		cid="$(git rev-parse "$ref")"
		[ "$cid" = "${commits[$m]}" ] || echo "Warning: previous commit $cid for $m" >&2
	fi
	git update-ref "$ref" "${commits[$m]}"
done