#!/usr/bin/env bash
# For each projects/<id>/conf.json with project_path pointing to a Git clone under ../
# (or anywhere), fetch origin and fast-forward the current branch if safe.
set -euo pipefail

ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
PROJECTS_CONF="$ROOT/projects"
LOG_PREFIX="[git-pull-project-clones]"

usage() {
	echo "Usage: $0 [--all | --project <id>]" >&2
	echo "  Reads projects/<id>/conf.json (jq required). Skips if cron.git_pull is false." >&2
	exit 1
}

filter_id=""
if [[ "${1:-}" == "--project" && -n "${2:-}" ]]; then
	filter_id="$2"
elif [[ -n "${1:-}" && "$1" != "--all" ]]; then
	usage
fi

err_count=0

command -v jq >/dev/null 2>&1 || {
	echo "$LOG_PREFIX jq not found; install jq." >&2
	exit 1
}

pull_clone() {
	local id="$1" path="$2"
	if [[ ! -d "$path" ]]; then
		echo "$LOG_PREFIX skip $id: project_path not a directory: $path"
		return 0
	fi
	if [[ ! -d "$path/.git" ]]; then
		echo "$LOG_PREFIX skip $id: not a git repository: $path"
		return 0
	fi
	local branch
	if ! branch="$(git -C "$path" symbolic-ref -q --short HEAD 2>/dev/null)"; then
		echo "$LOG_PREFIX skip $id: detached HEAD in $path"
		return 0
	fi
	if ! git -C "$path" remote get-url origin >/dev/null 2>&1; then
		echo "$LOG_PREFIX skip $id: no origin remote in $path"
		return 0
	fi
	echo "$LOG_PREFIX $id: fetch origin ($path, branch $branch)"
	if ! git -C "$path" fetch origin "$branch" 2>&1; then
		echo "$LOG_PREFIX $id: fetch failed" >&2
		return 1
	fi
	local head oref
	head="$(git -C "$path" rev-parse HEAD)"
	oref="origin/$branch"
	if ! git -C "$path" rev-parse --verify -q "$oref" >/dev/null 2>&1; then
		echo "$LOG_PREFIX skip $id: $oref missing after fetch"
		return 0
	fi
	local remote_sha
	remote_sha="$(git -C "$path" rev-parse "$oref")"
	if [[ "$head" == "$remote_sha" ]]; then
		echo "$LOG_PREFIX $id: up to date"
		return 0
	fi
	if ! git -C "$path" merge-base --is-ancestor "$head" "$remote_sha" 2>/dev/null; then
		echo "$LOG_PREFIX skip $id: not fast-forward (diverged or unrelated); manual merge required"
		return 0
	fi
	echo "$LOG_PREFIX $id: fast-forward to $oref"
	git -C "$path" merge --ff-only "$oref"
	echo "$LOG_PREFIX $id: done"
}

for conf in "$PROJECTS_CONF"/*/conf.json; do
	[[ -f "$conf" ]] || continue
	id="$(basename "$(dirname "$conf")")"
	if [[ -n "$filter_id" && "$id" != "$filter_id" ]]; then
		continue
	fi
	if [[ "$id" == "example" ]]; then
		echo "$LOG_PREFIX skip $id: template project"
		continue
	fi
	if [[ "$(jq -r '.cron.git_pull // true' "$conf")" == "false" ]]; then
		echo "$LOG_PREFIX skip $id: cron.git_pull is false"
		continue
	fi
	path="$(jq -r '.project_path // empty' "$conf")"
	if [[ -z "$path" || "$path" == "null" ]]; then
		echo "$LOG_PREFIX skip $id: empty project_path"
		continue
	fi
	if [[ "$path" != /* ]]; then
		path="$(cd "$ROOT" && realpath -m "$path" 2>/dev/null || echo "$ROOT/$path")"
	fi
	if ! pull_clone "$id" "$path"; then
		err_count=$((err_count + 1))
	fi
done

if [[ "$err_count" -gt 0 ]]; then
	echo "$LOG_PREFIX errors: $err_count (see output above)" >&2
	exit 1
fi