#!/bin/bash

# ============================================================================
# Install the SyncYomi library integrity guard as a user systemd timer.
#
# TachiyomiSY 1.13.2 can finish a backup restore, report success, and have
# written almost nothing (upstream jobobby04/TachiyomiSY#1634, #1638). The app
# then syncs that near-empty library up, replacing the good server copy. On
# 2026-08-09 the real library survived only as stale pages in the SQLite WAL.
#
# The guard cannot fix the app. It makes the silent case loud, and keeps
# restorable .tachibk snapshots so recovery never again depends on WAL forensics.
# ============================================================================

set -euo pipefail

SCRIPT_NAME="$(basename "$0")"
readonly SCRIPT_NAME
REPO_ROOT="$(cd "$(dirname "$0")/../../../.." && pwd)"
readonly REPO_ROOT
readonly UNIT_DIR="${HOME}/.config/systemd/user"
readonly SERVICE_NAME="syncyomi-guard.service"
readonly TIMER_NAME="syncyomi-guard.timer"
readonly SNAPSHOT_DIR="${HOME}/syncyomi/snapshots"
readonly STATE_DIR="${HOME}/.local/share/syncyomi_guard"
readonly DB_PATH="${HOME}/syncyomi/config/syncyomi.db"

log_info() { echo "[*] $*"; }
log_ok() { echo "[+] $*"; }
die() {
	echo "[!] $*" >&2
	exit 1
}

usage() {
	echo "Usage: ${SCRIPT_NAME} [--uninstall]"
	echo "  Installs a user timer that verifies the SyncYomi payload every 30 min."
	exit 0
}

require_python() {
	command -v python3 >/dev/null 2>&1 ||
		die "python3 not found — install it with: sudo pacman -S python"
}

# The guard reads the database through sudo-less paths, so it must be able to
# open it. A root-owned db (the container writes as root) is readable only if
# the mode allows it; check now rather than failing silently on the first timer.
check_readable() {
	[[ -f ${DB_PATH} ]] || die "no SyncYomi database at ${DB_PATH}"
	if ! head -c 1 "${DB_PATH}" >/dev/null 2>&1; then
		die "cannot read ${DB_PATH} as $(whoami) — run: sudo chmod o+r '${DB_PATH}'"
	fi
}

write_units() {
	mkdir -p "${UNIT_DIR}" "${SNAPSHOT_DIR}" "${STATE_DIR}"

	cat >"${UNIT_DIR}/${SERVICE_NAME}" <<EOF
# Generated by ${SCRIPT_NAME} — do not edit by hand.
[Unit]
Description=Verify the SyncYomi library payload has not silently collapsed
Documentation=https://github.com/jobobby04/TachiyomiSY/issues/1634

[Service]
Type=oneshot
WorkingDirectory=${REPO_ROOT}
Environment=PYTHONPATH=${REPO_ROOT}
ExecStart=/usr/bin/python3 -m python_pkg.syncyomi_guard \\
    --db ${DB_PATH} \\
    --state-dir ${STATE_DIR} \\
    --snapshot-dir ${SNAPSHOT_DIR}
EOF

	cat >"${UNIT_DIR}/${TIMER_NAME}" <<EOF
# Generated by ${SCRIPT_NAME} — do not edit by hand.
[Unit]
Description=Periodic SyncYomi library integrity check

[Timer]
OnCalendar=*:00/30
Persistent=true

[Install]
WantedBy=timers.target
EOF

	log_ok "Wrote ${UNIT_DIR}/${SERVICE_NAME} and ${TIMER_NAME}"
}

install_timer() {
	require_python
	check_readable
	write_units
	systemctl --user daemon-reload
	systemctl --user enable --now "${TIMER_NAME}"
	log_ok "Timer enabled (every 30 minutes)"

	log_info "Running one check now"
	if systemctl --user start "${SERVICE_NAME}"; then
		systemctl --user status "${SERVICE_NAME}" --no-pager -n 10 || true
	else
		die "first run failed — inspect: journalctl --user -u ${SERVICE_NAME}"
	fi
}

uninstall_timer() {
	systemctl --user disable --now "${TIMER_NAME}" 2>/dev/null || true
	rm -f "${UNIT_DIR}/${SERVICE_NAME}" "${UNIT_DIR}/${TIMER_NAME}"
	systemctl --user daemon-reload
	log_ok "Removed timer and service (snapshots in ${SNAPSHOT_DIR} kept)"
}

main() {
	case "${1:-}" in
	--uninstall) uninstall_timer ;;
	-h | --help) usage ;;
	"") install_timer ;;
	*) die "Unknown option: $1" ;;
	esac
}

main "$@"