#!/usr/bin/env python3
"""AgentCheckin scheduler daemon.

Responsibilities:
  * run check-ins at the configured daily times (default 00:05/09:00/12:30/19:00),
    each slot at most once per day; idempotent so missed slots self-heal
  * honour manual trigger files written by the CGI API ("run now")
  * keep state.json fresh (daemon liveness, next run time)
  * survive reboots: on start, if today has no run yet, run once (catch-up)

The daemon writes its own pidfile so cmd/main and the web UI can check it.
"""
import os
import signal
import sys
import time

sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))

from common import (DATA_DIR, PID_FILE, TRIGGER_FILE, load_settings, load_state,
                    save_state, log, today_str, fmt_now, now_ts, fmt_ts,
                    ensure_dirs)
import engine

TICK_SECONDS = 15
_running = True


def _handle_signal(signum, frame):
    global _running
    _running = False


def write_pidfile():
    ensure_dirs()
    with open(PID_FILE, "w") as f:
        f.write(str(os.getpid()))


def remove_pidfile():
    try:
        if os.path.exists(PID_FILE):
            with open(PID_FILE) as f:
                if f.read().strip() == str(os.getpid()):
                    os.unlink(PID_FILE)
    except OSError:
        pass


def slot_today_ts(hhmm):
    """Unix ts of today's HH:MM local time."""
    now = time.localtime()
    hh, mm = int(hhmm[:2]), int(hhmm[3:5])
    return int(time.mktime((now.tm_year, now.tm_mon, now.tm_mday, hh, mm, 0, 0, 0, -1)))


def compute_next_run(settings):
    """Next scheduled slot ts (today or tomorrow), or None."""
    times = settings.get("schedule_times") or []
    now = now_ts()
    candidates = []
    for hhmm in times:
        ts = slot_today_ts(hhmm)
        candidates.append(ts if ts > now else ts + 86400)
    return min(candidates) if candidates else None


def tick():
    settings = load_settings()
    state = load_state()
    today = today_str()
    times = settings.get("schedule_times") or []
    slot_runs = state.get("slot_runs") or {}
    now = now_ts()

    # 1) manual trigger
    if os.path.exists(TRIGGER_FILE):
        try:
            os.unlink(TRIGGER_FILE)
        except OSError:
            pass
        log("trigger file detected -> running check-in")
        engine.run_all(reason="manual")
        return

    # 2) catch-up: today has no run recorded at all (fresh boot / first install).
    #    Mark every slot whose time has already passed as covered by this run.
    #    NOTE: check key existence — an empty result dict is still "a run".
    if today not in (state.get("today") or {}):
        if times:
            log("no run recorded today -> startup catch-up")
            engine.run_all(reason="startup-catchup")
            state = load_state()
            slot_runs = state.setdefault("slot_runs", {})
            changed = False
            for hhmm in times:
                if now >= slot_today_ts(hhmm) and slot_runs.get(hhmm) != today:
                    slot_runs[hhmm] = today
                    changed = True
            if changed:
                save_state(state)
            return

    # 3) scheduled slots (each at most once per day)
    for hhmm in times:
        ts = slot_today_ts(hhmm)
        if now >= ts and slot_runs.get(hhmm) != today:
            log("schedule slot %s due" % hhmm)
            engine.run_all(reason="schedule:%s" % hhmm)
            mark_slot_ran(hhmm)
            return


def mark_slot_ran(hhmm):
    state = load_state()
    state.setdefault("slot_runs", {})[hhmm] = today_str()
    save_state(state)


def update_liveness():
    state = load_state()
    settings = load_settings()
    prev = state.get("daemon") or {}
    # reset started_at when the pid changed (fresh daemon process)
    started_at = prev.get("started_at") if prev.get("pid") == os.getpid() else fmt_now()
    state["daemon"] = {
        "pid": os.getpid(),
        "started_at": started_at,
        "last_tick": fmt_now(),
    }
    nxt = compute_next_run(settings)
    state["next_run_at"] = fmt_ts(nxt) if nxt else None
    state["next_run_ts"] = nxt
    save_state(state)


def main():
    signal.signal(signal.SIGTERM, _handle_signal)
    signal.signal(signal.SIGINT, _handle_signal)
    ensure_dirs()
    write_pidfile()
    log("daemon started (pid %d), data dir %s" % (os.getpid(), DATA_DIR))
    try:
        while _running:
            try:
                tick()
            except Exception as e:
                log("tick error: %s" % e, "ERROR")
            try:
                update_liveness()
            except Exception as e:
                log("liveness update failed: %s" % e, "ERROR")
            # sleep in small slices so SIGTERM is responsive
            for _ in range(TICK_SECONDS):
                if not _running:
                    break
                time.sleep(1)
    finally:
        remove_pidfile()
        log("daemon stopped")
    return 0


if __name__ == "__main__":
    sys.exit(main())