#!/usr/bin/env python3
"""Prometheus exporter for go2rtc and Frigate camera stream health."""

import logging
import signal
import sys
import time
from pathlib import Path

import requests
import yaml
from prometheus_client import Gauge, start_http_server

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s %(levelname)s %(message)s",
    datefmt="%Y-%m-%d %H:%M:%S",
)
log = logging.getLogger("go2rtc-exporter")

# --- Metrics ---

go2rtc_stream_up = Gauge(
    "go2rtc_stream_up",
    "Whether a go2rtc stream has active producers (1=up, 0=down)",
    ["camera"],
)
go2rtc_stream_bytes_per_second = Gauge(
    "go2rtc_stream_bytes_per_second",
    "Bytes per second received by go2rtc producer",
    ["camera"],
)
go2rtc_stream_consumers = Gauge(
    "go2rtc_stream_consumers",
    "Number of consumers connected to the stream",
    ["camera"],
)
frigate_camera_fps = Gauge(
    "frigate_camera_fps",
    "Camera FPS reported by Frigate",
    ["camera"],
)
go2rtc_up = Gauge(
    "go2rtc_up",
    "Whether go2rtc API is reachable (1=up, 0=down)",
)
frigate_up = Gauge(
    "frigate_up",
    "Whether Frigate API is reachable (1=up, 0=down)",
)

# --- State ---

prev_bytes: dict[str, int] = {}
prev_time: dict[str, float] = {}


def load_config(path: str) -> dict:
    with open(path) as f:
        return yaml.safe_load(f)


def poll_go2rtc(config: dict) -> None:
    url = f"{config['go2rtc_url']}/api/streams"
    timeout = config.get("request_timeout", 5)
    cameras = config["cameras"]

    try:
        resp = requests.get(url, timeout=timeout)
        resp.raise_for_status()
        streams = resp.json()
        go2rtc_up.set(1)
    except Exception as e:
        log.warning("go2rtc unreachable: %s", e)
        go2rtc_up.set(0)
        for cam in cameras:
            go2rtc_stream_up.labels(camera=cam).set(0)
            go2rtc_stream_bytes_per_second.labels(camera=cam).set(0)
            go2rtc_stream_consumers.labels(camera=cam).set(0)
        return

    now = time.monotonic()

    for cam in cameras:
        stream = streams.get(cam)
        if stream is None:
            go2rtc_stream_up.labels(camera=cam).set(0)
            go2rtc_stream_bytes_per_second.labels(camera=cam).set(0)
            go2rtc_stream_consumers.labels(camera=cam).set(0)
            continue

        producers = stream.get("producers") or []
        consumers = stream.get("consumers") or []

        # A stream is "up" if it has at least one producer
        has_producer = len(producers) > 0
        go2rtc_stream_up.labels(camera=cam).set(1 if has_producer else 0)
        go2rtc_stream_consumers.labels(camera=cam).set(len(consumers))

        # Calculate bytes/sec from delta
        total_bytes = sum(p.get("bytes_recv", 0) for p in producers)

        if cam in prev_bytes and cam in prev_time:
            dt = now - prev_time[cam]
            if dt > 0:
                dbytes = total_bytes - prev_bytes[cam]
                # Handle counter reset (go2rtc restart)
                if dbytes < 0:
                    dbytes = total_bytes
                bps = dbytes / dt
                go2rtc_stream_bytes_per_second.labels(camera=cam).set(round(bps, 1))
            else:
                go2rtc_stream_bytes_per_second.labels(camera=cam).set(0)
        else:
            # First poll — no delta yet
            go2rtc_stream_bytes_per_second.labels(camera=cam).set(0)

        prev_bytes[cam] = total_bytes
        prev_time[cam] = now


def poll_frigate(config: dict) -> None:
    url = f"{config['frigate_url']}/api/stats"
    timeout = config.get("request_timeout", 5)
    cameras = config["cameras"]

    try:
        resp = requests.get(url, timeout=timeout)
        resp.raise_for_status()
        stats = resp.json()
        frigate_up.set(1)
    except Exception as e:
        log.warning("Frigate unreachable: %s", e)
        frigate_up.set(0)
        for cam in cameras:
            frigate_camera_fps.labels(camera=cam).set(0)
        return

    cam_stats = stats.get("cameras", {})
    for cam in cameras:
        cs = cam_stats.get(cam)
        if cs and isinstance(cs, dict):
            frigate_camera_fps.labels(camera=cam).set(cs.get("camera_fps", 0))
        else:
            frigate_camera_fps.labels(camera=cam).set(0)


def main() -> None:
    config_path = Path(__file__).parent / "config.yaml"
    if len(sys.argv) > 1:
        config_path = Path(sys.argv[1])

    config = load_config(str(config_path))
    port = config.get("metrics_port", 9199)
    interval = config.get("poll_interval", 15)

    log.info("Starting go2rtc exporter on port %d (poll every %ds)", port, interval)
    log.info("Monitoring cameras: %s", ", ".join(config["cameras"]))

    start_http_server(port)

    shutdown = False

    def handle_signal(signum, frame):
        nonlocal shutdown
        log.info("Received signal %d, shutting down", signum)
        shutdown = True

    signal.signal(signal.SIGTERM, handle_signal)
    signal.signal(signal.SIGINT, handle_signal)

    while not shutdown:
        try:
            poll_go2rtc(config)
            poll_frigate(config)
        except Exception:
            log.exception("Unexpected error during poll")
        time.sleep(interval)

    log.info("Exporter stopped")


if __name__ == "__main__":
    main()