"""Shared C920 capture: small gst-launch pool, latest I420 frames in mmap."""
from __future__ import annotations

import argparse
import json
import logging
import os
import select
import signal
import subprocess
import sys
import time

from capture_va import (
    GST_GROUP_SIZE,
    grouped_cameras,
    shared_capture_cmd,
)
from frame_shm import LatestFrameWriter, frame_bytes
from uvc_exposure import pin_devices

log = logging.getLogger("cameras.capture_daemon")

READY_NAME = "ready"


def _open_pipes(n: int) -> tuple[list[int], list[int]]:
    reads: list[int] = []
    writes: list[int] = []
    for _ in range(n):
        r, w = os.pipe()
        try:
            import fcntl
            fcntl.fcntl(r, fcntl.F_SETPIPE_SZ, 1048576)
            fcntl.fcntl(w, fcntl.F_SETPIPE_SZ, 1048576)
        except OSError:
            pass
        os.set_inheritable(w, True)
        os.set_inheritable(r, False)
        reads.append(r)
        writes.append(w)
    return reads, writes


def main(argv: list[str] | None = None) -> int:
    ap = argparse.ArgumentParser(description="Shared JPEG capture daemon")
    ap.add_argument("--cameras-json", required=True,
                    help="JSON list of {identity, video_device}")
    ap.add_argument("--width", type=int, default=640)
    ap.add_argument("--height", type=int, default=360)
    ap.add_argument("--fps", type=int, default=30)
    ap.add_argument("--shm-dir", default="/run/livekit-cameras/raw")
    ap.add_argument("--vaapi-device", default="/dev/dri/renderD129")
    ap.add_argument("--group-size", type=int, default=GST_GROUP_SIZE)
    args = ap.parse_args(argv)

    logging.basicConfig(
        level=logging.INFO,
        format="%(asctime)s [capture-daemon] %(levelname)s %(message)s")

    cams = json.loads(args.cameras_json)
    pairs = [(c["identity"], c["video_device"]) for c in cams]
    if not pairs:
        log.error("no cameras")
        return 2

    os.environ["LIBVA_DRIVER_NAME"] = "iHD"

    need = frame_bytes(args.width, args.height)
    os.makedirs(args.shm_dir, exist_ok=True)
    writers = [
        LatestFrameWriter(os.path.join(args.shm_dir, f"{ident}.i420"),
                          args.width, args.height)
        for ident, _dev in pairs
    ]
    reads, writes = _open_pipes(len(pairs))
    env = dict(os.environ)
    env["LIBVA_DRM_DEVICE"] = args.vaapi_device
    env["LIBVA_DRIVER_NAME"] = "iHD"
    env["GST_REGISTRY_UPDATE"] = "no"

    groups = grouped_cameras(pairs, writes, args.group_size)
    log.info("starting %d gst-launch for %d cameras %dx%d@%d (group=%d)",
             len(groups), len(pairs), args.width, args.height, args.fps,
             args.group_size)
    procs: list[subprocess.Popen] = []
    for g_cams, g_fds in groups:
        cmd = shared_capture_cmd(g_cams, args.width, args.height, args.fps, g_fds)
        procs.append(subprocess.Popen(
            cmd,
            stdin=subprocess.DEVNULL,
            stdout=subprocess.DEVNULL,
            stderr=None,
            pass_fds=tuple(g_fds),
            env=env,
            close_fds=True,
        ))
    for w in writes:
        os.close(w)
    for r in reads:
        os.set_blocking(r, False)
    pin_devices([dev for _ident, dev in pairs])

    bufs = [bytearray() for _ in pairs]
    seqs = [0] * len(pairs)
    stop = False

    def _stop(_signum=None, _frame=None):
        nonlocal stop
        stop = True

    signal.signal(signal.SIGTERM, _stop)
    signal.signal(signal.SIGINT, _stop)

    ready_path = os.path.join(args.shm_dir, READY_NAME)
    if os.path.exists(ready_path):
        os.unlink(ready_path)
    marked = False
    last_log = time.monotonic()
    fd_index = {r: i for i, r in enumerate(reads)}

    try:
        while not stop:
            dead = [p for p in procs if p.poll() is not None]
            if dead:
                log.error("gst exited rc=%s", [p.returncode for p in dead])
                break
            ready, _, _ = select.select(reads, [], [], 0.2)
            now_ns = time.time_ns()
            for r in ready:
                i = fd_index[r]
                while True:
                    try:
                        chunk = os.read(r, max(need, need - len(bufs[i])))
                    except BlockingIOError:
                        break
                    if not chunk:
                        break
                    bufs[i].extend(chunk)
                    while len(bufs[i]) >= need:
                        frame = bytearray(bufs[i][:need])
                        del bufs[i][:need]
                        seqs[i] = writers[i].write(frame, now_ns)
            if not marked and any(s > 0 for s in seqs):
                pin_devices([dev for _ident, dev in pairs])
                open(ready_path, "w").write("ok\n")
                marked = True
                log.info("ready first frames %s",
                         ",".join(f"{pairs[i][0]}={seqs[i]}" for i in range(len(pairs))))
            now = time.monotonic()
            if now - last_log >= 5.0:
                last_log = now
                log.info("seqs %s",
                         " ".join(f"{pairs[i][0]}:{seqs[i]}" for i in range(len(pairs))))
    finally:
        for proc in procs:
            if proc.poll() is None:
                proc.terminate()
                try:
                    proc.wait(timeout=5)
                except subprocess.TimeoutExpired:
                    proc.kill()
        for r in reads:
            try:
                os.close(r)
            except OSError:
                pass
        for w in writers:
            w.close()
        if os.path.exists(ready_path):
            os.unlink(ready_path)
    return 0


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