"""Local imported-video browsing, playback, thumbnails, and retention."""
import os
import subprocess
import time
import threading

import gevent
from gevent import sleep
from gevent.lock import Semaphore
from modules import app_dash, app_sql


BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
THUMBNAIL_DIR = os.path.join(BASE_DIR, "dash", "thumbnails")
RETENTION_SETTING = "local_video_retention_days"
CONVERT_SETTING = "video_convert_enabled"
_thumbnail_lock = Semaphore()
_generating = set()
_generating_lock = Semaphore()
_converting = set()
_converting_lock = Semaphore()


def is_convert_enabled():
    return app_sql.get_setting(CONVERT_SETTING, "0") == "1"


def queue_convert(relative_path):
    """Spawn a background greenlet to re-encode relative_path to web-ready MP4.
    No-op if conversion is disabled, already running, or file is already MP4."""
    if not is_convert_enabled():
        return
    if relative_path.lower().endswith(".mp4"):
        return
    with _converting_lock:
        if relative_path in _converting:
            return
        _converting.add(relative_path)
    gevent.sleep(0)  # yield before spawning thread
    t = threading.Thread(target=_convert_bg, args=(relative_path,), daemon=True)
    t.start()


def _convert_bg(relative_path):
    try:
        source_path = _local_path(relative_path)
        mp4_relative = os.path.splitext(relative_path)[0] + ".mp4"
        mp4_path = _local_path(mp4_relative)

        if not app_dash.begin_local_video_use(relative_path):
            return

        try:
            tmp_path = mp4_path + ".converting.mp4"
            cmd = [
                "ffmpeg", "-nostdin", "-loglevel", "error", "-y",
                "-i", source_path,
                "-c:v", "h264_v4l2m2m",
                "-c:a", "aac",
                "-movflags", "faststart",
                "-f", "mp4",
                tmp_path,
            ]
            proc = subprocess.Popen(cmd, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
            proc.wait()  # real thread — blocking wait is fine
            if proc.returncode == 0 and os.path.isfile(tmp_path) and os.path.getsize(tmp_path) > 0:
                os.replace(tmp_path, mp4_path)
                # Delete original now that MP4 is ready
                try:
                    os.remove(source_path)
                except OSError:
                    pass
                # Also remove old thumbnail so it gets regenerated from MP4
                _source, thumb = _thumbnail_path(relative_path)
                if os.path.isfile(thumb):
                    try:
                        os.remove(thumb)
                    except OSError:
                        pass
            elif os.path.exists(tmp_path):
                os.remove(tmp_path)
        finally:
            app_dash.end_local_video_use(relative_path)
    finally:
        with _converting_lock:
            _converting.discard(relative_path)


def _local_path(relative_path):
    return app_dash.safe_video_path(app_dash.DEFAULT_DESTINATION, relative_path)


def _thumbnail_path(relative_path):
    source_root = os.path.realpath(app_dash.DEFAULT_DESTINATION)
    source_path = app_dash.safe_video_path(source_root, relative_path)
    thumbnail_root = os.path.realpath(THUMBNAIL_DIR)
    thumbnail_path = os.path.realpath(
        os.path.join(thumbnail_root, relative_path + ".jpg")
    )
    if os.path.commonpath([thumbnail_root, thumbnail_path]) != thumbnail_root:
        raise ValueError("Thumbnail path escapes the cache directory.")
    return source_path, thumbnail_path


def list_local_videos():
    files = []
    errors = []
    total_size = 0
    uploaded_stats = app_sql.uploaded_dashcam_file_stats()
    for abs_path, relative_path in app_dash.find_video_files(
        app_dash.DEFAULT_DESTINATION
    ):
        try:
            stat = os.stat(abs_path)
        except OSError as e:
            errors.append(f"{relative_path}: {e}")
            continue
        with _converting_lock:
            converting = relative_path in _converting
        files.append(
            {
                "path": relative_path,
                "size": stat.st_size,
                "modified_at": stat.st_mtime,
                "uploaded": (
                    relative_path,
                    stat.st_size,
                    stat.st_mtime,
                ) in uploaded_stats,
                "converting": converting,
            }
        )
        total_size += stat.st_size
    files.sort(key=lambda item: item["path"].lower())
    return {
        "status": "ok",
        "files": files,
        "count": len(files),
        "total_size": total_size,
        "errors": errors,
        "retention_days": retention_days(),
    }


def get_local_video_path(relative_path):
    return _local_path(relative_path)


def get_thumbnail_path(relative_path):
    """Return the thumbnail path if it exists, or kick off background generation.

    Raises:
        FileNotFoundError: source video not found.
        ValueError: path escapes base directory.
        RuntimeError("generating"): thumbnail is being generated — caller should 202.
        RuntimeError: ffmpeg failed (only propagated synchronously on first generation if
                      the greenlet hasn't launched yet, but typically never reaches caller).
    """
    source_path, thumbnail_path = _thumbnail_path(relative_path)
    source_mtime = os.path.getmtime(source_path)

    # Fast path: thumbnail already exists and is fresh.
    if (
        os.path.isfile(thumbnail_path)
        and os.path.getmtime(thumbnail_path) >= source_mtime
    ):
        return thumbnail_path

    # Check if generation is already running.
    with _generating_lock:
        if relative_path in _generating:
            raise RuntimeError("generating")
        _generating.add(relative_path)

    # Spawn background greenlet so the HTTP thread returns immediately.
    gevent.spawn(_generate_thumbnail_bg, relative_path, source_path, thumbnail_path)
    raise RuntimeError("generating")


def _generate_thumbnail_bg(relative_path, source_path, thumbnail_path):
    """Generate thumbnail in background greenlet. Cleans up _generating on exit."""
    try:
        if not app_dash.begin_local_video_use(relative_path):
            return
        try:
            os.makedirs(os.path.dirname(thumbnail_path), exist_ok=True)
            temporary_path = thumbnail_path + ".tmp.jpg"
            for seek_seconds in ("1", "0"):
                command = [
                    "ffmpeg",
                    "-nostdin",
                    "-loglevel",
                    "error",
                    "-ss",
                    seek_seconds,
                    "-i",
                    source_path,
                    "-frames:v",
                    "1",
                    "-vf",
                    "scale=320:-2",
                    "-q:v",
                    "5",
                    "-y",
                    temporary_path,
                ]
                try:
                    process = subprocess.Popen(
                        command,
                        stdout=subprocess.DEVNULL,
                        stderr=subprocess.PIPE,
                        text=True,
                    )
                except FileNotFoundError:
                    return
                while process.poll() is None:
                    sleep(0.05)
                process.communicate()
                if (
                    process.returncode == 0
                    and os.path.isfile(temporary_path)
                    and os.path.getsize(temporary_path) > 0
                ):
                    os.replace(temporary_path, thumbnail_path)
                    return
                if os.path.exists(temporary_path):
                    os.remove(temporary_path)
        finally:
            app_dash.end_local_video_use(relative_path)
    finally:
        with _generating_lock:
            _generating.discard(relative_path)


def delete_local_video(relative_path):
    try:
        video_path, thumbnail_path = _thumbnail_path(relative_path)
    except ValueError as e:
        return {"status": "invalid_path", "message": str(e)}
    except FileNotFoundError:
        return {
            "status": "not_found",
            "message": f"Local video not found: {relative_path}",
        }
    if not app_dash.begin_local_video_delete(relative_path):
        return {
            "status": "busy",
            "message": "This video is currently uploading or being deleted. Try again shortly.",
        }
    try:
        try:
            os.remove(video_path)
            if os.path.isfile(thumbnail_path):
                os.remove(thumbnail_path)
        except OSError as e:
            return {"status": "delete_failed", "message": str(e)}
    finally:
        app_dash.end_local_video_delete(relative_path)
    return {"status": "ok", "deleted": relative_path}


def retention_days():
    value = app_sql.get_setting(RETENTION_SETTING, "0")
    try:
        days = int(value)
    except (TypeError, ValueError):
        print(f"Invalid {RETENTION_SETTING} setting {value!r}; retention disabled.")
        return 0
    return max(days, 0)


def cleanup_uploaded_videos(now=None):
    """Delete uploaded local copies older than the configured number of days."""
    days = retention_days()
    if days <= 0:
        return {"enabled": False, "deleted": [], "errors": []}

    cutoff = (time.time() if now is None else now) - days * 86400
    deleted = []
    errors = []
    uploaded_stats = app_sql.uploaded_dashcam_file_stats()
    for abs_path, relative_path in app_dash.find_video_files(
        app_dash.DEFAULT_DESTINATION
    ):
        try:
            stat = os.stat(abs_path)
            if stat.st_mtime >= cutoff:
                continue
            if (relative_path, stat.st_size, stat.st_mtime) not in uploaded_stats:
                continue
            if not app_dash.begin_local_video_delete(relative_path):
                continue
            try:
                _source, thumbnail_path = _thumbnail_path(relative_path)
                os.remove(abs_path)
                if os.path.isfile(thumbnail_path):
                    os.remove(thumbnail_path)
                deleted.append(relative_path)
            finally:
                app_dash.end_local_video_delete(relative_path)
        except (OSError, ValueError) as e:
            errors.append(f"{relative_path}: {e}")
    return {"enabled": True, "deleted": deleted, "errors": errors}