"""
Frame-Service - 关键帧抽帧与人物头像裁剪（Oracle 端集中计算）

新架构 v4（2026-08-21 重构）:
- extract_frame: 按 video_id + 绝对时间戳，ffmpeg 精确抽帧，磁盘缓存
- build_avatar:  用该人物候选事件里随视频分析一次性产出的 bbox（person_appearances
                 里的 [ymin,xmin,ymax,xmax]）直接裁剪，不再额外调用模型定位人物。

v3 曾经的做法是在展示缩略图/头像时另外调用一次 Gemini 做人物定位校验，这会和核心
视频分析共用同一份 Gemini Key 抢配额（实测两边同时打 429），且当时的坐标解析本身
也有 bug（错把 Gemini 原生 [ymin,xmin,ymax,xmax]/1000 当成 [x1,y1,x2,y2]/1）。v4
把 bbox 改成随视频分析那一次 Gemini 调用一并产出（见 ai_orchestrator/prompts.py 的
person_appearances.bbox 字段），frame_service 只做纯本地的抽帧/裁剪，不再对任何
模型发起请求，从架构上消除配额争抢。

所有产物落到 CACHE_DIR，以 (video_id, offset) 或 label 为 key，避免重复计算。
NAS 侧只负责代理与展示，不做任何图像计算。
"""
import os
import shutil
import subprocess
import tempfile
from datetime import datetime

from .logger import setup_logger

logger = setup_logger('fam-edge.frame_service')

try:
    from .config_loader import load_config
    _CFG = load_config().get('frame_service', {})
except Exception:
    _CFG = {}

CACHE_DIR = _CFG.get('cache_dir', '/opt/fam-edge/frames_cache')
FFMPEG = shutil.which('ffmpeg') or 'ffmpeg'
FFPROBE = shutil.which('ffprobe') or 'ffprobe'
AVATAR_W = int(_CFG.get('avatar_width', 160))
FRAME_W = int(_CFG.get('frame_width', 400))


def _ensure_dir():
    os.makedirs(CACHE_DIR, exist_ok=True)


def _parse_dt(ts_str: str):
    try:
        return datetime.strptime(ts_str.strip()[:19], '%Y-%m-%d %H:%M:%S')
    except (ValueError, TypeError):
        return None


def _run_ffmpeg(args, timeout=60) -> bool:
    try:
        proc = subprocess.run([FFMPEG, '-hide_banner', '-loglevel', 'error', *args],
                              capture_output=True, timeout=timeout)
        return proc.returncode == 0
    except (subprocess.TimeoutExpired, OSError):
        return False


def _out_size(path):
    """ffprobe 读图片宽高 -> (w, h) 或 None"""
    try:
        out = subprocess.run(
            [FFPROBE, '-v', 'error', '-select_streams', 'v:0',
             '-show_entries', 'stream=width,height', '-of', 'csv=s=x:p=0', path],
            capture_output=True, text=True, timeout=20).stdout.strip()
        w, h = out.split('x')
        return int(w), int(h)
    except Exception:
        return None


def extract_frame(db, video_id: int, ts: str, width: int = FRAME_W) -> bytes:
    """按 video_id + 绝对时间戳抽帧，返回 jpeg bytes（带磁盘缓存）"""
    if not FFMPEG:
        return None
    row = db.get_video_by_id(video_id)
    if not row:
        return None
    local_path = row['local_path']
    if not local_path or not os.path.isfile(local_path):
        logger.warning(f"[video_id={video_id}] 视频文件不存在: {local_path}")
        return None
    start = _parse_dt(row['event_start_time'] or '')
    t = _parse_dt(ts)
    if t and start:
        offset = max(0.0, (t - start).total_seconds())
    else:
        offset = 0.0

    _ensure_dir()
    cache = os.path.join(CACHE_DIR, f"frame_{video_id}_{int(offset)}.jpg")
    if os.path.isfile(cache) and os.path.getsize(cache) > 0:
        with open(cache, 'rb') as f:
            return f.read()

    fd, tmp = tempfile.mkstemp(suffix='.jpg', dir=CACHE_DIR)
    os.close(fd)
    try:
        # 粗 seek（-i 前，关键帧快进）+ 精 seek（-i 后，逐帧解码）：
        # 纯输入端 seek 只能跳到最近关键帧，事件按 3s 密度打点时若 GOP 间隔
        # 大于 3s 会抽到别的关键帧，导致画面与描述对不上。
        coarse = max(0.0, offset - 5.0)
        fine = offset - coarse
        ok = _run_ffmpeg([
            '-ss', f'{coarse:.3f}', '-i', local_path,
            '-ss', f'{fine:.3f}',
            '-frames:v', '1', '-vf', f'scale={width}:-2',
            '-q:v', '5', '-f', 'image2', '-y', tmp,
        ], timeout=120)
        if not ok or not os.path.isfile(tmp) or os.path.getsize(tmp) == 0:
            return None
        with open(tmp, 'rb') as f:
            data = f.read()
        os.replace(tmp, cache)  # 原子落缓存
        return data
    finally:
        if os.path.exists(tmp):
            try:
                os.remove(tmp)
            except OSError:
                pass


def _bbox_to_pixels(bbox, width, height):
    """bbox 为 [ymin,xmin,ymax,xmax]，0-1000 归一化 -> 像素 (x1,y1,x2,y2)。"""
    ymin, xmin, ymax, xmax = bbox
    x1, y1 = xmin / 1000.0 * width, ymin / 1000.0 * height
    x2, y2 = xmax / 1000.0 * width, ymax / 1000.0 * height
    return int(x1), int(y1), int(x2), int(y2)


def _crop_ffmpeg(img_path: str, bbox_px, target_w) -> bool:
    """按像素 bbox 裁剪居中并缩小为正方形，覆盖 img_path。失败返回 False。"""
    size = _out_size(img_path)
    if not size:
        return False
    w, h = size
    x1, y1, x2, y2 = bbox_px
    x1, x2 = max(0, x1), min(w, x2)
    y1, y2 = max(0, y1), min(h, y2)
    if x2 - x1 <= 0 or y2 - y1 <= 0:
        return False
    px, py = int((x2 - x1) * 0.3), int((y2 - y1) * 0.3)
    x1, y1 = max(0, x1 - px), max(0, y1 - py)
    x2, y2 = min(w, x2 + px), min(h, y2 + py)
    cw, ch = x2 - x1, y2 - y1
    if cw <= 0 or ch <= 0:
        return False
    return _apply_filter(img_path, f'crop={cw}:{ch}:{x1}:{y1},scale={target_w}:{target_w}')


def _center_square_ffmpeg(img_path: str, target_w) -> bool:
    """整帧居中正方形裁剪缩小，当人物没有 bbox 时兜底"""
    size = _out_size(img_path)
    if not size:
        return False
    w, h = size
    side = min(w, h)
    cx, cy = (w - side) // 2, (h - side) // 2
    return _apply_filter(img_path, f'crop={side}:{side}:{cx}:{cy},scale={target_w}:{target_w}')


def _apply_filter(img_path: str, vf: str) -> bool:
    fd, tmp = tempfile.mkstemp(suffix='.jpg', dir=CACHE_DIR)
    os.close(fd)
    try:
        if not _run_ffmpeg(['-i', img_path, '-vf', vf,
                            '-q:v', '5', '-frames:v', '1', '-f', 'image2', '-y', tmp]):
            return False
        os.replace(tmp, img_path)
        return True
    finally:
        if os.path.exists(tmp):
            try:
                os.remove(tmp)
            except OSError:
                pass


def build_avatar(db, label: str, width: int = AVATAR_W) -> bytes:
    """为人物构建头像：用候选事件里已经随视频分析产出的 bbox 直接裁剪；
    没有任何候选事件带 bbox 时，回退整帧居中裁剪。零额外模型调用。
    cache key = avatar_{label}。"""
    _ensure_dir()
    cache = os.path.join(CACHE_DIR, f"avatar_{label}.jpg")
    if os.path.isfile(cache) and os.path.getsize(cache) > 0:
        with open(cache, 'rb') as f:
            return f.read()

    events = db.get_events_for_label(label, limit=6)
    if not events:
        return None

    fd, tmp = tempfile.mkstemp(suffix='.jpg', dir=CACHE_DIR)
    os.close(fd)
    try:
        crop_data = None
        first_good = None
        for ev in events:
            src = extract_frame(db, ev['video_id'], ev['ts'], width=600)
            if src is None:
                continue
            with open(tmp, 'wb') as f:
                f.write(src)
            if first_good is None:
                first_good = os.path.getsize(tmp) > 0
            bbox = ev.get('bbox')
            if bbox:
                size = _out_size(tmp)
                if size and _crop_ffmpeg(tmp, _bbox_to_pixels(bbox, *size), width):
                    crop_data = ('bbox', os.path.getsize(tmp))
                    break
        # 兜底：首张可用的帧整帧居中（候选事件都没有 bbox 时）
        if crop_data is None:
            if first_good and _center_square_ffmpeg(tmp, width):
                crop_data = ('fallback', os.path.getsize(tmp))
        if crop_data is None:
            return None
        with open(tmp, 'rb') as f:
            data = f.read()
        if data:
            os.replace(tmp, cache)
        return data
    finally:
        if os.path.exists(tmp):
            try:
                os.remove(tmp)
            except OSError:
                pass