"""썸네일 생성 — 영상 5초 프레임 추출 + 텍스트 오버레이."""
import os
import subprocess
import logging
from PIL import Image, ImageDraw, ImageFont

from . import storage

logger = logging.getLogger("music-lab.thumb")
THUMB_TIMEOUT_S = 60


class ThumbGenerationError(Exception):
    pass


def generate(*, pipeline_id: int, video_path: str,
             track_title: str = "", overlay_text: bool = True) -> dict:
    out_path = os.path.join(storage.pipeline_dir(pipeline_id), "thumbnail.jpg")
    cmd = ["ffmpeg", "-y", "-i", video_path,
           "-ss", "00:00:05", "-vframes", "1", "-q:v", "2", out_path]
    result = subprocess.run(cmd, capture_output=True, text=True, timeout=THUMB_TIMEOUT_S)
    if result.returncode != 0:
        raise ThumbGenerationError(f"ffmpeg 썸네일 실패: {result.stderr[-500:]}")

    if overlay_text and track_title:
        _overlay_title(out_path, track_title)

    return {"url": storage.media_url(pipeline_id, "thumbnail.jpg"), "used_fallback": False}


def _overlay_title(path: str, title: str) -> None:
    try:
        with Image.open(path) as src:
            img = src.convert("RGB")
        try:
            font = ImageFont.truetype("/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf", 80)
        except OSError:
            font = ImageFont.load_default()
        draw = ImageDraw.Draw(img)
        # 하단 30% 영역에 검정 반투명 박스 + 흰 글씨
        w, h = img.size
        box_h = int(h * 0.3)
        with Image.new("RGBA", (w, box_h), (0, 0, 0, 160)) as overlay:
            img.paste(overlay, (0, h - box_h), overlay)
        bbox = draw.textbbox((0, 0), title, font=font)
        tw = bbox[2] - bbox[0]
        draw.text(((w - tw) // 2, h - box_h + 30), title, fill=(255, 255, 255), font=font)
        img.save(path, "JPEG", quality=92)
    except Exception as e:
        logger.warning("썸네일 오버레이 실패: %s", e)