import os
import shutil
import subprocess
import tempfile
from pathlib import Path

from PIL import Image

from config import Config
from models import JobStore


def _ffmpeg_available() -> bool:
    return shutil.which('ffmpeg') is not None


def _prepare_image(image_path: Path, output_path: Path, width: int, height: int) -> None:
    img = Image.open(image_path)
    img = img.convert('RGB')

    # Fit inside target box, then letterbox/pillarbox with black to exact 16:9
    img.thumbnail((width, height), Image.LANCZOS)

    canvas = Image.new('RGB', (width, height), (0, 0, 0))
    x = (width - img.width) // 2
    y = (height - img.height) // 2
    canvas.paste(img, (x, y))
    canvas.save(output_path, 'JPEG', quality=95)


def _build_video(image_path: Path, audio_path: Path, output_path: Path, cfg: Config) -> None:
    if not _ffmpeg_available():
        raise RuntimeError('ffmpeg is not installed or not on PATH')

    with tempfile.TemporaryDirectory() as tmpdir:
        tmp = Path(tmpdir)
        prepared_image = tmp / 'prepared.jpg'
        _prepare_image(image_path, prepared_image, cfg.VIDEO_WIDTH, cfg.VIDEO_HEIGHT)

        cmd = [
            'ffmpeg',
            '-y',
            '-loop', '1',
            '-framerate', str(cfg.VIDEO_FPS),
            '-i', str(prepared_image),
            '-i', str(audio_path),
            '-c:v', cfg.VIDEO_CODEC,
            '-pix_fmt', 'yuv420p',
            '-preset', 'medium',
            '-b:v', cfg.VIDEO_BITRATE,
            '-c:a', cfg.AUDIO_CODEC,
            '-b:a', cfg.AUDIO_BITRATE,
            '-movflags', '+faststart',
            '-shortest',
            str(output_path),
        ]
        result = subprocess.run(cmd, capture_output=True, text=True)
        if result.returncode != 0:
            raise RuntimeError(f'ffmpeg failed: {result.stderr}')


def process_job(job_id: int, store: JobStore, cfg: Config) -> None:
    job = store.get_job(job_id)
    if job is None:
        return

    image_path = cfg.UPLOAD_FOLDER / job['image_file']
    audio_path = cfg.UPLOAD_FOLDER / job['audio_file']
    output_filename = f"job-{job_id}.{cfg.OUTPUT_FORMAT}"
    output_path = cfg.OUTPUT_FOLDER / output_filename

    try:
        cfg.OUTPUT_FOLDER.mkdir(parents=True, exist_ok=True)
        _build_video(image_path, audio_path, output_path, cfg)
        store.update_status(job_id, 'complete', output_file=output_filename)
    except Exception as exc:
        store.update_status(job_id, 'error', error_message=str(exc))
        raise