import logging
import subprocess
from dataclasses import dataclass
from pathlib import Path

logger = logging.getLogger(__name__)


@dataclass
class ChunkInfo:
    """Metadata for a single audio chunk."""

    path: str
    start_offset: float
    duration: float


def get_audio_duration(wav_path: str) -> float:
    """Get duration of audio file in seconds using ffprobe."""
    cmd = [
        "ffprobe", "-v", "quiet",
        "-show_entries", "format=duration",
        "-of", "csv=p=0",
        wav_path,
    ]
    result = subprocess.run(cmd, capture_output=True, text=True, timeout=30)
    if result.returncode != 0:
        raise RuntimeError(f"ffprobe failed: {result.stderr[:300]}")
    return float(result.stdout.strip())


def chunk_audio(wav_path: str, max_duration_sec: int = 1800) -> list[ChunkInfo]:
    """Split audio into chunks if longer than max_duration_sec.

    Args:
        wav_path: Path to the preprocessed WAV file.
        max_duration_sec: Maximum chunk duration in seconds (default 30 min).

    Returns:
        List of ChunkInfo with paths and timing metadata.
    """
    total_duration = get_audio_duration(wav_path)
    logger.info("Audio duration: %.1f sec", total_duration)

    if total_duration <= max_duration_sec:
        return [ChunkInfo(path=wav_path, start_offset=0.0, duration=total_duration)]

    chunks = []
    src = Path(wav_path)
    chunk_dir = src.parent / "chunks"
    chunk_dir.mkdir(exist_ok=True)

    offset = 0.0
    idx = 0
    while offset < total_duration:
        chunk_path = str(chunk_dir / f"{src.stem}_chunk{idx:03d}.wav")
        remaining = total_duration - offset
        duration = min(max_duration_sec, remaining)

        cmd = [
            "ffmpeg", "-y",
            "-ss", str(offset),
            "-i", wav_path,
            "-t", str(duration),
            "-c", "copy",
            chunk_path,
        ]
        result = subprocess.run(cmd, capture_output=True, text=True, timeout=300)
        if result.returncode != 0:
            raise RuntimeError(f"Chunk {idx} failed: {result.stderr[:300]}")

        chunks.append(ChunkInfo(
            path=chunk_path,
            start_offset=offset,
            duration=duration,
        ))
        logger.info("Chunk %d: %.1fs - %.1fs", idx, offset, offset + duration)

        offset += duration
        idx += 1

    return chunks