import argparse
import os
import re
import subprocess
from pathlib import Path

SRT_BLOCK_RE = re.compile(
    r"\s*(\d+)\s+([\d:,]+)\s+-->\s+([\d:,]+)\s+(.+?)(?=\n\s*\d+\s+\d\d:|\Z)",
    re.S,
)


def to_seconds(timestamp: str) -> float:
    h, m, rest = timestamp.split(":")
    s, ms = rest.split(",")
    return int(h) * 3600 + int(m) * 60 + int(s) + int(ms) / 1000


def read_srt(path: Path) -> list[tuple[float, float, str]]:
    text = path.read_text(encoding="utf-8-sig")
    captions = []
    for _, start, end, body in SRT_BLOCK_RE.findall(text):
        clean_text = " ".join(line.strip() for line in body.strip().splitlines())
        captions.append((to_seconds(start), to_seconds(end), clean_text))
    if not captions:
        raise ValueError(f"No captions found in {path}")
    return captions


def resolve_path(value: str) -> Path:
    return Path(value).expanduser().resolve()


def ps_quote(value: str) -> str:
    return "'" + value.replace("'", "''") + "'"


def media_duration(path: Path) -> float:
    result = subprocess.run(
        [
            "ffprobe",
            "-v", "error",
            "-show_entries", "format=duration",
            "-of", "default=noprint_wrappers=1:nokey=1",
            str(path),
        ],
        check=True,
        capture_output=True,
        text=True,
    )
    return float(result.stdout.strip())


def run(command: list[str]) -> None:
    print("Running:", " ".join(command))
    subprocess.run(command, check=True)


def speak_to_wav(text: str, voice: str, rate: int, output: Path) -> None:
    ps_script = f"""
Add-Type -AssemblyName System.Speech
$synth = New-Object System.Speech.Synthesis.SpeechSynthesizer
$synth.SelectVoice({ps_quote(voice)})
$synth.Rate = {rate}
$synth.SetOutputToWaveFile({ps_quote(str(output))})
$synth.Speak({ps_quote(text)})
$synth.Dispose()
"""
    run(["powershell", "-NoProfile", "-ExecutionPolicy", "Bypass", "-Command", ps_script])


def main() -> None:
    parser = argparse.ArgumentParser(description="Create a timed voiceover WAV/MP3 from an SRT file on Windows.")
    parser.add_argument("--srt", required=True, help="Input SRT file")
    parser.add_argument("--voice", default="Microsoft David Desktop", help="Windows voice name")
    parser.add_argument("--rate", type=int, default=0, help="Windows speech rate from -10 to 10. Higher is faster.")
    parser.add_argument("--wav", required=True, help="Output WAV file")
    parser.add_argument("--mp3", default=None, help="Optional output MP3 file")
    args = parser.parse_args()

    srt_path = resolve_path(args.srt)
    wav_output = resolve_path(args.wav)
    mp3_output = resolve_path(args.mp3) if args.mp3 else None
    work_dir = Path(__file__).resolve().parent / "voice_parts"

    if not srt_path.exists():
        raise FileNotFoundError(f"SRT not found: {srt_path}")

    work_dir.mkdir(parents=True, exist_ok=True)
    wav_output.parent.mkdir(parents=True, exist_ok=True)
    if mp3_output:
        mp3_output.parent.mkdir(parents=True, exist_ok=True)

    captions = read_srt(srt_path)
    segment_files = []

    for i, (start, end, text) in enumerate(captions, 1):
        duration = end - start
        raw_wav = work_dir / f"raw_{i:03d}.wav"
        segment_wav = work_dir / f"seg_{i:03d}.wav"

        speak_to_wav(text, args.voice, args.rate, raw_wav)

        spoken_duration = media_duration(raw_wav)
        if spoken_duration > duration:
            print(f"Warning: caption {i} speech is {spoken_duration:.2f}s but slot is {duration:.2f}s; it will be trimmed.")

        run([
            "ffmpeg", "-y",
            "-i", str(raw_wav),
            "-af", f"apad,atrim=0:{duration}",
            "-ar", "44100",
            "-ac", "2",
            str(segment_wav),
        ])
        segment_files.append(segment_wav)

    concat_list = work_dir / "list.txt"
    concat_list.write_text("".join(f"file '{os.path.abspath(file)}'\n" for file in segment_files), encoding="utf-8")

    run(["ffmpeg", "-y", "-f", "concat", "-safe", "0", "-i", str(concat_list), "-c:a", "pcm_s16le", str(wav_output)])
    print(f"Done: {wav_output}")

    if mp3_output:
        run(["ffmpeg", "-y", "-i", str(wav_output), "-codec:a", "libmp3lame", "-b:a", "192k", str(mp3_output)])
        print(f"Done: {mp3_output}")


if __name__ == "__main__":
    main()