#!/usr/bin/env python3
"""
Class recording watcher for Rocinante.

Watches C:/Recordings (mounted as /recordings) for new .wav files.
For each file detected:
  1. Waits for the file to finish being written
  2. Converts WAV -> MP3 via ffmpeg (deletes original WAV)
  3. Splits long recordings into 10-minute chunks
  4. Transcribes each chunk via local faster-whisper-server (large-v3, CUDA)
  5. Stitches results back together with corrected timestamps
  6. POSTs transcript + metadata to n8n /webhook/class/ingest

Folder convention: subfolder name = class name
  /recordings/HIST-2020/lecture-03-3.wav  ->  class=HIST-2020, title=lecture 03 3
"""

import os
import time
import subprocess
import logging
import requests
from pathlib import Path
from watchdog.observers.polling import PollingObserver as Observer
from watchdog.events import FileSystemEventHandler

# Config from environment
WHISPER_URL    = os.environ.get("WHISPER_URL",    "http://whisper:8000")
N8N_WEBHOOK    = os.environ.get("N8N_WEBHOOK_URL", "https://n8n.paccoco.com/webhook/class/ingest")
WATCH_DIR      = os.environ.get("WATCH_DIR",       "/recordings")
WHISPER_MODEL  = os.environ.get("WHISPER_MODEL",   "large-v3")
CHUNK_MINUTES  = int(os.environ.get("CHUNK_MINUTES", "10"))

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s  %(levelname)-8s  %(message)s",
    datefmt="%Y-%m-%d %H:%M:%S",
)
log = logging.getLogger("watcher")


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------

def wait_for_file_stable(path: Path, interval: float = 2.0, required_stable: int = 3) -> None:
    """Block until the file size stops changing (i.e. the copy is complete)."""
    log.info(f"Waiting for {path.name} to finish writing...")
    prev_size = -1
    stable_count = 0
    while stable_count < required_stable:
        try:
            size = path.stat().st_size
        except FileNotFoundError:
            time.sleep(interval)
            continue
        if size == prev_size and size > 0:
            stable_count += 1
        else:
            stable_count = 0
        prev_size = size
        time.sleep(interval)
    log.info(f"{path.name} is stable ({prev_size:,} bytes)")

    # Extra check: verify the file handle is released and readable
    for attempt in range(60):
        try:
            with open(path, 'rb') as f:
                f.read(1024)
            break
        except (PermissionError, OSError) as e:
            log.info(f"File not yet readable ({e}), retrying... ({attempt + 1}/60)")
            time.sleep(5)
    else:
        raise RuntimeError(f"File {path.name} is not readable after 60 attempts")


def convert_to_mp3(wav_path: Path) -> Path:
    mp3_path = wav_path.with_suffix(".mp3")
    log.info(f"Converting to MP3: {wav_path.name}")
    result = subprocess.run(
        [
            "ffmpeg", "-y",
            "-i", str(wav_path),
            "-codec:a", "libmp3lame",
            "-qscale:a", "4",
            str(mp3_path),
        ],
        capture_output=True,
        text=True,
    )
    if result.returncode != 0:
        raise RuntimeError(f"ffmpeg failed:\n{result.stderr}")
    wav_path.unlink()
    log.info(f"Deleted original WAV: {wav_path.name}")
    return mp3_path


def get_duration(mp3_path: Path) -> float:
    """Return audio duration in seconds via ffprobe."""
    result = subprocess.run(
        [
            "ffprobe", "-v", "quiet",
            "-show_entries", "format=duration",
            "-of", "csv=p=0",
            str(mp3_path),
        ],
        capture_output=True,
        text=True,
    )
    return float(result.stdout.strip() or "0")


def split_into_chunks(mp3_path: Path, chunk_minutes: int = CHUNK_MINUTES) -> list:
    """Split MP3 into chunks. Returns [mp3_path] if short enough."""
    duration = get_duration(mp3_path)
    chunk_secs = chunk_minutes * 60

    if duration <= chunk_secs:
        log.info(f"Recording is {duration/60:.1f}min — no splitting needed")
        return [mp3_path]

    total_chunks = int(duration / chunk_secs) + 1
    log.info(f"Recording is {duration/60:.1f}min — splitting into {total_chunks} x {chunk_minutes}min chunks")

    chunks = []
    start = 0.0
    i = 0
    while start < duration:
        chunk_path = mp3_path.parent / f"{mp3_path.stem}_chunk{i:03d}.mp3"
        subprocess.run(
            [
                "ffmpeg", "-y",
                "-i", str(mp3_path),
                "-ss", str(start),
                "-t", str(chunk_secs),
                "-codec:a", "copy",
                str(chunk_path),
            ],
            capture_output=True,
        )
        chunks.append((chunk_path, start))
        start += chunk_secs
        i += 1

    return chunks


def transcribe_chunk(mp3_path: Path) -> dict:
    with open(mp3_path, "rb") as f:
        resp = requests.post(
            f"{WHISPER_URL}/v1/audio/transcriptions",
            files={"file": (mp3_path.name, f, "audio/mpeg")},
            data={
                "model":           WHISPER_MODEL,
                "language":        "en",
                "response_format": "verbose_json",
            },
            timeout=3600,
        )
    resp.raise_for_status()
    return resp.json()


def transcribe(mp3_path: Path) -> dict:
    """Transcribe an MP3, splitting into chunks if needed."""
    chunks = split_into_chunks(mp3_path)

    # Short recording — single chunk, no splitting
    if len(chunks) == 1 and isinstance(chunks[0], Path):
        log.info(f"Transcribing {mp3_path.name} with {WHISPER_MODEL}...")
        result = transcribe_chunk(mp3_path)
        result["segments"] = deduplicate_hallucinations(result.get("segments", []))
        log.info("Transcription complete")
        return result

    # Long recording — transcribe each chunk and stitch
    all_segments = []
    all_text = []

    for i, (chunk_path, time_offset) in enumerate(chunks):
        log.info(f"Transcribing chunk {i+1}/{len(chunks)}: {chunk_path.name} (offset {time_offset/60:.1f}min)")
        try:
            result = transcribe_chunk(chunk_path)
            segments = result.get("segments", [])
            for s in segments:
                s["start"] = s.get("start", 0) + time_offset
                s["end"]   = s.get("end",   0) + time_offset
            all_segments.extend(segments)
            all_text.append(result.get("text", "").strip())
        except Exception as e:
            log.error(f"Chunk {i+1} failed: {e}")
        finally:
            chunk_path.unlink(missing_ok=True)

    all_segments = deduplicate_hallucinations(all_segments)
    total_duration = get_duration(mp3_path)
    log.info(f"Transcription complete — {len(chunks)} chunks stitched")
    return {
        "text":     " ".join(all_text),
        "segments": all_segments,
        "duration": total_duration,
    }


def is_silence(text: str) -> bool:
    """Return True if the segment is just silence/noise markers."""
    stripped = text.strip()
    return not stripped or all(c in '.…♪ \t' for c in stripped)


def deduplicate_hallucinations(segments: list, max_repeats: int = 3) -> list:
    """
    Remove Whisper phrase-loop hallucinations.

    When Whisper gets stuck it emits the same segment text hundreds of times
    in a row (e.g. "I'm also a software engineer." × 200).  This function
    collapses any run longer than `max_repeats` down to at most `max_repeats`
    occurrences and logs a warning so the truncation is visible in the logs.
    """
    if not segments:
        return segments

    result = []
    i = 0
    while i < len(segments):
        text = segments[i].get("text", "").strip().lower()
        j = i + 1
        while j < len(segments) and segments[j].get("text", "").strip().lower() == text:
            j += 1
        count = j - i
        if count > max_repeats:
            log.warning(
                f"Hallucination detected: '{segments[i].get('text', '').strip()[:60]}'"
                f" × {count} — keeping {max_repeats}, dropping {count - max_repeats}"
            )
            result.extend(segments[i : i + max_repeats])
        else:
            result.extend(segments[i:j])
        i = j

    return result


def build_timestamped(segments: list) -> str:
    lines = []
    for s in segments:
        text = s.get('text', '').strip()
        if is_silence(text):
            continue
        mins = int(s.get("start", 0) // 60)
        secs = int(s.get("start", 0) % 60)
        lines.append(f"[{mins}:{secs:02d}] {text}")
    return "\n".join(lines)


def send_to_n8n(class_name: str, lecture_title: str, result: dict) -> None:
    segments = result.get("segments", [])
    # Filter silence from full text
    meaningful = [s.get("text", "") for s in segments if not is_silence(s.get("text", ""))]
    full_text = " ".join(meaningful).strip() or result.get("text", "").strip()
    duration  = result.get("duration") or (segments[-1].get("end", 0) if segments else 0)

    payload = {
        "class_name":             class_name,
        "lecture_title":          lecture_title,
        "transcript":             full_text,
        "timestamped_transcript": build_timestamped(segments),
        "duration_seconds":       duration,
    }

    log.info(f"Sending to n8n: {class_name} / {lecture_title} ({len(full_text)} chars)")
    resp = requests.post(N8N_WEBHOOK, json=payload, timeout=300)
    resp.raise_for_status()
    log.info(f"n8n accepted — HTTP {resp.status_code}")


# ---------------------------------------------------------------------------
# Processing pipeline
# ---------------------------------------------------------------------------

def process_wav(wav_path: Path) -> None:
    # Must be inside a class subfolder, not the root recordings dir
    if wav_path.parent == Path(WATCH_DIR):
        log.warning(f"Skipping {wav_path.name} — drop files into a class subfolder, e.g. /recordings/HIST-2020/")
        return

    class_name    = wav_path.parent.name
    lecture_title = wav_path.stem.replace("-", " ").replace("_", " ")

    log.info(f"--- Processing: {class_name} / {lecture_title} ---")

    wait_for_file_stable(wav_path)
    mp3_path = convert_to_mp3(wav_path)

    result = transcribe(mp3_path)
    send_to_n8n(class_name, lecture_title, result)

    log.info(f"--- Done: {class_name} / {lecture_title} ---")


# ---------------------------------------------------------------------------
# Watchdog handler
# ---------------------------------------------------------------------------

class WavHandler(FileSystemEventHandler):
    def on_created(self, event):
        if event.is_directory:
            return
        path = Path(event.src_path)
        if path.suffix.lower() == ".wav":
            log.info(f"Detected new WAV: {path}")
            try:
                process_wav(path)
            except Exception as exc:
                log.error(f"Failed to process {path}: {exc}", exc_info=True)


# ---------------------------------------------------------------------------
# Entry point
# ---------------------------------------------------------------------------

def scan_existing(watch_dir: Path) -> None:
    """Process any .wav files already present at startup."""
    existing = list(watch_dir.rglob("*.wav")) + list(watch_dir.rglob("*.WAV"))
    if not existing:
        return
    log.info(f"Found {len(existing)} existing WAV(s) at startup — processing...")
    for wav in existing:
        try:
            process_wav(wav)
        except Exception as exc:
            log.error(f"Failed to process {wav}: {exc}", exc_info=True)


if __name__ == "__main__":
    watch_dir = Path(WATCH_DIR)
    watch_dir.mkdir(parents=True, exist_ok=True)

    log.info(f"Whisper URL  : {WHISPER_URL}")
    log.info(f"n8n webhook  : {N8N_WEBHOOK}")
    log.info(f"Watching     : {watch_dir} (recursive)")

    # Process any WAVs already sitting in the folder
    scan_existing(watch_dir)

    observer = Observer()
    observer.schedule(WavHandler(), str(watch_dir), recursive=True)
    observer.start()
    log.info("Watcher started — drop a .wav into a class subfolder to begin")

    try:
        while True:
            time.sleep(1)
    except KeyboardInterrupt:
        pass
    finally:
        observer.stop()
        observer.join()
        log.info("Watcher stopped")