#!/usr/bin/env python3
"""
Overnight Video Transcoder
Transcodes large video files to HEVC to save space.
Runs via cron between 02:00-07:00.

Usage:
    overnight_transcoder.py          # Normal run
    overnight_transcoder.py --dry    # Dry run - show what would be transcoded
    overnight_transcoder.py --stats  # Show statistics
    overnight_transcoder.py --verbose # Extra debug output
"""

import os
import sys
import json
import subprocess
import shutil
import logging
import argparse
import sqlite3
import traceback
import re
import signal
from pathlib import Path
from datetime import datetime, time
from typing import Optional, List, Dict, Tuple
from contextlib import contextmanager

# Parse arguments
parser = argparse.ArgumentParser(description="Overnight video transcoder")
parser.add_argument("--dry", action="store_true", help="Dry run - don't transcode, just show what would happen")
parser.add_argument("--stats", action="store_true", help="Show cache statistics and exit")
parser.add_argument("--failed", action="store_true", help="Show failed transcodes and exit")
parser.add_argument("--retry-failed", action="store_true", help="Reset failed files to pending for retry")
parser.add_argument("--clear-cache", action="store_true", help="Clear the cache and exit")
parser.add_argument("--verbose", "-v", action="store_true", help="Verbose debug output")
parser.add_argument("--json-log", action="store_true", help="Output structured JSON logs (one per line)")
args = parser.parse_args()

DRY_RUN = args.dry
VERBOSE = args.verbose
JSON_LOG = args.json_log

# Track current transcode for signal handling
CURRENT_TRANSCODE = {"path": None, "pid": None, "start_time": None}

# Configuration
CONFIG = {
    "source_dirs": [
        "/disks/Plex/Anime",
        "/disks/Plex/Films",
        "/disks/Plex/TV",
    ],
    "cleanup_dir": "/disks/Plex/.cleanup",
    "log_dir": "/var/log",
    "log_file": "/var/log/transcoder.log",
    "db_file": "/var/lib/transcoder/cache.db",
    "video_extensions": [".mkv", ".mp4", ".avi", ".m4v", ".mov", ".wmv"],
    "cutoff_time": time(6, 30),  # Don't start new encodes after 06:30
    "cleanup_days": 7,  # Delete originals after 7 days
    
    # FFmpeg settings
    "crf": 20,
    "preset": "slow",
    "audio_codec": "ac3",
    "audio_bitrate": "640k",
    "threads": 12,
}


def init_db() -> sqlite3.Connection:
    """Initialize the SQLite database for caching file info."""
    db_path = Path(CONFIG["db_file"])
    db_path.parent.mkdir(parents=True, exist_ok=True)
    
    conn = sqlite3.connect(CONFIG["db_file"])
    
    # Main files table - tracks all video files
    conn.execute("""
        CREATE TABLE IF NOT EXISTS files (
            path TEXT PRIMARY KEY,
            filename TEXT,
            directory TEXT,
            original_size INTEGER,
            mtime REAL,
            video_codec TEXT,
            audio_codec TEXT,
            is_hevc INTEGER,
            first_seen REAL,
            scanned_at REAL,
            
            -- Transcode info (NULL if not transcoded)
            status TEXT DEFAULT 'pending',  -- pending, transcoding, done, failed, stalled
            transcoded_at REAL,
            transcoded_size INTEGER,
            transcode_duration_secs REAL,
            transcode_settings TEXT,  -- JSON: {crf, preset, audio_codec, audio_bitrate}
            failure_reason TEXT,
            
            -- Computed (updated after transcode)
            space_saved INTEGER,
            compression_ratio REAL
        )
    """)
    conn.execute("CREATE INDEX IF NOT EXISTS idx_is_hevc ON files(is_hevc)")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_status ON files(status)")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_size ON files(original_size)")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_directory ON files(directory)")
    
    # Stats summary table - running totals
    conn.execute("""
        CREATE TABLE IF NOT EXISTS stats (
            id INTEGER PRIMARY KEY CHECK (id = 1),  -- Single row
            total_files_transcoded INTEGER DEFAULT 0,
            total_space_saved INTEGER DEFAULT 0,
            total_transcode_time_secs REAL DEFAULT 0,
            last_updated REAL
        )
    """)
    conn.execute("INSERT OR IGNORE INTO stats (id) VALUES (1)")
    
    conn.commit()
    return conn


def get_audio_codec(filepath: str) -> Optional[str]:
    """Get the audio codec of a file using ffprobe."""
    try:
        result = subprocess.run([
            "ffprobe", "-v", "quiet",
            "-select_streams", "a:0",
            "-show_entries", "stream=codec_name",
            "-of", "json",
            filepath
        ], capture_output=True, text=True, timeout=30)
        
        if result.returncode == 0:
            data = json.loads(result.stdout)
            streams = data.get("streams", [])
            if streams:
                return streams[0].get("codec_name", "").lower()
    except Exception as e:
        log.warning(f"Failed to probe audio {filepath}: {e}")
    return None


def get_cached_file(conn: sqlite3.Connection, filepath: str, size: int, mtime: float) -> Optional[dict]:
    """Get cached file info if file hasn't changed. Returns dict or None."""
    cursor = conn.execute(
        """SELECT video_codec, audio_codec, is_hevc, status 
           FROM files WHERE path = ? AND original_size = ? AND mtime = ?""",
        (filepath, size, mtime)
    )
    row = cursor.fetchone()
    if row:
        return {
            "video_codec": row[0],
            "audio_codec": row[1],
            "is_hevc": bool(row[2]),
            "status": row[3]
        }
    return None


def cache_file(conn: sqlite3.Connection, filepath: str, size: int, mtime: float, 
               video_codec: str, audio_codec: str, is_hevc: bool):
    """Cache file info."""
    p = Path(filepath)
    now = datetime.now().timestamp()
    
    # Check if file already exists (to preserve first_seen)
    cursor = conn.execute("SELECT first_seen FROM files WHERE path = ?", (filepath,))
    row = cursor.fetchone()
    first_seen = row[0] if row else now
    
    conn.execute("""
        INSERT OR REPLACE INTO files 
        (path, filename, directory, original_size, mtime, video_codec, audio_codec, 
         is_hevc, first_seen, scanned_at, status)
        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 
                COALESCE((SELECT status FROM files WHERE path = ?), 'pending'))
    """, (filepath, p.name, str(p.parent), size, mtime, video_codec, audio_codec,
          int(is_hevc), first_seen, now, filepath))
    conn.commit()


def update_transcode_result(conn: sqlite3.Connection, filepath: str, new_path: str,
                            new_size: int, duration_secs: float, settings: dict,
                            success: bool, failure_reason: str = None):
    """Update database after transcode attempt."""
    now = datetime.now().timestamp()
    
    if success:
        cursor = conn.execute("SELECT original_size FROM files WHERE path = ?", (filepath,))
        row = cursor.fetchone()
        original_size = row[0] if row else 0
        
        space_saved = original_size - new_size
        compression_ratio = new_size / original_size if original_size > 0 else 0
        
        conn.execute("""
            UPDATE files SET
                status = 'done',
                transcoded_at = ?,
                transcoded_size = ?,
                transcode_duration_secs = ?,
                transcode_settings = ?,
                space_saved = ?,
                compression_ratio = ?,
                failure_reason = NULL
            WHERE path = ?
        """, (now, new_size, duration_secs, json.dumps(settings), 
              space_saved, compression_ratio, filepath))
        
        # Update running totals
        conn.execute("""
            UPDATE stats SET
                total_files_transcoded = total_files_transcoded + 1,
                total_space_saved = total_space_saved + ?,
                total_transcode_time_secs = total_transcode_time_secs + ?,
                last_updated = ?
            WHERE id = 1
        """, (space_saved, duration_secs, now))
    else:
        conn.execute("""
            UPDATE files SET
                status = 'failed',
                failure_reason = ?
            WHERE path = ?
        """, (failure_reason, filepath))
    
    conn.commit()


def remove_from_cache(conn: sqlite3.Connection, filepath: str):
    """Remove a file from the cache."""
    conn.execute("DELETE FROM files WHERE path = ?", (filepath,))
    conn.commit()


def get_cache_stats(conn: sqlite3.Connection) -> dict:
    """Get comprehensive stats from the cache."""
    # File counts and sizes
    cursor = conn.execute("""
        SELECT 
            COUNT(*) as total,
            SUM(CASE WHEN is_hevc = 1 THEN 1 ELSE 0 END) as hevc_count,
            SUM(CASE WHEN is_hevc = 0 AND status = 'pending' THEN 1 ELSE 0 END) as pending_count,
            SUM(CASE WHEN status = 'done' THEN 1 ELSE 0 END) as done_count,
            SUM(CASE WHEN status = 'failed' THEN 1 ELSE 0 END) as failed_count,
            SUM(CASE WHEN is_hevc = 1 THEN original_size ELSE 0 END) as hevc_size,
            SUM(CASE WHEN is_hevc = 0 AND status = 'pending' THEN original_size ELSE 0 END) as pending_size
        FROM files
    """)
    row = cursor.fetchone()
    file_stats = {
        "total": row[0] or 0,
        "hevc_count": row[1] or 0,
        "pending_count": row[2] or 0,
        "done_count": row[3] or 0,
        "failed_count": row[4] or 0,
        "hevc_size": row[5] or 0,
        "pending_size": row[6] or 0,
    }
    
    # Running totals
    cursor = conn.execute("SELECT * FROM stats WHERE id = 1")
    row = cursor.fetchone()
    if row:
        file_stats["total_transcoded"] = row[1] or 0
        file_stats["total_space_saved"] = row[2] or 0
        file_stats["total_transcode_time"] = row[3] or 0
    
    # By directory breakdown
    cursor = conn.execute("""
        SELECT directory, 
               COUNT(*) as count,
               SUM(CASE WHEN is_hevc = 0 AND status = 'pending' THEN original_size ELSE 0 END) as pending_size
        FROM files 
        GROUP BY directory
        ORDER BY pending_size DESC
        LIMIT 10
    """)
    file_stats["by_directory"] = cursor.fetchall()
    
    return file_stats

# Ensure log directory exists (skip for /var/log which requires root)
if not CONFIG["log_dir"].startswith("/var/"):
    Path(CONFIG["log_dir"]).mkdir(parents=True, exist_ok=True)

# Set up logging
log_level = logging.DEBUG if VERBOSE else logging.INFO
logging.basicConfig(
    level=log_level,
    format='%(asctime)s [%(levelname)s] %(message)s',
    handlers=[
        logging.FileHandler(CONFIG["log_file"]),
        logging.StreamHandler(sys.stdout)
    ]
)
log = logging.getLogger(__name__)


def log_json(event: str, **data):
    """Write structured JSON log entry (for machine parsing)."""
    if not JSON_LOG:
        return
    entry = {
        "ts": datetime.now().isoformat(),
        "event": event,
        **data
    }
    print(json.dumps(entry), file=sys.stderr)


def format_bytes(size: int) -> str:
    """Human-readable byte size."""
    for unit in ['B', 'KB', 'MB', 'GB', 'TB']:
        if abs(size) < 1024.0:
            return f"{size:.2f} {unit}"
        size /= 1024.0
    return f"{size:.2f} PB"


def format_duration(seconds: float) -> str:
    """Human-readable duration."""
    if seconds < 60:
        return f"{seconds:.1f}s"
    elif seconds < 3600:
        return f"{seconds/60:.1f}m"
    else:
        return f"{seconds/3600:.1f}h"


def get_disk_space(path: str) -> dict:
    """Get disk space info for a path."""
    try:
        stat = os.statvfs(path)
        total = stat.f_blocks * stat.f_frsize
        free = stat.f_bavail * stat.f_frsize
        used = total - free
        return {
            "total": total,
            "free": free,
            "used": used,
            "percent_used": (used / total * 100) if total > 0 else 0
        }
    except Exception as e:
        log.warning(f"Failed to get disk space for {path}: {e}")
        return None


def check_disk_space():
    """Log disk space for all source directories."""
    log.info("=" * 50)
    log.info("Disk Space Check")
    log.info("=" * 50)
    
    checked_mounts = set()
    for source_dir in CONFIG["source_dirs"]:
        # Get mount point to avoid duplicate checks
        try:
            mount = subprocess.run(
                ["df", "--output=target", source_dir],
                capture_output=True, text=True
            ).stdout.strip().split('\n')[-1]
        except:
            mount = source_dir
        
        if mount in checked_mounts:
            continue
        checked_mounts.add(mount)
        
        space = get_disk_space(source_dir)
        if space:
            log.info(f"  {mount}:")
            log.info(f"    Total: {format_bytes(space['total'])}")
            log.info(f"    Free:  {format_bytes(space['free'])} ({100-space['percent_used']:.1f}% available)")
            log_json("disk_space", mount=mount, **space)
            
            if space['percent_used'] > 90:
                log.warning(f"    ⚠️  LOW DISK SPACE on {mount}!")
    log.info("")


def get_video_duration(filepath: str) -> Optional[float]:
    """Get video duration in seconds using ffprobe."""
    try:
        result = subprocess.run([
            "ffprobe", "-v", "quiet",
            "-show_entries", "format=duration",
            "-of", "json",
            filepath
        ], capture_output=True, text=True, timeout=30)
        
        if result.returncode == 0:
            data = json.loads(result.stdout)
            return float(data.get("format", {}).get("duration", 0))
    except Exception as e:
        log.debug(f"Failed to get duration for {filepath}: {e}")
    return None


def handle_interrupt(signum, frame):
    """Handle SIGINT/SIGTERM gracefully."""
    log.warning("=" * 50)
    log.warning("INTERRUPT RECEIVED - cleaning up...")
    log.warning("=" * 50)
    
    if CURRENT_TRANSCODE["path"]:
        log.warning(f"Interrupted transcode: {CURRENT_TRANSCODE['path']}")
        if CURRENT_TRANSCODE["start_time"]:
            elapsed = (datetime.now() - CURRENT_TRANSCODE["start_time"]).total_seconds()
            log.warning(f"Elapsed time: {format_duration(elapsed)}")
        
        # Try to kill ffmpeg if running
        if CURRENT_TRANSCODE["pid"]:
            try:
                os.kill(CURRENT_TRANSCODE["pid"], signal.SIGTERM)
                log.info("Sent SIGTERM to ffmpeg process")
            except:
                pass
        
        # Clean up partial output
        temp_path = Path(CURRENT_TRANSCODE["path"]).with_suffix(".transcoding.mkv")
        if temp_path.exists():
            log.info(f"Removing partial output: {temp_path}")
            temp_path.unlink()
    
    log_json("interrupted", 
             file=CURRENT_TRANSCODE["path"],
             elapsed=elapsed if CURRENT_TRANSCODE["start_time"] else None)
    sys.exit(1)


# Register signal handlers
signal.signal(signal.SIGINT, handle_interrupt)
signal.signal(signal.SIGTERM, handle_interrupt)


def get_video_codec(filepath: str) -> Optional[str]:
    """Get the video codec of a file using ffprobe."""
    try:
        result = subprocess.run([
            "ffprobe", "-v", "quiet",
            "-select_streams", "v:0",
            "-show_entries", "stream=codec_name",
            "-of", "json",
            filepath
        ], capture_output=True, text=True, timeout=30)
        
        if result.returncode == 0:
            data = json.loads(result.stdout)
            streams = data.get("streams", [])
            if streams:
                return streams[0].get("codec_name", "").lower()
    except Exception as e:
        log.warning(f"Failed to probe {filepath}: {e}")
    return None


def is_hevc(filepath: str) -> bool:
    """Check if a file is already HEVC encoded."""
    codec = get_video_codec(filepath)
    return codec in ["hevc", "h265"]


def get_file_size_gb(filepath: str) -> float:
    """Get file size in GB."""
    return os.path.getsize(filepath) / (1024 ** 3)


def find_videos_to_transcode(conn: sqlite3.Connection) -> List[Dict]:
    """Find all non-HEVC videos, sorted by size (biggest first). Uses cache for speed."""
    videos = []
    cache_hits = 0
    cache_misses = 0
    files_scanned = 0
    dirs_scanned = 0
    
    scan_start = datetime.now()
    log.info("Scanning source directories...")
    
    for source_dir in CONFIG["source_dirs"]:
        if not os.path.exists(source_dir):
            log.warning(f"  ⚠ Source directory not found: {source_dir}")
            continue
        
        dir_start = datetime.now()
        dir_files = 0
        dir_size = 0
        log.info(f"  📁 Scanning: {source_dir}")
            
        for root, dirs, files in os.walk(source_dir):
            # Skip cleanup directory
            if ".cleanup" in root:
                continue
            
            dirs_scanned += 1
                
            for filename in files:
                ext = os.path.splitext(filename)[1].lower()
                if ext not in CONFIG["video_extensions"]:
                    continue
                    
                filepath = os.path.join(root, filename)
                files_scanned += 1
                dir_files += 1
                
                try:
                    stat = os.stat(filepath)
                    size = stat.st_size
                    mtime = stat.st_mtime
                    dir_size += size
                    
                    # Check cache first
                    cached = get_cached_file(conn, filepath, size, mtime)
                    if cached:
                        video_codec = cached["video_codec"]
                        audio_codec = cached["audio_codec"]
                        is_hevc = cached["is_hevc"]
                        status = cached["status"]
                        cache_hits += 1
                    else:
                        # Need to probe this file
                        log.debug(f"    Probing: {filename}")
                        video_codec = get_video_codec(filepath)
                        audio_codec = get_audio_codec(filepath)
                        is_hevc = video_codec in ["hevc", "h265"] if video_codec else False
                        status = "done" if is_hevc else "pending"
                        cache_file(conn, filepath, size, mtime, 
                                  video_codec or "unknown", audio_codec or "unknown", is_hevc)
                        cache_misses += 1
                    
                    videos.append({
                        "path": filepath,
                        "size": size,
                        "size_gb": size / (1024 ** 3),
                        "video_codec": video_codec,
                        "audio_codec": audio_codec,
                        "is_hevc": is_hevc,
                        "status": status
                    })
                except OSError as e:
                    log.warning(f"    ⚠ Cannot access {filepath}: {e}")
        
        dir_elapsed = (datetime.now() - dir_start).total_seconds()
        log.info(f"     Found {dir_files} videos ({format_bytes(dir_size)}) in {format_duration(dir_elapsed)}")
        log_json("scan_directory", 
                 directory=source_dir,
                 files=dir_files,
                 size=dir_size,
                 elapsed=dir_elapsed)
    
    scan_elapsed = (datetime.now() - scan_start).total_seconds()
    cache_rate = (cache_hits / (cache_hits + cache_misses) * 100) if (cache_hits + cache_misses) > 0 else 0
    
    log.info("")
    log.info(f"Scan complete in {format_duration(scan_elapsed)}")
    log.info(f"  Files scanned:  {files_scanned}")
    log.info(f"  Dirs traversed: {dirs_scanned}")
    log.info(f"  Cache hits:     {cache_hits} ({cache_rate:.1f}%)")
    log.info(f"  Cache misses:   {cache_misses} (probed)")
    log.info("")
    
    log_json("scan_complete",
             files=files_scanned,
             dirs=dirs_scanned,
             cache_hits=cache_hits,
             cache_misses=cache_misses,
             elapsed=scan_elapsed)
    
    # Sort by size descending (biggest first)
    videos.sort(key=lambda x: x["size"], reverse=True)
    return videos


def is_past_cutoff() -> bool:
    """Check if we're past the cutoff time for starting new encodes."""
    now = datetime.now().time()
    return now >= CONFIG["cutoff_time"]


def verify_output(filepath: str, min_size_ratio: float = 0.1) -> bool:
    """Verify the transcoded file is valid."""
    if not os.path.exists(filepath):
        return False
    
    # Check file size is reasonable (at least 10% of some minimum)
    size = os.path.getsize(filepath)
    if size < 1024 * 1024:  # Less than 1MB is definitely wrong
        return False
    
    # Check it's valid video with ffprobe
    codec = get_video_codec(filepath)
    if codec != "hevc":
        return False
    
    return True


def transcode_file(input_path: str, conn: sqlite3.Connection) -> Optional[dict]:
    """Transcode a single file to HEVC. Returns result dict on success."""
    
    input_file = Path(input_path)
    output_path = input_file.with_suffix(".transcoding.mkv")
    final_path = input_file.with_suffix(".mkv")
    
    original_size = os.path.getsize(input_path)
    video_duration = get_video_duration(input_path)
    
    log.info("")
    log.info("=" * 60)
    log.info(f"TRANSCODE START: {input_file.name}")
    log.info("=" * 60)
    log.info(f"  Input path:    {input_path}")
    log.info(f"  Output path:   {output_path}")
    log.info(f"  Original size: {format_bytes(original_size)}")
    if video_duration:
        log.info(f"  Duration:      {format_duration(video_duration)}")
    
    log_json("transcode_start", 
             file=input_path,
             size=original_size,
             duration=video_duration)
    
    # Mark as transcoding in DB
    conn.execute("UPDATE files SET status = 'transcoding' WHERE path = ?", (input_path,))
    conn.commit()
    
    start_time = datetime.now()
    CURRENT_TRANSCODE["path"] = input_path
    CURRENT_TRANSCODE["start_time"] = start_time
    
    settings = {
        "crf": CONFIG["crf"],
        "preset": CONFIG["preset"],
        "audio_codec": CONFIG["audio_codec"],
        "audio_bitrate": CONFIG["audio_bitrate"],
        "threads": CONFIG["threads"]
    }
    
    # Build ffmpeg command
    cmd = [
        "ffmpeg", "-y",
        "-threads", str(CONFIG["threads"]),
        "-progress", "pipe:1",  # Progress to stdout for parsing
        "-i", input_path,
        "-c:v", "libx265",
        "-preset", CONFIG["preset"],
        "-crf", str(CONFIG["crf"]),
        "-x265-params", f"pools={CONFIG['threads']}",
        "-c:a", CONFIG["audio_codec"],
        "-b:a", CONFIG["audio_bitrate"],
        "-c:s", "copy",  # Copy subtitles
        str(output_path)
    ]
    
    # Log the full command for debugging
    cmd_str = ' '.join(f'"{c}"' if ' ' in c else c for c in cmd)
    log.info(f"  FFmpeg command:")
    log.debug(f"    {cmd_str}")
    if not VERBOSE:
        log.info(f"    (use --verbose to see full command)")
    log.info("")
    log_json("ffmpeg_command", command=cmd_str)
    
    # Log stderr to file to prevent pipe buffer deadlock
    stderr_log_path = Path(CONFIG["log_dir"]) / "transcoder_ffmpeg_stderr.log"
    stderr_file = open(stderr_log_path, "a")
    stderr_file.write(f"\n{'='*60}\n{datetime.now()} - {input_path}\n{'='*60}\n")
    stderr_file.flush()
    
    try:
        # Use Popen for progress monitoring
        # stderr goes to file (not PIPE) to prevent buffer deadlock
        process = subprocess.Popen(
            cmd,
            stdout=subprocess.PIPE,
            stderr=stderr_file,
            text=True
        )
        CURRENT_TRANSCODE["pid"] = process.pid
        log.debug(f"  FFmpeg PID: {process.pid}")
        
        # Monitor progress
        last_progress_log = datetime.now()
        progress_interval = 60  # Log progress every 60 seconds
        current_time_us = 0
        
        import select
        last_output_size = 0
        last_output_growth = datetime.now()
        stall_timeout = 600  # 10 minutes with no output growth = stalled
        
        while True:
            # Use select for non-blocking read with timeout
            ready, _, _ = select.select([process.stdout], [], [], 30)
            
            if ready:
                line = process.stdout.readline()
                if not line and process.poll() is not None:
                    break
                
                # Parse progress output
                if line.startswith("out_time_us="):
                    try:
                        current_time_us = int(line.split("=")[1])
                    except:
                        pass
            elif process.poll() is not None:
                break
            
            # Log progress periodically
            now = datetime.now()
            if (now - last_progress_log).total_seconds() >= progress_interval:
                elapsed = (now - start_time).total_seconds()
                
                if video_duration and current_time_us > 0:
                    current_secs = current_time_us / 1_000_000
                    percent = (current_secs / video_duration) * 100
                    eta_secs = (elapsed / percent * 100) - elapsed if percent > 0 else 0
                    
                    log.info(f"  ⏳ Progress: {percent:.1f}% | Elapsed: {format_duration(elapsed)} | ETA: {format_duration(eta_secs)}")
                    log_json("transcode_progress",
                             file=input_path,
                             percent=percent,
                             elapsed=elapsed,
                             eta=eta_secs)
                else:
                    log.info(f"  ⏳ Elapsed: {format_duration(elapsed)}")
                
                # Check output size growth and detect stalls
                if output_path.exists():
                    current_size = os.path.getsize(output_path)
                    log.info(f"     Output size: {format_bytes(current_size)}")
                    
                    if current_size > last_output_size:
                        last_output_size = current_size
                        last_output_growth = now
                    elif (now - last_output_growth).total_seconds() > stall_timeout:
                        log.error(f"  🛑 STALL DETECTED: Output file hasn't grown in {stall_timeout}s")
                        log.error(f"     Output stuck at {format_bytes(current_size)}")
                        log.error(f"     Killing ffmpeg (PID {process.pid})")
                        process.kill()
                        process.wait(timeout=30)
                        
                        # Mark as stalled in DB with timestamp for 7-day cooldown
                        conn.execute(
                            "UPDATE files SET status = 'stalled', failure_reason = ?, transcoded_at = ? WHERE path = ?",
                            (f"Output stalled at {format_bytes(current_size)} after {format_duration(elapsed)}", 
                             datetime.now().timestamp(), input_path)
                        )
                        conn.commit()
                        
                        # Clean up partial output
                        if output_path.exists():
                            output_path.unlink()
                            log.info(f"  Cleaned up partial file: {output_path}")
                        
                        stderr_file.close()
                        return None
                
                last_progress_log = now
        
        # Wait for process to finish (stderr already going to file)
        process.wait(timeout=60)
        stderr_file.close()
        
        if process.returncode != 0:
            # Read last 1000 chars of stderr log for error reporting
            try:
                with open(stderr_log_path, 'r') as f:
                    f.seek(max(0, os.path.getsize(stderr_log_path) - 1000))
                    error_msg = f.read()
            except:
                error_msg = "Unknown error (check transcoder_ffmpeg_stderr.log)"
            log.error("=" * 60)
            log.error("TRANSCODE FAILED")
            log.error("=" * 60)
            log.error(f"  File: {input_path}")
            log.error(f"  Exit code: {process.returncode}")
            log.error(f"  FFmpeg error output:")
            for line in error_msg.split('\n')[-20:]:  # Last 20 lines
                if line.strip():
                    log.error(f"    {line}")
            log.error("=" * 60)
            
            log_json("transcode_failed",
                     file=input_path,
                     exit_code=process.returncode,
                     error=error_msg[-500:])
            
            if output_path.exists():
                output_path.unlink()
            update_transcode_result(conn, input_path, None, 0, 0, settings, False, error_msg[-500:])
            CURRENT_TRANSCODE["path"] = None
            return None
            
    except subprocess.TimeoutExpired:
        log.error("=" * 60)
        log.error(f"TRANSCODE TIMEOUT (8 hours): {input_path}")
        log.error("=" * 60)
        log_json("transcode_timeout", file=input_path)
        process.kill()
        if output_path.exists():
            output_path.unlink()
        update_transcode_result(conn, input_path, None, 0, 0, settings, False, "Timeout (8 hours)")
        CURRENT_TRANSCODE["path"] = None
        return None
    except Exception as e:
        log.error("=" * 60)
        log.error(f"TRANSCODE ERROR: {input_path}")
        log.error("=" * 60)
        log.error(f"  Exception: {type(e).__name__}: {e}")
        log.error(f"  Traceback:")
        for line in traceback.format_exc().split('\n'):
            if line.strip():
                log.error(f"    {line}")
        log.error("=" * 60)
        
        log_json("transcode_error",
                 file=input_path,
                 error=str(e),
                 traceback=traceback.format_exc())
        
        if output_path.exists():
            output_path.unlink()
        update_transcode_result(conn, input_path, None, 0, 0, settings, False, str(e))
        CURRENT_TRANSCODE["path"] = None
        return None
    
    # Verify output
    log.info("  Verifying output file...")
    if not verify_output(str(output_path)):
        log.error("=" * 60)
        log.error("OUTPUT VERIFICATION FAILED")
        log.error("=" * 60)
        log.error(f"  File: {output_path}")
        if output_path.exists():
            log.error(f"  Output size: {format_bytes(os.path.getsize(output_path))}")
            output_codec = get_video_codec(str(output_path))
            log.error(f"  Output codec: {output_codec}")
        else:
            log.error("  Output file does not exist!")
        log.error("=" * 60)
        
        log_json("transcode_verify_failed", file=input_path)
        if output_path.exists():
            output_path.unlink()
        update_transcode_result(conn, input_path, None, 0, 0, settings, False, "Output verification failed")
        CURRENT_TRANSCODE["path"] = None
        return None
    
    new_size = os.path.getsize(output_path)
    duration_secs = (datetime.now() - start_time).total_seconds()
    space_saved = original_size - new_size
    compression_ratio = new_size / original_size if original_size > 0 else 0
    encode_speed = video_duration / duration_secs if video_duration and duration_secs > 0 else 0
    
    log.info("")
    log.info("=" * 60)
    log.info("✅ TRANSCODE COMPLETE")
    log.info("=" * 60)
    log.info(f"  File:        {input_file.name}")
    log.info(f"  Duration:    {format_duration(duration_secs)}")
    log.info(f"  Original:    {format_bytes(original_size)}")
    log.info(f"  New size:    {format_bytes(new_size)}")
    log.info(f"  Saved:       {format_bytes(space_saved)} ({100*(1-compression_ratio):.1f}% reduction)")
    log.info(f"  Ratio:       {compression_ratio:.2f}x")
    if encode_speed > 0:
        log.info(f"  Speed:       {encode_speed:.2f}x realtime")
    log.info("=" * 60)
    log.info("")
    
    log_json("transcode_complete",
             file=input_path,
             original_size=original_size,
             new_size=new_size,
             space_saved=space_saved,
             duration_secs=duration_secs,
             compression_ratio=compression_ratio,
             encode_speed=encode_speed)
    
    # Move original to cleanup directory
    cleanup_dir = Path(CONFIG["cleanup_dir"])
    cleanup_dir.mkdir(parents=True, exist_ok=True)
    
    timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
    cleanup_name = f"{timestamp}_{input_file.name}"
    cleanup_path = cleanup_dir / cleanup_name
    
    log.info(f"  Moving original to cleanup: {cleanup_path}")
    try:
        shutil.move(input_path, cleanup_path)
        log.info(f"  ✓ Original moved successfully")
        log_json("original_moved", source=input_path, dest=str(cleanup_path))
    except Exception as e:
        log.error(f"  ✗ Failed to move original: {e}")
        log.error(f"    Traceback: {traceback.format_exc()}")
        # Don't fail the whole operation, but keep both files
    
    # Rename output to final name
    log.info(f"  Renaming output: {output_path} -> {final_path}")
    try:
        output_path.rename(final_path)
        log.info(f"  ✓ Output renamed successfully")
    except Exception as e:
        log.error(f"  ✗ Failed to rename output: {e}")
        final_path = output_path
    
    # Fix permissions - mediaserver group
    log.debug("  Setting permissions (mediaserver:664)")
    try:
        subprocess.run(["chgrp", "mediaserver", str(final_path)], check=False)
        subprocess.run(["chmod", "664", str(final_path)], check=False)
        log.debug("  ✓ Permissions set")
    except Exception as e:
        log.warning(f"  ✗ Failed to set permissions: {e}")
    
    # Update database with success
    update_transcode_result(conn, input_path, str(final_path), new_size, duration_secs, settings, True)
    
    CURRENT_TRANSCODE["path"] = None
    return {
        "output_path": str(final_path),
        "new_size": new_size,
        "duration_secs": duration_secs,
        "space_saved": space_saved
    }


def cleanup_old_files():
    """Delete original files older than cleanup_days."""
    cleanup_dir = Path(CONFIG["cleanup_dir"])
    if not cleanup_dir.exists():
        log.debug("Cleanup directory doesn't exist, skipping cleanup")
        return
    
    log.info("Checking cleanup directory for old originals...")
    cutoff = datetime.now().timestamp() - (CONFIG["cleanup_days"] * 24 * 3600)
    cutoff_date = datetime.fromtimestamp(cutoff).strftime('%Y-%m-%d %H:%M')
    log.debug(f"  Cutoff date: {cutoff_date} ({CONFIG['cleanup_days']} days ago)")
    
    deleted_count = 0
    deleted_size = 0
    kept_count = 0
    kept_size = 0
    
    for filepath in cleanup_dir.iterdir():
        if filepath.is_file():
            mtime = filepath.stat().st_mtime
            size = filepath.stat().st_size
            
            if mtime < cutoff:
                try:
                    filepath.unlink()
                    deleted_count += 1
                    deleted_size += size
                    log.info(f"  🗑️  Deleted: {filepath.name} ({format_bytes(size)})")
                    log_json("cleanup_deleted", file=str(filepath), size=size)
                except Exception as e:
                    log.warning(f"  ⚠ Failed to delete {filepath}: {e}")
            else:
                kept_count += 1
                kept_size += size
                days_old = (datetime.now().timestamp() - mtime) / 86400
                log.debug(f"  ⏳ Keeping: {filepath.name} ({days_old:.1f} days old)")
    
    if deleted_count > 0:
        log.info(f"  Cleanup: deleted {deleted_count} files, freed {format_bytes(deleted_size)}")
        log_json("cleanup_complete", deleted=deleted_count, freed=deleted_size)
    else:
        log.info(f"  Cleanup: nothing to delete ({kept_count} files still in retention)")
    
    if kept_count > 0:
        log.debug(f"  Retention: {kept_count} files ({format_bytes(kept_size)}) waiting)")


def main():
    # Initialize database
    conn = init_db()
    
    # Handle --stats flag
    if args.stats:
        stats = get_cache_stats(conn)
        print("=" * 60)
        print("Transcoder Statistics")
        print("=" * 60)
        print(f"Total files scanned:   {stats['total']}")
        print(f"Already HEVC:          {stats['hevc_count']} ({stats['hevc_size']/(1024**3):.2f} GB)")
        print(f"Pending transcode:     {stats['pending_count']} ({stats['pending_size']/(1024**3):.2f} GB)")
        print(f"Completed:             {stats['done_count']}")
        print(f"Failed:                {stats['failed_count']}")
        print("")
        print("--- Lifetime Stats ---")
        print(f"Total transcoded:      {stats.get('total_transcoded', 0)} files")
        print(f"Total space saved:     {stats.get('total_space_saved', 0)/(1024**3):.2f} GB")
        total_time = stats.get('total_transcode_time', 0)
        print(f"Total transcode time:  {total_time/3600:.1f} hours")
        if stats['pending_count'] > 0:
            est_savings = stats['pending_size'] * 0.5
            print(f"\nEstimated remaining:   ~{est_savings/(1024**3):.2f} GB savings")
        
        if stats.get('by_directory'):
            print("\n--- Top Directories (by pending size) ---")
            for dir_path, count, pending in stats['by_directory'][:5]:
                if pending > 0:
                    # Shorten path for display
                    short = dir_path.replace("/disks/Plex/", "")
                    print(f"  {short}: {pending/(1024**3):.2f} GB pending")
        
        print("=" * 60)
        conn.close()
        return
    
    # Handle --clear-cache flag
    if args.clear_cache:
        conn.execute("DELETE FROM files")
        conn.execute("UPDATE stats SET total_files_transcoded=0, total_space_saved=0, total_transcode_time_secs=0")
        conn.commit()
        print("Cache cleared.")
        conn.close()
        return
    
    # Handle --failed flag
    if args.failed:
        cursor = conn.execute("""
            SELECT path, original_size, failure_reason 
            FROM files WHERE status = 'failed'
            ORDER BY original_size DESC
        """)
        rows = cursor.fetchall()
        print("=" * 60)
        print(f"Failed Transcodes ({len(rows)} files)")
        print("=" * 60)
        for path, size, reason in rows:
            print(f"\n{path}")
            print(f"  Size: {size/(1024**3):.2f} GB")
            print(f"  Reason: {reason}")
        if not rows:
            print("No failed transcodes!")
        print("=" * 60)
        conn.close()
        return
    
    # Handle --retry-failed flag
    if args.retry_failed:
        cursor = conn.execute("UPDATE files SET status = 'pending', failure_reason = NULL WHERE status = 'failed'")
        count = cursor.rowcount
        conn.commit()
        print(f"Reset {count} failed files to pending.")
        conn.close()
        return
    
    session_start = datetime.now()
    
    log.info("")
    log.info("=" * 70)
    log.info("  OVERNIGHT VIDEO TRANSCODER")
    log.info("=" * 70)
    log.info(f"  Started:   {session_start.strftime('%Y-%m-%d %H:%M:%S')}")
    log.info(f"  Mode:      {'DRY RUN' if DRY_RUN else 'LIVE'}")
    log.info(f"  Verbose:   {'YES' if VERBOSE else 'NO'}")
    log.info(f"  JSON log:  {'YES' if JSON_LOG else 'NO'}")
    log.info(f"  Cutoff:    {CONFIG['cutoff_time']}")
    log.info(f"  Settings:  CRF={CONFIG['crf']}, preset={CONFIG['preset']}, audio={CONFIG['audio_codec']}@{CONFIG['audio_bitrate']}")
    log.info("=" * 70)
    log.info("")
    
    log_json("session_start",
             mode="dry_run" if DRY_RUN else "live",
             config=CONFIG)
    
    # Check disk space first
    check_disk_space()
    
    # Run cleanup first (skip in dry run)
    if not DRY_RUN:
        cleanup_old_files()
    
    # Find videos to transcode
    videos = find_videos_to_transcode(conn)
    
    # Filter to non-HEVC pending only (using cached codec info)
    to_transcode = []
    hevc_count = 0
    hevc_size = 0
    
    for video in videos:
        if video.get("is_hevc", False) or video.get("status") == "done":
            hevc_count += 1
            hevc_size += video["size"]
        elif video.get("status") == "pending":
            to_transcode.append(video)
    
    log.info(f"Already HEVC: {hevc_count} files ({hevc_size / (1024**3):.2f} GB)")
    log.info(f"Need transcoding: {len(to_transcode)} files")
    
    if DRY_RUN:
        log.info("")
        log.info("=" * 60)
        log.info("DRY RUN - Files that would be transcoded (biggest first):")
        log.info("=" * 60)
        
        total_size = 0
        estimated_savings = 0
        
        for i, video in enumerate(to_transcode[:20], 1):  # Show top 20
            size_gb = video["size_gb"]
            total_size += video["size"]
            # Estimate ~50% compression for HEVC
            est_saved = video["size"] * 0.5
            estimated_savings += est_saved
            
            log.info(f"{i:2}. [{size_gb:6.2f} GB] {video['path']}")
        
        if len(to_transcode) > 20:
            log.info(f"    ... and {len(to_transcode) - 20} more files")
        
        log.info("")
        log.info("=" * 60)
        log.info(f"Total to transcode: {total_size / (1024**3):.2f} GB")
        log.info(f"Estimated savings (~50%): {estimated_savings / (1024**3):.2f} GB")
        log.info("=" * 60)
        return
    
    # Normal run
    transcoded_count = 0
    total_saved = 0
    failed_count = 0
    skipped_count = 0
    
    log.info("")
    log.info("=" * 60)
    log.info("Starting transcode queue")
    log.info("=" * 60)
    log.info(f"  Files to process: {len(to_transcode)}")
    log.info(f"  Total size:       {format_bytes(sum(v['size'] for v in to_transcode))}")
    log.info("")
    
    for i, video in enumerate(to_transcode, 1):
        # Check cutoff time
        if is_past_cutoff():
            remaining = len(to_transcode) - i + 1
            log.info("")
            log.info("=" * 60)
            log.info(f"⏰ CUTOFF TIME REACHED ({CONFIG['cutoff_time']})")
            log.info(f"   Stopping with {remaining} files remaining in queue")
            log.info("=" * 60)
            log_json("cutoff_reached", remaining_files=remaining)
            break
        
        # Skip already done or failed
        if video.get("status") in ["done", "failed"]:
            log.debug(f"  Skipping (status={video['status']}): {video['path']}")
            skipped_count += 1
            continue
        
        # Skip stalled files unless 7 days have passed
        if video.get("status") == "stalled":
            row = conn.execute(
                "SELECT transcoded_at FROM files WHERE path = ?", (video['path'],)
            ).fetchone()
            if row and row[0]:
                stalled_at = datetime.fromtimestamp(row[0])
                days_since = (datetime.now() - stalled_at).days
                if days_since < 7:
                    log.debug(f"  Skipping stalled file ({days_since}d ago, retry after 7d): {video['path']}")
                    skipped_count += 1
                    continue
                else:
                    log.info(f"  Retrying stalled file ({days_since}d cooldown passed): {video['path']}")
            else:
                log.debug(f"  Skipping stalled file (no timestamp): {video['path']}")
                skipped_count += 1
                continue
        
        log.info(f"[{i}/{len(to_transcode)}] Queued: {Path(video['path']).name}")
        log.info(f"    Size:   {format_bytes(video['size'])}")
        log.info(f"    Codec:  video={video.get('video_codec', 'unknown')}, audio={video.get('audio_codec', 'unknown')}")
        log.info(f"    Path:   {video['path']}")
        
        log_json("transcode_queued",
                 index=i,
                 total=len(to_transcode),
                 file=video['path'],
                 size=video['size'],
                 video_codec=video.get('video_codec'),
                 audio_codec=video.get('audio_codec'))
        
        # Transcode
        result = transcode_file(video["path"], conn)
        
        if result:
            total_saved += result["space_saved"]
            transcoded_count += 1
            log.info(f"  Running totals: {transcoded_count} done, {format_bytes(total_saved)} saved")
        else:
            failed_count += 1
            log.error(f"  ❌ Transcode #{i} failed: {video['path']}")
            log.info(f"  Running totals: {transcoded_count} done, {failed_count} failed")
    
    session_end = datetime.now()
    session_duration = (session_end - session_start).total_seconds()
    
    log.info("")
    log.info("=" * 70)
    log.info("  SESSION COMPLETE")
    log.info("=" * 70)
    log.info(f"  Started:     {session_start.strftime('%Y-%m-%d %H:%M:%S')}")
    log.info(f"  Ended:       {session_end.strftime('%Y-%m-%d %H:%M:%S')}")
    log.info(f"  Duration:    {format_duration(session_duration)}")
    log.info(f"  Transcoded:  {transcoded_count} files")
    log.info(f"  Failed:      {failed_count} files")
    log.info(f"  Skipped:     {skipped_count} files")
    log.info(f"  Space saved: {format_bytes(total_saved)}")
    
    # Get updated lifetime stats
    stats = get_cache_stats(conn)
    log.info("")
    log.info("  --- Lifetime Totals ---")
    log.info(f"  Total transcoded: {stats.get('total_transcoded', 0)} files")
    log.info(f"  Total saved:      {format_bytes(stats.get('total_space_saved', 0))}")
    log.info(f"  Pending:          {stats.get('pending_count', 0)} files ({format_bytes(stats.get('pending_size', 0))})")
    log.info("=" * 70)
    log.info("")
    
    log_json("session_complete",
             started=session_start.isoformat(),
             ended=session_end.isoformat(),
             duration_secs=session_duration,
             transcoded=transcoded_count,
             space_saved=total_saved,
             lifetime_transcoded=stats.get('total_transcoded', 0),
             lifetime_saved=stats.get('total_space_saved', 0),
             pending_count=stats.get('pending_count', 0))
    
    conn.close()


if __name__ == "__main__":
    main()