import os
import json
import ffmpeg
import hashlib
from pathlib import Path
from typing import List, Dict, Optional
from .utils import get_logger, VIDEOS_DIR, THUMBNAILS_DIR, CONFIG_DIR

logger = get_logger(__name__)
LIBRARY_CACHE = CONFIG_DIR / "library_cache.json"

class MediaItem:
    def __init__(self, path: Path, duration: float, thumbnail_path: str):
        self.path = path
        self.duration = duration
        self.thumbnail_path = thumbnail_path
        self.id = hashlib.md5(str(path).encode()).hexdigest()

    def to_dict(self):
        return {
            "id": self.id,
            "filename": self.path.name,
            "path": str(self.path),
            "duration": self.duration,
            "thumbnail": self.thumbnail_path
        }

def get_video_duration(path: Path) -> float:
    try:
        probe = ffmpeg.probe(str(path))
        video_info = next(s for s in probe['streams'] if s['codec_type'] == 'video')
        return float(probe['format']['duration'])
    except Exception as e:
        logger.error(f"Error probing {path}: {e}")
        return 0.0

def generate_thumbnail(path: Path) -> Optional[str]:
    thumb_name = hashlib.md5(str(path).encode()).hexdigest() + ".jpg"
    thumb_path = THUMBNAILS_DIR / thumb_name
    
    if thumb_path.exists():
        return thumb_name

    try:
        # Get duration to pick a frame from the middle
        duration = get_video_duration(path)
        # Take a frame at 50% or 10s if duration is long
        time = min(10, duration / 2) if duration > 0 else 0
        
        (
            ffmpeg
            .input(str(path), ss=time)
            .filter('scale', 640, -1)
            .output(str(thumb_path), vframes=1)
            .overwrite_output()
            .run(quiet=True)
        )
        return thumb_name
    except Exception as e:
        logger.error(f"Error generating thumbnail for {path}: {e}")
        return None

def scan_library() -> Dict[str, List[Dict]]:
    logger.info(f"Scanning library in {VIDEOS_DIR}...")
    
    cache = {}
    if LIBRARY_CACHE.exists():
        try:
            with open(LIBRARY_CACHE, 'r') as f:
                cache = json.load(f)
        except Exception:
            logger.warning("Could not read library cache.")

    valid_extensions = {'.mp4', '.mkv', '.avi', '.mov', '.m4v'}
    stories = []
    music = []

    for root, _, files in os.walk(VIDEOS_DIR):
        for file in files:
            path = Path(root) / file
            if path.suffix.lower() not in valid_extensions:
                continue

            rel_path = str(path.relative_to(VIDEOS_DIR))
            
            # Check cache
            item_data = cache.get(rel_path)
            if item_data and os.path.getmtime(path) == item_data.get('mtime'):
                # Check if thumbnail still exists
                if (THUMBNAILS_DIR / item_data['thumbnail']).exists():
                    item = item_data
                else:
                    item_data = None # Force re-gen
            
            if not item_data or os.path.getmtime(path) != item_data.get('mtime'):
                duration = get_video_duration(path)
                thumb_name = generate_thumbnail(path)
                
                if thumb_name:
                    item = {
                        "id": hashlib.md5(str(path).encode()).hexdigest(),
                        "filename": path.name,
                        "path": rel_path,
                        "duration": duration,
                        "thumbnail": thumb_name,
                        "mtime": os.path.getmtime(path)
                    }
                    cache[rel_path] = item
                else:
                    continue

            # Categorize
            # Stories < 15m (900s)
            # Music > 2h (7200s)
            if item['duration'] < 900:
                stories.append(item)
            elif item['duration'] > 7200:
                music.append(item)
    
    # Save cache
    with open(LIBRARY_CACHE, 'w') as f:
        json.dump(cache, f)

    return {
        "stories": stories,
        "music": music
    }