"""File system scanning functions."""

import glob
from pathlib import Path
from typing import Dict, Iterator, List, Optional, Tuple

from hivescan.models import ContentType, ParsedContent
from hivescan.parsing import parse_download, parse_episode_from_filename
from hivescan.utils import get_media_folder_path, sanitize_filename


# Video file extensions
VIDEO_EXTENSIONS = {'.mkv', '.mp4', '.avi', '.m4v', '.mov', '.wmv', '.flv', '.webm', '.ts', '.m2ts'}

# Caches for expensive operations
_episode_files_cache: Dict[str, Dict[Tuple[int, int], List[Tuple[str, int]]]] = {}
_playable_file_cache: Dict[str, Optional[str]] = {}


def scan_downloads(base_pattern: str) -> Iterator[ParsedContent]:
    """
    Scan download directories matching the pattern.

    Args:
        base_pattern: Glob pattern for finding download directories

    Yields:
        ParsedContent objects for each found download
    """
    exclude_patterns = [".torrents", "incomplete", ".incomplete"]

    for path_str in glob.glob(base_pattern):
        path = Path(path_str)

        if path.name.startswith("."):
            continue

        if any(excl.lower() in path.name.lower() for excl in exclude_patterns):
            continue

        if not path.exists():
            continue

        yield parse_download(path)


def categorize_downloads(downloads: list[ParsedContent]) -> dict[ContentType, list[ParsedContent]]:
    """Categorize downloads by content type."""
    categories: dict[ContentType, list[ParsedContent]] = {
        ContentType.MOVIE: [],
        ContentType.SERIES: [],
        ContentType.OTHER: [],
    }

    for download in downloads:
        categories[download.content_type].append(download)

    return categories


def find_episode_files(path: Path) -> Dict[Tuple[int, int], List[Tuple[str, int]]]:
    """
    Find all episode video files in a directory.

    Args:
        path: Path to search (can be a season pack directory or single file)

    Returns:
        Dict mapping (season_num, episode_num) to list of (file_path, file_size) tuples
    """
    cache_key = str(path)
    if cache_key in _episode_files_cache:
        return _episode_files_cache[cache_key]

    episodes: Dict[Tuple[int, int], List[Tuple[str, int]]] = {}

    if path.is_file():
        if path.suffix.lower() in VIDEO_EXTENSIONS:
            ep_info = parse_episode_from_filename(path.name)
            if ep_info:
                episodes[ep_info] = [(str(path), path.stat().st_size)]
        _episode_files_cache[cache_key] = episodes
        return episodes

    try:
        for f in path.rglob("*"):
            if f.is_file() and f.suffix.lower() in VIDEO_EXTENSIONS:
                if 'sample' in f.name.lower():
                    continue
                ep_info = parse_episode_from_filename(f.name)
                if ep_info:
                    if ep_info not in episodes:
                        episodes[ep_info] = []
                    episodes[ep_info].append((str(f), f.stat().st_size))
    except (OSError, PermissionError):
        pass

    _episode_files_cache[cache_key] = episodes
    return episodes


def find_playable_file(path: Path) -> Optional[str]:
    """
    Find the main playable media file in a directory.

    For Blu-ray discs: Returns BDMV/index.bdmv
    For other content: Returns the largest video file
    """
    cache_key = str(path)
    if cache_key in _playable_file_cache:
        return _playable_file_cache[cache_key]

    if path.is_file():
        if path.suffix.lower() in VIDEO_EXTENSIONS:
            result = str(path)
            _playable_file_cache[cache_key] = result
            return result
        _playable_file_cache[cache_key] = None
        return None

    # Check for Blu-ray disc structure
    bdmv_index = path / "BDMV" / "index.bdmv"
    if bdmv_index.exists():
        result = str(bdmv_index)
        _playable_file_cache[cache_key] = result
        return result

    # Check nested Blu-ray structure (e.g., MovieName/DISC1/BDMV/)
    try:
        for subdir in path.iterdir():
            if subdir.is_dir():
                nested_bdmv = subdir / "BDMV" / "index.bdmv"
                if nested_bdmv.exists():
                    result = str(nested_bdmv)
                    _playable_file_cache[cache_key] = result
                    return result
    except (OSError, PermissionError):
        pass

    # Find largest video file
    video_files = []
    try:
        for f in path.rglob("*"):
            if f.is_file() and f.suffix.lower() in VIDEO_EXTENSIONS:
                if 'sample' in f.name.lower():
                    continue
                video_files.append((f, f.stat().st_size))
    except (OSError, PermissionError):
        pass

    if not video_files:
        _playable_file_cache[cache_key] = None
        return None

    video_files.sort(key=lambda x: x[1], reverse=True)
    result = str(video_files[0][0])
    _playable_file_cache[cache_key] = result
    return result


def find_cover_image(title: str, year: Optional[int], media_type: str, cover_dir: Path) -> Optional[str]:
    """Find a cover image for the given media item."""
    media_folder = get_media_folder_path(title, year, media_type, cover_dir)
    cover_path = media_folder / "cover.jpg"
    if cover_path.exists():
        return str(cover_path)

    # Legacy structure fallback
    subdir = "movies" if media_type == "movie" else "series"
    if media_type == "movie" and year:
        legacy_path = cover_dir / subdir / f"{sanitize_filename(title)} ({year}).jpg"
        if legacy_path.exists():
            return str(legacy_path)

    legacy_path = cover_dir / subdir / f"{sanitize_filename(title)}.jpg"
    if legacy_path.exists():
        return str(legacy_path)

    return None