# app/modules/cms/services/media_service.py
"""
Media service for store media library management.

This module provides:
- File upload and storage
- Thumbnail generation for images
- Media metadata management
- Media usage tracking
"""

import logging
import mimetypes
import shutil
import uuid
from datetime import UTC, datetime
from pathlib import Path
from typing import Any

from sqlalchemy import func, or_
from sqlalchemy.orm import Session

from app.modules.cms.exceptions import (
    MediaFileTooLargeException,
    MediaNotFoundException,
    MediaValidationException,
    UnsupportedMediaTypeException,
)
from app.modules.cms.models import MediaFile

logger = logging.getLogger(__name__)

# Base upload directory
UPLOAD_DIR = Path("uploads")
STORE_UPLOAD_DIR = UPLOAD_DIR / "stores"

# Allowed file types and their categories
ALLOWED_EXTENSIONS = {
    # Images
    "jpg": "image",
    "jpeg": "image",
    "png": "image",
    "gif": "image",
    "webp": "image",
    "svg": "image",
    # Videos
    "mp4": "video",
    "webm": "video",
    "mov": "video",
    # Documents
    "pdf": "document",
    "doc": "document",
    "docx": "document",
    "xls": "document",
    "xlsx": "document",
    "csv": "document",
    "txt": "document",
}

# Maximum file sizes (in bytes)
MAX_FILE_SIZES = {
    "image": 10 * 1024 * 1024,  # 10 MB
    "video": 100 * 1024 * 1024,  # 100 MB
    "document": 20 * 1024 * 1024,  # 20 MB
}

# Thumbnail settings
THUMBNAIL_SIZE = (200, 200)

# Image variant settings (ported from ImageService)
IMAGE_VARIANT_QUALITY = 85
IMAGE_MAX_DIMENSION = 2000
IMAGE_VARIANT_SIZES = {
    "800": 800,
    "200": 200,
}


class MediaService:
    """Service for store media library operations."""

    def _get_store_upload_path(self, store_id: int, folder: str = "general") -> Path:
        """Get the upload directory path for a store."""
        return STORE_UPLOAD_DIR / str(store_id) / folder

    def _ensure_upload_dir(self, path: Path) -> None:
        """Ensure upload directory exists."""
        path.mkdir(parents=True, exist_ok=True)

    def _get_file_extension(self, filename: str) -> str:
        """Extract file extension from filename."""
        return filename.rsplit(".", 1)[-1].lower() if "." in filename else ""

    def _get_media_type(self, extension: str) -> str | None:
        """Get media type from file extension."""
        return ALLOWED_EXTENSIONS.get(extension)

    def _generate_unique_filename(self, original_filename: str) -> str:
        """Generate a unique filename using UUID."""
        ext = self._get_file_extension(original_filename)
        return f"{uuid.uuid4().hex}.{ext}" if ext else uuid.uuid4().hex

    def _validate_file(
        self, filename: str, file_size: int
    ) -> tuple[str, str]:
        """
        Validate uploaded file.

        Returns:
            Tuple of (extension, media_type)

        Raises:
            MediaValidationException: If file is invalid
            UnsupportedMediaTypeException: If file type is not supported
            MediaFileTooLargeException: If file exceeds size limit
        """
        ext = self._get_file_extension(filename)

        if not ext:
            raise MediaValidationException("File must have an extension", field="file")

        media_type = self._get_media_type(ext)
        if not media_type:
            raise UnsupportedMediaTypeException(
                ext, allowed_types=list(ALLOWED_EXTENSIONS.keys())
            )

        max_size = MAX_FILE_SIZES.get(media_type, 10 * 1024 * 1024)
        if file_size > max_size:
            raise MediaFileTooLargeException(file_size, max_size, media_type)

        return ext, media_type

    def _get_image_dimensions(self, file_path: Path) -> tuple[int, int] | None:
        """Get image dimensions if PIL is available."""
        try:
            from PIL import Image

            with Image.open(file_path) as img:
                return img.size
        except ImportError:
            logger.debug("PIL not available, skipping image dimension detection")
            return None
        except OSError as e:
            logger.warning(f"Could not get image dimensions: {e}")
            return None

    def _resize_image(self, img: "Image.Image", max_dimension: int) -> "Image.Image":
        """Resize image while maintaining aspect ratio.

        Args:
            img: PIL Image
            max_dimension: Maximum width or height

        Returns:
            Resized PIL Image (or original if already smaller)
        """
        width, height = img.size
        if width <= max_dimension and height <= max_dimension:
            return img

        if width > height:
            new_width = max_dimension
            new_height = int(height * (max_dimension / width))
        else:
            new_height = max_dimension
            new_width = int(width * (max_dimension / height))

        from PIL import Image
        return img.resize((new_width, new_height), Image.Resampling.LANCZOS)

    def _generate_image_variants(
        self, source_path: Path, filename_stem: str
    ) -> dict[str, str]:
        """Generate WebP image variants at multiple sizes.

        Args:
            source_path: Path to the original image file
            filename_stem: UUID stem for naming variants

        Returns:
            Dict of size_name -> relative path (from UPLOAD_DIR)
        """
        try:
            from PIL import Image

            variants: dict[str, str] = {}
            parent_dir = source_path.parent

            with Image.open(source_path) as img:
                # Convert to RGB if needed (for PNG with transparency)
                if img.mode in ("RGBA", "P"):
                    img = img.convert("RGB")

                # Resize original if larger than max dimension
                img = self._resize_image(img, IMAGE_MAX_DIMENSION)

                for size_name, max_dim in IMAGE_VARIANT_SIZES.items():
                    variant_img = self._resize_image(img.copy(), max_dim)
                    variant_filename = f"{filename_stem}_{size_name}.webp"
                    variant_path = parent_dir / variant_filename

                    variant_img.save(
                        variant_path, "WEBP", quality=IMAGE_VARIANT_QUALITY
                    )

                    variants[size_name] = str(
                        variant_path.relative_to(UPLOAD_DIR)
                    )
                    logger.debug(
                        f"Generated {size_name}px variant: {variant_path}"
                    )

            return variants

        except ImportError:
            logger.debug("PIL not available, skipping variant generation")
            return {}
        except OSError as e:
            logger.warning(f"Could not generate image variants: {e}")
            return {}

    async def upload_file(
        self,
        db: Session,
        store_id: int,
        file_content: bytes,
        filename: str,
        folder: str = "general",
    ) -> MediaFile:
        """
        Upload a file to the media library.

        Args:
            db: Database session
            store_id: Store ID
            file_content: File content as bytes
            filename: Original filename
            folder: Folder to store in (products, general, etc.)

        Returns:
            Created MediaFile record
        """
        # Validate file
        file_size = len(file_content)
        ext, media_type = self._validate_file(filename, file_size)

        # Generate unique filename
        unique_filename = self._generate_unique_filename(filename)

        # Get upload path
        upload_path = self._get_store_upload_path(store_id, folder)
        self._ensure_upload_dir(upload_path)

        # Save file
        file_path = upload_path / unique_filename
        file_path.write_bytes(file_content)

        # Get relative path for storage
        relative_path = str(file_path.relative_to(UPLOAD_DIR))

        # Get MIME type
        mime_type, _ = mimetypes.guess_type(filename)

        # Get image dimensions and generate variants
        width, height = None, None
        thumbnail_path = None
        extra_metadata: dict[str, Any] = {}

        if media_type == "image":
            dimensions = self._get_image_dimensions(file_path)
            if dimensions:
                width, height = dimensions

            # Generate WebP variants (800px, 200px)
            stem = unique_filename.rsplit(".", 1)[0] if "." in unique_filename else unique_filename
            variants = self._generate_image_variants(file_path, stem)
            if variants:
                extra_metadata["variants"] = variants
                # Use the 200px variant as thumbnail
                if "200" in variants:
                    thumbnail_path = variants["200"]

        # Create database record
        media_file = MediaFile(
            store_id=store_id,
            filename=unique_filename,
            original_filename=filename,
            file_path=relative_path,
            media_type=media_type,
            mime_type=mime_type,
            file_size=file_size,
            width=width,
            height=height,
            thumbnail_path=thumbnail_path,
            folder=folder,
            extra_metadata=extra_metadata if extra_metadata else None,
        )

        db.add(media_file)
        db.flush()
        db.refresh(media_file)

        logger.info(
            f"Uploaded media file {media_file.id} for store {store_id}: {filename}"
        )

        return media_file

    def get_media(
        self, db: Session, store_id: int, media_id: int
    ) -> MediaFile:
        """
        Get a media file by ID.

        Raises:
            MediaNotFoundException: If media not found or doesn't belong to store
        """
        media = (
            db.query(MediaFile)
            .filter(
                MediaFile.id == media_id,
                MediaFile.store_id == store_id,
            )
            .first()
        )

        if not media:
            raise MediaNotFoundException(media_id)

        return media

    def get_media_library(
        self,
        db: Session,
        store_id: int,
        skip: int = 0,
        limit: int = 100,
        media_type: str | None = None,
        folder: str | None = None,
        search: str | None = None,
    ) -> tuple[list[MediaFile], int]:
        """
        Get store media library with filtering.

        Args:
            db: Database session
            store_id: Store ID
            skip: Pagination offset
            limit: Pagination limit
            media_type: Filter by media type
            folder: Filter by folder
            search: Search in filename

        Returns:
            Tuple of (media_files, total_count)
        """
        query = db.query(MediaFile).filter(MediaFile.store_id == store_id)

        if media_type:
            query = query.filter(MediaFile.media_type == media_type)

        if folder:
            query = query.filter(MediaFile.folder == folder)

        if search:
            search_pattern = f"%{search}%"
            query = query.filter(
                or_(
                    MediaFile.filename.ilike(search_pattern),
                    MediaFile.original_filename.ilike(search_pattern),
                    MediaFile.alt_text.ilike(search_pattern),
                )
            )

        # Order by newest first
        query = query.order_by(MediaFile.created_at.desc())

        total = query.count()
        media_files = query.offset(skip).limit(limit).all()

        return media_files, total

    def update_media_metadata(
        self,
        db: Session,
        store_id: int,
        media_id: int,
        filename: str | None = None,
        alt_text: str | None = None,
        description: str | None = None,
        folder: str | None = None,
        metadata: dict | None = None,
    ) -> MediaFile:
        """
        Update media file metadata.

        Args:
            db: Database session
            store_id: Store ID
            media_id: Media file ID
            filename: New display filename
            alt_text: Alt text for images
            description: File description
            folder: Move to different folder
            metadata: Additional metadata

        Returns:
            Updated MediaFile
        """
        media = self.get_media(db, store_id, media_id)

        if filename is not None:
            media.original_filename = filename

        if alt_text is not None:
            media.alt_text = alt_text

        if description is not None:
            media.description = description

        if folder is not None and folder != media.folder:
            # Move file to new folder
            old_path = UPLOAD_DIR / media.file_path
            new_dir = self._get_store_upload_path(store_id, folder)
            self._ensure_upload_dir(new_dir)
            new_path = new_dir / media.filename

            if old_path.exists():
                shutil.move(str(old_path), str(new_path))
                media.file_path = str(new_path.relative_to(UPLOAD_DIR))

            media.folder = folder

        if metadata is not None:
            media.extra_metadata = metadata

        media.updated_at = datetime.now(UTC)
        db.flush()

        logger.info(f"Updated media metadata for {media_id}")

        return media

    def delete_media(
        self, db: Session, store_id: int, media_id: int
    ) -> bool:
        """
        Delete a media file.

        Args:
            db: Database session
            store_id: Store ID
            media_id: Media file ID

        Returns:
            True if deleted successfully
        """
        media = self.get_media(db, store_id, media_id)

        # Delete physical files
        file_path = UPLOAD_DIR / media.file_path
        if file_path.exists():
            file_path.unlink()

        if media.thumbnail_path:
            thumb_path = UPLOAD_DIR / media.thumbnail_path
            if thumb_path.exists():
                thumb_path.unlink()

        # Delete variant files
        if media.extra_metadata and "variants" in media.extra_metadata:
            for variant_path in media.extra_metadata["variants"].values():
                vpath = UPLOAD_DIR / variant_path
                if vpath.exists():
                    vpath.unlink()

        # Delete database record
        db.delete(media)

        logger.info(f"Deleted media file {media_id} for store {store_id}")

        return True

    def get_storage_stats(self, db: Session) -> dict:
        """Get storage statistics from MediaFile records.

        Returns:
            Dict with storage metrics for health monitoring.
        """
        total_files = db.query(func.count(MediaFile.id)).scalar() or 0
        total_size = db.query(func.sum(MediaFile.file_size)).scalar() or 0

        # Count distinct folders as proxy for directory count
        directory_count = (
            db.query(func.count(func.distinct(MediaFile.folder))).scalar() or 0
        )

        # Image-specific stats
        image_count = (
            db.query(func.count(MediaFile.id))
            .filter(MediaFile.media_type == "image")
            .scalar()
            or 0
        )

        return {
            "total_files": total_files,
            "total_size_bytes": total_size,
            "total_size_mb": round(total_size / (1024 * 1024), 2) if total_size else 0,
            "total_size_gb": round(total_size / (1024 * 1024 * 1024), 3) if total_size else 0,
            "directory_count": directory_count,
            "max_files_per_dir": 0,  # Not applicable for DB-backed tracking
            "avg_files_per_dir": round(total_files / directory_count, 1) if directory_count else 0,
            "products_estimated": image_count,
        }


# Create service instance
media_service = MediaService()