"""
Media upload and management for StarPunk

Per ADR-057 and ADR-058:
- Social media attachment model (media at top of note)
- Pillow-based image optimization
- 10MB max file size, 4096x4096 max dimensions
- Auto-resize to 2048px for performance
- 4 images max per note
"""

from PIL import Image, ImageOps
from pathlib import Path
from datetime import datetime
import uuid
import io
from typing import Optional, List, Dict, Tuple
from flask import current_app

# Allowed MIME types per Q11
ALLOWED_MIME_TYPES = {
    'image/jpeg': ['.jpg', '.jpeg'],
    'image/png': ['.png'],
    'image/gif': ['.gif'],
    'image/webp': ['.webp']
}

# Limits per Q&A and ADR-058
MAX_FILE_SIZE = 10 * 1024 * 1024  # 10MB
MAX_DIMENSION = 4096              # 4096x4096 max
RESIZE_DIMENSION = 2048           # Auto-resize to 2048px
MAX_IMAGES_PER_NOTE = 4


def validate_image(file_data: bytes, filename: str) -> Tuple[str, int, int]:
    """
    Validate image file

    Per Q11: Validate MIME type using Pillow
    Per Q6: Reject if >10MB or >4096px

    Args:
        file_data: Raw file bytes
        filename: Original filename

    Returns:
        Tuple of (mime_type, width, height)

    Raises:
        ValueError: If file is invalid
    """
    # Check file size first (before loading)
    if len(file_data) > MAX_FILE_SIZE:
        raise ValueError(f"File too large. Maximum size is 10MB")

    # Try to open with Pillow (validates integrity)
    try:
        img = Image.open(io.BytesIO(file_data))
        img.verify()  # Verify it's a valid image

        # Re-open after verify (verify() closes the file)
        img = Image.open(io.BytesIO(file_data))
    except Exception as e:
        raise ValueError(f"Invalid or corrupted image: {e}")

    # Check format is allowed
    if img.format:
        format_lower = img.format.lower()
        mime_type = f'image/{format_lower}'

        # Special case: JPEG format can be reported as 'jpeg'
        if format_lower == 'jpeg':
            mime_type = 'image/jpeg'

        if mime_type not in ALLOWED_MIME_TYPES:
            raise ValueError(f"Invalid image format. Accepted: JPEG, PNG, GIF, WebP")
    else:
        raise ValueError("Could not determine image format")

    # Check dimensions
    width, height = img.size
    if max(width, height) > MAX_DIMENSION:
        raise ValueError(f"Image dimensions too large. Maximum is {MAX_DIMENSION}x{MAX_DIMENSION} pixels")

    return mime_type, width, height


def optimize_image(image_data: bytes) -> Tuple[Image.Image, int, int]:
    """
    Optimize image for web display

    Per ADR-058:
    - Auto-resize if >2048px (maintaining aspect ratio)
    - Correct EXIF orientation
    - 95% quality

    Per Q12: Preserve GIF animation during resize

    Args:
        image_data: Raw image bytes

    Returns:
        Tuple of (optimized_image, width, height)
    """
    img = Image.open(io.BytesIO(image_data))

    # Correct EXIF orientation (per ADR-058)
    img = ImageOps.exif_transpose(img) if img.format != 'GIF' else img

    # Get original dimensions
    width, height = img.size

    # Resize if needed (per ADR-058: >2048px gets resized)
    if max(width, height) > RESIZE_DIMENSION:
        # For GIFs, we need special handling to preserve animation
        if img.format == 'GIF' and getattr(img, 'is_animated', False):
            # For animated GIFs, just return original
            # Per Q12: Preserve GIF animation
            # Note: Resizing animated GIFs is complex, skip for v1.2.0
            return img, width, height
        else:
            # Calculate new size maintaining aspect ratio
            img.thumbnail((RESIZE_DIMENSION, RESIZE_DIMENSION), Image.Resampling.LANCZOS)
            width, height = img.size

    return img, width, height


def save_media(file_data: bytes, filename: str) -> Dict:
    """
    Save uploaded media file

    Per Q5: UUID-based filename to avoid collisions
    Per Q2: Date-organized path: /media/YYYY/MM/uuid.ext
    Per Q6: Validate, optimize, then save

    Args:
        file_data: Raw file bytes
        filename: Original filename

    Returns:
        Media metadata dict (for database insert)

    Raises:
        ValueError: If validation fails
    """
    from starpunk.database import get_db

    # Validate image
    mime_type, orig_width, orig_height = validate_image(file_data, filename)

    # Optimize image
    optimized_img, width, height = optimize_image(file_data)

    # Generate UUID-based filename (per Q5)
    file_ext = Path(filename).suffix.lower()
    if not file_ext:
        # Determine extension from MIME type
        for mime, exts in ALLOWED_MIME_TYPES.items():
            if mime == mime_type:
                file_ext = exts[0]
                break

    stored_filename = f"{uuid.uuid4()}{file_ext}"

    # Create date-based path (per Q2)
    now = datetime.now()
    year = now.strftime('%Y')
    month = now.strftime('%m')
    relative_path = f"{year}/{month}/{stored_filename}"

    # Get media directory from app config
    media_dir = Path(current_app.config.get('DATA_PATH', 'data')) / 'media'
    full_dir = media_dir / year / month
    full_dir.mkdir(parents=True, exist_ok=True)

    # Save optimized image
    full_path = full_dir / stored_filename

    # Determine save format and quality
    save_format = optimized_img.format or 'PNG'
    save_kwargs = {'optimize': True}

    if save_format in ['JPEG', 'JPG']:
        save_kwargs['quality'] = 95  # Per ADR-058
    elif save_format == 'PNG':
        save_kwargs['optimize'] = True
    elif save_format == 'WEBP':
        save_kwargs['quality'] = 95

    optimized_img.save(full_path, format=save_format, **save_kwargs)

    # Get actual file size after optimization
    actual_size = full_path.stat().st_size

    # Insert into database
    db = get_db(current_app)
    cursor = db.execute(
        """
        INSERT INTO media (filename, stored_filename, path, mime_type, size, width, height)
        VALUES (?, ?, ?, ?, ?, ?, ?)
        """,
        (filename, stored_filename, relative_path, mime_type, actual_size, width, height)
    )
    db.commit()
    media_id = cursor.lastrowid

    return {
        'id': media_id,
        'filename': filename,
        'stored_filename': stored_filename,
        'path': relative_path,
        'mime_type': mime_type,
        'size': actual_size,
        'width': width,
        'height': height
    }


def attach_media_to_note(note_id: int, media_ids: List[int], captions: List[str]) -> None:
    """
    Attach media files to note

    Per Q4: Happens after note creation
    Per Q7: Captions are optional per image

    Args:
        note_id: Note to attach to
        media_ids: List of media IDs (max 4)
        captions: List of captions (same length as media_ids)

    Raises:
        ValueError: If more than MAX_IMAGES_PER_NOTE
    """
    from starpunk.database import get_db

    if len(media_ids) > MAX_IMAGES_PER_NOTE:
        raise ValueError(f"Maximum {MAX_IMAGES_PER_NOTE} images per note")

    db = get_db(current_app)

    # Delete existing associations (for edit case)
    db.execute("DELETE FROM note_media WHERE note_id = ?", (note_id,))

    # Insert new associations
    for i, (media_id, caption) in enumerate(zip(media_ids, captions)):
        db.execute(
            """
            INSERT INTO note_media (note_id, media_id, display_order, caption)
            VALUES (?, ?, ?, ?)
            """,
            (note_id, media_id, i, caption or None)
        )

    db.commit()


def get_note_media(note_id: int) -> List[Dict]:
    """
    Get all media attached to a note

    Returns list sorted by display_order

    Args:
        note_id: Note ID to get media for

    Returns:
        List of media dicts with metadata
    """
    from starpunk.database import get_db

    db = get_db(current_app)
    rows = db.execute(
        """
        SELECT
            m.id,
            m.filename,
            m.stored_filename,
            m.path,
            m.mime_type,
            m.size,
            m.width,
            m.height,
            nm.caption,
            nm.display_order
        FROM note_media nm
        JOIN media m ON nm.media_id = m.id
        WHERE nm.note_id = ?
        ORDER BY nm.display_order
        """,
        (note_id,)
    ).fetchall()

    return [
        {
            'id': row[0],
            'filename': row[1],
            'stored_filename': row[2],
            'path': row[3],
            'mime_type': row[4],
            'size': row[5],
            'width': row[6],
            'height': row[7],
            'caption': row[8],
            'display_order': row[9]
        }
        for row in rows
    ]


def delete_media(media_id: int) -> None:
    """
    Delete media file and database record

    Per Q8: Cleanup orphaned files

    Args:
        media_id: Media ID to delete
    """
    from starpunk.database import get_db

    db = get_db(current_app)

    # Get media path before deleting
    row = db.execute("SELECT path FROM media WHERE id = ?", (media_id,)).fetchone()
    if not row:
        return

    media_path = row[0]

    # Delete database record (cascade will delete note_media entries)
    db.execute("DELETE FROM media WHERE id = ?", (media_id,))
    db.commit()

    # Delete file from disk
    media_dir = Path(current_app.config.get('DATA_PATH', 'data')) / 'media'
    full_path = media_dir / media_path

    if full_path.exists():
        full_path.unlink()
        current_app.logger.info(f"Deleted media file: {media_path}")