"""
OpenCV-based image processing pipeline for smart photo handling.

Handles:
- EXIF orientation detection and auto-rotation
- Smart cropping using OpenCV contour detection
- Text orientation detection using Hough lines
- Resize and compression to 1200px
- Thumbnail generation (200px square)
- Fallback to Pillow for basic processing if OpenCV fails
"""

import io
import logging
from typing import Dict, Optional, Tuple
from PIL import Image
from PIL.ExifTags import TAGS
import piexif
import cv2
import numpy as np

logger = logging.getLogger(__name__)


def strip_exif_orientation(file_bytes: bytes) -> bytes:
    """
    Remove EXIF orientation metadata from image bytes.

    Returns image bytes with orientation tag removed (or set to 1 = normal).
    This ensures both Gemini and our backend analyze the same raw image.

    Args:
        file_bytes: Raw image file bytes

    Returns:
        Image bytes with EXIF orientation stripped
    """
    try:
        image = Image.open(io.BytesIO(file_bytes))

        # Try to get and remove EXIF orientation
        try:
            exif_dict = piexif.load(image.info.get('exif', b''))
            if piexif.ImageIFD.Orientation in exif_dict['0th']:
                del exif_dict['0th'][piexif.ImageIFD.Orientation]
                exif_bytes = piexif.dump(exif_dict)
            else:
                exif_bytes = None
        except:
            exif_bytes = None

        # Save image without orientation
        output = io.BytesIO()
        if exif_bytes:
            image.save(output, format='JPEG', quality=85, exif=exif_bytes)
        else:
            image.save(output, format='JPEG', quality=85)

        return output.getvalue()
    except Exception as e:
        logger.warning(f"Failed to strip EXIF orientation: {e}, returning original bytes")
        return file_bytes


class ImageProcessor:
    """Service for processing uploaded images with smart features."""

    MAX_FILE_SIZE = 10 * 1024 * 1024  # 10MB
    LONG_SIDE = 1200
    THUMBNAIL_SIZE = 200
    JPEG_QUALITY = 85

    # Algorithm parameters (Issue 4: DRY Violation - Magic Numbers)
    CANNY_CROP_THRESHOLDS = (100, 200)
    CANNY_TEXT_THRESHOLDS = (50, 150)
    HOUGH_THRESHOLD = 100
    CROP_PADDING_FACTOR = 0.1
    ANGLE_UPSIDE_DOWN_THRESHOLD = 80  # degrees
    ANGLE_SIDEWAYS_THRESHOLD = 45  # degrees

    def __init__(self):
        """Initialize the image processor."""
        self.logger = logger

    def process_photo(
        self, file_bytes: bytes, crop_bounds: Optional[Dict] = None, rotation_degrees: float = 0
    ) -> Dict:
        """
        Process a photo with EXIF rotation, smart cropping, and compression.

        Args:
            file_bytes: Raw image file bytes
            crop_bounds: Optional manual crop bounds {x, y, width, height}
            rotation_degrees: Optional manual rotation in degrees (applied after crop)

        Returns:
            {
                'status': 'success' | 'error',
                'cropped_image_bytes': bytes or None,
                'thumbnail_bytes': bytes or None,
                'original_size': (width, height),
                'crop_size': (width, height) or None,
                'text_angle': float or None,
                'metadata': {
                    'exif_orientation': int,
                    'crop_method': 'manual' | 'opencv' | 'pillow' | 'none',
                    'file_size_bytes': int
                }
            }
        """
        try:
            # Validate file size
            if len(file_bytes) > self.MAX_FILE_SIZE:
                return {
                    'status': 'error',
                    'error': f'File too large: {len(file_bytes)} > {self.MAX_FILE_SIZE}',
                    'cropped_image_bytes': None,
                    'thumbnail_bytes': None,
                }

            # Open image with PIL (without applying EXIF yet, so crop_bounds match AI analysis)
            image = Image.open(io.BytesIO(file_bytes))
            original_size = image.size
            msg = f"[PROCESS] Input: {len(file_bytes)} bytes, size={original_size}, crop_bounds={crop_bounds}, rotation={rotation_degrees}°"
            self.logger.info(msg)
            print(f">>> {msg}")  # Explicit print for visibility

            # Extract EXIF orientation (but don't apply it)
            exif_orientation = self._extract_exif_orientation(image)
            if exif_orientation and exif_orientation > 1:
                self.logger.info(f"[PROCESS] Note: Image has EXIF orientation {exif_orientation}, will be applied after crop")

            # Smart cropping (on raw image - crop_bounds come from Gemini analyzing same raw image)
            cropped_image = image
            crop_size = None
            text_angle = None
            crop_method = 'none'

            if crop_bounds:
                # Manual crop bounds provided (from AI, based on raw image)
                crop_rect = (
                    crop_bounds['x'],
                    crop_bounds['y'],
                    crop_bounds['x'] + crop_bounds['width'],
                    crop_bounds['y'] + crop_bounds['height'],
                )
                msg1 = f"[CROP] Manual bounds: {crop_rect}"
                self.logger.info(msg1)
                print(f">>> {msg1}")  # Explicit print
                cropped_image = image.crop(crop_rect)
                crop_size = cropped_image.size
                crop_method = 'manual'
                msg2 = f"[CROP] Result size: {crop_size}, pixels={crop_size[0]*crop_size[1]}"
                self.logger.info(msg2)
                print(f">>> {msg2}")  # Explicit print
            else:
                # Try OpenCV smart crop on raw image
                self.logger.info("[CROP] Attempting OpenCV smart crop...")
                try:
                    crop_result = self._smart_crop_opencv(image)
                    if crop_result is not None:
                        cropped_image, crop_size = crop_result
                        crop_method = 'opencv'
                        self.logger.info(f"[CROP] OpenCV success: {crop_size}, pixels={crop_size[0]*crop_size[1]}")

                        # Detect text orientation within the cropped region
                        text_angle, angle_status = self._detect_text_orientation(
                            cropped_image
                        )
                        if text_angle is not None:
                            self.logger.info(
                                f"[CROP] Text angle: {text_angle}° ({angle_status})"
                            )
                            if angle_status in ['upside_down', 'sideways']:
                                cropped_image = self._rotate_image(
                                    cropped_image, text_angle
                                )
                    else:
                        self.logger.warning("[CROP] OpenCV returned None, using full image")
                        crop_method = 'pillow'
                except (IOError, ValueError, cv2.error) as e:
                    # Fallback to Pillow if OpenCV fails
                    self.logger.warning(
                        f"[CROP] OpenCV failed: {e}, using full image"
                    )
                    crop_method = 'pillow'

            # Now apply EXIF orientation to the cropped image
            if exif_orientation and exif_orientation > 1:
                cropped_image = self._rotate_by_orientation(cropped_image, exif_orientation)
                self.logger.info(f"Applied EXIF rotation: {exif_orientation}")

            # Apply manual rotation if provided (rotation_degrees already signed: positive=CCW, negative=CW)
            if abs(rotation_degrees) > 0.5:
                cropped_image = cropped_image.rotate(rotation_degrees, expand=True)
                msg = f"Applied manual rotation: {rotation_degrees}°"
                self.logger.info(msg)
                print(f">>> {msg}")  # Explicit print

            # Resize and compress
            compressed_bytes = self._resize_and_compress(cropped_image)

            # Generate thumbnail
            thumbnail_bytes = self._generate_thumbnail(image)

            return {
                'status': 'success',
                'cropped_image_bytes': compressed_bytes,
                'thumbnail_bytes': thumbnail_bytes,
                'original_size': original_size,
                'crop_size': crop_size,
                'text_angle': text_angle,
                'metadata': {
                    'exif_orientation': exif_orientation or 1,
                    'crop_method': crop_method,
                    'file_size_bytes': len(file_bytes),
                },
            }

        except (IOError, ValueError, cv2.error) as e:
            self.logger.error(f"Image processing failed: {e}")
            return {
                'status': 'error',
                'error': str(e),
                'cropped_image_bytes': None,
                'thumbnail_bytes': None,
            }

    def _extract_exif_orientation(self, image: Image.Image) -> Optional[int]:
        """
        Extract EXIF orientation tag from image.

        Returns:
            Orientation value (1-8) or None if not present
        """
        try:
            # Use piexif for EXIF extraction (avoiding private PIL API)
            if hasattr(image, 'info') and 'exif' in image.info:
                exif_dict = piexif.load(image.info['exif'])
                orientation = exif_dict['0th'].get(piexif.ImageIFD.Orientation)
                if orientation:
                    return orientation

            return None
        except (piexif.InvalidImageData, ValueError, IOError) as e:
            self.logger.debug(f"Could not extract EXIF orientation: {e}")
            return None

    def _rotate_by_orientation(
        self, image: Image.Image, orientation: int
    ) -> Image.Image:
        """
        Rotate image based on EXIF orientation tag.

        Args:
            image: PIL Image
            orientation: EXIF orientation value (1-8)

        Returns:
            Rotated PIL Image
        """
        if orientation == 1:
            return image
        elif orientation == 2:
            return image.transpose(Image.Transpose.FLIP_LEFT_RIGHT)
        elif orientation == 3:
            return image.transpose(Image.Transpose.ROTATE_180)
        elif orientation == 4:
            return image.transpose(Image.Transpose.FLIP_TOP_BOTTOM)
        elif orientation == 5:
            return image.transpose(Image.Transpose.TRANSPOSE)
        elif orientation == 6:
            return image.transpose(Image.Transpose.ROTATE_270)
        elif orientation == 7:
            return image.transpose(Image.Transpose.TRANSVERSE)
        elif orientation == 8:
            return image.transpose(Image.Transpose.ROTATE_90)
        return image

    def _smart_crop_opencv(
        self, image: Image.Image
    ) -> Optional[Tuple[Image.Image, Tuple[int, int]]]:
        """
        Use OpenCV to detect and crop the main object in the image.

        Args:
            image: PIL Image

        Returns:
            Tuple of (cropped PIL Image, crop size) or None if no contours found
        """
        try:
            # Convert PIL image to OpenCV format
            cv_image = cv2.cvtColor(np.array(image), cv2.COLOR_RGB2BGR)
            gray = cv2.cvtColor(cv_image, cv2.COLOR_BGR2GRAY)

            # Edge detection
            edges = cv2.Canny(gray, *self.CANNY_CROP_THRESHOLDS)

            # Find contours
            contours, _ = cv2.findContours(
                edges, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE
            )

            if not contours:
                self.logger.debug("No contours found in image")
                return None

            # Get bounding box of largest contour
            largest_contour = max(contours, key=cv2.contourArea)
            x, y, w, h = cv2.boundingRect(largest_contour)

            # Apply padding around bounds
            pad_x = int(w * self.CROP_PADDING_FACTOR)
            pad_y = int(h * self.CROP_PADDING_FACTOR)

            x1 = max(0, x - pad_x)
            y1 = max(0, y - pad_y)
            x2 = min(cv_image.shape[1], x + w + pad_x)
            y2 = min(cv_image.shape[0], y + h + pad_y)

            # Crop image
            cropped = image.crop((x1, y1, x2, y2))
            crop_size = cropped.size

            self.logger.debug(
                f"OpenCV crop bounds: ({x1}, {y1}, {x2}, {y2}), size: {crop_size}"
            )

            return cropped, crop_size

        except (IOError, ValueError, cv2.error) as e:
            self.logger.warning(f"OpenCV smart crop failed: {e}")
            return None

    def _detect_text_orientation(
        self, image: Image.Image
    ) -> Tuple[Optional[float], str]:
        """
        Detect text orientation using Hough line transform.

        Args:
            image: PIL Image

        Returns:
            Tuple of (angle in degrees, status string)
            status: 'normal', 'upside_down', 'sideways', 'not_detected'
        """
        try:
            # Convert to OpenCV format
            cv_image = cv2.cvtColor(np.array(image), cv2.COLOR_RGB2BGR)

            # DoS prevention: check resolution
            if cv_image.shape[0] * cv_image.shape[1] > 2000 * 2000:  # >4MP
                self.logger.warning("ROI too large for text detection, skipping")
                return None, 'not_detected'

            gray = cv2.cvtColor(cv_image, cv2.COLOR_BGR2GRAY)

            # Edge detection
            edges = cv2.Canny(gray, *self.CANNY_TEXT_THRESHOLDS)

            # Hough line detection
            lines = cv2.HoughLines(edges, 1, np.pi / 180, self.HOUGH_THRESHOLD)

            if lines is None or len(lines) == 0:
                self.logger.debug("No lines detected for text orientation")
                return None, 'not_detected'

            # Extract angles from lines
            angles = []
            for line in lines:
                rho, theta = line[0]
                angle = np.degrees(theta)
                angles.append(angle)

            # Normalize angles to 0-180 range
            angles = np.array(angles)
            angles = np.where(angles > 90, angles - 180, angles)

            # Find dominant angle
            mean_angle = np.mean(angles)

            # Determine orientation status
            status = 'normal'
            corrected_angle = mean_angle

            # Check for upside-down text (~180°)
            if abs(mean_angle) > self.ANGLE_UPSIDE_DOWN_THRESHOLD:
                status = 'upside_down'
                corrected_angle = mean_angle + 180 if mean_angle > 0 else mean_angle - 180
            # Check for sideways text (~90°)
            elif abs(mean_angle) > self.ANGLE_SIDEWAYS_THRESHOLD:
                status = 'sideways'

            self.logger.debug(
                f"Text orientation: angle={mean_angle:.1f}°, status={status}"
            )

            return corrected_angle, status

        except (IOError, ValueError, cv2.error) as e:
            self.logger.warning(f"Text orientation detection failed: {e}")
            return None, 'not_detected'

    def _rotate_image(self, image: Image.Image, angle: float) -> Image.Image:
        """
        Rotate image by specified angle.

        Args:
            image: PIL Image
            angle: Rotation angle in degrees

        Returns:
            Rotated PIL Image
        """
        return image.rotate(angle, expand=False, fillcolor='white')

    def _resize_and_compress(self, image: Image.Image) -> bytes:
        """
        Resize image to 1200px on long side and compress to JPEG.

        Args:
            image: PIL Image

        Returns:
            Compressed JPEG bytes
        """
        # Get current size
        width, height = image.size
        max_dim = max(width, height)

        # Only resize if necessary
        if max_dim > self.LONG_SIDE:
            scale = self.LONG_SIDE / max_dim
            new_width = int(width * scale)
            new_height = int(height * scale)
            image = image.resize((new_width, new_height), Image.Resampling.LANCZOS)
            self.logger.debug(
                f"Resized from {(width, height)} to {(new_width, new_height)}"
            )

        # Convert to RGB if necessary (for JPEG)
        if image.mode in ('RGBA', 'LA', 'P'):
            # Extract alpha channel if present
            mask = None
            if image.mode == 'RGBA':
                alpha = image.split()[3]
                mask = alpha
            elif image.mode == 'LA':
                alpha = image.split()[1]
                mask = alpha

            rgb_image = Image.new('RGB', image.size, (255, 255, 255))
            rgb_image.paste(image, mask=mask)
            image = rgb_image

        # Compress to JPEG
        output = io.BytesIO()
        image.save(output, format='JPEG', quality=self.JPEG_QUALITY, optimize=True)
        compressed_bytes = output.getvalue()

        self.logger.debug(
            f"Compressed to JPEG: {len(compressed_bytes)} bytes, "
            f"quality={self.JPEG_QUALITY}"
        )

        return compressed_bytes

    def _generate_thumbnail(self, image: Image.Image) -> bytes:
        """
        Generate 200px square thumbnail with center crop.

        Args:
            image: PIL Image

        Returns:
            Thumbnail JPEG bytes
        """
        try:
            # Get current size
            width, height = image.size

            # Center crop to square
            min_dim = min(width, height)
            left = (width - min_dim) // 2
            top = (height - min_dim) // 2
            right = left + min_dim
            bottom = top + min_dim

            square = image.crop((left, top, right, bottom))

            # Resize to thumbnail size
            thumbnail = square.resize(
                (self.THUMBNAIL_SIZE, self.THUMBNAIL_SIZE),
                Image.Resampling.LANCZOS,
            )

            # Convert to RGB if necessary
            if thumbnail.mode in ('RGBA', 'LA', 'P'):
                # Extract alpha channel if present
                mask = None
                if thumbnail.mode == 'RGBA':
                    alpha = thumbnail.split()[3]
                    mask = alpha
                elif thumbnail.mode == 'LA':
                    alpha = thumbnail.split()[1]
                    mask = alpha

                rgb_thumbnail = Image.new('RGB', thumbnail.size, (255, 255, 255))
                rgb_thumbnail.paste(thumbnail, mask=mask)
                thumbnail = rgb_thumbnail

            # Compress
            output = io.BytesIO()
            thumbnail.save(output, format='JPEG', quality=self.JPEG_QUALITY, optimize=True)
            thumbnail_bytes = output.getvalue()

            self.logger.debug(
                f"Generated thumbnail: {self.THUMBNAIL_SIZE}x{self.THUMBNAIL_SIZE}, "
                f"{len(thumbnail_bytes)} bytes"
            )

            return thumbnail_bytes

        except (IOError, ValueError, cv2.error) as e:
            self.logger.error(f"Thumbnail generation failed: {e}")
            return b''