"""Real-ESRGAN model management and processing."""
import logging
import os
from typing import Optional, Tuple

import cv2
import numpy as np

from app.config import settings
from app.services import model_manager
import urllib.request

logger = logging.getLogger(__name__)

try:
    from basicsr.archs.rrdbnet_arch import RRDBNet
    from realesrgan import RealESRGANer
    REALESRGAN_AVAILABLE = True
except ImportError:
    REALESRGAN_AVAILABLE = False
    logger.warning('Real-ESRGAN not available. Install via: pip install realesrgan')


class RealESRGANBridge:
    """Bridge to Real-ESRGAN functionality."""

    def __init__(self):
        """Initialize the Real-ESRGAN bridge."""
        self.upsampler: Optional[RealESRGANer] = None
        self.current_model: Optional[str] = None
        self.initialized = False

    def initialize(self) -> bool:
        """Initialize Real-ESRGAN upsampler."""
        if not REALESRGAN_AVAILABLE:
            logger.error('Real-ESRGAN library not available')
            return False

        try:
            logger.info('Initializing Real-ESRGAN upsampler...')
            
            # Setup model loader
            scale = 4
            model_name = settings.default_model
            
            # Determine model path
            model_path = os.path.join(settings.models_dir, f'{model_name}.pth')
            if not os.path.exists(model_path):
                logger.warning(f'Model not found at {model_path}, will attempt to auto-download')
                if settings.auto_model_download:
                    # Try to locate known model URL and download it
                    try:
                        meta = model_manager.KNOWN_MODELS.get(model_name)
                        if meta and meta.get('url'):
                            os.makedirs(settings.models_dir, exist_ok=True)
                            url = meta['url']
                            logger.info(f'Downloading model {model_name} from {url}')
                            urllib.request.urlretrieve(url, model_path)
                            logger.info(f'Model downloaded to {model_path}')
                        else:
                            logger.error(f'No download URL known for model: {model_name}')
                    except Exception as e:
                        logger.error(f'Automatic model download failed: {e}', exc_info=True)

            if not os.path.exists(model_path):
                logger.error(f'Model file still not found: {model_path} - aborting initialization')
                return False
            
            # Load model
            model = RRDBNet(
                num_in_ch=3,
                num_out_ch=3,
                num_feat=64,
                num_block=23,
                num_grow_ch=32,
                scale=scale
            )
            
            self.upsampler = RealESRGANer(
                scale=scale,
                model_path=model_path,
                model=model,
                tile=settings.tile_size,
                tile_pad=settings.tile_pad,
                pre_pad=0,
                half=False,
            )
            
            self.current_model = model_name
            self.initialized = True
            logger.info(f'Real-ESRGAN initialized with model: {model_name}')
            return True
        except Exception as e:
            logger.error(f'Failed to initialize Real-ESRGAN: {e}', exc_info=True)
            return False

    def load_model(self, model_name: str) -> bool:
        """Load a specific upscaling model."""
        try:
            if not REALESRGAN_AVAILABLE:
                logger.error('Real-ESRGAN not available')
                return False

            logger.info(f'Loading model: {model_name}')
            
            # Extract scale from model name
            scale = 4
            if 'x2' in model_name.lower():
                scale = 2
            elif 'x3' in model_name.lower():
                scale = 3
            elif 'x4' in model_name.lower():
                scale = 4
            
            model_path = os.path.join(settings.models_dir, f'{model_name}.pth')
            
            if not os.path.exists(model_path):
                logger.error(f'Model file not found: {model_path}')
                return False
            
            model = RRDBNet(
                num_in_ch=3,
                num_out_ch=3,
                num_feat=64,
                num_block=23,
                num_grow_ch=32,
                scale=scale
            )
            
            self.upsampler = RealESRGANer(
                scale=scale,
                model_path=model_path,
                model=model,
                tile=settings.tile_size,
                tile_pad=settings.tile_pad,
                pre_pad=0,
                half=False,
            )
            
            self.current_model = model_name
            logger.info(f'Model loaded: {model_name}')
            return True
        except Exception as e:
            logger.error(f'Failed to load model {model_name}: {e}', exc_info=True)
            return False

    def upscale(
        self,
        input_path: str,
        output_path: str,
        model_name: Optional[str] = None,
        outscale: Optional[float] = None,
    ) -> Tuple[bool, str, Optional[Tuple[int, int]]]:
        """
        Upscale an image.
        
        Returns: (success, message, output_size)
        """
        try:
            if not self.initialized:
                if not self.initialize():
                    return False, 'Failed to initialize Real-ESRGAN', None

            if model_name and model_name != self.current_model:
                if not self.load_model(model_name):
                    return False, f'Failed to load model: {model_name}', None

            if not self.upsampler:
                return False, 'Upsampler not initialized', None

            # Read image
            logger.info(f'Reading image: {input_path}')
            input_img = cv2.imread(str(input_path), cv2.IMREAD_UNCHANGED)
            if input_img is None:
                return False, f'Failed to read image: {input_path}', None

            input_shape = input_img.shape[:2]
            logger.info(f'Input image shape: {input_shape}')

            # Upscale
            logger.info(f'Upscaling with model: {self.current_model}')
            output, _ = self.upsampler.enhance(input_img, outscale=outscale or 4)

            # Save output
            cv2.imwrite(str(output_path), output)
            output_shape = output.shape[:2]
            logger.info(f'Output image shape: {output_shape}')
            logger.info(f'Upscaled image saved: {output_path}')

            return True, 'Upscaling completed successfully', tuple(output_shape)
        except Exception as e:
            logger.error(f'Upscaling failed: {e}', exc_info=True)
            return False, f'Upscaling failed: {str(e)}', None

    def get_upscale_factor(self) -> int:
        """Get current upscaling factor."""
        if self.upsampler:
            return self.upsampler.scale
        return 4


# Global instance
_bridge: Optional[RealESRGANBridge] = None


def get_bridge() -> RealESRGANBridge:
    """Get or create the global Real-ESRGAN bridge."""
    global _bridge
    if _bridge is None:
        _bridge = RealESRGANBridge()
    return _bridge