"""
Luminance Stack Processor - Professional ComfyUI Custom Nodes
Implements HDR processing using the Debevec Algorithm for multiple exposure fusion

Author: Sumit Chatterjee
Version: 1.0.1
Semantic Versioning: MAJOR.MINOR.PATCH
"""

import numpy as np
import torch
import cv2
from typing import Tuple, List
import logging

# Set up logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)


def tensor_to_cv2(tensor: torch.Tensor) -> np.ndarray:
    """Convert ComfyUI tensor to OpenCV format for HDR processing"""
    # ComfyUI tensors are typically [B, H, W, C] in 0-1 range
    if len(tensor.shape) == 4:
        tensor = tensor.squeeze(0)  # Remove batch dimension
    
    # Convert to numpy and scale to 8-bit (input images are already 8-bit)
    image = tensor.cpu().numpy()
    
    # Apply gamma correction (sRGB to linear) before HDR processing
    # This is crucial for proper camera response function recovery
    image_linear = np.where(image <= 0.04045, 
                           image / 12.92,
                           np.power((image + 0.055) / 1.055, 2.4))
    
    # Convert back to 8-bit for OpenCV HDR functions (since inputs are 8-bit)
    image_8bit = np.clip(image_linear * 255.0, 0, 255).astype(np.uint8)
    
    logger.info(f"Converted tensor to CV2: shape={image_8bit.shape}, dtype={image_8bit.dtype}, range=[{image_8bit.min()}, {image_8bit.max()}]")
    
    return image_8bit


def cv2_to_tensor(hdr_image: np.ndarray, output_16bit_linear: bool = True) -> torch.Tensor:
    """Convert OpenCV HDR image to ComfyUI tensor format"""
    
    if output_16bit_linear:
        # Convert HDR linear data to 16-bit linear format
        # Scale to 16-bit range while preserving linear characteristics
        
        # Find a reasonable scaling factor based on HDR content
        # Use 95th percentile to avoid extreme outliers affecting scaling
        scale_reference = np.percentile(hdr_image, 95.0)
        
        if scale_reference > 0:
            # Scale so that the 95th percentile maps to ~80% of 16-bit range
            # This preserves highlights while utilizing most of the 16-bit range
            scale_factor = (0.8 * 65535.0) / scale_reference
            scaled_linear = hdr_image * scale_factor
        else:
            scaled_linear = hdr_image * 65535.0
        
        # Clamp to 16-bit range but preserve linear values above 1.0
        hdr_16bit_linear = np.clip(scaled_linear, 0.0, 65535.0)
        
        # Convert to ComfyUI tensor format (0-1 range) while preserving 16-bit precision
        normalized_16bit = hdr_16bit_linear / 65535.0
        
        logger.info(f"HDR 16-bit linear output:")
        logger.info(f"  Original range: [{hdr_image.min():.6f}, {hdr_image.max():.6f}]")
        logger.info(f"  16-bit range: [{hdr_16bit_linear.min():.1f}, {hdr_16bit_linear.max():.1f}]")
        logger.info(f"  Final range: [{normalized_16bit.min():.6f}, {normalized_16bit.max():.6f}]")
        logger.info(f"  Scale factor: {scale_factor:.2f}")
        
    else:
        # Legacy floating point output (not recommended for 16-bit workflow)
        max_val = np.percentile(hdr_image, 99.9)
        if max_val > 0:
            normalized_16bit = hdr_image / max_val
        else:
            normalized_16bit = hdr_image
        
        normalized_16bit = np.clip(normalized_16bit, 0.0, 10.0)
    
    # Add batch dimension and convert to tensor
    tensor = torch.from_numpy(normalized_16bit.astype(np.float32)).unsqueeze(0)
    return tensor


class DebevecHDRProcessor:
    """Core HDR processing using multiple algorithms"""
    
    def __init__(self):
        self.calibrator = cv2.createCalibrateDebevec()
        self.merge_debevec = cv2.createMergeDebevec()
        # Alternative algorithms
        self.merge_mertens = cv2.createMergeMertens()
        self.merge_robertson = cv2.createMergeRobertson()
        self.calibrator_robertson = cv2.createCalibrateRobertson()
        
    def process_hdr(self, images: List[np.ndarray], exposure_times: List[float], algorithm: str = "mertens") -> np.ndarray:
        """
        Process multiple exposure images using various HDR algorithms
        
        Args:
            images: List of 8-bit images (OpenCV format) - CRITICAL: Must be 8-bit for OpenCV HDR
            exposure_times: List of exposure times in seconds  
            algorithm: HDR algorithm to use ("mertens", "debevec", "robertson")
            
        Returns:
            HDR merged image in linear colorspace (float32)
        """
        try:
            # Validate input format - OpenCV HDR functions require 8-bit input
            processed_images = []
            for i, img in enumerate(images):
                if img.dtype != np.uint8:
                    logger.warning(f"Image {i} is not 8-bit (dtype: {img.dtype}), this may cause issues")
                
                # CRITICAL FIX: Convert BGR to RGB for proper color handling
                # OpenCV uses BGR by default, but HDR processing expects RGB
                if len(img.shape) == 3 and img.shape[2] == 3:  # RGB
                    img_rgb = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
                    processed_images.append(img_rgb)
                else:
                    logger.error(f"Image {i} has invalid shape: {img.shape}")
                    raise ValueError(f"Image must be 3-channel RGB, got shape: {img.shape}")
            
            # Convert exposure times to numpy array
            times = np.array(exposure_times, dtype=np.float32)
            
            logger.info(f"Processing {len(processed_images)} images with {algorithm} algorithm")
            logger.info(f"Exposure times: {times}")
            logger.info(f"Image formats: {[img.shape for img in processed_images]}")
            logger.info(f"Image dtypes: {[img.dtype for img in processed_images]}")
            
            # Process using selected algorithm
            if algorithm == "mertens":
                # Mertens Exposure Fusion - often produces better results
                logger.info("Using Mertens Exposure Fusion algorithm...")
                hdr_radiance = self.merge_mertens.process(processed_images)
                # Mertens output is typically in 0-1 range, scale appropriately
                if hdr_radiance.max() <= 1.0:
                    hdr_radiance = hdr_radiance * 2.0  # Boost for better dynamic range
                
            elif algorithm == "robertson":
                # Robertson algorithm - alternative to Debevec
                logger.info("Using Robertson algorithm...")
                response = self.calibrator_robertson.process(processed_images, times)
                hdr_radiance = self.merge_robertson.process(processed_images, times, response)
                
            else:  # Default to Debevec
                # Estimate camera response function using Debevec method
                logger.info("Using Debevec algorithm...")
                response = self.calibrator.process(processed_images, times)
                logger.info(f"Response function shape: {response.shape}")
                
                # Merge images into HDR using Debevec algorithm
                hdr_radiance = self.merge_debevec.process(processed_images, times, response)
            
            # Validate HDR output
            if hdr_radiance is None or hdr_radiance.size == 0:
                raise ValueError("HDR merge produced empty result")
            
            logger.info(f"HDR merge completed with {algorithm} algorithm:")
            logger.info(f"  Output shape: {hdr_radiance.shape}")
            logger.info(f"  Output dtype: {hdr_radiance.dtype}")
            logger.info(f"  Value range: [{hdr_radiance.min():.6f}, {hdr_radiance.max():.6f}]")
            logger.info(f"  Mean value: {hdr_radiance.mean():.6f}")
            
            # Check for valid HDR data
            if np.all(hdr_radiance == 0):
                raise ValueError("HDR merge produced all-zero result")
            
            # CRITICAL FIX: Convert back from RGB to BGR for consistency
            # This ensures the output color channels are in the expected order
            if len(hdr_radiance.shape) == 3 and hdr_radiance.shape[2] == 3:
                hdr_radiance = cv2.cvtColor(hdr_radiance, cv2.COLOR_RGB2BGR)
            
            # The result is already in linear colorspace (scene radiance values)
            # Don't apply tone mapping - preserve the HDR data as-is
            return hdr_radiance.astype(np.float32)
            
        except Exception as e:
            logger.error(f"HDR processing error: {str(e)}")
            logger.error(f"Image count: {len(images)}")
            logger.error(f"Image shapes: {[img.shape if img is not None else 'None' for img in images]}")
            logger.error(f"Exposure times: {exposure_times}")
            
            # Fallback: return the middle exposure image in linear space
            if images:
                middle_idx = len(images) // 2
                fallback = images[middle_idx].astype(np.float32) / 255.0
                # Convert back to linear space (reverse gamma correction)
                fallback_linear = np.where(fallback <= 0.04045, 
                                         fallback / 12.92,
                                         np.power((fallback + 0.055) / 1.055, 2.4))
                logger.info(f"Using fallback image (index {middle_idx})")
                return fallback_linear.astype(np.float32)
            raise e


class LuminanceStackProcessor3Stops:
    """
    Professional ComfyUI Custom Node for 3-stop HDR processing
    Processes EV+2, EV+0, EV-2 exposures using Debevec Algorithm
    """
    
    @classmethod
    def INPUT_TYPES(cls):
        return {
            "required": {
                "ev_plus_2": ("IMAGE",),
                "ev_0": ("IMAGE",),
                "ev_minus_2": ("IMAGE",),
            },
            "optional": {
                "exposure_step": ("FLOAT", {
                    "default": 2.0,
                    "min": 0.5,
                    "max": 5.0,
                    "step": 0.1,
                    "display": "number"
                }),
                "hdr_algorithm": (["mertens", "debevec", "robertson"], {
                    "default": "mertens"
                }),
            }
        }
    
    RETURN_TYPES = ("IMAGE",)
    RETURN_NAMES = ("hdr_image",)
    FUNCTION = "process_3_stop_hdr"
    CATEGORY = "image/luminance"
    
    def __init__(self):
        self.processor = DebevecHDRProcessor()
    
    def process_3_stop_hdr(self, ev_plus_2, ev_0, ev_minus_2, exposure_step=2.0, hdr_algorithm="mertens"):
        """
        Process 3-stop HDR merge
        
        Args:
            ev_plus_2: Overexposed image (+2 EV)
            ev_0: Normal exposure image (0 EV)  
            ev_minus_2: Underexposed image (-2 EV)
            exposure_step: EV step size
            
        Returns:
            Tuple containing merged HDR image
        """
        try:
            # Convert tensors to OpenCV format
            img_plus_2 = tensor_to_cv2(ev_plus_2)
            img_0 = tensor_to_cv2(ev_0)
            img_minus_2 = tensor_to_cv2(ev_minus_2)
            
            # Calculate exposure times based on EV values
            # EV difference formula: time = base_time * 2^(-EV_difference)
            base_time = 1.0 / 60.0  # 1/60s as base exposure
            
            time_plus_2 = base_time * (2.0 ** (-exposure_step))  # Shorter time (overexposed)
            time_0 = base_time  # Normal exposure
            time_minus_2 = base_time * (2.0 ** exposure_step)  # Longer time (underexposed)
            
            images = [img_plus_2, img_0, img_minus_2]
            times = [time_plus_2, time_0, time_minus_2]
            
            logger.info(f"3-Stop HDR: Processing with times {times} using {hdr_algorithm} algorithm")
            
            # Process HDR using selected algorithm (default: Mertens for better results)
            hdr_result = self.processor.process_hdr(images, times, algorithm=hdr_algorithm)
            
            # Convert back to tensor - output 16-bit linear data
            output_tensor = cv2_to_tensor(hdr_result, output_16bit_linear=True)
            
            return (output_tensor,)
            
        except Exception as e:
            logger.error(f"3-Stop HDR processing failed: {str(e)}")
            # Return middle exposure as fallback
            return (ev_0,)


class LuminanceStackProcessor5Stops:
    """
    Professional ComfyUI Custom Node for 5-stop HDR processing  
    Processes EV+4, EV+2, EV+0, EV-2, EV-4 exposures using Debevec Algorithm
    """
    
    @classmethod
    def INPUT_TYPES(cls):
        return {
            "required": {
                "ev_plus_4": ("IMAGE",),
                "ev_plus_2": ("IMAGE",),
                "ev_0": ("IMAGE",),
                "ev_minus_2": ("IMAGE",),
                "ev_minus_4": ("IMAGE",),
            },
            "optional": {
                "exposure_step": ("FLOAT", {
                    "default": 2.0,
                    "min": 0.5, 
                    "max": 5.0,
                    "step": 0.1,
                    "display": "number"
                }),
                "hdr_algorithm": (["mertens", "debevec", "robertson"], {
                    "default": "mertens"
                }),
            }
        }
    
    RETURN_TYPES = ("IMAGE",)
    RETURN_NAMES = ("hdr_image",)
    FUNCTION = "process_5_stop_hdr"
    CATEGORY = "image/luminance"
    
    def __init__(self):
        self.processor = DebevecHDRProcessor()
    
    def process_5_stop_hdr(self, ev_plus_4, ev_plus_2, ev_0, ev_minus_2, ev_minus_4, exposure_step=2.0, hdr_algorithm="mertens"):
        """
        Process 5-stop HDR merge
        
        Args:
            ev_plus_4: Most overexposed image (+4 EV)
            ev_plus_2: Overexposed image (+2 EV)
            ev_0: Normal exposure image (0 EV)
            ev_minus_2: Underexposed image (-2 EV)
            ev_minus_4: Most underexposed image (-4 EV)
            exposure_step: EV step size
            
        Returns:
            Tuple containing merged HDR image
        """
        try:
            # Convert tensors to OpenCV format
            img_plus_4 = tensor_to_cv2(ev_plus_4)
            img_plus_2 = tensor_to_cv2(ev_plus_2)
            img_0 = tensor_to_cv2(ev_0)
            img_minus_2 = tensor_to_cv2(ev_minus_2)
            img_minus_4 = tensor_to_cv2(ev_minus_4)
            
            # Calculate exposure times based on EV values
            base_time = 1.0 / 60.0  # 1/60s as base exposure
            
            time_plus_4 = base_time * (2.0 ** (-2 * exposure_step))
            time_plus_2 = base_time * (2.0 ** (-exposure_step))
            time_0 = base_time
            time_minus_2 = base_time * (2.0 ** exposure_step)
            time_minus_4 = base_time * (2.0 ** (2 * exposure_step))
            
            images = [img_plus_4, img_plus_2, img_0, img_minus_2, img_minus_4]
            times = [time_plus_4, time_plus_2, time_0, time_minus_2, time_minus_4]
            
            logger.info(f"5-Stop HDR: Processing with times {times} using {hdr_algorithm} algorithm")
            
            # Process HDR using selected algorithm (default: Mertens for better results)
            hdr_result = self.processor.process_hdr(images, times, algorithm=hdr_algorithm)
            
            # Convert back to tensor - output 16-bit linear data  
            output_tensor = cv2_to_tensor(hdr_result, output_16bit_linear=True)
            
            return (output_tensor,)
            
        except Exception as e:
            logger.error(f"5-Stop HDR processing failed: {str(e)}")
            # Return middle exposure as fallback
            return (ev_0,)


# Node class mappings for ComfyUI
NODE_CLASS_MAPPINGS = {
    "LuminanceStackProcessor3Stops": LuminanceStackProcessor3Stops,
    "LuminanceStackProcessor5Stops": LuminanceStackProcessor5Stops,
}

# Display names for nodes in ComfyUI interface
NODE_DISPLAY_NAME_MAPPINGS = {
    "LuminanceStackProcessor3Stops": "Luminance Stack Processor (3 Stops)",
    "LuminanceStackProcessor5Stops": "Luminance Stack Processor (5 Stops)",
}