from __future__ import annotations
import numpy as np
from PIL import Image
from datasets import load_dataset
from typing import List, Tuple, Optional
import os
import pickle
import hashlib
from scipy.spatial.distance import cdist
from .utils import pil_to_np, np_to_pil
from .config import Config, MatchSpace


class TileManager:
    """Manages a collection of image tiles for mosaic generation."""
    
    # Global cache that persists across module reloads
    _global_cache = {}
    
    def __init__(self, config: Config):
        self.config = config
        self.tiles = []
        self.tile_colors = []
        self.tile_colors_lab = []  # Pre-computed LAB colors
        self._tiles_loaded = False
        # Don't load tiles immediately - load them lazily
    
    def _stable_cache_key(self) -> str:
        """Create a stable cache key string for disk and memory caches."""
        key = f"ds={self.config.hf_dataset}|split={self.config.hf_split}|limit={self.config.hf_limit}|tile={self.config.tile_size}|norm={self.config.tile_norm_brightness}"
        return hashlib.sha256(key.encode("utf-8")).hexdigest()
    
    def _ensure_tiles_loaded(self):
        """Ensure tiles are loaded, using cache if available."""
        if self._tiles_loaded:
            return
            
        config_hash = self._stable_cache_key()
        
        # Check if we can use cached tiles from global cache
        if config_hash in TileManager._global_cache:
            cached_data = TileManager._global_cache[config_hash]
            self.tiles = cached_data['tiles'].copy()
            self.tile_colors = cached_data['tile_colors'].copy()
            self.tile_colors_lab = cached_data['tile_colors_lab'].copy()
            self._tiles_loaded = True
            print(f"Using cached tiles ({len(self.tiles)} tiles)")
            return
        
        # Try disk cache if available
        if self.config.tiles_cache_dir:
            os.makedirs(self.config.tiles_cache_dir, exist_ok=True)
            cache_path = os.path.join(self.config.tiles_cache_dir, f"tiles_{config_hash}.pkl")
            if os.path.exists(cache_path):
                try:
                    with open(cache_path, "rb") as f:
                        cached_data = pickle.load(f)
                    self.tiles = cached_data['tiles']
                    self.tile_colors = cached_data['tile_colors']
                    self.tile_colors_lab = cached_data['tile_colors_lab']
                    self._tiles_loaded = True
                    # Also populate in-memory cache
                    TileManager._global_cache[config_hash] = {
                        'tiles': [tile.copy() for tile in self.tiles],
                        'tile_colors': [color.copy() for color in self.tile_colors],
                        'tile_colors_lab': [color.copy() for color in self.tile_colors_lab]
                    }
                    print(f"Loaded tiles from disk cache: {cache_path}")
                    return
                except Exception as e:
                    print(f"Failed to load disk cache {cache_path}: {e}")
        
        # Load tiles from dataset or fallback
        self._load_tiles_from_source()
        
        # Cache the tiles in global cache for future use
        TileManager._global_cache[config_hash] = {
            'tiles': [tile.copy() for tile in self.tiles],
            'tile_colors': [color.copy() for color in self.tile_colors],
            'tile_colors_lab': [color.copy() for color in self.tile_colors_lab]
        }
        
        # Also persist to disk cache if configured
        if self.config.tiles_cache_dir:
            try:
                os.makedirs(self.config.tiles_cache_dir, exist_ok=True)
                cache_path = os.path.join(self.config.tiles_cache_dir, f"tiles_{config_hash}.pkl")
                with open(cache_path, "wb") as f:
                    pickle.dump({
                        'tiles': self.tiles,
                        'tile_colors': self.tile_colors,
                        'tile_colors_lab': self.tile_colors_lab
                    }, f)
                print(f"Saved tiles to disk cache: {cache_path}")
            except Exception as e:
                print(f"Failed to save tiles to disk cache: {e}")
        
        self._tiles_loaded = True
    
    def _load_tiles_from_source(self):
        """Load tiles from Hugging Face dataset or create fallback."""
        print(f"Loading tiles from {self.config.hf_dataset}...")
        
        try:
            # Try to load from Hugging Face dataset
            dataset = load_dataset(
                self.config.hf_dataset,
                split=self.config.hf_split,
                cache_dir=self.config.hf_cache_dir if self.config.hf_cache_dir else None,
                streaming=True  # keep streaming but respect HF cache_dir
            )
            
            # Limit number of tiles
            tile_count = min(self.config.hf_limit, 200)  # Increased for better diversity
            
            loaded_count = 0
            for item in dataset:
                if loaded_count >= tile_count:
                    break
                    
                # Get image from dataset
                if 'image' in item:
                    img = item['image']
                elif 'img' in item:
                    img = item['img']
                else:
                    # Try to find image key
                    for key in item.keys():
                        if isinstance(item[key], Image.Image):
                            img = item[key]
                            break
                    else:
                        continue
                
                # Convert to RGB and resize
                img = img.convert('RGB')
                img = img.resize(
                    (self.config.tile_size, self.config.tile_size), 
                    Image.LANCZOS
                )
                
                # Convert to numpy array
                tile_array = pil_to_np(img)
                
                # Normalize brightness if enabled
                if self.config.tile_norm_brightness:
                    tile_array = self._normalize_brightness(tile_array)
                
                self.tiles.append(tile_array)
                
                # Calculate representative color for this tile
                tile_color = np.mean(tile_array, axis=(0, 1))
                self.tile_colors.append(tile_color)
                
                # Pre-compute LAB color for faster matching
                tile_color_lab = self._rgb_to_lab(tile_color)
                self.tile_colors_lab.append(tile_color_lab)
                
                loaded_count += 1
            
            print(f"Loaded {len(self.tiles)} tiles successfully")
            
        except Exception as e:
            print(f"Error loading tiles from Hugging Face: {e}")
            print("Creating fallback tiles...")
            # Create fallback tiles if loading fails
            self._create_fallback_tiles()
    
    def _create_fallback_tiles(self):
        """Create simple colored tiles as fallback with extensive color palette."""
        print("Creating fallback tiles...")
        colors = [
            # Primary colors
            [1.0, 0.0, 0.0],  # Red
            [0.0, 1.0, 0.0],  # Green
            [0.0, 0.0, 1.0],  # Blue
            [1.0, 1.0, 0.0],  # Yellow
            [1.0, 0.0, 1.0],  # Magenta
            [0.0, 1.0, 1.0],  # Cyan
            
            # Grayscale spectrum
            [0.0, 0.0, 0.0],  # Black
            [0.1, 0.1, 0.1],  # Very Dark Gray
            [0.2, 0.2, 0.2],  # Dark Gray
            [0.3, 0.3, 0.3],  # Medium Dark Gray
            [0.4, 0.4, 0.4],  # Medium Gray
            [0.5, 0.5, 0.5],  # Mid Gray
            [0.6, 0.6, 0.6],  # Light Gray
            [0.7, 0.7, 0.7],  # Lighter Gray
            [0.8, 0.8, 0.8],  # Very Light Gray
            [0.9, 0.9, 0.9],  # Almost White
            [1.0, 1.0, 1.0],  # White
            
            # Extended color palette
            [1.0, 0.5, 0.0],  # Orange
            [1.0, 0.3, 0.0],  # Dark Orange
            [0.5, 0.0, 1.0],  # Purple
            [0.3, 0.0, 0.5],  # Dark Purple
            [0.0, 0.5, 0.0],  # Dark Green
            [0.0, 0.8, 0.0],  # Bright Green
            [0.0, 0.0, 0.5],  # Dark Blue
            [0.0, 0.0, 0.8],  # Bright Blue
            [0.5, 0.5, 0.0],  # Olive
            [0.7, 0.7, 0.0],  # Yellow Olive
            [0.5, 0.0, 0.5],  # Dark Magenta
            [0.8, 0.0, 0.8],  # Bright Magenta
            [0.0, 0.5, 0.5],  # Teal
            [0.0, 0.8, 0.8],  # Bright Teal
            [0.8, 0.6, 0.4],  # Tan
            [0.6, 0.4, 0.2],  # Brown
            [0.9, 0.9, 0.7],  # Cream
            [0.7, 0.5, 0.3],  # Light Brown
            [0.4, 0.2, 0.1],  # Dark Brown
            [0.9, 0.7, 0.5],  # Peach
            [0.5, 0.7, 0.9],  # Light Blue
            [0.7, 0.9, 0.5],  # Light Green
            [0.9, 0.5, 0.7],  # Pink
            [0.3, 0.7, 0.3],  # Forest Green
            [0.7, 0.3, 0.3],  # Dark Red
            [0.3, 0.3, 0.7],  # Navy Blue
        ]
        
        for color in colors:
            tile = np.full(
                (self.config.tile_size, self.config.tile_size, 3), 
                color, 
                dtype=np.float32
            )
            self.tiles.append(tile)
            self.tile_colors.append(np.array(color))
            
            # Pre-compute LAB color for fallback tiles too
            tile_color_lab = self._rgb_to_lab(np.array(color))
            self.tile_colors_lab.append(tile_color_lab)
    
    def _normalize_brightness(self, tile: np.ndarray) -> np.ndarray:
        """Normalize tile brightness to mean brightness."""
        mean_brightness = np.mean(tile)
        if mean_brightness > 0:
            tile = tile / mean_brightness
            tile = np.clip(tile, 0, 1)
        return tile
    
    def get_best_tile(self, target_color: np.ndarray, match_space: MatchSpace) -> np.ndarray:
        """Find the best matching tile for a given target color using improved matching."""
        # Ensure tiles are loaded
        self._ensure_tiles_loaded()
        
        if not self.tiles:
            return np.zeros((self.config.tile_size, self.config.tile_size, 3))
        
        if match_space == MatchSpace.LAB:
            # Use pre-computed LAB colors for perceptual matching
            target_lab = self._rgb_to_lab(target_color).reshape(1, -1)
            tile_colors_array = np.array(self.tile_colors_lab)
            
            # Use perceptual color distance with weighted components
            distances = self._calculate_perceptual_distance(target_lab, tile_colors_array)
        else:
            # RGB color space matching with brightness weighting
            target_rgb = target_color.reshape(1, -1)
            tile_colors_array = np.array(self.tile_colors)
            distances = self._calculate_rgb_distance(target_rgb, tile_colors_array)
        
        # Add some randomness to avoid always picking the same tile
        # This helps with visual variety
        noise_factor = 0.1
        distances = distances * (1 + noise_factor * np.random.random(len(distances)))
        
        # Find best match
        best_idx = np.argmin(distances)
        return self.tiles[best_idx]
    
    def _rgb_to_lab(self, rgb: np.ndarray) -> np.ndarray:
        """Improved RGB to LAB conversion approximation."""
        r, g, b = rgb
        
        # Better perceptual color space conversion
        # Convert to XYZ color space first (simplified)
        # This is still an approximation but better than the previous version
        
        # Gamma correction
        def gamma_correct(c):
            return c / 12.92 if c <= 0.04045 else ((c + 0.055) / 1.055) ** 2.4
        
        r = gamma_correct(r)
        g = gamma_correct(g)
        b = gamma_correct(b)
        
        # RGB to XYZ matrix (sRGB to XYZ)
        x = 0.4124564 * r + 0.3575761 * g + 0.1804375 * b
        y = 0.2126729 * r + 0.7151522 * g + 0.0721750 * b
        z = 0.0193339 * r + 0.1191920 * g + 0.9503041 * b
        
        # XYZ to LAB conversion (simplified)
        # Reference white (D65)
        xn, yn, zn = 0.95047, 1.00000, 1.08883
        
        fx = x / xn
        fy = y / yn
        fz = z / zn
        
        # Apply cube root
        def f(t):
            return t ** (1/3) if t > 0.008856 else (7.787 * t + 16/116)
        
        fx, fy, fz = f(fx), f(fy), f(fz)
        
        L = 116 * fy - 16
        a = 500 * (fx - fy)
        b_lab = 200 * (fy - fz)
        
        return np.array([L, a, b_lab])
    
    def _calculate_perceptual_distance(self, target_lab: np.ndarray, tile_colors_lab: np.ndarray) -> np.ndarray:
        """Calculate perceptual color distances for many targets vs many tiles.
        Returns an array of shape (num_targets, num_tiles).
        """
        weights = np.array([2.0, 1.0, 1.0])
        # target_lab: (N,3), tile_colors_lab: (M,3)
        # diff -> (N,M,3)
        diff = target_lab[:, None, :] - tile_colors_lab[None, :, :]
        weighted_diff = diff * weights[None, None, :]
        distances = np.sqrt(np.sum(weighted_diff**2, axis=2))  # (N,M)
        return distances
    
    def _calculate_rgb_distance(self, target_rgb: np.ndarray, tile_colors_rgb: np.ndarray) -> np.ndarray:
        """Calculate RGB distances for many targets vs many tiles.
        Returns an array of shape (num_targets, num_tiles).
        """
        weights = np.array([1.0, 1.0, 1.0])
        diff = target_rgb[:, None, :] - tile_colors_rgb[None, :, :]  # (N,M,3)
        weighted_diff = diff * weights[None, None, :]
        distances = np.sqrt(np.sum(weighted_diff**2, axis=2))  # (N,M)
        return distances
    
    def get_tile_count(self) -> int:
        """Get number of available tiles."""
        self._ensure_tiles_loaded()
        return len(self.tiles)
    
    def get_tile_stats(self) -> dict:
        """Get statistics about loaded tiles."""
        self._ensure_tiles_loaded()
        if not self.tiles:
            return {"count": 0}
        
        return {
            "count": len(self.tiles),
            "tile_size": self.config.tile_size,
            "color_range": {
                "min": np.min(self.tile_colors, axis=0).tolist(),
                "max": np.max(self.tile_colors, axis=0).tolist(),
                "mean": np.mean(self.tile_colors, axis=0).tolist()
            }
        }
    
    @classmethod
    def clear_cache(cls):
        """Clear the global tile cache."""
        cls._global_cache.clear()
        print("Tile cache cleared")
    
    @classmethod
    def get_cache_info(cls):
        """Get information about the current cache."""
        return {
            "cached_configs": len(cls._global_cache),
            "cache_keys": list(cls._global_cache.keys())
        }