"""
Simplified ReID - Basic threshold matching only
No adaptive thresholds, no quality scoring, no smart storage
"""
import numpy as np
import cv2
import torch
import timm
from sklearn.metrics.pairwise import cosine_similarity
from typing import Dict, Optional
from collections import defaultdict
from datetime import datetime


class SimplifiedReID:
    """Simplified ReID with basic threshold matching"""
    
    def __init__(self, device: str = 'cuda'):
        self.device = device if torch.cuda.is_available() else 'cpu'
        
        # Single threshold for all matching
        self.threshold = 0.40
        
        # Session tracking (temp IDs)
        self.temp_id_features = {}  # temp_id -> list of feature vectors
        self.next_temp_id = 1
        self.current_frame = 0
        self.current_video_source = "unknown"
        
        # Initialize model
        self._initialize_model()
        
        print(f"Simplified ReID initialized on {self.device}")
    
    def _initialize_model(self):
        """Load MegaDescriptor model"""
        try:
            self.model = timm.create_model(
                'hf-hub:BVRA/MegaDescriptor-L-384',
                pretrained=True
            )
            self.model.to(self.device).eval()
            
            self.transform = timm.data.create_transform(
                input_size=(384, 384),
                is_training=False,
                mean=[0.5, 0.5, 0.5],
                std=[0.5, 0.5, 0.5]
            )
            print("MegaDescriptor-L-384 loaded")
        except Exception as e:
            print(f"Error loading model: {e}")
            self.model = None
    
    def set_threshold(self, threshold: float):
        """Set matching threshold"""
        self.threshold = max(0.10, min(0.95, threshold))
        print(f"Threshold set to: {self.threshold:.2f}")
    
    def set_video_source(self, video_path: str):
        """Set current video source"""
        self.current_video_source = video_path
    
    def reset_session(self):
        """Clear session data"""
        self.temp_id_features.clear()
        self.next_temp_id = 1
        self.current_frame = 0
        print("Session reset")
    
    def extract_features(self, image: np.ndarray) -> Optional[np.ndarray]:
        """Extract feature vector from image"""
        if image is None or image.size == 0 or self.model is None:
            return None
        
        try:
            img_rgb = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
            from PIL import Image
            pil_img = Image.fromarray(img_rgb)
            img_tensor = self.transform(pil_img).unsqueeze(0).to(self.device)
            
            with torch.no_grad():
                features = self.model(img_tensor)
            
            features = features.squeeze().cpu().numpy()
            features = features / (np.linalg.norm(features) + 1e-7)
            
            return features
        except Exception as e:
            print(f"Feature extraction error: {e}")
            return None
    
    def match_or_register(self, track) -> Dict:
        """
        Simple matching: compare features against existing temp_ids
        If match found -> return temp_id
        If no match -> create new temp_id
        """
        self.current_frame += 1
        
        # Get image crop from track
        detection = None
        for det in reversed(track.detections[-3:]):
            if det.image_crop is not None:
                detection = det
                break
        
        if detection is None or detection.image_crop is None:
            return {'temp_id': 0}
        
        # Extract features
        features = self.extract_features(detection.image_crop)
        if features is None:
            return {'temp_id': 0}
        
        # Search for match in existing temp_ids
        best_temp_id = None
        best_score = -1.0
        
        for temp_id, features_list in self.temp_id_features.items():
            # Compare against all stored features for this temp_id
            similarities = []
            for stored_features in features_list:
                sim = np.dot(features, stored_features)
                similarities.append(sim)
            
            if similarities:
                max_sim = max(similarities)
                if max_sim > best_score:
                    best_score = max_sim
                    best_temp_id = temp_id
        
        # Check if best score passes threshold
        if best_temp_id is not None and best_score >= self.threshold:
            # Match found - add features to existing temp_id
            self.temp_id_features[best_temp_id].append(features)
            
            # Limit storage (keep last 30)
            if len(self.temp_id_features[best_temp_id]) > 30:
                self.temp_id_features[best_temp_id] = self.temp_id_features[best_temp_id][-30:]
            
            return {
                'temp_id': best_temp_id,
                'confidence': best_score,
                'match_type': 'existing'
            }
        else:
            # No match - create new temp_id
            new_temp_id = self.next_temp_id
            self.next_temp_id += 1
            self.temp_id_features[new_temp_id] = [features]
            
            print(f"New temp_id: {new_temp_id} (threshold: {self.threshold:.2f})")
            
            return {
                'temp_id': new_temp_id,
                'confidence': 1.0,
                'match_type': 'new'
            }
    
    def get_statistics(self) -> Dict:
        """Get simple statistics"""
        return {
            'temp_ids': len(self.temp_id_features),
            'threshold': self.threshold,
            'current_frame': self.current_frame
        }