app.py

"""
Document Forgery Detection - Gradio Interface for Hugging Face Spaces

This app provides a web interface for detecting and classifying document forgeries.
"""

import gradio as gr
import torch
import cv2
import numpy as np
from PIL import Image
import json
from pathlib import Path
import sys
from typing import Dict, List, Tuple

# Add src to path
sys.path.insert(0, str(Path(__file__).parent))

from src.models import get_model
from src.config import get_config
from src.data.preprocessing import DocumentPreprocessor
from src.data.augmentation import DatasetAwareAugmentation
from src.features.region_extraction import get_mask_refiner, get_region_extractor
from src.features.feature_extraction import get_feature_extractor
from src.training.classifier import ForgeryClassifier

# Class names
CLASS_NAMES = {0: 'Copy-Move', 1: 'Splicing', 2: 'Text Substitution'}
CLASS_COLORS = {
    0: (217, 83, 79),    # #d9534f - Muted red
    1: (92, 184, 92),    # #5cb85c - Muted green
    2: (65, 105, 225)    # #4169E1 - Royal blue
}

# Actual model performance metrics
MODEL_METRICS = {
    'segmentation': {
        'dice': 0.6212,
        'iou': 0.4506,
        'precision': 0.7077,
        'recall': 0.5536
    },
    'classification': {
        'overall_accuracy': 0.8897,
        'per_class': {
            'copy_move': 0.92,
            'splicing': 0.85,
            'generation': 0.90
        }
    }
}


class ForgeryDetector:
    """Main forgery detection pipeline"""
    
    def __init__(self):
        print("Loading models...")
        
        # Load config
        self.config = get_config('config.yaml')
        self.device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')
        
        # Load segmentation model
        self.model = get_model(self.config).to(self.device)
        checkpoint = torch.load('models/best_doctamper.pth', map_location=self.device)
        self.model.load_state_dict(checkpoint['model_state_dict'])
        self.model.eval()
        
        # Load classifier
        self.classifier = ForgeryClassifier(self.config)
        self.classifier.load('models/classifier')
        
        # Initialize components
        self.preprocessor = DocumentPreprocessor(self.config, 'doctamper')
        self.augmentation = DatasetAwareAugmentation(self.config, 'doctamper', is_training=False)
        self.mask_refiner = get_mask_refiner(self.config)
        self.region_extractor = get_region_extractor(self.config)
        self.feature_extractor = get_feature_extractor(self.config, is_text_document=True)
        
        print("✓ Models loaded successfully!")
    
    def detect(self, image):
        """
        Detect forgeries in document image or PDF
        
        Args:
            image: PIL Image, numpy array, or path to PDF file
            
        Returns:
            original_image: Original uploaded image
            overlay_image: Image with detection overlay
            results_html: Detection results as HTML
        """
        # Handle PDF files
        if isinstance(image, str) and image.lower().endswith('.pdf'):
            import fitz  # PyMuPDF
            pdf_document = fitz.open(image)
            page = pdf_document[0]
            pix = page.get_pixmap(matrix=fitz.Matrix(2, 2))
            image = np.frombuffer(pix.samples, dtype=np.uint8).reshape(pix.height, pix.width, pix.n)
            if pix.n == 4:
                image = cv2.cvtColor(image, cv2.COLOR_RGBA2RGB)
            pdf_document.close()
        
        # Convert PIL to numpy
        if isinstance(image, Image.Image):
            image = np.array(image)
        
        # Convert to RGB
        if len(image.shape) == 2:
            image = cv2.cvtColor(image, cv2.COLOR_GRAY2RGB)
        elif image.shape[2] == 4:
            image = cv2.cvtColor(image, cv2.COLOR_RGBA2RGB)
        
        original_image = image.copy()
        
        # Preprocess
        preprocessed, _ = self.preprocessor(image, None)
        
        # Augment
        augmented = self.augmentation(preprocessed, None)
        image_tensor = augmented['image'].unsqueeze(0).to(self.device)
        
        # Run localization
        with torch.no_grad():
            logits, decoder_features = self.model(image_tensor)
            prob_map = torch.sigmoid(logits).cpu().numpy()[0, 0]
        
        # Refine mask
        binary_mask = (prob_map > 0.5).astype(np.uint8)
        refined_mask = self.mask_refiner.refine(binary_mask, original_size=original_image.shape[:2])
        
        # Extract regions
        regions = self.region_extractor.extract(refined_mask, prob_map, original_image)
        
        # Classify regions
        results = []
        for region in regions:
            # Extract features
            features = self.feature_extractor.extract(
                preprocessed,
                region['region_mask'],
                [f.cpu() for f in decoder_features]
            )
            
            # Reshape features to 2D array
            if features.ndim == 1:
                features = features.reshape(1, -1)
            
            # Pad/truncate features to match classifier
            expected_features = 526
            current_features = features.shape[1]
            if current_features < expected_features:
                padding = np.zeros((features.shape[0], expected_features - current_features))
                features = np.hstack([features, padding])
            elif current_features > expected_features:
                features = features[:, :expected_features]
            
            # Classify
            predictions, confidences = self.classifier.predict(features)
            forgery_type = int(predictions[0])
            confidence = float(confidences[0])
            
            if confidence > 0.6:
                results.append({
                    'region_id': region['region_id'],
                    'bounding_box': region['bounding_box'],
                    'forgery_type': CLASS_NAMES[forgery_type],
                    'confidence': confidence
                })
        
        # Create visualization
        overlay = self._create_overlay(original_image, results)
        
        # Create HTML response
        results_html = self._create_html_report(results)
        
        return original_image, overlay, results_html
    
    def _create_overlay(self, image, results):
        """Create overlay visualization"""
        overlay = image.copy()
        
        for result in results:
            bbox = result['bounding_box']
            x, y, w, h = bbox
            
            forgery_type = result['forgery_type']
            confidence = result['confidence']
            
            # Get color
            forgery_id = [k for k, v in CLASS_NAMES.items() if v == forgery_type][0]
            color = CLASS_COLORS[forgery_id]
            
            # Draw rectangle
            cv2.rectangle(overlay, (x, y), (x+w, y+h), color, 2)
            
            # Draw label
            label = f"{forgery_type}: {confidence:.1%}"
            font = cv2.FONT_HERSHEY_SIMPLEX
            font_scale = 0.5
            thickness = 1
            (label_w, label_h), baseline = cv2.getTextSize(label, font, font_scale, thickness)
            
            cv2.rectangle(overlay, (x, y-label_h-8), (x+label_w+4, y), color, -1)
            cv2.putText(overlay, label, (x+2, y-4), font, font_scale, (255, 255, 255), thickness)
        
        return overlay
    
    def _create_html_report(self, results):
        """Create HTML report with detection results"""
        num_detections = len(results)
        
        if num_detections == 0:
            return """
            <div style='padding:12px; border:1px solid #5cb85c; border-radius:8px;'>
                ✓ <b>No forgery detected.</b><br>
                The document appears to be authentic.
            </div>
            """
        
        # Calculate statistics
        avg_confidence = sum(r['confidence'] for r in results) / num_detections
        type_counts = {}
        for r in results:
            ft = r['forgery_type']
            type_counts[ft] = type_counts.get(ft, 0) + 1
        
        html = f"""
        <div style='padding:12px; border:1px solid #d9534f; border-radius:8px;'>
            <b>⚠️ Forgery Detected</b><br><br>
            
            <b>Summary:</b><br>
            • Regions detected: {num_detections}<br>
            • Average confidence: {avg_confidence*100:.1f}%<br><br>
            
            <b>Model Performance:</b><br>
            • Segmentation Dice: {MODEL_METRICS['segmentation']['dice']*100:.1f}%<br>
            • Classification Accuracy: {MODEL_METRICS['classification']['overall_accuracy']*100:.1f}%<br><br>
            
            <b>Detections:</b><br>
        """
        
        for i, result in enumerate(results, 1):
            forgery_type = result['forgery_type']
            confidence = result['confidence']
            bbox = result['bounding_box']
            
            forgery_id = [k for k, v in CLASS_NAMES.items() if v == forgery_type][0]
            color_rgb = CLASS_COLORS[forgery_id]
            color_hex = f"#{color_rgb[0]:02x}{color_rgb[1]:02x}{color_rgb[2]:02x}"
            
            html += f"""
            <div style='margin:8px 0; padding:8px; border-left:3px solid {color_hex}; background:#f9f9f9;'>
                <b>Region {i}:</b> {forgery_type} ({confidence*100:.1f}%)<br>
                <small>Location: ({bbox[0]}, {bbox[1]}) | Size: {bbox[2]}×{bbox[3]}px</small>
            </div>
            """
        
        html += """
        </div>
        """
        
        return html


# Initialize detector
detector = ForgeryDetector()


def detect_forgery(file):
    """Gradio interface function"""
    try:
        if file is None:
            return None, None, "<div style='padding:12px; border:1px solid #d9534f; border-radius:8px;'>❌ <b>No file uploaded.</b></div>"
        
        # Get file path
        file_path = file.name if hasattr(file, 'name') else file
        
        # Check if PDF
        if file_path.lower().endswith('.pdf'):
            original, overlay, results_html = detector.detect(file_path)
        else:
            image = Image.open(file_path)
            original, overlay, results_html = detector.detect(image)
        
        return original, overlay, results_html
    
    except Exception as e:
        import traceback
        error_details = traceback.format_exc()
        print(f"Error: {error_details}")
        error_html = f"""
        <div style='padding:12px; border:1px solid #d9534f; border-radius:8px;'>
            ❌ <b>Error:</b> {str(e)}
        </div>
        """
        return None, None, error_html


# Custom CSS - subtle styling
custom_css = """
.predict-btn {
    background-color: #4169E1 !important;
    color: white !important;
}
.clear-btn {
    background-color: #6A89A7 !important;
    color: white !important;
}
"""

# Create Gradio interface
with gr.Blocks(css=custom_css) as demo:
    
    gr.Markdown(
        """
        # 📄 Document Forgery Detection
        Upload a document image or PDF to detect and classify forgeries.
        """
    )
    
    with gr.Row():
        with gr.Column(scale=1):
            gr.Markdown("### Upload Document")
            input_file = gr.File(
                label="Document (Image or PDF)",
                file_types=["image", ".pdf"],
                type="filepath"
            )
            
            with gr.Row():
                clear_btn = gr.Button("🧹 Clear", elem_classes="clear-btn")
                analyze_btn = gr.Button("🔍 Analyze", elem_classes="predict-btn")
            
            gr.Markdown(
                """
                **Supported formats:**
                - Images: JPG, PNG, BMP, TIFF, WebP
                - PDF: First page analyzed
                
                **Forgery types:**
                - Copy-Move: Duplicated regions
                - Splicing: Mixed sources
                - Text Substitution: Modified text
                """
            )
        
        with gr.Column(scale=1):
            gr.Markdown("### Original Image")
            original_image = gr.Image(label="Uploaded Document", type="numpy")
    
    with gr.Row():
        with gr.Column(scale=1):
            gr.Markdown("### Detection Result")
            output_image = gr.Image(label="Annotated Document", type="numpy")
        
        with gr.Column(scale=1):
            gr.Markdown("### Analysis Report")
            output_html = gr.HTML(
                value="<i>No analysis yet. Upload a document and click Analyze.</i>"
            )
    
    gr.Markdown(
        """
        ---
        **Model Architecture:**
        - **Localization:** MobileNetV3-Small + UNet (Dice: 62.1%, IoU: 45.1%)
        - **Classification:** LightGBM with 526 features (Accuracy: 88.97%)
        - **Training:** 140K samples (DocTamper + SCD + FCD datasets)
        """
    )
    
    # Event handlers
    analyze_btn.click(
        fn=detect_forgery,
        inputs=[input_file],
        outputs=[original_image, output_image, output_html]
    )
    
    clear_btn.click(
        fn=lambda: (None, None, None, "<i>No analysis yet. Upload a document and click Analyze.</i>"),
        inputs=None,
        outputs=[input_file, original_image, output_image, output_html]
    )


if __name__ == "__main__":
    demo.launch()