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main.py

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+import os
+import io
+import json
+import requests
+from typing import Dict, List, Any, Optional
+from fastapi import FastAPI, HTTPException, Body
+from pydantic import BaseModel
+import torch
+from transformers import AutoTokenizer, AutoModelForSequenceClassification
+from newspaper import Article
+from bs4 import BeautifulSoup
+import easyocr
+from PIL import Image
+import google.generativeai as genai
+from datetime import datetime
+
+# Initialize FastAPI app
+app = FastAPI(title="TruthLens Backend")
+
+# Load Hugging Face model (RoBERTa-based fake news detector)
+MODEL_NAME = "Pulk17/Fake-News-Detection"
+tokenizer = None
+model = None
+
+def load_model():
+    """Lazy load the Hugging Face model"""
+    global tokenizer, model
+    if tokenizer is None or model is None:
+        print("Loading Hugging Face model...")
+        tokenizer = AutoTokenizer.from_pretrained(MODEL_NAME)
+        model = AutoModelForSequenceClassification.from_pretrained(MODEL_NAME)
+        model.eval()
+    return tokenizer, model
+
+# Environment variables
+# Ensure you set these in your environment or .env file
+GOOGLE_FACT_CHECK_API_KEY = os.environ.get('GOOGLE_FACT_CHECK_API_KEY', '')
+HIVE_API_KEY = os.environ.get('HIVE_API_KEY', '')
+GEMINI_API_KEY = os.environ.get('GEMINI_API_KEY', '')
+
+# Initialize Gemini
+if GEMINI_API_KEY:
+    genai.configure(api_key=GEMINI_API_KEY)
+    gemini_model = genai.GenerativeModel('gemini-pro')
+else:
+    gemini_model = None
+
+# Request Models
+class TextRequest(BaseModel):
+    text: str
+
+class UrlRequest(BaseModel):
+    url: str
+
+class ImageRequest(BaseModel):
+    image_url: str
+
+# Helper functions
+def get_fact_checks(text: str) -> List[Dict[str, str]]:
+    """Get fact checks from Google Fact Check Tools API"""
+    if not GOOGLE_FACT_CHECK_API_KEY:
+        return []
+    
+    try:
+        # Extract key claims (first 100 chars as query)
+        query = text[:100]
+        
+        url = "https://factchecktools.googleapis.com/v1alpha1/claims:search"
+        params = {
+            "query": query,
+            "key": GOOGLE_FACT_CHECK_API_KEY,
+            "languageCode": "en"
+        }
+        
+        response = requests.get(url, params=params, timeout=10)
+        
+        if response.status_code == 200:
+            data = response.json()
+            claims = data.get('claims', [])
+            
+            fact_checks = []
+            for claim in claims[:3]:  # Top 3 fact checks
+                fact_check = {
+                    "claim": claim.get('text', ''),
+                    "claimant": claim.get('claimant', ''),
+                    "rating": claim.get('claimReview', [{}])[0].get('textualRating', 'Unknown'),
+                    "url": claim.get('claimReview', [{}])[0].get('url', '')
+                }
+                fact_checks.append(fact_check)
+            
+            return fact_checks
+        else:
+            print(f"Fact check API error: {response.status_code}")
+            return []
+            
+    except Exception as e:
+        print(f"Error getting fact checks: {e}")
+        return []
+
+def extract_claims_with_gemini(text: str) -> List[str]:
+    """Use Gemini to extract key factual claims for building a search query"""
+    if not gemini_model:
+        return [text[:100]]
+    
+    try:
+        prompt = f"""
+        Extract the single most important factual claim from the following text that can be used to search in a fact-check database. 
+        Output ONLY the extracted claim string, nothing else.
+        
+        Text: {text[:1000]}
+        """
+        response = gemini_model.generate_content(prompt)
+        claim = response.text.strip()
+        return [claim] if claim else [text[:100]]
+    except Exception as e:
+        print(f"Gemini claim extraction error: {e}")
+        return [text[:100]]
+
+def generate_explanation_with_gemini(text: str, label: str, confidence: float, fact_checks: List[Dict]) -> str:
+    """Use Gemini to explain the reasoning behind the detection result"""
+    if not gemini_model:
+        return f"The news has been classified as {label} with {confidence:.2%} confidence."
+    
+    try:
+        fact_check_context = ""
+        if fact_checks:
+            fact_check_context = "Relevant fact checks found:\n" + "\n".join([f"- {fc['claim']} (Rating: {fc['rating']})" for fc in fact_checks])
+        
+        prompt = f"""
+        Act as a professional fact-checker for an app called TruthLens. 
+        Analyze the following news text and the AI detection result.
+        
+        News Text: {text[:1000]}
+        AI Classification: {label}
+        Confidence: {confidence:.2%}
+        {fact_check_context}
+        
+        Provide a concise, human-readable explanation (2-3 sentences) explaining why this news is likely {label}. 
+        Focus on style, source (if present), or specific fact-check evidence.
+        """
+        response = gemini_model.generate_content(prompt)
+        return response.text.strip()
+    except Exception as e:
+        print(f"Gemini explanation error: {e}")
+        return f"Analysis complete: The model identified this content as {label}."
+
+def detect_ai_image(image_bytes: bytes) -> Dict[str, Any]:
+    """Detect AI-generated content using Hive Moderation API"""
+    if not HIVE_API_KEY:
+        return {"probability": 0.0, "generator": None}
+    
+    try:
+        url = "https://api.hivemoderation.com/v2/task/sync"
+        
+        headers = {
+            "Authorization": f"Token {HIVE_API_KEY}",
+            "Content-Type": "application/json"
+        }
+        
+        # Convert image to base64
+        import base64
+        image_b64 = base64.b64encode(image_bytes).decode('utf-8')
+        
+        payload = {
+            "image": image_b64,
+            "models": ["ai_generated"]
+        }
+        
+        response = requests.post(url, headers=headers, json=payload, timeout=30)
+        
+        if response.status_code == 200:
+            data = response.json()
+            ai_generated = data.get('status', [{}])[0].get('response', {}).get('output', [{}])[0]
+            
+            return {
+                "probability": ai_generated.get('score', 0.0),
+                "generator": ai_generated.get('class', None)
+            }
+        else:
+            print(f"Hive API error: {response.status_code}")
+            return {"probability": 0.0, "generator": None}
+            
+    except Exception as e:
+        print(f"Error detecting AI image: {e}")
+        return {"probability": 0.0, "generator": None}
+
+def calculate_risk_level(
+    label: str,
+    confidence: float,
+    fact_checks: List[Dict],
+    image_ai_result: Optional[Dict] = None
+) -> str:
+    """Calculate overall risk level"""
+    
+    # Base risk on label and confidence
+    if label == "FAKE" and confidence > 0.8:
+        base_risk = "high"
+    elif label == "FAKE" and confidence > 0.5:
+        base_risk = "medium"
+    elif label == "REAL" and confidence > 0.8:
+        base_risk = "low"
+    else:
+        base_risk = "medium"
+    
+    # Adjust based on fact checks
+    if fact_checks:
+        fake_ratings = sum(1 for fc in fact_checks if 'false' in fc['rating'].lower() or 'fake' in fc['rating'].lower() or 'satire' in fc['rating'].lower())
+        if fake_ratings >= 2:
+            base_risk = "high"
+    
+    # Adjust based on AI image detection
+    if image_ai_result and image_ai_result['probability'] > 0.7:
+        if base_risk == "low":
+            base_risk = "medium"
+        elif base_risk == "medium":
+            base_risk = "high"
+    
+    return base_risk
+
+def extract_article_text(url: str) -> str:
+    """Extract article text from URL using newspaper3k"""
+    try:
+        article = Article(url)
+        article.download()
+        article.parse()
+        return article.text
+    except Exception as e:
+        print(f"Error extracting article with newspaper3k: {e}")
+        # Fallback to BeautifulSoup
+        try:
+            response = requests.get(url, timeout=30)
+            soup = BeautifulSoup(response.content, 'html.parser')
+            
+            # Remove script and style elements
+            for script in soup(["script", "style"]):
+                script.decompose()
+            
+            # Get text
+            text = soup.get_text()
+            
+            # Clean up whitespace
+            lines = (line.strip() for line in text.splitlines())
+            chunks = (phrase.strip() for line in lines for phrase in line.split("  "))
+            text = ' '.join(chunk for chunk in chunks if chunk)
+            
+            return text
+        except Exception as e2:
+            print(f"Error with BeautifulSoup fallback: {e2}")
+            return ""
+
+# Endpoints
+
+@app.post("/detect-text")
+async def detect_text(request: TextRequest):
+    try:
+        text = request.text
+        if not text:
+            raise HTTPException(status_code=400, detail="Text is required")
+        
+        # Load model
+        tok, mdl = load_model()
+        
+        # Tokenize and predict
+        inputs = tok(text, return_tensors="pt", truncation=True, max_length=512, padding=True)
+        
+        with torch.no_grad():
+            outputs = mdl(**inputs)
+            logits = outputs.logits
+            probabilities = torch.softmax(logits, dim=1)
+            prediction = torch.argmax(probabilities, dim=1).item()
+            confidence = probabilities[0][prediction].item()
+        
+        label = "REAL" if prediction == 1 else "FAKE"
+        
+        # Enhanced Fact Checking with Gemini
+        extracted_claims = extract_claims_with_gemini(text)
+        fact_checks = get_fact_checks(extracted_claims[0])
+        
+        # Gemini Explanation
+        explanation = generate_explanation_with_gemini(text, label, confidence, fact_checks)
+        
+        risk_level = calculate_risk_level(label, confidence, fact_checks)
+        
+        return {
+            "input_type": "text",
+            "text": text,
+            "label": label,
+            "confidence": confidence,
+            "explanation": explanation,
+            "fact_checks": fact_checks,
+            "risk_level": risk_level,
+            "timestamp": datetime.now().isoformat()
+        }
+        
+    except Exception as e:
+        print(f"Error in detect_text: {str(e)}")
+        raise HTTPException(status_code=500, detail=str(e))
+
+@app.post("/detect-url")
+async def detect_url(request: UrlRequest):
+    try:
+        url = request.url
+        if not url:
+            raise HTTPException(status_code=400, detail="URL is required")
+        
+        article_text = extract_article_text(url)
+        if not article_text:
+            raise HTTPException(status_code=400, detail="Failed to extract article text from URL")
+        
+        tok, mdl = load_model()
+        
+        inputs = tok(article_text, return_tensors="pt", truncation=True, max_length=512, padding=True)
+        
+        with torch.no_grad():
+            outputs = mdl(**inputs)
+            logits = outputs.logits
+            probabilities = torch.softmax(logits, dim=1)
+            prediction = torch.argmax(probabilities, dim=1).item()
+            confidence = probabilities[0][prediction].item()
+        
+        label = "REAL" if prediction == 1 else "FAKE"
+        
+        # Enhanced Fact Checking with Gemini
+        extracted_claims = extract_claims_with_gemini(article_text)
+        fact_checks = get_fact_checks(extracted_claims[0])
+        
+        # Gemini Explanation
+        explanation = generate_explanation_with_gemini(article_text, label, confidence, fact_checks)
+        
+        risk_level = calculate_risk_level(label, confidence, fact_checks)
+        
+        return {
+            "input_type": "url",
+            "url": url,
+            "text": article_text[:500],
+            "label": label,
+            "confidence": confidence,
+            "explanation": explanation,
+            "fact_checks": fact_checks,
+            "risk_level": risk_level,
+            "timestamp": datetime.now().isoformat()
+        }
+        
+    except Exception as e:
+        print(f"Error in detect_url: {str(e)}")
+        raise HTTPException(status_code=500, detail=str(e))
+
+@app.post("/detect-image")
+async def detect_image(request: ImageRequest):
+    try:
+        image_url = request.image_url
+        if not image_url:
+            raise HTTPException(status_code=400, detail="Image URL is required")
+        
+        response = requests.get(image_url, timeout=30)
+        response.raise_for_status()
+        image_bytes = response.content
+        
+        reader = easyocr.Reader(['en'])
+        # EasyOCR can read from bytes directly
+        ocr_results = reader.readtext(image_bytes)
+        extracted_text = ' '.join([result[1] for result in ocr_results])
+        
+        image_ai_result = detect_ai_image(image_bytes)
+        
+        if extracted_text.strip():
+            tok, mdl = load_model()
+            inputs = tok(extracted_text, return_tensors="pt", truncation=True, max_length=512, padding=True)
+            
+            with torch.no_grad():
+                outputs = mdl(**inputs)
+                logits = outputs.logits
+                probabilities = torch.softmax(logits, dim=1)
+                prediction = torch.argmax(probabilities, dim=1).item()
+                confidence = probabilities[0][prediction].item()
+            
+            label = "REAL" if prediction == 1 else "FAKE"
+            # Enhanced Fact Checking with Gemini
+            extracted_claims = extract_claims_with_gemini(extracted_text)
+            fact_checks = get_fact_checks(extracted_claims[0])
+        else:
+            label = "FAKE" if image_ai_result['probability'] > 0.7 else "REAL"
+            confidence = image_ai_result['probability'] if label == "FAKE" else (1 - image_ai_result['probability'])
+            fact_checks = []
+        
+        # Gemini Explanation
+        explanation = generate_explanation_with_gemini(extracted_text if extracted_text else "No text found in image", label, confidence, fact_checks)
+        
+        risk_level = calculate_risk_level(label, confidence, fact_checks, image_ai_result)
+        
+        return {
+            "input_type": "image",
+            "image_url": image_url,
+            "text": extracted_text[:500] if extracted_text else None,
+            "label": label,
+            "confidence": confidence,
+            "explanation": explanation,
+            "fact_checks": fact_checks,
+            "image_ai_result": image_ai_result,
+            "risk_level": risk_level,
+            "timestamp": datetime.now().isoformat()
+        }
+        
+    except Exception as e:
+        print(f"Error in detect_image: {str(e)}")
+        raise HTTPException(status_code=500, detail=str(e))
+
+if __name__ == "__main__":
+    import uvicorn
+    uvicorn.run(app, host="0.0.0.0", port=8000)

requirements.txt

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+fastapi==0.109.0
+uvicorn==0.27.0
+requests==2.31.0
+torch==2.1.2
+transformers==4.36.2
+newspaper3k==0.2.8
+beautifulsoup4==4.12.2
+easyocr==1.7.1
+Pillow==10.2.0
+python-multipart==0.0.6
+pydantic==2.5.3
+lxml_html_clean
+opencv-python-headless
+google-generativeai==0.3.2