main.py

import os
import re
import traceback
from fastapi import FastAPI, HTTPException, Depends, Request, status
from pydantic import BaseModel
from dotenv import load_dotenv
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
import jwt
from jwt import PyJWKClient
import base64
from slowapi import Limiter, _rate_limit_exceeded_handler
from slowapi.util import get_remote_address
from slowapi.errors import RateLimitExceeded

# Load environment variables from .env file
load_dotenv()

if not os.getenv("GROQ_API_KEY") and not os.getenv("HF_TOKEN"):
    load_dotenv(dotenv_path='.env.example')

if not os.getenv("GROQ_API_KEY") and os.getenv("HF_TOKEN"):
    os.environ["GROQ_API_KEY"] = os.getenv("HF_TOKEN")

from humanizer import humanize_text
from usage import check_usage_limit, increment_usage, get_user_profile, upgrade_user_plan, cancel_user_subscription

from fastapi.middleware.cors import CORSMiddleware
from fastapi import Request
import hmac
import json
import razorpay

RAZORPAY_KEY_ID = os.getenv("RAZORPAY_KEY_ID")
RAZORPAY_KEY_SECRET = os.getenv("RAZORPAY_KEY_SECRET")
RAZORPAY_WEBHOOK_SECRET = os.getenv("RAZORPAY_WEBHOOK_SECRET")
RAZORPAY_STARTER_PLAN_ID = os.getenv("RAZORPAY_STARTER_PLAN_ID")
RAZORPAY_PRO_PLAN_ID = os.getenv("RAZORPAY_PRO_PLAN_ID")

razorpay_client = razorpay.Client(auth=(RAZORPAY_KEY_ID or "", RAZORPAY_KEY_SECRET or ""))


SUPABASE_URL = os.getenv("SUPABASE_URL")
JWKS_URL = f"{SUPABASE_URL}/auth/v1/.well-known/jwks.json" if SUPABASE_URL else ""
jwks_client = PyJWKClient(JWKS_URL) if JWKS_URL else None

security = HTTPBearer()

def verify_token(credentials: HTTPAuthorizationCredentials = Depends(security)):
    token = credentials.credentials
    try:
        if not jwks_client:
            raise ValueError("SUPABASE_URL is not set.")
            
        signing_key = jwks_client.get_signing_key_from_jwt(token)
        payload = jwt.decode(
            token,
            signing_key.key,
            algorithms=["HS256", "RS256", "ES256"],
            audience="authenticated",
            options={"verify_aud": True}
        )
        user_id = payload.get("sub")
        if not user_id:
            raise HTTPException(status_code=401, detail="Invalid token claims")
        return user_id
    except Exception as e:
        raise HTTPException(status_code=401, detail=f"Invalid or expired token: {str(e)}")

INJECTION_PATTERNS = [
    r"ignore\s*(all\s*)?(previous|prior|above)\s*(instructions?|prompts?|context)",
    r"forget\s*(what|everything|all)\s*(you\s*)?(were\s*)?(told|said|given|know)",
    r"you\s*are\s*now\s*(a|an|the)",
    r"act\s*as\s*(if\s*)?(you\s*are\s*)?(a|an|the)",
    r"new\s*(system\s*)?prompt",
    r"override\s*(system|instructions?|prompt)",
    r"pretend\s*(you\s*are|to\s*be)",
    r"\b(DAN|STAN)\b",
    r"(jailbreak|developer\s*mode|god\s*mode)",
    r"disregard\s*(all\s*)?(previous|prior)\s*(instructions?|rules?)",
    r"your\s*(true|real|actual)\s*(self|purpose|goal|task)",
]

def sanitize_input(text: str) -> str:
    for pattern in INJECTION_PATTERNS:
        if re.search(pattern, text, re.IGNORECASE):
            raise HTTPException(status_code=400, detail="Input contains disallowed content.")

    try:
        decoded = base64.b64decode(text + "==").decode("utf-8", errors="ignore")
        for pattern in INJECTION_PATTERNS:
            if re.search(pattern, decoded, re.IGNORECASE):
                raise HTTPException(status_code=400, detail="Input contains disallowed content.")
    except Exception:
        pass

    return text

app = FastAPI(title="AI Humanizer API")

limiter = Limiter(key_func=get_remote_address)
app.state.limiter = limiter
app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)

app.add_middleware(
    CORSMiddleware,
    allow_origins=[
        "https://humanizer-frontend-beige.vercel.app",
        "http://localhost:3000"
    ],
    allow_methods=["*"],
    allow_headers=["*"],
)

class HumanizeRequest(BaseModel):
    text: str
    mode: str = "standard"
    readability: str = "neutral"
    purpose: str = "professional"

class HumanizeResponse(BaseModel):
    humanized: str
    mode: str
    readability: str
    purpose: str
    usage: dict  # { count, limit, plan }

class CreateOrderRequest(BaseModel):
    plan: str

class VerifyPaymentRequest(BaseModel):
    razorpay_order_id: str
    razorpay_payment_id: str
    razorpay_signature: str
    user_id: str
    plan: str

@app.post("/humanize", response_model=HumanizeResponse)
@limiter.limit("10/minute")
async def humanize(request: Request, body: HumanizeRequest, user_id: str = Depends(verify_token)):
    # Force enhanced mode as requested
    body.mode = "enhanced"

    # Check usage limit
    usage = check_usage_limit(user_id)
    if not usage["allowed"]:
        raise HTTPException(
            status_code=402,
            detail={
                "message": "You have reached your free limit. Please upgrade to continue.",
                "plan": usage["plan"],
                "count": usage["count"],
                "limit": usage["limit"],
            }
        )

    clean_text = sanitize_input(body.text)
    if not clean_text:
        raise HTTPException(
            status_code=400,
            detail="Input text is empty or invalid after sanitization."
        )

    try:
        humanized_text = await humanize_text(
            clean_text,
            mode=body.mode,
            readability=body.readability,
            purpose=body.purpose,
        )

        # Increment usage after successful humanization
        increment_usage(user_id)

        return HumanizeResponse(
            humanized=humanized_text,
            mode=body.mode,
            readability=body.readability,
            purpose=body.purpose,
            usage={
                "count": usage["count"] + 1,
                "limit": usage["limit"],
                "plan": usage["plan"],
            }
        )
    except Exception as e:
        import traceback
        raise HTTPException(status_code=500, detail=traceback.format_exc())

@app.get("/user-plan")
async def get_user_plan(user_id: str = Depends(verify_token)):
    profile = get_user_profile(user_id)
    if not profile:
        raise HTTPException(status_code=404, detail="User not found")
    return {"plan": profile.get("plan", "free")}

@app.post("/api/create-order")
@limiter.limit("5/minute")
async def create_order(request: Request, body: CreateOrderRequest, user_id: str = Depends(verify_token)):
    if not user_id:
        raise HTTPException(status_code=401, detail="Unauthorized")
    if body.plan not in ["starter", "pro"]:
        raise HTTPException(status_code=400, detail="Invalid plan")
    
    # Map plans to amounts (e.g. Starter = $9 = ₹750 = 75000 paise)
    amount = 75000 if request.plan == "starter" else 150000
    
    if amount < 100:
        raise HTTPException(status_code=400, detail="Amount must be at least 100 paise")
    
    try:
        order_data = {
            "amount": amount,
            "currency": "INR",
            "receipt": request.user_id
        }
        order = razorpay_client.order.create(order_data)
        return {
            "order_id": order["id"],
            "amount": amount,
            "currency": "INR",
            "key_id": RAZORPAY_KEY_ID
        }
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))

@app.post("/api/verify-payment")
async def verify_payment(request: VerifyPaymentRequest):
    if not request.razorpay_order_id or not request.razorpay_payment_id or not request.razorpay_signature:
        raise HTTPException(status_code=400, detail="Missing required fields")
        
    try:
        expected_signature = hmac.new(
            key=RAZORPAY_KEY_SECRET.encode('utf-8'),
            msg=(request.razorpay_order_id + "|" + request.razorpay_payment_id).encode('utf-8'),
            digestmod='sha256'
        ).hexdigest()
        
        if not hmac.compare_digest(expected_signature, request.razorpay_signature):
            raise HTTPException(status_code=400, detail="Invalid signature")
            
        profile = get_user_profile(request.user_id)
        if profile and profile.get("plan") != request.plan:
            upgrade_user_plan(request.user_id, request.plan)
            
        return {"status": "ok"}
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))

if __name__ == "__main__":
    import uvicorn
    uvicorn.run("main:app", host="127.0.0.1", port=8000, reload=True)