from fastapi import FastAPI, Depends, HTTPException, Request, Form, status
from fastapi.responses import RedirectResponse, HTMLResponse
from fastapi.templating import Jinja2Templates
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from pydantic import BaseModel
from sqlalchemy.orm import Session
from database import get_db, get_user_by_email
from models import User
from passlib.context import CryptContext
from datetime import datetime, timedelta
import jwt
from emailx import send_verification_email, generate_verification_token

from fastapi.staticfiles import StaticFiles

from typing import Optional
import httpx
import os
from starlette.middleware.sessions import SessionMiddleware
from authlib.integrations.starlette_client import OAuth



# Environment variables
GOOGLE_CLIENT_ID = os.getenv('GOOGLE_CLIENT_ID')
GOOGLE_CLIENT_SECRET = os.getenv('GOOGLE_CLIENT_SECRET')
SECRET_KEY = os.getenv('SecretKey', 'default_secret')
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

# FastAPI and OAuth setup
app = FastAPI()
app.add_middleware(SessionMiddleware, secret_key=SECRET_KEY)
oauth = OAuth()

# Password context
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

# OAuth2 scheme
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

class TokenData(BaseModel):
    token: str

class UserCreate(BaseModel):
    username: str
    email: str
    password: str
    confirm_password: str
# OAuth Configuration
oauth.register(
    name='google',
    client_id=os.environ['GOOGLE_CLIENT_ID'],
    client_secret=os.environ['GOOGLE_CLIENT_SECRET'],
    access_token_url='https://accounts.google.com/o/oauth2/token',
    authorize_url='https://accounts.google.com/o/oauth2/auth',
    authorize_params=None,
    api_base_url='https://www.googleapis.com/oauth2/v1/',
    client_kwargs={'scope': 'openid email profile'}
)

# Static and template configurations
app.mount("/static", StaticFiles(directory="static"), name="static")
templates = Jinja2Templates(directory="templates")

# OAuth routes
@app.get("/login/oauth")
async def login_oauth(request: Request):
    redirect_uri = request.url_for('auth_callback')
    return await oauth.google.authorize_redirect(request, redirect_uri)
    
@app.get("/auth/callback")
async def auth_callback(request: Request, db: Session = Depends(get_db)):
    token = await oauth.google.authorize_access_token(request)
    user_info = await oauth.google.parse_id_token(request, token)
    request.session["user_info"] = user_info

    db_user = db.query(User).filter(User.email == user_info['email']).first()
    if not db_user:
        db_user = User(email=user_info['email'], username=user_info['name'], is_verified=True)
        db.add(db_user)
        db.commit()
        db.refresh(db_user)

    access_token = create_access_token(data={"sub": db_user.email}, expires_delta=timedelta(minutes=30))
    response = RedirectResponse(url="/protected")
    response.set_cookie(key="access_token", value=f"Bearer {access_token}", httponly=True)
    return response

@app.get("/", response_class=HTMLResponse)
async def landing(request: Request):
    return templates.TemplateResponse("landing.html", {"request": request})

def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)

def get_password_hash(password):
    return pwd_context.hash(password)

def authenticate_user(db: Session, username: str, password: str):
    user = db.query(User).filter(User.username == username).first()
    if not user or not verify_password(password, user.hashed_password):
        return False
    return user

    
def create_access_token(data: dict, expires_delta: timedelta = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)):
    to_encode = data.copy()
    expire = datetime.utcnow() + expires_delta
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

def verify_token(token: str = Depends(oauth2_scheme)):
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        return payload.get("sub")
    except jwt.ExpiredSignatureError:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Token has expired")

def validate_token(token: str):
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token")
        return TokenData(username=username)
    except JWTError:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token")

@app.get("/token/validate")
async def token_validate(token: str = Depends(oauth2_scheme)):
    return validate_token(token)

@app.post("/login")
async def login(form_data: OAuth2PasswordRequestForm = Depends(), db: Session = Depends(get_db)):
    return await login_for_access_token(form_data.username, form_data.password, db)

async def login_for_access_token(username: str, password: str, db: Session):
    user = authenticate_user(db, username, password)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )
    access_token = create_access_token(data={"sub": user.username})
    return {"access_token": access_token, "token_type": "bearer"}

def authenticate_user(db: Session, email: str, password: str):
    user = get_user_by_email(db, email)
    if not user or not pwd_context.verify(password, user.hashed_password):
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Incorrect email or password")
    return user

def register_user(user_data: UserCreate, db: Session):
    if get_user_by_email(db, user_data.email):
        raise HTTPException(status_code=400, detail="Email already registered")

    hashed_password = pwd_context.hash(user_data.password)
    verification_token = generate_verification_token(user_data.email)
    reset_link = f"http://gregniuki-loginauth.hf.space/verify?token={verification_token}"
    send_verification_email(user_data.email, reset_link)

    new_user = User(
        email=user_data.email,
        username=user_data.username,
        hashed_password=hashed_password,
        email_verification_token=verification_token
    )
    db.add(new_user)
    db.commit()
    db.refresh(new_user)
    return new_user
    
def verify_email(verification_token: str, db: Session = Depends(get_db)):
    # Verify the email using the token
    user = get_user_by_verification_token(db, verification_token)
    
    if not user:
        raise HTTPException(status_code=400, detail="Invalid verification token")

    if user.is_verified:
        raise HTTPException(status_code=400, detail="Email already verified")

    # Mark the email as verified
    user.is_verified = True
    user.email_verification_token = None  # Optionally clear the verification token
    db.commit()
    return {"message": "Email verification successful"}
    
def get_user_by_verification_token(db: Session, verification_token: str):
    return db.query(User).filter(User.email_verification_token == verification_token).first()

def reset_password(user: User, db: Session):
    verification_token = generate_verification_token(user.email)
    reset_link = f"http://gregniuki-loginauth.hf.space/reset-password?token={verification_token}"
    send_verification_email(user.email, reset_link)

    user.email_verification_token = verification_token
    db.commit()

def get_current_user(token: str = Depends(verify_token)):
    return token