import random
import jwt
import datetime
import os
from dotenv import load_dotenv
from sendgrid import SendGridAPIClient
from sendgrid.helpers.mail import Mail

# -----------------------------
# LOAD ENV VARIABLES
# -----------------------------
load_dotenv()

SECRET_KEY = os.getenv("JWT_SECRET", "fallback_secret")
SENDGRID_API_KEY = os.getenv("SENDGRID_API_KEY")
FROM_EMAIL = os.getenv("SENDGRID_FROM_EMAIL")


# -----------------------------
# GENERATE 6 DIGIT OTP
# -----------------------------
def generate_otp():
    otp = str(random.randint(100000, 999999))
    return otp


# -----------------------------
# CREATE JWT TOKEN
# -----------------------------
def create_jwt(email):

    payload = {
        "email": email,
        "exp": datetime.datetime.now(datetime.timezone.utc) + datetime.timedelta(hours=1)
    }

    token = jwt.encode(payload, SECRET_KEY, algorithm="HS256")

    return token


# -----------------------------
# VERIFY JWT TOKEN
# -----------------------------
def verify_jwt(token):

    try:
        decoded = jwt.decode(token, SECRET_KEY, algorithms=["HS256"])
        return decoded

    except jwt.ExpiredSignatureError:
        print("Token expired")
        return None

    except jwt.InvalidTokenError:
        print("Invalid token")
        return None


# -----------------------------
# SEND OTP VIA SENDGRID EMAIL
# -----------------------------
def send_otp_via_sendgrid(receiver_email, otp):

    message = Mail(
        from_email=FROM_EMAIL,
        to_emails=receiver_email,
        subject="FitPlan AI OTP Verification",
        html_content=f"""
        <h2>Your FitPlan AI Login OTP</h2>
        <p>Your verification code is:</p>
        <h1>{otp}</h1>
        <p>This OTP is valid for login verification.</p>
        """
    )

    try:

        sg = SendGridAPIClient(SENDGRID_API_KEY)

        response = sg.send(message)

        if response.status_code == 202:
            return True
        else:
            return False

    except Exception as e:
        print("SendGrid Error:", e)
        return False