import { OAuth2Client } from "google-auth-library";
import { models } from "@b/db";
import { handleReferralRegister } from "@b/utils/affiliate";
import {
  returnUserWithTokens,
  userRegisterResponseSchema,
  userRegisterSchema,
} from "../utils";
import { serverErrorResponse } from "@b/utils/query";

const client = new OAuth2Client(process.env.NEXT_PUBLIC_GOOGLE_CLIENT_ID);

export const metadata: OperationObject = {
  summary: "Registers a new user with Google",
  operationId: "registerUserWithGoogle",
  tags: ["Auth"],
  description: "Registers a new user using Google and returns a session token",
  requiresAuth: false,
  requestBody: {
    required: true,
    content: {
      "application/json": {
        schema: userRegisterSchema,
      },
    },
  },
  responses: {
    200: {
      description: "User registered successfully",
      content: {
        "application/json": {
          schema: {
            type: "object",
            properties: userRegisterResponseSchema,
          },
        },
      },
    },
    500: serverErrorResponse,
  },
};

async function verifyGoogleToken(token: string) {
  const ticket = await client.verifyIdToken({
    idToken: token,
    audience: process.env.NEXT_PUBLIC_GOOGLE_CLIENT_ID,
  });
  return ticket.getPayload();
}

async function fetchGoogleUserInfo(token: string) {
  const response = await fetch(
    `https://www.googleapis.com/oauth2/v3/userinfo?access_token=${token}`
  );
  if (!response.ok) {
    throw new Error("Failed to fetch user info from Google");
  }
  return response.json();
}

// Function to sanitize names by removing non-letter characters (supports Unicode, allows spaces)
function sanitizeName(name: string): string {
  return name.replace(/[^\p{L}\s]/gu, "");
}

// Function to validate names (supports Unicode, allows spaces)
function isValidName(name: string): boolean {
  return /^[\p{L}\s]+$/u.test(name);
}

export default async (data: Handler) => {
  const { body } = data;
  const { token, ref } = body;

  let payload;
  try {
    payload = await verifyGoogleToken(token);
  } catch (error) {
    payload = await fetchGoogleUserInfo(token);
  }

  if (!payload) {
    throw new Error("Invalid Google token");
  }

  const {
    sub: googleId,
    email,
    given_name: firstName,
    family_name: lastName,
  } = payload;

  if (!googleId || !email || !firstName || !lastName) {
    throw new Error("Incomplete user information from Google");
  }

  // Sanitize and validate names
  const sanitizedFirstName = sanitizeName(firstName);
  const sanitizedLastName = sanitizeName(lastName);

  if (!isValidName(sanitizedFirstName) || !isValidName(sanitizedLastName)) {
    throw new Error(
      "First name and last name must only contain letters and spaces"
    );
  }

  // Check if user already exists
  let user = await models.user.findOne({ where: { email } });

  let isNewUser = false;
  if (!user) {
    const roleName =
      process.env.NEXT_PUBLIC_DEMO_STATUS === "true" ? "Admin" : "User";
    await models.role.upsert({ name: roleName });

    // Fetch the role to get its ID
    const role = await models.role.findOne({ where: { name: roleName } });

    if (!role) throw new Error("Role not found after upsert.");

    // Create the user with the roleId
    user = await models.user.create({
      firstName: sanitizedFirstName,
      lastName: sanitizedLastName,
      email,
      roleId: role.id,
      emailVerified: true,
    });

    // Create a provider_user entry
    await models.providerUser.create({
      provider: "GOOGLE",
      providerUserId: googleId,
      userId: user.id,
    });

    try {
      if (ref) await handleReferralRegister(ref, user.id);
    } catch (error) {
      console.error("Error handling referral registration:", error);
    }
    isNewUser = true;
  } else {
    // Check if the user has a provider_user entry
    const providerUser = await models.providerUser.findOne({
      where: { providerUserId: googleId, provider: "GOOGLE" },
    });

    if (!providerUser) {
      // Create a provider_user entry
      await models.providerUser.create({
        provider: "GOOGLE",
        providerUserId: googleId,
        userId: user.id,
      });
    }
  }

  return await returnUserWithTokens({
    user: user,
    message: isNewUser
      ? "You have been registered successfully"
      : "You have been logged in successfully",
  });
};