// app/utils/emailVerification.util.js

const crypto = require("crypto");

const redis = require("../config/redisClient");

const EMAIL_VERIFICATION_TTL =
  Number(
    process.env.EMAIL_VERIFICATION_TTL_SECONDS
  ) || 1800;

const generateEmailVerificationToken = () => {
  return crypto
    .randomBytes(32)
    .toString("hex");
};

const hashEmailVerificationToken = (token) => {
  return crypto
    .createHash("sha256")
    .update(token)
    .digest("hex");
};

const createEmailVerification = async (userId) => {

  // 1. Generate raw token
  const token =
    generateEmailVerificationToken();


  // 2. Hash token
  const tokenHash =
    hashEmailVerificationToken(token);


  // 3. Create Redis key
  const redisKey =
    `email-verification:${tokenHash}`;

  await redis.set(
    redisKey,
    userId,
    "EX",
    EMAIL_VERIFICATION_TTL
  );

  return token;
};


/**
 * Check a verification token.
 */
const verifyEmailVerificationToken =
  async (token) => {

    if (
      !token ||
      typeof token !== "string"
    ) {
      return null;
    }


    // 1. Hash token received from user
    const tokenHash =
      hashEmailVerificationToken(token);


    // 2. Build same Redis key
    const redisKey =
      `email-verification:${tokenHash}`;


    // 3. Search Redis
    const userId =
      await redis.get(redisKey);

    if (!userId) {
      return null;
    }


    return {
      userId,
      redisKey,
    };
  };

const deleteEmailVerification =
  async (redisKey) => {

    await redis.del(redisKey);
  };


module.exports = {
  createEmailVerification,
  verifyEmailVerificationToken,
  deleteEmailVerification,
  hashEmailVerificationToken,
};