import { ErrorTypes } from 'librechat-data-provider';
// Note: checkUserKeyExpiry moved to @librechat/api (utils/key.ts) as it's a pure validation utility
import { encrypt, decrypt } from '~/crypto';
import logger from '~/config/winston';

/** Factory function that takes mongoose instance and returns the key methods */
export function createKeyMethods(mongoose: typeof import('mongoose')) {
  /**
   * Retrieves and decrypts the key value for a given user identified by userId and identifier name.
   * @param params - The parameters object
   * @param params.userId - The unique identifier for the user
   * @param params.name - The name associated with the key
   * @returns The decrypted key value
   * @throws Error if the key is not found or if there is a problem during key retrieval
   * @description This function searches for a user's key in the database using their userId and name.
   *              If found, it decrypts the value of the key and returns it. If no key is found, it throws
   *              an error indicating that there is no user key available.
   */
  async function getUserKey(params: { userId: string; name: string }): Promise<string> {
    const { userId, name } = params;
    const Key = mongoose.models.Key;
    const keyValue = (await Key.findOne({ userId, name }).lean()) as {
      value: string;
    } | null;
    if (!keyValue) {
      throw new Error(
        JSON.stringify({
          type: ErrorTypes.NO_USER_KEY,
        }),
      );
    }
    return await decrypt(keyValue.value);
  }

  /**
   * Retrieves, decrypts, and parses the key values for a given user identified by userId and name.
   * @param params - The parameters object
   * @param params.userId - The unique identifier for the user
   * @param params.name - The name associated with the key
   * @returns The decrypted and parsed key values
   * @throws Error if the key is invalid or if there is a problem during key value parsing
   * @description This function retrieves a user's encrypted key using their userId and name, decrypts it,
   *              and then attempts to parse the decrypted string into a JSON object. If the parsing fails,
   *              it throws an error indicating that the user key is invalid.
   */
  async function getUserKeyValues(params: {
    userId: string;
    name: string;
  }): Promise<Record<string, string>> {
    const { userId, name } = params;
    const userValues = await getUserKey({ userId, name });
    try {
      return JSON.parse(userValues) as Record<string, string>;
    } catch (e) {
      logger.error('[getUserKeyValues]', e);
      throw new Error(
        JSON.stringify({
          type: ErrorTypes.INVALID_USER_KEY,
        }),
      );
    }
  }

  /**
   * Retrieves the expiry information of a user's key identified by userId and name.
   * @param params - The parameters object
   * @param params.userId - The unique identifier for the user
   * @param params.name - The name associated with the key
   * @returns The expiry date of the key or null if the key doesn't exist
   * @description This function fetches a user's key from the database using their userId and name and
   *              returns its expiry date. If the key is not found, it returns null for the expiry date.
   */
  async function getUserKeyExpiry(params: {
    userId: string;
    name: string;
  }): Promise<{ expiresAt: Date | 'never' | null }> {
    const { userId, name } = params;
    const Key = mongoose.models.Key;
    const keyValue = (await Key.findOne({ userId, name }).lean()) as {
      expiresAt?: Date;
    } | null;
    if (!keyValue) {
      return { expiresAt: null };
    }
    return { expiresAt: keyValue.expiresAt || 'never' };
  }

  /**
   * Updates or inserts a new key for a given user identified by userId and name, with a specified value and expiry date.
   * @param params - The parameters object
   * @param params.userId - The unique identifier for the user
   * @param params.name - The name associated with the key
   * @param params.value - The value to be encrypted and stored as the key's value
   * @param params.expiresAt - The expiry date for the key [optional]
   * @returns The updated or newly inserted key document
   * @description This function either updates an existing user key or inserts a new one into the database,
   *              after encrypting the provided value. It sets the provided expiry date for the key (or unsets for no expiry).
   */
  async function updateUserKey(params: {
    userId: string;
    name: string;
    value: string;
    expiresAt?: Date | null;
  }): Promise<unknown> {
    const { userId, name, value, expiresAt = null } = params;
    const Key = mongoose.models.Key;
    const encryptedValue = await encrypt(value);
    const updateObject: { userId: string; name: string; value: string; expiresAt?: Date } = {
      userId,
      name,
      value: encryptedValue,
    };
    const updateQuery: { $set: typeof updateObject; $unset?: { expiresAt: string } } = {
      $set: updateObject,
    };
    if (expiresAt) {
      updateObject.expiresAt = new Date(expiresAt);
    } else {
      updateQuery.$unset = { expiresAt: '' };
    }
    return await Key.findOneAndUpdate({ userId, name }, updateQuery, {
      upsert: true,
      new: true,
    }).lean();
  }

  /**
   * Deletes a key or all keys for a given user identified by userId, optionally based on a specified name.
   * @param params - The parameters object
   * @param params.userId - The unique identifier for the user
   * @param params.name - The name associated with the key to delete. If not provided and all is true, deletes all keys
   * @param params.all - Whether to delete all keys for the user
   * @returns The result of the deletion operation
   * @description This function deletes a specific key or all keys for a user from the database.
   *              If a name is provided and all is false, it deletes only the key with that name.
   *              If all is true, it ignores the name and deletes all keys for the user.
   */
  async function deleteUserKey(params: {
    userId: string;
    name?: string;
    all?: boolean;
  }): Promise<unknown> {
    const { userId, name, all = false } = params;
    const Key = mongoose.models.Key;
    if (all) {
      return await Key.deleteMany({ userId });
    }
    return await Key.findOneAndDelete({ userId, name }).lean();
  }

  return {
    getUserKey,
    updateUserKey,
    deleteUserKey,
    getUserKeyValues,
    getUserKeyExpiry,
  };
}

export type KeyMethods = ReturnType<typeof createKeyMethods>;
