/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

import {
  checkValidArgs,
  checkValidInput,
  convertError,
  convertErrors,
} from "./helpers";
import RCTAsyncStorage from "./RCTAsyncStorage";
import type {
  AsyncStorageStatic,
  ErrorLike,
  KeyValuePair,
  MultiRequest,
} from "./types";

if (!RCTAsyncStorage) {
  throw new Error(`[@RNC/AsyncStorage]: NativeModule: AsyncStorage is null.

To fix this issue try these steps:

  • Uninstall, rebuild and restart the app.

  • Run the packager with \`--reset-cache\` flag.

  • If you are using CocoaPods on iOS, run \`pod install\` in the \`ios\` directory, then rebuild and re-run the app.

  • Make sure your project's \`package.json\` depends on \`@react-native-async-storage/async-storage\`, even if you only depend on it indirectly through other dependencies. CLI only autolinks native modules found in your \`package.json\`.

  • If this happens while testing with Jest, check out how to integrate AsyncStorage here: https://react-native-async-storage.github.io/async-storage/docs/advanced/jest

If none of these fix the issue, please open an issue on the GitHub repository: https://github.com/react-native-async-storage/async-storage/issues
`);
}

/**
 * `AsyncStorage` is a simple, unencrypted, asynchronous, persistent, key-value
 * storage system that is global to the app. It should be used instead of
 * LocalStorage.
 *
 * See https://react-native-async-storage.github.io/async-storage/docs/api
 */
const AsyncStorage = ((): AsyncStorageStatic => {
  let _getRequests: MultiRequest[] = [];
  let _getKeys: string[] = [];
  let _immediate: ReturnType<typeof setImmediate> | null = null;

  return {
    /**
     * Fetches an item for a `key` and invokes a callback upon completion.
     *
     * See https://react-native-async-storage.github.io/async-storage/docs/api#getitem
     */
    getItem: (key, callback) => {
      return new Promise((resolve, reject) => {
        checkValidInput(key);
        RCTAsyncStorage.multiGet(
          [key],
          (errors?: ErrorLike[], result?: string[][]) => {
            // Unpack result to get value from [[key,value]]
            const value = result?.[0]?.[1] ? result[0][1] : null;
            const errs = convertErrors(errors);
            callback?.(errs?.[0], value);
            if (errs) {
              reject(errs[0]);
            } else {
              resolve(value);
            }
          }
        );
      });
    },

    /**
     * Sets the value for a `key` and invokes a callback upon completion.
     *
     * See https://react-native-async-storage.github.io/async-storage/docs/api#setitem
     */
    setItem: (key, value, callback) => {
      return new Promise((resolve, reject) => {
        checkValidInput(key, value);
        RCTAsyncStorage.multiSet([[key, value]], (errors?: ErrorLike[]) => {
          const errs = convertErrors(errors);
          callback?.(errs?.[0]);
          if (errs) {
            reject(errs[0]);
          } else {
            resolve();
          }
        });
      });
    },

    /**
     * Removes an item for a `key` and invokes a callback upon completion.
     *
     * See https://react-native-async-storage.github.io/async-storage/docs/api#removeitem
     */
    removeItem: (key, callback) => {
      return new Promise((resolve, reject) => {
        checkValidInput(key);
        RCTAsyncStorage.multiRemove([key], (errors?: ErrorLike[]) => {
          const errs = convertErrors(errors);
          callback?.(errs?.[0]);
          if (errs) {
            reject(errs[0]);
          } else {
            resolve();
          }
        });
      });
    },

    /**
     * Merges an existing `key` value with an input value, assuming both values
     * are stringified JSON.
     *
     * See https://react-native-async-storage.github.io/async-storage/docs/api#mergeitem
     */
    mergeItem: (key, value, callback) => {
      return new Promise((resolve, reject) => {
        checkValidInput(key, value);
        RCTAsyncStorage.multiMerge([[key, value]], (errors?: ErrorLike[]) => {
          const errs = convertErrors(errors);
          callback?.(errs?.[0]);
          if (errs) {
            reject(errs[0]);
          } else {
            resolve();
          }
        });
      });
    },

    /**
     * Erases *all* `AsyncStorage` for all clients, libraries, etc. You probably
     * don't want to call this; use `removeItem` or `multiRemove` to clear only
     * your app's keys.
     *
     * See https://react-native-async-storage.github.io/async-storage/docs/api#clear
     */
    clear: (callback) => {
      return new Promise((resolve, reject) => {
        RCTAsyncStorage.clear((error?: ErrorLike) => {
          const err = convertError(error);
          callback?.(err);
          if (err) {
            reject(err);
          } else {
            resolve();
          }
        });
      });
    },

    /**
     * Gets *all* keys known to your app; for all callers, libraries, etc.
     *
     * See https://react-native-async-storage.github.io/async-storage/docs/api#getallkeys
     */
    getAllKeys: (callback) => {
      return new Promise((resolve, reject) => {
        RCTAsyncStorage.getAllKeys((error?: ErrorLike, keys?: string[]) => {
          const err = convertError(error);
          callback?.(err, keys);
          if (keys) {
            resolve(keys);
          } else {
            reject(err);
          }
        });
      });
    },

    /**
     * The following batched functions are useful for executing a lot of
     * operations at once, allowing for native optimizations and provide the
     * convenience of a single callback after all operations are complete.
     *
     * These functions return arrays of errors, potentially one for every key.
     * For key-specific errors, the Error object will have a key property to
     * indicate which key caused the error.
     */

    /**
     * Flushes any pending requests using a single batch call to get the data.
     *
     * See https://react-native-async-storage.github.io/async-storage/docs/api#flushgetrequests
     * */
    flushGetRequests: () => {
      const getRequests = _getRequests;
      const getKeys = _getKeys;

      _getRequests = [];
      _getKeys = [];

      RCTAsyncStorage.multiGet(
        getKeys,
        (errors?: ErrorLike[], result?: string[][]) => {
          // Even though the runtime complexity of this is theoretically worse vs if we used a map,
          // it's much, much faster in practice for the data sets we deal with (we avoid
          // allocating result pair arrays). This was heavily benchmarked.
          //
          // Is there a way to avoid using the map but fix the bug in this breaking test?
          // https://github.com/facebook/react-native/commit/8dd8ad76579d7feef34c014d387bf02065692264
          const map: Record<string, string> = {};
          result?.forEach(([key, value]) => {
            map[key] = value;
            return value;
          });
          const reqLength = getRequests.length;

          /**
           * As mentioned few lines above, this method could be called with the array of potential error,
           * in case of anything goes wrong. The problem is, if any of the batched calls fails
           * the rest of them would fail too, but the error would be consumed by just one. The rest
           * would simply return `undefined` as their result, rendering false negatives.
           *
           * In order to avoid this situation, in case of any call failing,
           * the rest of them will be rejected as well (with the same error).
           */
          const errorList = convertErrors(errors);
          const error = errorList?.length ? errorList[0] : null;

          for (let i = 0; i < reqLength; i++) {
            const request = getRequests[i];
            if (error) {
              request.callback?.(errorList);
              request.reject?.(error);
              continue;
            }
            const requestResult = request.keys.map<KeyValuePair>((key) => [
              key,
              map[key],
            ]);
            request.callback?.(null, requestResult);
            request.resolve?.(requestResult);
          }
        }
      );
    },

    /**
     * This allows you to batch the fetching of items given an array of `key`
     * inputs. Your callback will be invoked with an array of corresponding
     * key-value pairs found.
     *
     * See https://react-native-async-storage.github.io/async-storage/docs/api#multiget
     */
    multiGet: (keys, callback) => {
      if (!_immediate) {
        _immediate = setImmediate(() => {
          _immediate = null;
          AsyncStorage.flushGetRequests();
        });
      }

      const getRequest: MultiRequest = {
        keys: keys,
        callback: callback,
        // do we need this?
        keyIndex: _getKeys.length,
      };

      const promiseResult = new Promise<readonly KeyValuePair[]>(
        (resolve, reject) => {
          getRequest.resolve = resolve;
          getRequest.reject = reject;
        }
      );

      _getRequests.push(getRequest);
      // avoid fetching duplicates
      keys.forEach((key) => {
        if (_getKeys.indexOf(key) === -1) {
          _getKeys.push(key);
        }
      });

      return promiseResult;
    },

    /**
     * Use this as a batch operation for storing multiple key-value pairs. When
     * the operation completes you'll get a single callback with any errors.
     *
     * See https://react-native-async-storage.github.io/async-storage/docs/api#multiset
     */
    multiSet: (keyValuePairs, callback) => {
      checkValidArgs(keyValuePairs, callback);
      return new Promise((resolve, reject) => {
        keyValuePairs.forEach(([key, value]) => {
          checkValidInput(key, value);
        });

        RCTAsyncStorage.multiSet(keyValuePairs, (errors?: ErrorLike[]) => {
          const error = convertErrors(errors);
          callback?.(error);
          if (error) {
            reject(error);
          } else {
            resolve();
          }
        });
      });
    },

    /**
     * Call this to batch the deletion of all keys in the `keys` array.
     *
     * See https://react-native-async-storage.github.io/async-storage/docs/api#multiremove
     */
    multiRemove: (keys, callback) => {
      return new Promise((resolve, reject) => {
        keys.forEach((key) => checkValidInput(key));

        RCTAsyncStorage.multiRemove(keys, (errors?: ErrorLike[]) => {
          const error = convertErrors(errors);
          callback?.(error);
          if (error) {
            reject(error);
          } else {
            resolve();
          }
        });
      });
    },

    /**
     * Batch operation to merge in existing and new values for a given set of
     * keys. This assumes that the values are stringified JSON.
     *
     * See https://react-native-async-storage.github.io/async-storage/docs/api#multimerge
     */
    multiMerge: (keyValuePairs, callback) => {
      return new Promise((resolve, reject) => {
        RCTAsyncStorage.multiMerge(keyValuePairs, (errors?: ErrorLike[]) => {
          const error = convertErrors(errors);
          callback?.(error);
          if (error) {
            reject(error);
          } else {
            resolve();
          }
        });
      });
    },
  };
})();

export default AsyncStorage;