/**
 * 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.
 *
 * @emails oncall+recoil
 * @flow strict-local
 * @format
 */
'use strict';

import type { Loadable } from '../adt/Recoil_Loadable';
import type { RecoilValue, RecoilValueReadOnly } from '../core/Recoil_RecoilValue';

const {
  loadableWithError,
  loadableWithPromise,
  loadableWithValue
} = require('../adt/Recoil_Loadable');

const gkx = require('../util/Recoil_gkx');

const isPromise = require('../util/Recoil_isPromise');

const selectorFamily = require('./Recoil_selectorFamily'); /////////////////
//  TRUTH TABLE
/////////////////
// Dependencies        waitForNone         waitForAny        waitForAll
//  [loading, loading]  [Promise, Promise]  Promise           Promise
//  [value, loading]    [value, Promise]    [value, Promise]  Promise
//  [value, value]      [value, value]      [value, value]    [value, value]
//
//  [error, loading]    [Error, Promise]    Promise           Error
//  [error, error]      [Error, Error]      Error             Error
//  [value, error]      [value, Error]      [value, Error]    Error
// Issue parallel requests for all dependencies and return the current
// status if they have results, have some error, or are still pending.


declare function concurrentRequests(getRecoilValue: any, deps: any): any;
declare function isError(exp: any): any;
declare function unwrapDependencies(dependencies: $ReadOnlyArray<RecoilValueReadOnly<mixed>> | {
  +[string]: RecoilValueReadOnly<mixed>
}): $ReadOnlyArray<RecoilValue<mixed>>;
declare function getValueFromLoadablePromiseResult(result: any): any;
declare function wrapResults(dependencies: $ReadOnlyArray<RecoilValueReadOnly<mixed>> | {
  +[string]: RecoilValueReadOnly<mixed>
}, results: any): any;
declare function wrapLoadables(dependencies: $ReadOnlyArray<RecoilValueReadOnly<mixed>> | {
  +[string]: RecoilValueReadOnly<mixed>
}, results: any, exceptions: any): any;
declare function combineAsyncResultsWithSyncResults<T>(syncResults: Array<T>, asyncResults: Array<T>): Array<T>; // Selector that requests all dependencies in parallel and immediately returns
// current results without waiting.

const waitForNone: <RecoilValues: $ReadOnlyArray<RecoilValueReadOnly<mixed>> | $ReadOnly<{
  [string]: RecoilValueReadOnly<mixed>,
  ...
}>>(RecoilValues) => RecoilValueReadOnly<$ReadOnlyArray<Loadable<mixed>> | $ReadOnly<{
  [string]: Loadable<mixed>,
  ...
}>> = selectorFamily({
  key: '__waitForNone',
  get: (dependencies: $ReadOnly<{
    [string]: RecoilValueReadOnly<mixed>
  }> | $ReadOnlyArray<RecoilValueReadOnly<mixed>>) => ({
    get
  }) => {
    // Issue requests for all dependencies in parallel.
    const deps = unwrapDependencies(dependencies);
    const [results, exceptions] = concurrentRequests(get, deps); // Always return the current status of the results; never block.

    return wrapLoadables(dependencies, results, exceptions);
  }
}); // Selector that requests all dependencies in parallel and waits for at least
// one to be available before returning results.  It will only error if all
// dependencies have errors.

const waitForAny: <RecoilValues: $ReadOnlyArray<RecoilValueReadOnly<mixed>> | $ReadOnly<{
  [string]: RecoilValueReadOnly<mixed>,
  ...
}>>(RecoilValues) => RecoilValueReadOnly<$ReadOnlyArray<mixed> | $ReadOnly<{
  [string]: mixed,
  ...
}>> = selectorFamily({
  key: '__waitForAny',
  get: (dependencies: $ReadOnly<{
    [string]: RecoilValueReadOnly<mixed>
  }> | $ReadOnlyArray<RecoilValueReadOnly<mixed>>) => ({
    get
  }) => {
    // Issue requests for all dependencies in parallel.
    // Exceptions can either be Promises of pending results or real errors
    const deps = unwrapDependencies(dependencies);
    const [results, exceptions] = concurrentRequests(get, deps); // If any results are available, return the current status

    if (exceptions.some(exp => exp == null)) {
      return wrapLoadables(dependencies, results, exceptions);
    } // Since we are waiting for any results, only throw an error if all
    // dependencies have an error.  Then, throw the first one.


    if (exceptions.every(isError)) {
      throw exceptions.find(isError);
    }

    if (gkx('recoil_async_selector_refactor')) {
      // Otherwise, return a promise that will resolve when the next result is
      // available, whichever one happens to be next.  But, if all pending
      // dependencies end up with errors, then reject the promise.
      return new Promise((resolve, reject) => {
        for (const [i, exp] of exceptions.entries()) {
          if (isPromise(exp)) {
            exp.then(result => {
              results[i] = getValueFromLoadablePromiseResult(result);
              exceptions[i] = null;
              resolve(wrapLoadables(dependencies, results, exceptions));
            }).catch(error => {
              exceptions[i] = error;

              if (exceptions.every(isError)) {
                reject(exceptions[0]);
              }
            });
          }
        }
      });
    } else {
      throw new Promise((resolve, reject) => {
        for (const [i, exp] of exceptions.entries()) {
          if (isPromise(exp)) {
            exp.then(result => {
              results[i] = result;
              exceptions[i] = null;
              resolve(wrapLoadables(dependencies, results, exceptions));
            }).catch(error => {
              exceptions[i] = error;

              if (exceptions.every(isError)) {
                reject(exceptions[0]);
              }
            });
          }
        }
      });
    }
  }
}); // Selector that requests all dependencies in parallel and waits for all to be
// available before returning a value.  It will error if any dependencies error.

const waitForAll: <RecoilValues: $ReadOnlyArray<RecoilValueReadOnly<mixed>> | $ReadOnly<{
  [string]: RecoilValueReadOnly<mixed>,
  ...
}>>(RecoilValues) => RecoilValueReadOnly<$ReadOnlyArray<mixed> | $ReadOnly<{
  [string]: mixed,
  ...
}>> = selectorFamily({
  key: '__waitForAll',
  get: (dependencies: $ReadOnly<{
    [string]: RecoilValueReadOnly<mixed>
  }> | $ReadOnlyArray<RecoilValueReadOnly<mixed>>) => ({
    get
  }) => {
    // Issue requests for all dependencies in parallel.
    // Exceptions can either be Promises of pending results or real errors
    const deps = unwrapDependencies(dependencies);
    const [results, exceptions] = concurrentRequests(get, deps); // If all results are available, return the results

    if (exceptions.every(exp => exp == null)) {
      return wrapResults(dependencies, results);
    } // If we have any errors, throw the first error


    const error = exceptions.find(isError);

    if (error != null) {
      throw error;
    }

    if (gkx('recoil_async_selector_refactor')) {
      // Otherwise, return a promise that will resolve when all results are available
      return Promise.all(exceptions).then(exceptionResults => wrapResults(dependencies, combineAsyncResultsWithSyncResults(results, exceptionResults).map(getValueFromLoadablePromiseResult)));
    } else {
      throw Promise.all(exceptions).then(results => wrapResults(dependencies, results));
    }
  }
});
const noWait: (RecoilValue<mixed>) => RecoilValueReadOnly<Loadable<mixed>> = selectorFamily({
  key: '__noWait',
  get: dependency => ({
    get
  }) => {
    try {
      return loadableWithValue(get(dependency));
    } catch (exception) {
      return isPromise(exception) ? loadableWithPromise(exception) : loadableWithError(exception);
    }
  }
});
module.exports = {
  waitForNone,
  waitForAny,
  waitForAll,
  noWait
};