"use strict";

var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");

exports.__esModule = true;
exports.createSelectorHook = createSelectorHook;
exports.useSelector = void 0;

var _react = require("react");

var _useReduxContext2 = require("./useReduxContext");

var _Subscription = _interopRequireDefault(require("../utils/Subscription"));

var _useIsomorphicLayoutEffect = require("../utils/useIsomorphicLayoutEffect");

var _Context = require("../components/Context");

var refEquality = function refEquality(a, b) {
  return a === b;
};

function useSelectorWithStoreAndSubscription(selector, equalityFn, store, contextSub) {
  var _useReducer = (0, _react.useReducer)(function (s) {
    return s + 1;
  }, 0),
      forceRender = _useReducer[1];

  var subscription = (0, _react.useMemo)(function () {
    return new _Subscription["default"](store, contextSub);
  }, [store, contextSub]);
  var latestSubscriptionCallbackError = (0, _react.useRef)();
  var latestSelector = (0, _react.useRef)();
  var latestSelectedState = (0, _react.useRef)();
  var selectedState;

  try {
    if (selector !== latestSelector.current || latestSubscriptionCallbackError.current) {
      selectedState = selector(store.getState());
    } else {
      selectedState = latestSelectedState.current;
    }
  } catch (err) {
    if (latestSubscriptionCallbackError.current) {
      err.message += "\nThe error may be correlated with this previous error:\n" + latestSubscriptionCallbackError.current.stack + "\n\n";
    }

    throw err;
  }

  (0, _useIsomorphicLayoutEffect.useIsomorphicLayoutEffect)(function () {
    latestSelector.current = selector;
    latestSelectedState.current = selectedState;
    latestSubscriptionCallbackError.current = undefined;
  });
  (0, _useIsomorphicLayoutEffect.useIsomorphicLayoutEffect)(function () {
    function checkForUpdates() {
      try {
        var newSelectedState = latestSelector.current(store.getState());

        if (equalityFn(newSelectedState, latestSelectedState.current)) {
          return;
        }

        latestSelectedState.current = newSelectedState;
      } catch (err) {
        // we ignore all errors here, since when the component
        // is re-rendered, the selectors are called again, and
        // will throw again, if neither props nor store state
        // changed
        latestSubscriptionCallbackError.current = err;
      }

      forceRender({});
    }

    subscription.onStateChange = checkForUpdates;
    subscription.trySubscribe();
    checkForUpdates();
    return function () {
      return subscription.tryUnsubscribe();
    };
  }, [store, subscription]);
  return selectedState;
}
/**
 * Hook factory, which creates a `useSelector` hook bound to a given context.
 *
 * @param {React.Context} [context=ReactReduxContext] Context passed to your `<Provider>`.
 * @returns {Function} A `useSelector` hook bound to the specified context.
 */


function createSelectorHook(context) {
  if (context === void 0) {
    context = _Context.ReactReduxContext;
  }

  var useReduxContext = context === _Context.ReactReduxContext ? _useReduxContext2.useReduxContext : function () {
    return (0, _react.useContext)(context);
  };
  return function useSelector(selector, equalityFn) {
    if (equalityFn === void 0) {
      equalityFn = refEquality;
    }

    if (process.env.NODE_ENV !== 'production' && !selector) {
      throw new Error("You must pass a selector to useSelectors");
    }

    var _useReduxContext = useReduxContext(),
        store = _useReduxContext.store,
        contextSub = _useReduxContext.subscription;

    return useSelectorWithStoreAndSubscription(selector, equalityFn, store, contextSub);
  };
}
/**
 * A hook to access the redux store's state. This hook takes a selector function
 * as an argument. The selector is called with the store state.
 *
 * This hook takes an optional equality comparison function as the second parameter
 * that allows you to customize the way the selected state is compared to determine
 * whether the component needs to be re-rendered.
 *
 * @param {Function} selector the selector function
 * @param {Function=} equalityFn the function that will be used to determine equality
 *
 * @returns {any} the selected state
 *
 * @example
 *
 * import React from 'react'
 * import { useSelector } from 'react-redux'
 *
 * export const CounterComponent = () => {
 *   const counter = useSelector(state => state.counter)
 *   return <div>{counter}</div>
 * }
 */


var useSelector =
/*#__PURE__*/
createSelectorHook();
exports.useSelector = useSelector;