@gechiui/components/build-module/input-control/reducer/reducer.js

UI components for GeChiUI.

/**
 * External dependencies
 */
import { isEmpty } from 'lodash'; // eslint-disable-next-line no-restricted-imports

/**
 * GeChiUI dependencies
 */
import { useReducer } from '@gechiui/element';
/**
 * Internal dependencies
 */

import { initialInputControlState, initialStateReducer } from './state';
import * as actions from './actions';
/**
 * Prepares initialState for the reducer.
 *
 * @param  initialState The initial state.
 * @return Prepared initialState for the reducer
 */

function mergeInitialState() {
  let initialState = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : initialInputControlState;
  const {
    value
  } = initialState;
  return { ...initialInputControlState,
    ...initialState,
    initialValue: value
  };
}
/**
 * Composes multiple stateReducers into a single stateReducer, building
 * the pipeline to control the flow for state and actions.
 *
 * @param  fns State reducers.
 * @return The single composed stateReducer.
 */


export const composeStateReducers = function () {
  for (var _len = arguments.length, fns = new Array(_len), _key = 0; _key < _len; _key++) {
    fns[_key] = arguments[_key];
  }

  return function () {
    for (var _len2 = arguments.length, args = new Array(_len2), _key2 = 0; _key2 < _len2; _key2++) {
      args[_key2] = arguments[_key2];
    }

    return fns.reduceRight((state, fn) => {
      const fnState = fn(...args);
      return isEmpty(fnState) ? state : { ...state,
        ...fnState
      };
    }, {});
  };
};
/**
 * Creates a reducer that opens the channel for external state subscription
 * and modification.
 *
 * This technique uses the "stateReducer" design pattern:
 * https://kentcdodds.com/blog/the-state-reducer-pattern/
 *
 * @param  composedStateReducers A custom reducer that can subscribe and modify state.
 * @return The reducer.
 */

function inputControlStateReducer(composedStateReducers) {
  return (state, action) => {
    const nextState = { ...state
    };

    switch (action.type) {
      /**
       * Keyboard events
       */
      case actions.PRESS_UP:
        nextState.isDirty = false;
        break;

      case actions.PRESS_DOWN:
        nextState.isDirty = false;
        break;

      /**
       * Drag events
       */

      case actions.DRAG_START:
        nextState.isDragging = true;
        break;

      case actions.DRAG_END:
        nextState.isDragging = false;
        break;

      /**
       * Input events
       */

      case actions.CHANGE:
        nextState.error = null;
        nextState.value = action.payload.value;

        if (state.isPressEnterToChange) {
          nextState.isDirty = true;
        }

        break;

      case actions.COMMIT:
        nextState.value = action.payload.value;
        nextState.isDirty = false;
        break;

      case actions.RESET:
        nextState.error = null;
        nextState.isDirty = false;
        nextState.value = action.payload.value || state.initialValue;
        break;

      case actions.UPDATE:
        nextState.value = action.payload.value;
        nextState.isDirty = false;
        break;

      /**
       * Validation
       */

      case actions.INVALIDATE:
        nextState.error = action.payload.error;
        break;
    }

    if (action.payload.event) {
      nextState._event = action.payload.event;
    }
    /**
     * Send the nextState + action to the composedReducers via
     * this "bridge" mechanism. This allows external stateReducers
     * to hook into actions, and modify state if needed.
     */


    return composedStateReducers(nextState, action);
  };
}
/**
 * A custom hook that connects and external stateReducer with an internal
 * reducer. This hook manages the internal state of InputControl.
 * However, by connecting an external stateReducer function, other
 * components can react to actions as well as modify state before it is
 * applied.
 *
 * This technique uses the "stateReducer" design pattern:
 * https://kentcdodds.com/blog/the-state-reducer-pattern/
 *
 * @param  stateReducer An external state reducer.
 * @param  initialState The initial state for the reducer.
 * @return State, dispatch, and a collection of actions.
 */


export function useInputControlStateReducer() {
  let stateReducer = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : initialStateReducer;
  let initialState = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : initialInputControlState;
  const [state, dispatch] = useReducer(inputControlStateReducer(stateReducer), mergeInitialState(initialState));

  const createChangeEvent = type => (nextValue, event) => {
    /**
     * Persist allows for the (Synthetic) event to be used outside of
     * this function call.
     * https://reactjs.org/docs/events.html#event-pooling
     */
    if (event && event.persist) {
      event.persist();
    }

    dispatch({
      type,
      payload: {
        value: nextValue,
        event
      }
    });
  };

  const createKeyEvent = type => event => {
    /**
     * Persist allows for the (Synthetic) event to be used outside of
     * this function call.
     * https://reactjs.org/docs/events.html#event-pooling
     */
    if (event && event.persist) {
      event.persist();
    }

    dispatch({
      type,
      payload: {
        event
      }
    });
  };

  const createDragEvent = type => payload => {
    dispatch({
      type,
      payload
    });
  };
  /**
   * Actions for the reducer
   */


  const change = createChangeEvent(actions.CHANGE);

  const invalidate = (error, event) => dispatch({
    type: actions.INVALIDATE,
    payload: {
      error,
      event
    }
  });

  const reset = createChangeEvent(actions.RESET);
  const commit = createChangeEvent(actions.COMMIT);
  const update = createChangeEvent(actions.UPDATE);
  const dragStart = createDragEvent(actions.DRAG_START);
  const drag = createDragEvent(actions.DRAG);
  const dragEnd = createDragEvent(actions.DRAG_END);
  const pressUp = createKeyEvent(actions.PRESS_UP);
  const pressDown = createKeyEvent(actions.PRESS_DOWN);
  const pressEnter = createKeyEvent(actions.PRESS_ENTER);
  return {
    change,
    commit,
    dispatch,
    drag,
    dragEnd,
    dragStart,
    invalidate,
    pressDown,
    pressEnter,
    pressUp,
    reset,
    state,
    update
  };
}
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