@paprika/seducer/lib/esm/reducer.js

Seducer (simple reducer) is a wrapper on top of React.useReducer, making it easier to use

import logger from "./logger";
/**
 * Summary: Reducer controls all actions and reduce them to create the nextState
 *
 * Description. Curry function execute (actions, hasLogger, interceptors) and returns nextState
 *
 * (actions, hasLogger, interceptors) =>
 * @param {{[key]:(state: any, payload: any)=> any}} actions         An object with {key: value} format that define an action of an state
 * @param {boolean} hasLogger       Allowed to print a friendly log with the previous and next action
 * @param {{[key]:(state, payload)=> any}}   interceptors    An object with {key: value} which allows inversion of control by extending the actions object
 *
 * @return (state: any, action: {[key]: string, () => any}) => {...}
 *
 * @param any state  The current state of the useReducer state can be anything
 * @param {{key: {type:string, payload:any}}}  action  The action to be handle by the reducer and redirected to the their respective actions
 *
 * @return {any} nextState
 */

export var reducer = function reducer(actions, hasLogger) {
  var interceptors = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : {};
  return function (state, action) {
    var isAValidAction = "type" in action && ([action.type] in actions || interceptors && [action.type] in interceptors);

    if (isAValidAction) {
      var nextState = function nextState() {
        return actions[action.type](state, action.payload);
      };

      if (interceptors && [action.type] in interceptors) {
        return handleInterceptors({
          action: action,
          actions: actions,
          hasLogger: hasLogger,
          interceptors: interceptors,
          nextState: nextState,
          state: state
        });
      }

      return handleRegularRegularReducerFlow({
        action: action,
        hasLogger: hasLogger,
        nextState: nextState,
        state: state
      });
    }

    throw new Error("The type \"".concat(action.type, "\" lacks of an action implementation, did you forget to add it: \n").concat(action.type, "(state, payload) { \n  return state;\n} \n\nto your action object"));
  };
};
/**
 * Summary: Seducer permits to implement inversion of control without exposing the internal reducer and instead allowing the consumer to
 * extend its current action object, this has three benefits:
 *
 * First:   Abstract the concept of a reducer so the developer doesn't have to deal with
 *
 * Second:  Is quite simple to understand the concept of function and it's easy to explain to another developer that to override a function
 * has to declare another function with the same name, this is pretty common to do in OOP.
 *
 * Third:   In order to achieve inversion of control the library doesn't requires to export their internal reducer to the consumer
 * instead is transparent to them by simply overriding the already created actions.
 * In case duplication exists a third parameter will be sent to the action (state, payload, nextState) is
 * which is a function that the consumer can executed to generate the default nextState value that the component would generate
 * if wouldn't be intercepted.
 *
 *
 * @param {{ [key: string], () => any }} action
 * @param {{[key]:(state, payload)=> nextState}}   actions
 * @param {boolean}                                hasLogger
 * @param {{[key]:(state, payload)=> nextState}}   interceptors
 * @param {any}                                nextState    A function that when its call generate the nextState for a giving action.
 * @param {any}                                state
 */

function handleInterceptors(_ref) {
  var action = _ref.action,
      actions = _ref.actions,
      hasLogger = _ref.hasLogger,
      interceptors = _ref.interceptors,
      nextState = _ref.nextState,
      state = _ref.state;

  // if the interceptor action is overriding and original action
  if (action.type in actions) {
    var nextInterceptorState = interceptors[action.type](state, action.payload, nextState);
    return hasLogger ? logger(state, nextInterceptorState, action, true) : nextInterceptorState;
  } // if the action has been added as a new action


  var nextInterceptorStateWithoutOverride = interceptors[action.type](state, action.payload);
  return hasLogger ? logger(state, nextInterceptorStateWithoutOverride, action, true) : nextInterceptorStateWithoutOverride;
}
/**
 * Summary: A regular call to get the nextState for the reducer depending on the action that has been pass down by the consumer
 *
 *
 * @param {{ action: () => any, hasLogger: boolean, nextState: any, state: any}} options
 * @return {any} the next state value
 */


function handleRegularRegularReducerFlow(_ref2) {
  var action = _ref2.action,
      hasLogger = _ref2.hasLogger,
      nextState = _ref2.nextState,
      state = _ref2.state;
  return hasLogger ? logger(state, nextState(), action) : nextState();
}

export default reducer;
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