gnar-edge/es/redux/gnarReducers.js

A sharp set of utilities: base64, drain, handleChange, jwt, notifications

import { combineReducers } from 'redux';
import { handleActions } from 'redux-actions';

const isObject = obj => obj && typeof obj === 'object' && obj.constructor === Object;

const defaultMapReducer = (state, { payload }) => state.merge(payload);
const defaultObjectReducer = (state, { payload }) => ({ ...state, ...payload });

const simpleReducers = (obj, storeBranchName, defaultInitialState, defaultReducer) => {
  const { initialState, basicReducers, customReducers } = obj;
  const basicReducersBranch = `${storeBranchName}.basicReducers`;
  const customReducersBranch = `${storeBranchName}.customReducers`;
  const testDefaultInitialState = (defaultInitialState || (() => ({})))();
  if ('basicReducers' in obj && typeof basicReducers !== 'string' && !Array.isArray(basicReducers)) {
    const msg = `Expected array or string at ${basicReducersBranch}, received ${JSON.stringify(basicReducers)}`;
    throw new TypeError(msg);
  }
  if ('customReducers' in obj && !isObject(customReducers)) {
    throw new TypeError(`Expected object at ${customReducersBranch}, received ${JSON.stringify(customReducers)}`);
  }
  const effectiveBasicReducers =
    basicReducers && typeof basicReducers === 'string' ? [ basicReducers ] : basicReducers || [];
  const parsedReducers = {
    ...effectiveBasicReducers.reduce((memo, key, idx) => {
      if (typeof key !== 'string') {
        throw new TypeError(`Expected string at ${basicReducersBranch}.${idx}, received ${JSON.stringify(key)}`);
      }
      memo[key] = defaultReducer || (
        'asMutable' in testDefaultInitialState && 'merge' in testDefaultInitialState
          ? defaultMapReducer
          : defaultObjectReducer
      );
      return memo;
    }, {}),
    ...Object.keys(customReducers || {}).reduce((memo, key) => {
      const reducer = customReducers[key];
      if (typeof reducer !== 'function') {
        const fullBranch = `${customReducersBranch}.${key}`;
        throw new TypeError(`Expected function at ${fullBranch}, received ${JSON.stringify(reducer)}`);
      }
      memo[key] = reducer;
      return memo;
    }, {})
  };
  return handleActions(parsedReducers, initialState || (defaultInitialState || (() => ({})))());
};

const parseReducers = (obj, parentStoreBranchName, defaultInitialState, defaultReducer) => combineReducers(
  Object.keys(obj).reduce((memo, key) => {
    const storeBranchName = `${parentStoreBranchName}${parentStoreBranchName ? '.' : ''}${key}`;
    const val = obj[key];
    memo[key] = isObject(val)
      ? 'basicReducers' in val || 'customReducers' in val
        ? simpleReducers(val, storeBranchName, defaultInitialState, defaultReducer)
        : parseReducers(val, storeBranchName, defaultInitialState, defaultReducer)
      : typeof val === 'string' || Array.isArray(val)
        ? simpleReducers({ basicReducers: val }, storeBranchName, defaultInitialState, defaultReducer)
        : val;
    return memo;
  }, {})
);

export default (obj, defaultInitialState, defaultReducer) =>
  parseReducers(obj, '', defaultInitialState, defaultReducer);