class Dispatcher extends Rx.Subject{

  dispatch(value : any) : void {

    this.next(value);

  }

}

​

class Store extends Rx.BehaviorSubject{

  constructor(

    private dispatcher,

    private reducer,

    preMiddleware,

    postMiddleware,

    initialState = {}

  ){

    super(initialState);

    this.dispatcher 

       //The let operate accepts the source observable, returning a new observable

       //@ngrx/store composes middleware so you can supply more than 1 function,

       //for our simple example we will accept one pre and post middleware

       //Middleware signature: (obs) => obs

       .let(preMiddleware)

       .scan((state, action) => this.reducer(state, action), initialState)

       .let(postMiddleware) 

       .subscribe(state => super.next(state));

  }

​

  dispatch(value){

    this.dispatcher.dispatch(value);  

  }

​

  next(value){

    this.dispatcher.dispatch(value);

  }

}

​

const combineReducers = reducers => (state = {}, action) => {

  return Object.keys(reducers).reduce((nextState, key) => {

    nextState[key] = reducers[key](state[key], action);

    return nextState;

  }, {});

};

​

//Add a few basic reducers

const person = (state = {}, action) => {

  switch(action.type){

    case 'ADD_INFO':

      return Object.assign({}, state, action.payload)

    default:

      return state;

  }

}

​

const hoursWorked = (state = 0, action) => {

  switch(action.type){

    case 'ADD_HOUR':

      return state + 1;

    case 'SUBTRACT_HOUR':

      return state - 1;

    default:

      return state;

  }

}

​

//this is handled behind the scenes with @ngrx/store provideStore

const appReducer = combineReducers({person, hoursWorked});

const preMiddleware = obs => { return obs.do(val => console.log('ACTION: ', val))};

const postMiddleware = obs => { return obs.do(val => console.log('STATE: ', val))};

//create our store and dependencies

const dispatcher = new Dispatcher();

const store = new Store(dispatcher, appReducer, preMiddleware, postMiddleware, {hoursWorked: 10});

const subscriber = store.subscribe(val => console.log('VALUE FROM STORE:', val));

//dispatch a few actions

dispatcher.dispatch({

  type: 'ADD_INFO', 

  payload: {

    name: 'Brian', 

    message: 'Exploring Reduce!'

  }

});

dispatcher.dispatch({

  type: 'ADD_INFO', 

  payload: {

    goal: 'Learn @ngrx/store!'

  }

});

​