let createStore = (reducer, initialState = {}, middlewares = []) => {
    let state = initialState;
    let subscribers = [];

    let store = {
        dispatch: (action) => {
            next(store, middlewares, action);
        },
        getState: () => {
            return state;
        },
        subscribe: (subscriber) => {
            subscribers.push(subscriber);
        }
    };

    let next = (store, middlewares, action) => {
        let [ middleware, ...rest ] = middlewares;

        if (middleware) {
            middleware(store, (action) => next(store, rest, action), action);
        } else {
            let prevState = state;

            state = reducer(state, action);

            subscribers.forEach((subscriber) => subscriber(state, prevState));
        }
    };

    return store;
};

let logger = (store, next, action) => {
    console.log(action);

    next(action);
};

let store = createStore(
    (state, action) => {
        switch (action.type) {
            case 'ADD_ITEM': {
                return {
                    ...state,
                    items: [ ...state.items, action.payload ]
                };
            }
            default: {
                return state;
            }
        }
    },
    {items: []},
    [logger]
);

store.subscribe(({items}) => console.log(items));

setTimeout(() => {
    store.dispatch({
        type: 'ADD_ITEM',
        payload: {
            id: 1,
            value: 'Item 1'
        }
    });
}, 3000);