hw_javascript/09/index.js

function reducer(state, { type, good, count, money }) {
  if (!state) {
    let state = {
      пиво: {
        количество: 100,
        цена: 25,
      },
      чипсы: {
        количество: 100,
        цена: 35,
      },
      сиги: {
        количество: 100,
        цена: 60,
      },
    };
    let newState = {};
    for (let [key, value] of Object.entries(state)) {
      newState[key] = "";
      if (typeof value === "object") {
        newState[`${key}-количество`] = value["количество"];
        newState[`${key}-цена`] = value["цена"];
      }
    }
    return newState;
  }

  if (type === "КУПИТЬ") {
    if (money / count >= state[`${good}-цена`]) {
      if (state[`${good}-количество`] - count >= 0) {
        return {
          ...state,
          [`${good}-количество`]: state[`${good}-количество`] - count,
        };
      } else {
        alert(
          `Товар '${good}' закончилось! ${
            state[`${good}-количество`] !== 0
              ? "Выдано остаток: " + state[`${good}-количество`]
              : `На складе нет остатков товара '${good}'!`
          }`
        );
        return {
          ...state,
          [`${good}-количество`]: 0,
        };
      }
    } else {
      alert(
        `У вас не хватает денег! Для ${count} товара '${good}' необходимо ${
          state[`${good}-цена`] * count
        } гривнів`
      );
    }
  }

  return state;
}

function createStore(reducer) {
  let state = reducer(undefined, {});
  let cbs = [];

  const getState = () => state;
  const subscribe = (cb) => (
    cbs.push(cb), () => (cbs = cbs.filter((c) => c !== cb))
  );

  const dispatch = (action) => {
    const newState = reducer(state, action);
    if (newState !== state) {
      state = newState;
      for (let cb of cbs) cb();
    }
  };

  return {
    getState,
    dispatch,
    subscribe,
  };
}

const store = createStore(reducer);

const unsubscribe = store.subscribe(() => console.log(store.getState()));

let buySmth = (good, count, money) => ({
  type: "КУПИТЬ",
  good,
  count,
  money,
});

for (let [key] of Object.entries(store.getState())) {
  if (!key.includes("-")) {
    let option = new Option(key);
    goods.append(option);
  }
}

let fields = Object.keys(store.getState());
for (let i = 0; i < fields.length; i++) {
  let h = document.createElement("h1");
  h.id = fields[i];
  h.className = "goods";
  h.innerText = `${fields[i]} : ${store.getState()[fields[i]]}`;
  shop.append(h);
}

quantity.oninput = () => {
  if (quantity.value === "" || +quantity.value < 1) {
    quantity.value = 1;
  }
};

money.oninput = () => {
  if (money.value === "" || +money.value < 1) {
    money.value = 1;
  }
};

buy.onclick = () => {
  let headers = document.querySelectorAll(".goods");
  for (let i = 0; i < headers.length; i++) {
    if (`${goods.value}-количество` === headers[i].id) {
      store.subscribe(
        () =>
          (headers[i].innerText = `${headers[i].id} : ${
            store.getState()[headers[i].id]
          }`)
      );
      store.dispatch(buySmth(goods.value, quantity.value, money.value));
      money.value = 1;
    }
  }
};
store.getState();