cartReducer.js

import { createStore, applyMiddleware } from 'redux';
import thunk from 'redux-thunk';
import { composeWithDevTools } from 'redux-devtools-extension';
import { 
    ADD_TO_CART,
    REMOVE_ITEM
} from '../actions/action-types/cart-actions'

const initState = {
    products: [
        {
            id: 1,
            title: "Long Sleeve Leopard T-Shirt",
            price: 250,
            image: require("../../images/products/img1.jpg")
        },
        {
            id: 2,
            title: "Gildan Men's Crew T-Shirt",
            price: 150,
            image: require("../../images/products/img4.jpg")
        }],
    addedItems:[],
    total: 0,
    shipping: 0
}

const cartReducer= (state = initState, action) => {
   
    if(action.type === ADD_TO_CART){
        let addedItem = state.products.find(item => item.id === action.id)
        //check if the action id exists in the addedItems
        let existed_item= state.addedItems.find(item=> action.id === item.id)
        if(existed_item)
        {
            addedItem.quantity += 1 
            return {
                ...state,
                total: state.total + addedItem.newPrice 
            }
        } else {
            addedItem.quantity = 1;
            //calculating the total
            let newTotal = state.total + addedItem.newPrice 
            
            return {
                ...state,
                addedItems: [...state.addedItems, addedItem],
                total : newTotal
            }
            
        }
    }
    
    if(action.type === REMOVE_ITEM){
        let itemToRemove= state.addedItems.find(item=> action.id === item.id)
        let new_items = state.addedItems.filter(item=> action.id !== item.id)
        
        //calculating the total
        let newTotal = state.total - (itemToRemove.newPrice * itemToRemove.quantity );

        return {
            ...state,
            addedItems: new_items,
            total: newTotal
        }
    }
    
    else {
        return state
    }
}

export const initStore = (initialState = initState) => {
    return createStore(
        cartReducer,
        initialState,
        composeWithDevTools(applyMiddleware(thunk))
    )
}