02. Inventory Managment

class InventoryManager {
    constructor(capacity) {
        this.capacity = capacity;
        this.items = [];
        this.outOfStock = [];
    }

    addItem(itemName, quantity) {
        if (quantity <= 0) {
            throw new Error("Quantity must be greater than zero.");
        }

        if (this.items.length >= this.capacity) {
            throw new Error("The inventory is already full.");
        }

        let index = this.items.findIndex(items => items.name === itemName);

        if (index === -1) {
            let item = {
                itemName,
                quantity,
            }
            this.items.push(item);
        } else {
            this.items[index].quantity += quantity;
        }

        return `Added ${quantity} ${itemName}(s) to the inventory.`;
    }

    sellItem(itemName, quantity) {
        if (quantity <= 0) {
            throw new Error("Quantity must be greater than zero.");
        }

        let index = this.items.findIndex(items => items.itemName === itemName);

        if (index === -1) {
            throw new Error(`The item ${itemName} is not available in the inventory.`)
        }

        let availableQuantity = this.items[index].quantity;

        if (quantity > availableQuantity) {
            throw new Error(`Not enough ${itemName}(s) in stock.`);
        }

        this.items[index].quantity -= quantity;

        if (this.items[index].quantity === 0) {
            this.outOfStock.push(this.items[index].itemName);
            this.items.splice(index, 1);
        }

        return `Sold ${quantity} ${itemName}(s) from the inventory.`;
    }

    restockItem(itemName, quantity) {
        if (quantity <= 0) {
            throw new Error("Quantity must be greater than zero.");
        }

        let index = this.items.findIndex(items => items.itemName === itemName);

        if (index !== -1) {
            this.items[index].quantity += quantity;
        } else {
            let itemToAdd = {
                itemName,
                quantity
            };
            this.items.push(itemToAdd);
            if (this.outOfStock.includes(itemName)) {
                let indexR = this.outOfStock.indexOf(itemName);
                this.outOfStock.splice(indexR, 1);
            }
        }

        return `Restocked ${quantity} ${itemName}(s) in the inventory.`
    }

    getInventorySummary() {
        let result = 'Current Inventory:';

        for (const item of this.items) {
            result += `\n${item.itemName}: ${item.quantity}`;
        }

        if (this.outOfStock.length !== 0) {
            result += `\nOut of Stock: ${this.outOfStock.join(',')}`;
        }

        return result;
    }
}