swt23w23/src/main/java/catering/inventory/InventoryMutateForm.java

/*
 * Copyright (C) 2023 Simon Bruder
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package catering.inventory;

import static org.salespointframework.core.Currencies.EURO;

import org.javamoney.moneta.Money;
import org.salespointframework.catalog.Product;
import org.salespointframework.inventory.UniqueInventoryItem;
import org.salespointframework.quantity.Quantity;

import catering.catalog.Consumable;
import catering.catalog.Rentable;
import jakarta.validation.constraints.NotEmpty;
import jakarta.validation.constraints.NotNull;
import jakarta.validation.constraints.PositiveOrZero; // NonNegative in enterprise java

/**
 * Abstract class for handling inventory mutations.
 *
 * It has children for every product type.
 *
 * The current implementation requires {@link #forProductType(Class)} and {@link #of(Product, UniqueInventoryItem)}
 * to also be updated when a new child class is added.
 */
abstract class InventoryMutateForm {
	private @NotEmpty String name;
	private @NotNull Quantity quantity;
	private @NotNull @PositiveOrZero Double retailPrice;

	public InventoryMutateForm() {
	}

	public String getName() {
		return name;
	}

	public Quantity getQuantity() {
		return quantity;
	}

	public Double getRetailPrice() {
		return retailPrice;
	}

	public void setName(String name) {
		this.name = name;
	}

	public void setQuantity(Quantity quantity) {
		this.quantity = quantity;
	}

	public void setRetailPrice(Double retailPrice) {
		this.retailPrice = retailPrice;
	}

	/**
	 * Creates an empty {@link InventoryMutateForm} for {@link Product}s of the given {@link Class}.
	 *
	 * @param <T> a child class of {@link Product}
	 * @param type the concrete {@link Product} the form should mutate
	 * @return an object of an {@link InventoryMutateForm} subclass
	 * @throws IllegalArgumentException if the {@literal type} is not supported
	 */
	public static <T extends Product> InventoryMutateForm forProductType(Class<T> type) {
		// Java can’t switch over Class in JDK17 (without preview features)
		// See https://openjdk.org/jeps/406 for improvement in higher versions.
		if (type.equals(Consumable.class)) {
			return new ConsumableMutateForm();
		} else if (type.equals(Rentable.class)) {
			return new RentableMutateForm();
		} else {
			throw new IllegalArgumentException(
					"InventoryMutateForm::forProductType not supported for given types");
		}
	}

	/**
	 * Creates a populated {@link InventoryMutateForm} from a given {@link Product} and {@link UniqueInventoryItem}.
	 *
	 * @param product an instance of a {@link Product} subclass
	 * @param item an {@link UniqueInventoryItem} holding a {@link Quantity}
	 * @return an object of an {@link InventoryMutateForm} subclass
	 */
	public static InventoryMutateForm of(Product product, UniqueInventoryItem item) {
		if (product instanceof Consumable consumable) {
			return ConsumableMutateForm.of(consumable, item);
		} else if (product instanceof Rentable rentable) {
			return RentableMutateForm.of(rentable, item);
		} else {
			throw new IllegalArgumentException("InventoryMutateForm::ofProductAndItem not supported for given types");
		}
	}

	/**
	 * Creates a new {@link Product} from a populated {@link InventoryMutateForm}.
	 *
	 * @return an instance of a {@link Product} subclass
	 */
	public abstract Product toProduct();

	/**
	 * Modifies a given {@link Product} to match the values from the {@link InventoryMutateForm}.
	 *
	 * As the {@link Quantity} is stored inside of the {@link UniqueInventoryItem},
	 * it has to be updated manually.
	 *
	 * @param product the {@link Product} to be updated
	 */
	public void modifyProduct(Product product) {
		product.setName(getName());
		product.setPrice(Money.of(getRetailPrice(), EURO));
		modifyProductPrimitive(product);
	}

	protected abstract void modifyProductPrimitive(Product product);
}