Shopping List

CommandManager.java

package pt.isec.pa.shopping_list.model.command;

import java.util.ArrayDeque;
import java.util.Deque;

public class CommandManager {
    private Deque<ICommand> history;
    private Deque<ICommand> redoCmds;
    //private Stack<ICommand> history;
    //private Stack<ICommand> redoCmds;

    public CommandManager() {
        history = new ArrayDeque<>();
        redoCmds = new ArrayDeque<>();
        //history = new Stack<>();
        //redoCmds = new Stack<>();
    }

    public boolean invokeCommand(ICommand cmd) {
        redoCmds.clear();
        if (cmd.execute()) {
            history.push(cmd);
            return true;
        }
        history.clear();
        return false;
    }

    public boolean undo() {
        if (history.isEmpty())
            return false;
        ICommand cmd = history.pop();
        cmd.undo();
        redoCmds.push(cmd);
        return true;
    }

    public boolean redo() {
        if (redoCmds.isEmpty())
            return false;
        ICommand cmd = redoCmds.pop();
        cmd.execute();
        history.push(cmd);
        return true;
    }

    public boolean hasUndo() {
        return history.size()>0;
    }

    public boolean hasRedo() {
        return redoCmds.size()>0;
    }
}

ICommand.java

package pt.isec.pa.shopping_list.model.command;

public interface ICommand {
    boolean execute();
    boolean undo();
}

Main.java

package pt.isec.pa.shopping_list;

import pt.isec.pa.shopping_list.model.ShoppingListManager;
import pt.isec.pa.shopping_list.ui.ShoppingListUI;

public class Main {
    public static void main(String[] args) {
        ShoppingListManager sm = new ShoppingListManager();
        ShoppingListUI ui = new ShoppingListUI(sm);
        ui.start();
    }
}

PAInput.java

package pt.isec.pa.shopping_list.ui.utils;

import java.util.Scanner;

public final class PAInput {
    private PAInput() {}

    private static Scanner sc;

    static {
        resetScanner();
    }

    public static void resetScanner() {
        sc = new Scanner(System.in);
    }

    public static String readString(String title,boolean onlyOneWord) {
        String value;
        do {
            if (title != null)
                System.out.print(title);
            else
                System.out.print("> ");
            value = sc.nextLine().trim();            
        } while (value.isBlank());
        if (onlyOneWord) {
            Scanner auxsc = new Scanner(value);
            value = auxsc.next();
        }
        return value;
    }

    public static int readInt(String title) {
        while (true) {
            if (title != null)
                System.out.print(title);
            else
                System.out.print("> ");
            if (sc.hasNextInt()) {
                int intValue = sc.nextInt();
                sc.nextLine();
                return intValue;
            } else
                sc.nextLine();            
        }
    }

    public static double readNumber(String title) {
        while (true) {
            if (title != null)
                System.out.print(title);
            else
                System.out.print("> ");
            if (sc.hasNextDouble()) {
                double doubleValue = sc.nextDouble();
                sc.nextLine();
                return doubleValue;
            } else
                sc.nextLine();            
        }
    }

    public static int chooseOption(String title, String ... options) {
        int option = -1;
        do {
            if (title != null)
                System.out.println(System.lineSeparator()+title);
            System.out.println();
            for(int i = 0; i < options.length; i++) {
                System.out.printf("%3d - %s\n",i+1,options[i]);
            }
            System.out.print("\nOption: ");
            if (sc.hasNextInt())
                option = sc.nextInt();
            sc.nextLine();    
        } while (option < 1 || option > options.length);
        return option;
    }

}

Product.java

package pt.isec.pa.shopping_list.model.data;

record Product(String name, double qt) {
    @Override
    public String toString() {
        return String.format("%-20s %8.2f",name,qt);
    }
}

ShoppingList.java

package pt.isec.pa.shopping_list.model.data;

import java.util.ArrayList;

public class ShoppingList {
    private ArrayList<Product> list;

    public ShoppingList() {
        list = new ArrayList<>();
    }

    public boolean addProduct(String name, double qt) {
        if (name!=null && !name.isBlank() && qt>0) {
            list.add(new Product(name, qt));
            return true;
        }
        return false;
    }

    public boolean removeProduct(String name, double qt) {
        return list.remove(new Product(name,qt));
    }

    public double getQuantity(String name) {
        for(Product p : list)
            if (p.name().equals(name))
                return p.qt();
        return -1;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder("Shopping List:\n");
        for(Product p : list) sb.append("\t- ").append(p).append("\n");
        return sb.toString();
    }
}

ShoppingListUI.java

package pt.isec.pa.shopping_list.ui;

import pt.isec.pa.shopping_list.model.ShoppingListManager;
import pt.isec.pa.shopping_list.ui.utils.PAInput;

public class ShoppingListUI {
    ShoppingListManager sm;

    public ShoppingListUI(ShoppingListManager sm) {
        this.sm = sm;
    }

    public void start() {
        boolean finish = false;
        do {
            System.out.println("\n\n"+sm+"\n");
            int op = PAInput.chooseOption("Shopping List",
                    "Add product","Remove product","Undo","Redo","Quit");
            switch (op) {
                case 1 -> sm.addProduct(
                        PAInput.readString("Product name: ",false),
                        PAInput.readNumber("Quantity: ")
                );
                case 2 -> sm.removeProduct(
                        PAInput.readString("Product name: ",false),
                        PAInput.readNumber("Quantity: ")
                );
                case 3 -> sm.undo();
                case 4 -> sm.redo();
                case 5 ->finish = true;
            }
        } while (!finish);
    }
}