import java.util.*;
import java.util.concurrent.TimeUnit;

public class ArithmeticPractice {
private Set generatedQuestions = new HashSet<>();
private List questions = new ArrayList<>();
private List answers = new ArrayList<>();
private List results = new ArrayList<>();
private int totalQuestions = 30;
private int timeLimit = 5 * 60; // 5分鐘，單位：秒
private Scanner scanner = new Scanner(System.in);
private boolean isTimeOut = false;

public static void main(String[] args) {
    ArithmeticPractice practice = new ArithmeticPractice();
    practice.generateQuestions();
    practice.startPractice();
    practice.showResults();
}

// 生成30道不重復的題目
private void generateQuestions() {
    System.out.println("正在生成" + totalQuestions + "道題目...");

    while (questions.size() < totalQuestions) {
        int num1 = (int) (Math.random() * 100);
        int num2 = (int) (Math.random() * 100);
        int operator = (int) (Math.random() * 4); // 0:+,1:-,2:*,3:/
        String opSymbol = "";
        int result = 0;
        boolean valid = true;

        switch (operator) {
            case 0: // 加法
                opSymbol = "+";
                result = num1 + num2;
                break;
            case 1: // 減法，確保結果非負
                opSymbol = "-";
                if (num1 < num2) {
                    valid = false;
                } else {
                    result = num1 - num2;
                }
                break;
            case 2: // 乘法，確保結果不超過三位數
                opSymbol = "*";
                result = num1 * num2;
                if (result >= 1000) {
                    valid = false;
                }
                break;
            case 3: // 除法，確保能整除且除數不為0
                opSymbol = "/";
                if (num2 == 0 || num1 % num2 != 0) {
                    valid = false;
                } else {
                    result = num1 / num2;
                }
                break;
        }

        // 檢查題目是否有效且不重復
        String question = num1 + " " + opSymbol + " " + num2 + " = ?";
        if (valid && !generatedQuestions.contains(question)) {
            generatedQuestions.add(question);
            questions.add(question);
            answers.add(result);
        }
    }
    System.out.println("題目生成完畢，準備開始答題！");
}

// 開始答題
private void startPractice() {
    System.out.println("\n答題開始！您有" + timeLimit/60 + "分鐘時間完成" + totalQuestions + "道題。");
    System.out.println("請輸入答案，然后按回車確認。");

    long startTime = System.currentTimeMillis();
    Thread timerThread = new Thread(new TimerRunnable(startTime));
    timerThread.start();

    for (int i = 0; i < totalQuestions; i++) {
        // 檢查是否超時
        if (System.currentTimeMillis() - startTime > timeLimit * 1000L) {
            System.out.println("\n時間到！未完成的題目將視為錯誤。");
            isTimeOut = true;
            // 剩余題目標記為錯誤
            for (int j = i; j < totalQuestions; j++) {
                results.add(false);
            }
            break;
        }

        // 顯示當前題目并獲取答案
        System.out.print("\n第" + (i + 1) + "題: " + questions.get(i));
        try {
            if (scanner.hasNextInt()) {
                int userAnswer = scanner.nextInt();
                boolean isCorrect = (userAnswer == answers.get(i));
                results.add(isCorrect);

                // 即時判斷并顯示結果
                if (isCorrect) {
                    System.out.println("正確！");
                } else {
                    System.out.println("錯誤！正確答案是：" + answers.get(i));
                }
            } else {
                // 非數字輸入視為錯誤
                scanner.next(); // 清除無效輸入
                results.add(false);
                System.out.println("輸入無效！正確答案是：" + answers.get(i));
            }
        } catch (Exception e) {
            results.add(false);
            System.out.println("輸入錯誤！正確答案是：" + answers.get(i));
        }
    }

    // 中斷計時線程
    timerThread.interrupt();
}

// 顯示答題結果
private void showResults() {
    int correctCount = 0;
    double accuracy = (double) correctCount / totalQuestions * 100;
    System.out.println("\n總題數: " + totalQuestions);
    System.out.println("做對: " + correctCount + "題");
    System.out.println("做錯: " + (totalQuestions - correctCount) + "題");
    System.out.printf("正確率: %.2f%%\n", accuracy);
    System.out.println("------------------------------");
}

// 倒計時線程
private class TimerRunnable implements Runnable {
    private long startTime;

    public TimerRunnable(long startTime) {
        this.startTime = startTime;
    }

    @Override
    public void run() {
        try {
            while (true) {
                long elapsedTime = (System.currentTimeMillis() - startTime) / 1000;
                long remainingTime = timeLimit - elapsedTime;

                if (remainingTime <= 0) {
                    break;
                }

                // 每分鐘提示一次剩余時間
                if (remainingTime % 60 == 0) {
                    System.out.println("\n剩余時間: " + remainingTime / 60 + "分" + remainingTime % 60 + "秒");
                }

                // 最后10秒每秒提示
                if (remainingTime <= 10) {
                    System.out.println("\n剩余時間: " + remainingTime + "秒");
                }

                TimeUnit.SECONDS.sleep(1);
            }
        } catch (InterruptedException e) {
            // 線程被中斷，正常退出
        }
    }
}

}