package com.example.mathsystemtogether;

import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.stage.Stage;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import java.util.*;
import java.util.regex.Pattern;
import java.io.*;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

/**
 * 注册控制器
 */
public class RegisterController {

    @FXML private TextField usernameField;
    @FXML private PasswordField passwordField;
    @FXML private PasswordField confirmPasswordField;
    @FXML private TextField emailField;
    @FXML private TextField verificationCodeField;
    @FXML private Button sendCodeButton;
    @FXML private Button registerButton;
    @FXML private Button backToLoginButton;
    @FXML private ComboBox<String> levelComboBox;
    @FXML private Label statusLabel;

    // 验证码相关
    private String generatedCode;
    private long codeGenerationTime;
    private static final int CODE_VALIDITY_MINUTES = 5;
    private static final String EMAIL_REGEX = "^[A-Za-z0-9+_.-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}$";
    private static final Pattern EMAIL_PATTERN = Pattern.compile(EMAIL_REGEX);
    
    // 密码强度验证正则表达式
    private static final String PASSWORD_REGEX = "^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d).+$";
    private static final Pattern PASSWORD_PATTERN = Pattern.compile(PASSWORD_REGEX);
    
    // 用户数据文件路径
    private static final String USER_DATA_FILE = "user_data.txt";
    
    // 邮件服务
    private EmailService emailService;

    @FXML
    public void initialize() {
        setupLevelComboBox();
        // 初始化时禁用注册按钮
        registerButton.setDisable(true);
        // 初始化邮件服务
        emailService = new EmailService();
        
        // 检查邮件服务配置
        if (!emailService.isAvailable()) {
            showStatus("⚠️ 邮件服务未配置，请检查mail.properties文件", true);
        }
    }

    private void setupLevelComboBox() {
        ObservableList<String> levels = FXCollections.observableArrayList("小学", "初中", "高中");
        levelComboBox.setItems(levels);
        levelComboBox.setValue("小学");
    }

    @FXML
    private void handleSendCode() {
        String email = emailField.getText().trim();
        
        if (email.isEmpty()) {
            showStatus("请输入邮箱地址", true);
            return;
        }
        
        if (!isValidEmail(email)) {
            showStatus("请输入有效的邮箱地址", true);
            return;
        }
        
        // 检查邮件服务是否可用
        if (!emailService.isAvailable()) {
            showStatus("❌ 邮件服务不可用，请检查配置", true);
            return;
        }
        
        // 生成6位数字验证码
        generatedCode = emailService.generateVerificationCode();
        codeGenerationTime = System.currentTimeMillis();
        
        // 发送真实邮件
        showStatus("📤 正在发送验证码到邮箱：" + email + "，请稍候...", false);
        
        // 在后台线程中发送邮件
        new Thread(() -> {
            boolean success = emailService.sendVerificationCode(email, generatedCode);
            
            javafx.application.Platform.runLater(() -> {
                if (success) {
                    showStatus("✅ 验证码已发送到邮箱：" + email + "，请查收邮件", false);
                    // 启用注册按钮
                    registerButton.setDisable(false);
                } else {
                    showStatus("❌ 邮件发送失败，请检查邮箱地址或稍后重试", true);
                    // 显示验证码用于调试（仅开发环境）
                    showStatus("❌ 邮件发送失败，请检查邮箱地址或稍后重试。验证码：" + generatedCode + "（调试用）", true);
                }
            });
        }).start();
        
        // 禁用发送按钮60秒
        sendCodeButton.setDisable(true);
        sendCodeButton.setText("60秒后可重发");
        
        // 启动倒计时
        startCountdown();
    }

    @FXML
    private void handleRegister() {
        String username = usernameField.getText().trim();
        String password = passwordField.getText();
        String confirmPassword = confirmPasswordField.getText();
        String email = emailField.getText().trim();
        String verificationCode = verificationCodeField.getText().trim();
        String level = levelComboBox.getValue();

        // 验证输入
        if (username.isEmpty() || password.isEmpty() || confirmPassword.isEmpty() || 
            email.isEmpty() || verificationCode.isEmpty()) {
            showStatus("请填写所有字段", true);
            return;
        }

        if (username.length() < 3) {
            showStatus("用户名至少需要3个字符", true);
            return;
        }

        if (password.length() < 6) {
            showStatus("密码至少需要6个字符", true);
            return;
        }
        
        if (!isValidPassword(password)) {
            showStatus("密码必须包含大小写字母和数字", true);
            return;
        }

        if (!password.equals(confirmPassword)) {
            showStatus("两次输入的密码不一致", true);
            return;
        }

        if (!isValidEmail(email)) {
            showStatus("请输入有效的邮箱地址", true);
            return;
        }

        // 验证验证码
        if (!verifyCode(verificationCode)) {
            showStatus("验证码错误或已过期", true);
            return;
        }

        // 检查用户名是否已存在
        if (isUserExists(username)) {
            showStatus("用户名已存在，请选择其他用户名", true);
            return;
        }

        // 检查邮箱是否已注册
        if (isEmailExists(email)) {
            showStatus("该邮箱已被注册", true);
            return;
        }

        // 保存用户信息
        if (saveUserData(username, password, email, level)) {
            showStatus("注册成功！正在跳转到登录界面...", false);
            
            // 延迟跳转到登录界面
            Timer timer = new Timer();
            timer.schedule(new TimerTask() {
                @Override
                public void run() {
                    javafx.application.Platform.runLater(() -> {
                        handleBackToLogin();
                    });
                }
            }, 2000);
        } else {
            showStatus("注册失败，请重试", true);
        }
    }

    @FXML
    private void handleBackToLogin() {
        try {
            // 关闭当前窗口
            Stage currentStage = (Stage) backToLoginButton.getScene().getWindow();
            currentStage.close();
            
            // 打开登录界面
            FXMLLoader loader = new FXMLLoader(getClass().getResource("exam-view.fxml"));
            Scene scene = new Scene(loader.load(), 900, 900);
            Stage loginStage = new Stage();
            loginStage.setTitle("数学考试系统 - 登录");
            loginStage.setScene(scene);
            loginStage.setResizable(true);
            loginStage.show();
            
        } catch (Exception e) {
            showStatus("跳转失败：" + e.getMessage(), true);
        }
    }


    private boolean verifyCode(String inputCode) {
        if (generatedCode == null) {
            return false;
        }
        
        // 检查验证码是否过期
        long currentTime = System.currentTimeMillis();
        long elapsedMinutes = (currentTime - codeGenerationTime) / (1000 * 60);
        
        if (elapsedMinutes > CODE_VALIDITY_MINUTES) {
            return false;
        }
        
        return generatedCode.equals(inputCode);
    }

    private boolean isValidEmail(String email) {
        return EMAIL_PATTERN.matcher(email).matches();
    }
    
    /**
     * 验证密码强度
     * 密码必须包含至少一个小写字母、一个大写字母和一个数字
     */
    private boolean isValidPassword(String password) {
        return PASSWORD_PATTERN.matcher(password).matches();
    }

    private boolean isUserExists(String username) {
        try {
            if (!Files.exists(Paths.get(USER_DATA_FILE))) {
                return false;
            }
            
            List<String> lines = Files.readAllLines(Paths.get(USER_DATA_FILE));
            for (String line : lines) {
                if (line.startsWith(username + "|")) {
                    return true;
                }
            }
        } catch (IOException e) {
            System.err.println("检查用户存在性时出错：" + e.getMessage());
        }
        return false;
    }

    private boolean isEmailExists(String email) {
        try {
            if (!Files.exists(Paths.get(USER_DATA_FILE))) {
                return false;
            }
            
            List<String> lines = Files.readAllLines(Paths.get(USER_DATA_FILE));
            for (String line : lines) {
                String[] parts = line.split("\\|");
                if (parts.length >= 3 && parts[2].equals(email)) {
                    return true;
                }
            }
        } catch (IOException e) {
            System.err.println("检查邮箱存在性时出错：" + e.getMessage());
        }
        return false;
    }

    private boolean saveUserData(String username, String password, String email, String level) {
        try {
            String userData = username + "|" + password + "|" + email + "|" + level + "|" + System.currentTimeMillis() + "\n";
            Files.write(Paths.get(USER_DATA_FILE), userData.getBytes(), StandardOpenOption.CREATE, StandardOpenOption.APPEND);
            return true;
        } catch (IOException e) {
            System.err.println("保存用户数据时出错：" + e.getMessage());
            return false;
        }
    }

    private void showStatus(String message, boolean isError) {
        statusLabel.setText(message);
        if (isError) {
            statusLabel.setStyle("-fx-text-fill: #DC143C; -fx-font-weight: bold; -fx-font-size: 14;");
        } else {
            statusLabel.setStyle("-fx-text-fill: #228B22; -fx-font-weight: bold; -fx-font-size: 14;");
        }
    }

    private void startCountdown() {
        Timer timer = new Timer();
        timer.schedule(new TimerTask() {
            int countdown = 60;
            
            @Override
            public void run() {
                javafx.application.Platform.runLater(() -> {
                    if (countdown > 0) {
                        sendCodeButton.setText(countdown + "秒后可重发");
                        countdown--;
                    } else {
                        sendCodeButton.setDisable(false);
                        sendCodeButton.setText("📤 发送验证码");
                        timer.cancel();
                    }
                });
            }
        }, 0, 1000);
    }
}