package com.mathlearning.service;

import com.mathlearning.model.User;
import java.io.*;
import java.util.ArrayList;
import java.util.List;

public class UserService {
  private static final String USER_DATA_FILE = "data/users.txt";
  private List<User> users;

  public UserService() {
    this.users = loadUsers();
  }

  public boolean registerUser(String email, String registrationCode) {
    // Check if email already exists
    for (User user : users) {
      if (user.getEmail().equals(email)) {
        return false;
      }
    }

    User newUser = new User(email, registrationCode);
    users.add(newUser);
    saveUsers();
    return true;
  }

  public boolean completeRegistration(String email, String password) {
    for (User user : users) {
      if (user.getEmail().equals(email) && !user.isRegistered()) {
        user.setPassword(password);
        user.setRegistered(true);
        saveUsers();
        return true;
      }
    }
    return false;
  }

  public boolean login(String email, String password) {
    for (User user : users) {
      if (user.getEmail().equals(email)
          && user.isRegistered()
          && user.getPassword().equals(password)) {
        return true;
      }
    }
    return false;
  }

  public boolean changePassword(String email, String oldPassword, String newPassword) {
    for (User user : users) {
      if (user.getEmail().equals(email) && user.getPassword().equals(oldPassword)) {
        user.setPassword(newPassword);
        saveUsers();
        return true;
      }
    }
    return false;
  }

  public User getUserByEmail(String email) {
    for (User user : users) {
      if (user.getEmail().equals(email)) {
        return user;
      }
    }
    return null;
  }

  public boolean updateUser(User updatedUser) {
    for (int i = 0; i < users.size(); i++) {
      if (users.get(i).getEmail().equals(updatedUser.getEmail())) {
        users.set(i, updatedUser);
        saveUsers();
        return true;
      }
    }
    return false;
  }

  private List<User> loadUsers() {
    List<User> userList = new ArrayList<>();
    try {
      File file = new File(USER_DATA_FILE);
      if (!file.exists()) {
        return userList;
      }

      BufferedReader reader = new BufferedReader(new FileReader(file));
      String line;
      while ((line = reader.readLine()) != null) {
        String[] parts = line.split("\\|");
        if (parts.length >= 4) {
          User user = new User(parts[0], parts[1]);
          user.setPassword(parts[2]);
          user.setRegistered(Boolean.parseBoolean(parts[3]));
          userList.add(user);
        }
      }
      reader.close();
    } catch (IOException e) {
      System.out.println("加载用户数据失败: " + e.getMessage());
    }
    return userList;
  }

  private void saveUsers() {
    try {
      File file = new File(USER_DATA_FILE);
      file.getParentFile().mkdirs();

      BufferedWriter writer = new BufferedWriter(new FileWriter(file));
      for (User user : users) {
        String line =
            user.getEmail()
                + "|"
                + user.getRegistrationCode()
                + "|"
                + (user.getPassword() != null ? user.getPassword() : "")
                + "|"
                + user.isRegistered();
        writer.write(line);
        writer.newLine();
      }
      writer.close();
    } catch (IOException e) {
      System.out.println("保存用户数据失败: " + e.getMessage());
    }
  }
}