package com.mathapp.services;

import com.mathapp.models.Question;
import com.mathapp.models.TestPaper;
import com.mathapp.models.User;

import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.time.format.DateTimeFormatter;
import java.util.List;
import java.util.stream.Stream;

public class DataPersistence {
  private static final Path USER_FILE_PATH = Paths.get("data", "users.txt");

  // 静态初始化块，确保目录存在
  static {
    try {
      Files.createDirectories(USER_FILE_PATH.getParent());
      if (!Files.exists(USER_FILE_PATH)) {
        Files.createFile(USER_FILE_PATH);
      }
    } catch (IOException e) {
      System.err.println("初始化用户数据文件失败: " + e.getMessage());
      e.printStackTrace();
    }
  }

  public static void saveUser(User user) {
    String userData = user.getEmail() + "::" + user.getHashedPassword() + System.lineSeparator();
    try {
      Files.writeString(USER_FILE_PATH, userData, StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.APPEND);
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

  public static User findUserByEmail(String email) {
    try (Stream<String> lines = Files.lines(USER_FILE_PATH, StandardCharsets.UTF_8)) {
      return lines.filter(line -> line.startsWith(email + "::"))
              .map(line -> {
                String[] parts = line.split("::");
                // 构造函数会处理密码哈希
                return new User(parts[0], parts[1], true);
              })
              .findFirst()
              .orElse(null);
    } catch (IOException e) {
      e.printStackTrace();
      return null;
    }
  }

  public static boolean updatePassword(String email, String newPassword) {
    try {
      List<String> lines = Files.readAllLines(USER_FILE_PATH, StandardCharsets.UTF_8);
      for (int i = 0; i < lines.size(); i++) {
        if (lines.get(i).startsWith(email + "::")) {
          User tempUser = new User(email, newPassword); // 用来生成新密码的哈希值
          lines.set(i, email + "::" + tempUser.getHashedPassword());
          Files.write(USER_FILE_PATH, lines, StandardCharsets.UTF_8);
          return true;
        }
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
    return false;
  }


  public static void saveTestPaper(TestPaper testPaper) {
    if (testPaper.username() == null) {
      System.err.println("无法保存试卷：用户名为空。");
      return;
    }

    String username = testPaper.username().split("@")[0]; // 使用邮箱前缀作为目录名

    try {
      Path userDir = Paths.get("data", username);
      Files.createDirectories(userDir);

      String timestamp = testPaper.timestamp().format(DateTimeFormatter.ofPattern("yyyyMMdd_HHmmss"));
      Path filePath = userDir.resolve(timestamp + ".txt");

      try (BufferedWriter writer = Files.newBufferedWriter(filePath, StandardCharsets.UTF_8)) {
        writer.write("用户: " + testPaper.username());
        writer.newLine();
        writer.write("时间: " + timestamp);
        writer.newLine();
        writer.write(String.format("得分: %d / %d", testPaper.score(), testPaper.questions().size()));
        writer.newLine();
        writer.write("====================================");
        writer.newLine();

        for (int i = 0; i < testPaper.questions().size(); i++) {
          Question q = testPaper.questions().get(i);
          writer.write(String.format("题目 %d: %s", (i + 1), q.problemStatement()));
          writer.newLine();
          writer.write("选项: " + String.join(" | ", q.options()));
          writer.newLine();
          writer.write("你的答案: " + testPaper.userAnswers().get(i));
          writer.newLine();
          writer.write("正确答案: " + q.correctAnswer());
          writer.newLine();
          writer.write("--------------------");
          writer.newLine();
        }
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}