import java.io.IOException;
import java.util.List;
import java.util.Scanner;

/**
 * 数学卷子自动生成程序主类
 */
public class MathPaperGenerator {
    private UserManager userManager;
    private MathProblemGenerator problemGenerator;
    private FileManager fileManager;
    private Scanner scanner;
    
    public MathPaperGenerator() {
        this.userManager = new UserManager();
        this.problemGenerator = new MathProblemGenerator();
        this.fileManager = new FileManager();
        this.scanner = new Scanner(System.in);
    }
    
    /**
     * 程序主入口
     */
    public static void main(String[] args) {
        MathPaperGenerator generator = new MathPaperGenerator();
        generator.run();
    }
    
    /**
     * 运行主程序
     */
    public void run() {
        System.out.println("欢迎使用中小学数学卷子自动生成程序！");
        System.out.println("=" + "=".repeat(40));
        
        while (true) {
            User currentUser = login();
            if (currentUser != null) {
                handleUserSession(currentUser);
            }
        }
    }
    
    /*用户登录*/
    private User login() {
        while (true) {
            System.out.print("请输入用户名和密码（用空格隔开）: ");
            String input = scanner.nextLine().trim();
            
            if (input.isEmpty()) {
                System.out.println("输入不能为空，请重新输入。");
                continue;
            }
            
            String[] parts = input.split("\\s+");
            String username = parts[0];
            String password = parts[1];
            
            User user = userManager.authenticate(username, password);
            if (user != null) {
                System.out.println("登录成功！当前选择为 " + user.getUserType() + " 出题");
                return user;
            } else {
                System.out.println("请输入正确的用户名、密码");
            }
        }
    }
    
    /**
     * 处理用户会话
     * @param user 当前登录用户
     */
    private void handleUserSession(User user) {
        String currentDifficulty = user.getUserType();
        
        while (true) {
            System.out.println("准备生成 " + currentDifficulty + " 数学题目，请输入生成题目数量（输入-1将退出当前用户，重新登录）：");
            String input = scanner.nextLine().trim();
            
            // 检查是否要切换类型
            if (input.startsWith("切换为")) {
                String newType = input.substring(3).trim();
                if (userManager.isValidUserType(newType)) {
                    currentDifficulty = newType;
                    System.out.println("已切换为 " + newType + " 出题模式");
                    continue;
                } else {
                    System.out.println("请输入小学、初中和高中三个选项中的一个");
                    continue;
                }
            }
            
            try {
                int count = Integer.parseInt(input);
                
                if (count == -1) {
                    System.out.println("退出当前用户，重新登录...");
                    System.out.println();
                    return;
                }
                
                if (count < 10 || count > 30) {
                    System.out.println("题目数量必须在10-30之间，请重新输入。");
                    continue;
                }
                
                // 生成题目
                generateAndSavePaper(user, currentDifficulty, count);
                
            } catch (NumberFormatException e) {
                System.out.println("请输入有效的数字。");
            }
        }
    }
    
    /**
     * 生成并保存题目
     * @param user 用户
     * @param difficulty 难度
     * @param count 题目数量
     */
    private void generateAndSavePaper(User user, String difficulty, int count) {
        try {
            System.out.println("正在生成 " + count + " 道 " + difficulty + " 数学题目...");
            
            // 生成不重复的题目
            List<MathProblem> problems = fileManager.generateUniqueProblems(
                user, problemGenerator, count, difficulty);
            
            if (problems.size() < count) {
                System.out.println("注意：由于重复限制，实际生成了 " + problems.size() + " 道题目。");
            }
            
            // 保存到文件
            String filePath = fileManager.savePaperToFile(user, problems, difficulty);
            
            System.out.println("题目生成完成！");
            System.out.println("文件已保存至: " + filePath);
            System.out.println("题目预览:");
            System.out.println("-" + "-".repeat(30));
            
            // 显示前5道题目作为预览
            int previewCount = Math.min(5, problems.size());
            for (int i = 0; i < previewCount; i++) {
                System.out.println((i + 1) + ". " + problems.get(i).toString());
            }
            
            if (problems.size() > 5) {
                System.out.println("... 还有 " + (problems.size() - 5) + " 道题目");
            }
            
            System.out.println("-" + "-".repeat(30));
            System.out.println();
            
        } catch (IOException e) {
            System.err.println("保存文件时出错: " + e.getMessage());
        } catch (Exception e) {
            System.err.println("生成题目时出错: " + e.getMessage());
        }
    }
}