package TodoListApp;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

// 待办事项管理类
class TodoListManager {
    private final List<TodoItem> todoList;
    private int nextId;

    public TodoListManager() {
        todoList = new ArrayList<>();
        nextId = 1; // 起始编号
    }

    // 添加待办事项
    public void addTodo(String description) throws EmptyDescriptionException{ //同时声明可能抛出的异常类型
        if(description == null || description.trim().isEmpty()){
            EmptyDescriptionException e = new EmptyDescriptionException("待办事项的描述不能为空。");
            throw e;
        }
        try {
            string sql = "insert into todos (description) values('"+description+"')"
            system.out.println(sql);
            Statement stmt = conn.createStatement();
            stmt.executeUpdate(sql)
        }
        TodoItem item = new TodoItem(nextId++, description);
        todoList.add(item);
        System.out.println("待办事项已添加： " + item);
    }o

    // 列出所有待办事项
    public void listTodos() {
        if (todoList.isEmpty()) {
            System.out.println("当前没有待办事项。");
            return;
        }
        System.out.println("\n===== 待办事项列表 =====");
        for (TodoItem item : todoList) {
            System.out.println(item);
        }
    }

    // 删除指定编号的待办事项
    public void removeTodo(int id) throws TodoNotFoundException{
        boolean removed = false;
        for (TodoItem item : todoList) {
            if (item.getId() == id) {
                todoList.remove(item);
                System.out.println("已删除待办事项： " + item);
                removed = true;
                break;
            }
        }
        if (!removed) {
            throw new TodoNotFoundException("未找到编号为 " + id + " 的待办事项。");
            //System.out.println("未找到编号为 " + id + " 的待办事项。");
        }
    }

    public void markAsCompleted(int id) {
        TodoItem item = null;
        for (TodoItem todo : todoList) {
            if (todo.getId() == id) {
                item = todo;
                break;
            }

        }
        if (item != null) {
            if (!item.isCompleted()) {
                item.setCompleted(true);
                System.out.println("待办事项已标记为完成： " + item);
            } else {
                System.out.println("待办事项已完成，无需重复标记。");
            }
        }
        else {
            System.out.println("未找到编号为：" + id + " 的待办事项。");
        }
    }

    public void saveToFile(String filename){

        try {
            File file = new File(filename);
            FileOutputStream fos = new FileOutputStream(file);

            for (TodoItem item : todoList) {
                String line = item.getId() + ":" + item.getDescription() + "\n";
                fos.write(line.getBytes());
            }
            System.out.println("待办事项已经保存到文件：" + filename);

            fos.close();
        }
        catch (IOException e){
            System.out.println("待办事项保存失败：" + e.getMessage());
        }
    }

    private void backupToFile(String backupFilename) {
        LocalDateTime now = LocalDateTime.now();
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd_HH-mm-ss");
        String timestamp = now.format(formatter);
        String fullBackupFilename = backupFilename + "_" + timestamp + ".bak";

        try (FileOutputStream fos = new FileOutputStream(new File(fullBackupFilename))) {
            for (TodoItem item : todoList) {
                String line = item.getId() + ":" + item.getDescription() + ":" + (item.isCompleted() ? "完成" : "未完成") + "\n";
                fos.write(line.getBytes());
            }
            System.out.println("待办事项已备份到文件：" + fullBackupFilename);
        } catch (IOException e) {
            System.out.println("待办事项备份失败：" + e.getMessage());
        }
    }
}