using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Xml;
using TMPro;
using Unity.VisualScripting;
using UnityEngine;
using UnityEngine.UI;
using static System.Collections.Specialized.BitVector32;

public class QuizSystem : MonoBehaviour
{
    public static QuizSystem Instance;

    public string FileName;
    // UI元素
    public TextMeshProUGUI questionText; // 显示问题文本
    public ToggleGroup optionsGroup; // 选项组，用于单选题
    public List<Toggle> optionToggles; // 选项切换按钮列表
    public TextMeshProUGUI progressText; // 显示答题进度
    public Button submitButton; // 提交按钮
    //上一题下一题页面
    public GameObject CtrlPage;
    public Button nextButton; // 下一题按钮
    //public Button previousButton; // 上一题按钮
    public TextMeshProUGUI hintText; // 显示提示文本
    //结果页面
    public GameObject ResultPage;//结果页面
    public TextMeshProUGUI resultText; // 显示结果文本
    public Button MoreOnceBtn;//再来一次

    //public Button hintButton; // 提示按钮
    //public Slider timeSlider; // 时间滑动条
    //public TextMeshProUGUI timerText; // 倒计时文本

    // 问题列表和当前状态
    private List<Question> questions = new List<Question>(); // 问题列表
    private int currentQuestionIndex = 0; // 当前问题索引
    private List<HashSet<int>> userAnswers = new List<HashSet<int>>(); // 用户答案列表
    //private bool isSubmitted = false; // 是否已提交

    // 总体倒计时
    //private float totalTime = 1800f; // 总时间（秒）
    //private float remainingTime; // 剩余时间

    private void Awake()
    {
        Instance = this;
    }

    void Start()
    {
        // 加载问题
        LoadQuestions();

        ToStartQuestion();

        // 初始化倒计时
        //remainingTime = totalTime;
        //UpdateTimerUI();
    }

    public void ToStartQuestion()
    {
        //结果和控制页面消失
        ResultPage.SetActive(false);
        CtrlPage.SetActive(false);

        userAnswers.Clear();

        // 初始化用户答案列表
        for (int i = 0; i < questions.Count; i++)
        {
            userAnswers.Add(new HashSet<int>());
        }

        currentQuestionIndex = 0;
        // 显示第一个问题
        DisplayQuestion();
    }

    void Update()
    {
        //// 更新倒计时
        //if (remainingTime > 0)
        //{
        //    remainingTime -= Time.deltaTime;
        //    UpdateTimerUI();
        //}
        //else if (!isSubmitted)
        //{
        //    // 时间到，自动提交
        //    OnSubmitButtonClicked();
        //}
    }

    void LoadQuestions()
    {
        questions = XmlTextReaderTest();
    }

    void DisplayQuestion()
    {
        // 检查是否超出问题列表
        if (currentQuestionIndex >= questions.Count)
        {
            return;
        }

        // 获取当前问题
        Question question = questions[currentQuestionIndex];
        questionText.text = question.Text;
        progressText.text = $"答题进度: {GetAnsweredCount()+1} / {questions.Count}";

        // 显示选项
        for (int i = 0; i < optionToggles.Count; i++)
        {
            if (i < question.Options.Length && (!question.IsJudgment || i < 2))
            {
                optionToggles[i].gameObject.SetActive(true);
                var label = optionToggles[i].GetComponentInChildren<Text>();
                if (label != null)
                {
                    string sign = "A:";
                    switch (i)
                    {
                        case 0: sign = "A:"; break;
                        case 1: sign = "B:"; break;
                        case 2: sign = "C:"; break;
                        case 3: sign = "D:"; break;
                    }
                    label.text = sign+question.Options[i];
                }
                optionToggles[i].isOn = userAnswers[currentQuestionIndex].Contains(i + 1);

                // 判断题或单选题使用 ToggleGroup
                optionToggles[i].group = (question.IsSingleChoice || question.IsJudgment) ? optionsGroup : null;
            }
            else
            {
                optionToggles[i].gameObject.SetActive(false);
            }
        }
    }

    //选择结束后确认该题结果
    public void OnSubmitButtonClicked()
    {
        // 提交答案
        SaveUserAnswers();
        //检查结果并显示
        CheckCurrentAnswer();
    }

    //保存用户答案
    void SaveUserAnswers()
    {
        // 保存用户选择的答案
        userAnswers[currentQuestionIndex].Clear();
        int index = 0;
        foreach (Toggle toggle in optionToggles)
        {
            if (toggle.isOn)
            {
                userAnswers[currentQuestionIndex].Add(index);
            }
            index++;
        }
    }

    //检查是否正确
    void CheckCurrentAnswer()
    {
        // 检查用户答案是否为正确答案的子集
        if (questions[currentQuestionIndex].CorrectAnswers.IsSubsetOf(userAnswers[currentQuestionIndex]))
        {
            OnHintViewShow("正确");
        }
        else
        {
            OnHintViewShow("错误");
        }
    }

    //显示正确还是错误
    public void OnHintViewShow(string result)
    {
        // 显示正确答案提示
        Question question = questions[currentQuestionIndex];
        string correctAnswerLetters = ConvertNumbersToLetters(question.CorrectAnswers);

        hintText.text = $"回答{result}，答案为: {correctAnswerLetters}";

        CtrlPage.SetActive(true);
    }

    //下一题
    public void OnNextButtonClicked()
    {
        // 切换到下一题
        if (currentQuestionIndex < questions.Count - 1)
        {
            //SaveUserAnswers();
            currentQuestionIndex++;
            DisplayQuestion();
            //hintText.gameObject.SetActive(false);
        }
        //计算结果并进入结果页面
        else
        {
            CheckAllAnswers();
        }

        //控制页面消失
        CtrlPage.SetActive(false);
    }

    //检查所有答案结果并显示结果页面
    void CheckAllAnswers()
    {
        // 检查所有答案并计算正确率
        int correctCount = 0;
        for (int i = 0; i < questions.Count; i++)
        {
            // 检查用户答案是否为正确答案的子集
            if (questions[i].CorrectAnswers.IsSubsetOf(userAnswers[i]))
            {
                correctCount++;
            }
        }
        resultText.text = $"正确率: {(float)correctCount / questions.Count * 100:F2}%";
        ResultPage.SetActive(true);
    }

    //再来一遍
    public void OnMoreDoOnce()
    {
        ToStartQuestion();
    }

    //上一题
    public void OnPreviousButtonClicked()
    {
        // 切换到上一题
        if (currentQuestionIndex > 0)
        {
            SaveUserAnswers();
            currentQuestionIndex--;
            DisplayQuestion();
            //isSubmitted = false; // 重置提交状态
            hintText.gameObject.SetActive(false);
        }
    }

    void UpdateTimerUI()
    {
        //// 更新滑动条和倒计时文本
        //if (!isSubmitted) // 仅在未提交时更新
        //{
        //    timeSlider.value = remainingTime / totalTime;
        //    timerText.text = $"剩余时间: {Mathf.Ceil(remainingTime)}秒";
        //}
    }

    //void LockSliderPosition()
    //{
    //    // 禁用滑块交互
    //    timeSlider.interactable = false;
    //}

    //void StopTimer()
    //{
    //    // 停止倒计时并更新文本
    //    timerText.text = $"本次用时：{totalTime - remainingTime:F0}s";
    //    timeSlider.value = 0; // 停止滑动条
    //}


    int GetAnsweredCount()
    {
        // 获取已回答的问题数量
        int count = 0;
        foreach (var answer in userAnswers)
        {
            if (answer.Count > 0)
            {
                count++;
            }
        }
        return count;
    }

    string ConvertNumbersToLetters(HashSet<int> numbers)
    {
        // 将数字转换为字母
        StringBuilder letters = new StringBuilder();
        foreach (int number in numbers)
        {
            if (number >= 0 && number <= 3)
            {
                char letter = (char)('A' + number);
                letters.Append(letter);
            }
        }
        return letters.ToString();
    }

    private List<Question> XmlTextReaderTest()
    {
        List<Question> questions = new List<Question>();

        // 构建文件路径
        string filePath = Path.Combine(Application.streamingAssetsPath, FileName+".xml");

        if (!File.Exists(filePath))
        {
            Debug.LogError("Questions file not found at: " + filePath);
            return questions;
        }

        string textmsg = File.ReadAllText(filePath);

        XmlDocument xmlDocument = new XmlDocument();
        try
        {
            xmlDocument.LoadXml(textmsg);
        }
        catch (XmlException e) {
            Debug.LogError($"XML格式错误：{e.Message}");
            return questions;
        }

        XmlNode rootNode = xmlDocument.SelectSingleNode("root");
        if (rootNode == null)
        {
            Debug.LogError("XML中未找到<root>节点");
            return questions;
        }

        //遍历所有<question>子节点
        XmlNodeList questionNodes = rootNode.SelectNodes("question");
        if (questionNodes == null || questionNodes.Count == 0)
        {
            Debug.LogWarning("未找到任何<question>节点");
            return questions;
        }

        // 提取每个question的属性值
        foreach (XmlNode node in questionNodes)
        {
            Question question = new Question();

            // 读取id属性（转换为int）
            if (!TryGetIntAttribute(node, "id", out int id))
            {
                Debug.LogWarning("跳过无效的question节点（缺少id或格式错误）");
                continue;
            }

            // 读取quesTitle属性（字符串）
            if (!TryGetStringAttribute(node, "quesTitle", out string title))
            {
                Debug.LogWarning($"id为{id}的节点缺少quesTitle属性");
                continue;
            }

            string[] allMsg = title.Split('|');
            question.Text = allMsg[0];
            if (allMsg.Length > 1) {
                question.Options=new string[allMsg.Length-1];
                for (int i = 1;i<allMsg.Length;i++)
                {
                    question.Options[i-1]=allMsg[i];
                }
            }
            else
            {
                question.Options=null;
            }

            // 读取answer属性（转换为string）
            if (!TryGetStringAttribute(node, "answer", out string answer))
            {
                Debug.LogWarning($"id为{id}的节点answer格式错误");
                continue;
            }
            question.CorrectAnswers = new HashSet<int>(Array.ConvertAll(answer.ToCharArray(), c => int.Parse(c.ToString())));

            // 读取type属性（转换为int）
            if (!TryGetIntAttribute(node, "type", out int type))
            {
                Debug.LogWarning($"id为{id}的节点type格式错误");
                continue;
            }
            question.IsSingleChoice = type == 1;
            question.IsJudgment = type == 0;// 判断题标识

            // 添加到列表
            questions.Add(question);
        }

        return questions;
    }

    // 辅助方法：获取节点的字符串属性
    private bool TryGetStringAttribute(XmlNode node, string attrName, out string value)
    {
        XmlAttribute attr = node.Attributes[attrName];
        if (attr != null)
        {
            value = attr.Value;
            return true;
        }
        value = null;
        return false;
    }

    // 辅助方法：获取节点的int属性（并验证格式）
    private bool TryGetIntAttribute(XmlNode node, string attrName, out int value)
    {
        if (TryGetStringAttribute(node, attrName, out string strValue))
        {
            return int.TryParse(strValue, out value);
        }
        value = 0;
        return false;
    }

}

public class Question
{
    public string Text; // 问题文本
    public string[] Options; // 选项数组
    public bool IsSingleChoice; // 是否为单选题
    public HashSet<int> CorrectAnswers; // 正确答案集合
    public bool IsJudgment; // 是否为判断题
}