package handlers

import (
	"ankao/internal/database"
	"ankao/internal/models"
	"encoding/json"
	"log"
	"net/http"
	"sort"
	"strconv"
	"time"

	"github.com/gin-gonic/gin"
)

// GetPracticeQuestions 获取练习题目列表
func GetPracticeQuestions(c *gin.Context) {
	typeParam := c.Query("type")
	searchQuery := c.Query("search")

	db := database.GetDB()
	var questions []models.PracticeQuestion
	var total int64

	query := db.Model(&models.PracticeQuestion{})

	// 根据题型过滤
	if typeParam != "" {
		query = query.Where("type = ?", typeParam)
	}

	// 根据搜索关键词过滤（搜索题目内容或题目编号）
	if searchQuery != "" {
		query = query.Where("question LIKE ? OR question_id LIKE ?", "%"+searchQuery+"%", "%"+searchQuery+"%")
	}

	// 获取总数
	query.Count(&total)

	// 查询所有题目 - 按题型和题目编号升序排序
	// 先将 question_id 转为文本，提取数字部分，再转为整数排序
	err := query.Order("type ASC, CAST(COALESCE(NULLIF(REGEXP_REPLACE(question_id::text, '[^0-9]', '', 'g'), ''), '0') AS INTEGER) ASC").Find(&questions).Error
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{
			"success": false,
			"message": "查询题目失败",
		})
		return
	}

	// 转换为DTO
	dtos := make([]models.PracticeQuestionDTO, len(questions))
	for i, q := range questions {
		dto := convertToDTO(q)
		dtos[i] = dto
	}

	c.JSON(http.StatusOK, gin.H{
		"success": true,
		"data":    dtos,
		"total":   total,
	})
}

// GetPracticeQuestionByID 获取单个练习题目
func GetPracticeQuestionByID(c *gin.Context) {
	idStr := c.Param("id")
	id, err := strconv.ParseUint(idStr, 10, 32)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{
			"success": false,
			"message": "无效的题目ID",
		})
		return
	}

	db := database.GetDB()
	var question models.PracticeQuestion

	if err := db.First(&question, id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{
			"success": false,
			"message": "题目不存在",
		})
		return
	}

	// 转换为DTO
	dto := convertToDTO(question)

	c.JSON(http.StatusOK, gin.H{
		"success": true,
		"data":    dto,
	})
}

// GetRandomPracticeQuestion 获取随机练习题目
func GetRandomPracticeQuestion(c *gin.Context) {
	typeParam := c.Query("type")

	db := database.GetDB()
	var question models.PracticeQuestion

	query := db.Model(&models.PracticeQuestion{})
	if typeParam != "" {
		query = query.Where("type = ?", typeParam)
	}

	// 使用PostgreSQL的随机排序
	if err := query.Order("RANDOM()").First(&question).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{
			"success": false,
			"message": "暂无题目",
		})
		return
	}

	// 转换为DTO
	dto := convertToDTO(question)

	c.JSON(http.StatusOK, gin.H{
		"success": true,
		"data":    dto,
	})
}

// SubmitPracticeAnswer 提交练习答案
func SubmitPracticeAnswer(c *gin.Context) {
	var submit models.PracticeAnswerSubmit
	if err := c.ShouldBindJSON(&submit); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{
			"success": false,
			"message": "请求参数错误",
		})
		return
	}

	// 获取用户ID（认证中间件已确保存在）
	userID, exists := c.Get("user_id")
	if !exists {
		c.JSON(http.StatusUnauthorized, gin.H{
			"success": false,
			"message": "未登录",
		})
		return
	}

	db := database.GetDB()
	var question models.PracticeQuestion

	if err := db.First(&question, submit.QuestionID).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{
			"success": false,
			"message": "题目不存在",
		})
		return
	}

	// 解析正确答案
	var correctAnswer interface{}
	if err := json.Unmarshal([]byte(question.AnswerData), &correctAnswer); err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{
			"success": false,
			"message": "答案数据错误",
		})
		return
	}

	// 验证答案
	correct := checkPracticeAnswer(question.Type, submit.Answer, correctAnswer)

	// 记录用户答题历史
	if uid, ok := userID.(uint); ok {
		record := models.UserAnswerRecord{
			UserID:     uid,
			QuestionID: question.ID,
			IsCorrect:  correct,
			AnsweredAt: time.Now(),
		}
		// 记录到数据库（忽略错误，不影响主流程）
		if err := db.Create(&record).Error; err != nil {
			log.Printf("记录答题历史失败: %v", err)
		}
	}

	// 如果答错，记录到错题本
	if !correct {
		if uid, ok := userID.(uint); ok {
			// 记录错题
			if err := recordWrongQuestion(uid, question.ID, submit.Answer, correctAnswer); err != nil {
				// 记录错题失败不影响主流程，只记录日志
				log.Printf("记录错题失败: %v", err)
			}
		}
	}

	result := models.PracticeAnswerResult{
		Correct:       correct,
		UserAnswer:    submit.Answer,
		CorrectAnswer: correctAnswer, // 始终返回正确答案
	}

	c.JSON(http.StatusOK, gin.H{
		"success": true,
		"data":    result,
	})
}

// GetPracticeQuestionTypes 获取题型列表
func GetPracticeQuestionTypes(c *gin.Context) {
	types := []gin.H{
		{
			"type":      "fill-in-blank",
			"type_name": "填空题",
		},
		{
			"type":      "true-false",
			"type_name": "判断题",
		},
		{
			"type":      "multiple-choice",
			"type_name": "选择题",
		},
		{
			"type":      "multiple-selection",
			"type_name": "多选题",
		},
		{
			"type":      "short-answer",
			"type_name": "简答题",
		},
	}

	c.JSON(http.StatusOK, gin.H{
		"success": true,
		"data":    types,
	})
}

// checkPracticeAnswer 检查练习答案是否正确
func checkPracticeAnswer(questionType string, userAnswer, correctAnswer interface{}) bool {
	switch questionType {
	case "true-false":
		// 判断题: boolean 比较
		userBool, ok1 := userAnswer.(bool)
		correctBool, ok2 := correctAnswer.(bool)
		return ok1 && ok2 && userBool == correctBool

	case "multiple-choice":
		// 单选题: 字符串比较
		userStr, ok1 := userAnswer.(string)
		correctStr, ok2 := correctAnswer.(string)
		return ok1 && ok2 && userStr == correctStr

	case "multiple-selection":
		// 多选题: 数组比较
		userArr, ok1 := toStringArray(userAnswer)
		correctArr, ok2 := toStringArray(correctAnswer)
		if !ok1 || !ok2 || len(userArr) != len(correctArr) {
			return false
		}

		// 转换为map进行比较
		userMap := make(map[string]bool)
		for _, v := range userArr {
			userMap[v] = true
		}
		for _, v := range correctArr {
			if !userMap[v] {
				return false
			}
		}
		return true

	case "fill-in-blank":
		// 填空题: 数组比较
		userArr, ok1 := toStringArray(userAnswer)
		correctArr, ok2 := toStringArray(correctAnswer)
		if !ok1 || !ok2 || len(userArr) != len(correctArr) {
			return false
		}

		// 逐个比较填空答案
		for i := range correctArr {
			if userArr[i] != correctArr[i] {
				return false
			}
		}
		return true

	case "short-answer":
		// 简答题: 字符串比较(简单实现,实际可能需要更复杂的判断)
		userStr, ok1 := userAnswer.(string)
		correctStr, ok2 := correctAnswer.(string)
		return ok1 && ok2 && userStr == correctStr
	}

	return false
}

// toStringArray 将interface{}转换为字符串数组
func toStringArray(v interface{}) ([]string, bool) {
	switch arr := v.(type) {
	case []string:
		return arr, true
	case []interface{}:
		result := make([]string, len(arr))
		for i, item := range arr {
			if str, ok := item.(string); ok {
				result[i] = str
			} else {
				return nil, false
			}
		}
		return result, true
	default:
		return nil, false
	}
}

// convertToDTO 将数据库模型转换为前端DTO
func convertToDTO(question models.PracticeQuestion) models.PracticeQuestionDTO {
	dto := models.PracticeQuestionDTO{
		ID:         question.ID,
		QuestionID: question.QuestionID,
		Type:       question.Type,    // 直接使用数据库中的type，不做映射
		Content:    question.Question,
		Category:   question.TypeName, // 使用typeName作为分类显示
		Options:    []models.Option{},
	}

	// 解析答案数据
	var answer interface{}
	if err := json.Unmarshal([]byte(question.AnswerData), &answer); err == nil {
		dto.Answer = answer
	}

	// 判断题自动生成选项
	if question.Type == "true-false" {
		dto.Options = []models.Option{
			{Key: "true", Value: "正确"},
			{Key: "false", Value: "错误"},
		}
		return dto
	}

	// 解析选项数据(如果有)
	if question.OptionsData != "" {
		var optionsMap map[string]string
		if err := json.Unmarshal([]byte(question.OptionsData), &optionsMap); err == nil {
			// 将map转换为Option数组，并按key排序
			keys := make([]string, 0, len(optionsMap))
			for key := range optionsMap {
				keys = append(keys, key)
			}
			// 对keys进行排序
			sort.Strings(keys)

			// 按排序后的key顺序添加选项
			for _, key := range keys {
				dto.Options = append(dto.Options, models.Option{
					Key:   key,
					Value: optionsMap[key],
				})
			}
		}
	}

	return dto
}

// GetStatistics 获取用户统计数据
func GetStatistics(c *gin.Context) {
	// 获取用户ID
	userID, exists := c.Get("user_id")
	if !exists {
		c.JSON(http.StatusUnauthorized, gin.H{
			"success": false,
			"message": "未登录",
		})
		return
	}

	uid, ok := userID.(uint)
	if !ok {
		c.JSON(http.StatusInternalServerError, gin.H{
			"success": false,
			"message": "用户ID格式错误",
		})
		return
	}

	db := database.GetDB()

	// 获取题库总数
	var totalQuestions int64
	db.Model(&models.PracticeQuestion{}).Count(&totalQuestions)

	// 获取用户已答题数（去重）
	var answeredQuestions int64
	db.Model(&models.UserAnswerRecord{}).
		Where("user_id = ?", uid).
		Distinct("question_id").
		Count(&answeredQuestions)

	// 获取用户答对题数
	var correctAnswers int64
	db.Model(&models.UserAnswerRecord{}).
		Where("user_id = ? AND is_correct = ?", uid, true).
		Count(&correctAnswers)

	// 获取用户错题数量（所有错题，包括已掌握和未掌握的）
	var wrongQuestions int64
	db.Model(&models.WrongQuestion{}).
		Where("user_id = ?", uid).
		Count(&wrongQuestions)

	// 计算正确率
	var accuracy float64
	if answeredQuestions > 0 {
		// 正确率 = 答对题数 / 总答题数
		var totalAnswers int64
		db.Model(&models.UserAnswerRecord{}).
			Where("user_id = ?", uid).
			Count(&totalAnswers)
		accuracy = float64(correctAnswers) / float64(totalAnswers) * 100
	}

	stats := models.UserStatistics{
		TotalQuestions:    int(totalQuestions),
		AnsweredQuestions: int(answeredQuestions),
		CorrectAnswers:    int(correctAnswers),
		WrongQuestions:    int(wrongQuestions),
		Accuracy:          accuracy,
	}

	c.JSON(http.StatusOK, gin.H{
		"success": true,
		"data":    stats,
	})
}

// CreatePracticeQuestion 创建新的练习题目
func CreatePracticeQuestion(c *gin.Context) {
	var req struct {
		Type       string                 `json:"type" binding:"required"`
		TypeName   string                 `json:"type_name"`
		Question   string                 `json:"question" binding:"required"`
		Answer     interface{}            `json:"answer" binding:"required"`
		Options    map[string]string      `json:"options"`
	}

	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{
			"success": false,
			"message": "请求参数错误: " + err.Error(),
		})
		return
	}

	db := database.GetDB()

	// 自动生成题目编号：找到该题型的最大编号并+1
	var maxQuestionID string
	err := db.Model(&models.PracticeQuestion{}).
		Where("type = ?", req.Type).
		Select("question_id").
		Order("CAST(COALESCE(NULLIF(REGEXP_REPLACE(question_id::text, '[^0-9]', '', 'g'), ''), '0') AS INTEGER) DESC").
		Limit(1).
		Pluck("question_id", &maxQuestionID).Error

	// 生成新的题目编号
	var newQuestionID string
	if err != nil || maxQuestionID == "" {
		// 没有找到该题型的题目，从1开始
		newQuestionID = "1"
	} else {
		// 从最大编号中提取数字并+1
		var maxNum int
		_, scanErr := strconv.Atoi(maxQuestionID)
		if scanErr == nil {
			maxNum, _ = strconv.Atoi(maxQuestionID)
		}
		newQuestionID = strconv.Itoa(maxNum + 1)
	}

	// 将答案序列化为JSON字符串
	answerData, err := json.Marshal(req.Answer)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{
			"success": false,
			"message": "答案格式错误",
		})
		return
	}

	// 将选项序列化为JSON字符串
	var optionsData string
	if req.Options != nil && len(req.Options) > 0 {
		optionsBytes, err := json.Marshal(req.Options)
		if err != nil {
			c.JSON(http.StatusBadRequest, gin.H{
				"success": false,
				"message": "选项格式错误",
			})
			return
		}
		optionsData = string(optionsBytes)
	}

	question := models.PracticeQuestion{
		QuestionID:  newQuestionID,
		Type:        req.Type,
		TypeName:    req.TypeName,
		Question:    req.Question,
		AnswerData:  string(answerData),
		OptionsData: optionsData,
	}

	if err := db.Create(&question).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{
			"success": false,
			"message": "创建题目失败",
		})
		return
	}

	// 返回创建的题目
	dto := convertToDTO(question)
	c.JSON(http.StatusOK, gin.H{
		"success": true,
		"data":    dto,
		"message": "创建成功",
	})
}

// UpdatePracticeQuestion 更新练习题目
func UpdatePracticeQuestion(c *gin.Context) {
	idStr := c.Param("id")
	id, err := strconv.ParseUint(idStr, 10, 32)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{
			"success": false,
			"message": "无效的题目ID",
		})
		return
	}

	var req struct {
		Type       string                 `json:"type"`
		TypeName   string                 `json:"type_name"`
		Question   string                 `json:"question"`
		Answer     interface{}            `json:"answer"`
		Options    map[string]string      `json:"options"`
	}

	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{
			"success": false,
			"message": "请求参数错误: " + err.Error(),
		})
		return
	}

	db := database.GetDB()
	var question models.PracticeQuestion

	// 查找题目是否存在
	if err := db.First(&question, id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{
			"success": false,
			"message": "题目不存在",
		})
		return
	}

	// 更新字段（注意：不允许修改 QuestionID，由系统自动生成）
	if req.Type != "" {
		question.Type = req.Type
	}
	if req.TypeName != "" {
		question.TypeName = req.TypeName
	}
	if req.Question != "" {
		question.Question = req.Question
	}
	if req.Answer != nil {
		answerData, err := json.Marshal(req.Answer)
		if err != nil {
			c.JSON(http.StatusBadRequest, gin.H{
				"success": false,
				"message": "答案格式错误",
			})
			return
		}
		question.AnswerData = string(answerData)
	}
	if req.Options != nil {
		optionsBytes, err := json.Marshal(req.Options)
		if err != nil {
			c.JSON(http.StatusBadRequest, gin.H{
				"success": false,
				"message": "选项格式错误",
			})
			return
		}
		question.OptionsData = string(optionsBytes)
	}

	// 保存更新
	if err := db.Save(&question).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{
			"success": false,
			"message": "更新题目失败",
		})
		return
	}

	// 返回更新后的题目
	dto := convertToDTO(question)
	c.JSON(http.StatusOK, gin.H{
		"success": true,
		"data":    dto,
		"message": "更新成功",
	})
}

// DeletePracticeQuestion 删除练习题目
func DeletePracticeQuestion(c *gin.Context) {
	idStr := c.Param("id")
	id, err := strconv.ParseUint(idStr, 10, 32)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{
			"success": false,
			"message": "无效的题目ID",
		})
		return
	}

	db := database.GetDB()

	// 检查题目是否存在
	var question models.PracticeQuestion
	if err := db.First(&question, id).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{
			"success": false,
			"message": "题目不存在",
		})
		return
	}

	// 删除题目
	if err := db.Delete(&question).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{
			"success": false,
			"message": "删除题目失败",
		})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"success": true,
		"message": "删除成功",
	})
}