package services

import (
	"time"

	"github.com/Nanqipro/YunQue-Tech-Projects/ai_english_learning/serve/internal/models"
	"gorm.io/gorm"
)

// WordBookService 生词本服务
type WordBookService struct {
	db *gorm.DB
}

func NewWordBookService(db *gorm.DB) *WordBookService {
	return &WordBookService{db: db}
}

// ToggleFavorite 切换单词收藏状态
func (s *WordBookService) ToggleFavorite(userID, wordID int64) (bool, error) {
	var progress models.UserWordProgress
	err := s.db.Where("user_id = ? AND vocabulary_id = ?", userID, wordID).First(&progress).Error
	
	if err == gorm.ErrRecordNotFound {
		// 如果没有进度记录，创建一个并设置为收藏
		now := time.Now()
		progress = models.UserWordProgress{
			UserID:         userID,
			VocabularyID:   wordID,
			Status:         "not_started",
			StudyCount:     0,
			CorrectCount:   0,
			WrongCount:     0,
			Proficiency:    0,
			ReviewInterval: 1,
			FirstStudiedAt: now,
			LastStudiedAt:  now,
		}
		
		// 通过GORM钩子设置IsFavorite（因为是bool类型的零值问题）
		if err := s.db.Create(&progress).Error; err != nil {
			return false, err
		}
		
		// 更新IsFavorite为true
		if err := s.db.Model(&progress).Update("is_favorite", true).Error; err != nil {
			return false, err
		}
		
		return true, nil
	} else if err != nil {
		return false, err
	}
	
	// 切换收藏状态
	newStatus := !progress.IsFavorite
	if err := s.db.Model(&progress).Update("is_favorite", newStatus).Error; err != nil {
		return false, err
	}
	
	return newStatus, nil
}

// GetFavoriteWords 获取生词本列表（带分页）
func (s *WordBookService) GetFavoriteWords(userID int64, page, pageSize int, sortBy, order string) ([]map[string]interface{}, int64, error) {
	var total int64
	
	// 统计总数
	s.db.Model(&models.UserWordProgress{}).
		Where("user_id = ? AND is_favorite = ?", userID, true).
		Count(&total)
	
	if total == 0 {
		return []map[string]interface{}{}, 0, nil
	}
	
	// 构建排序字段
	orderClause := "uwp.created_at DESC"
	switch sortBy {
	case "proficiency":
		orderClause = "uwp.proficiency " + order
	case "word":
		orderClause = "v.word " + order
	case "created_at":
		orderClause = "uwp.created_at " + order
	}
	
	// 查询收藏的单词及其详情
	var results []map[string]interface{}
	offset := (page - 1) * pageSize
	
	err := s.db.Raw(`
		SELECT 
			v.id,
			v.word,
			v.phonetic,
			v.audio_url,
			v.level,
			uwp.proficiency,
			uwp.study_count,
			uwp.status,
			uwp.next_review_at,
			uwp.created_at as favorited_at,
			GROUP_CONCAT(DISTINCT vd.definition_cn SEPARATOR '; ') as definitions,
			GROUP_CONCAT(DISTINCT vd.part_of_speech SEPARATOR ', ') as parts_of_speech
		FROM ai_user_word_progress uwp
		INNER JOIN ai_vocabulary v ON v.id = uwp.vocabulary_id
		LEFT JOIN ai_vocabulary_definitions vd ON vd.vocabulary_id = v.id
		WHERE uwp.user_id = ? AND uwp.is_favorite = true
		GROUP BY v.id, v.word, v.phonetic, v.audio_url, v.level, 
		         uwp.proficiency, uwp.study_count, uwp.status, uwp.next_review_at, uwp.created_at
		ORDER BY `+orderClause+`
		LIMIT ? OFFSET ?
	`, userID, pageSize, offset).Scan(&results).Error
	
	if err != nil {
		return nil, 0, err
	}
	
	return results, total, nil
}

// GetFavoriteWordsByBook 获取指定词汇书的生词本
func (s *WordBookService) GetFavoriteWordsByBook(userID int64, bookID string) ([]map[string]interface{}, error) {
	var results []map[string]interface{}
	
	err := s.db.Raw(`
		SELECT 
			v.id,
			v.word,
			v.phonetic,
			v.audio_url,
			v.level,
			uwp.proficiency,
			uwp.study_count,
			uwp.status,
			GROUP_CONCAT(DISTINCT vd.definition_cn SEPARATOR '; ') as definitions,
			GROUP_CONCAT(DISTINCT vd.part_of_speech SEPARATOR ', ') as parts_of_speech
		FROM ai_user_word_progress uwp
		INNER JOIN ai_vocabulary v ON v.id = uwp.vocabulary_id
		INNER JOIN ai_vocabulary_book_words vbw ON CAST(vbw.vocabulary_id AS UNSIGNED) = v.id
		LEFT JOIN ai_vocabulary_definitions vd ON vd.vocabulary_id = v.id
		WHERE uwp.user_id = ? AND uwp.is_favorite = true AND vbw.book_id = ?
		GROUP BY v.id, v.word, v.phonetic, v.audio_url, v.level,
		         uwp.proficiency, uwp.study_count, uwp.status
		ORDER BY uwp.created_at DESC
	`, userID, bookID).Scan(&results).Error
	
	if err != nil {
		return nil, err
	}
	
	return results, nil
}

// GetFavoriteStats 获取生词本统计信息
func (s *WordBookService) GetFavoriteStats(userID int64) (map[string]interface{}, error) {
	var stats struct {
		TotalWords      int64
		MasteredWords   int64
		ReviewingWords  int64
		LearningWords   int64
		AvgProficiency  float64
		NeedReviewToday int64
	}
	
	// 统计总数和各状态数量
	s.db.Raw(`
		SELECT 
			COUNT(*) as total_words,
			SUM(CASE WHEN status = 'mastered' THEN 1 ELSE 0 END) as mastered_words,
			SUM(CASE WHEN status = 'reviewing' THEN 1 ELSE 0 END) as reviewing_words,
			SUM(CASE WHEN status = 'learning' THEN 1 ELSE 0 END) as learning_words,
			AVG(proficiency) as avg_proficiency,
			SUM(CASE WHEN next_review_at IS NOT NULL AND next_review_at <= NOW() THEN 1 ELSE 0 END) as need_review_today
		FROM ai_user_word_progress
		WHERE user_id = ? AND is_favorite = true
	`, userID).Scan(&stats)
	
	return map[string]interface{}{
		"total_words":       stats.TotalWords,
		"mastered_words":    stats.MasteredWords,
		"reviewing_words":   stats.ReviewingWords,
		"learning_words":    stats.LearningWords,
		"avg_proficiency":   stats.AvgProficiency,
		"need_review_today": stats.NeedReviewToday,
	}, nil
}

// BatchAddToFavorite 批量添加到生词本
func (s *WordBookService) BatchAddToFavorite(userID int64, wordIDs []int64) (int, error) {
	count := 0
	now := time.Now()
	
	for _, wordID := range wordIDs {
		var progress models.UserWordProgress
		err := s.db.Where("user_id = ? AND vocabulary_id = ?", userID, wordID).First(&progress).Error
		
		if err == gorm.ErrRecordNotFound {
			// 创建新记录
			progress = models.UserWordProgress{
				UserID:         userID,
				VocabularyID:   wordID,
				Status:         "not_started",
				StudyCount:     0,
				CorrectCount:   0,
				WrongCount:     0,
				Proficiency:    0,
				ReviewInterval: 1,
				FirstStudiedAt: now,
				LastStudiedAt:  now,
			}
			if err := s.db.Create(&progress).Error; err != nil {
				continue
			}
			if err := s.db.Model(&progress).Update("is_favorite", true).Error; err != nil {
				continue
			}
			count++
		} else if err == nil && !progress.IsFavorite {
			// 更新现有记录
			if err := s.db.Model(&progress).Update("is_favorite", true).Error; err != nil {
				continue
			}
			count++
		}
	}
	
	return count, nil
}

// RemoveFromFavorite 从生词本移除
func (s *WordBookService) RemoveFromFavorite(userID, wordID int64) error {
	return s.db.Model(&models.UserWordProgress{}).
		Where("user_id = ? AND vocabulary_id = ?", userID, wordID).
		Update("is_favorite", false).Error
}