// Flashcards API service

export interface ExampleImage {
  id: string;
  imageUrl: string;
  isPrimary: boolean;
  qualityScore?: number;
  fileSize?: number;
  createdAt: string;
}

export interface Flashcard {
  id: string;
  word: string;
  translation: string;
  definition: string;
  partOfSpeech: string;
  pronunciation: string;
  example: string;
  exampleTranslation?: string;
  masteryLevel: number;
  timesReviewed: number;
  isFavorite: boolean;
  nextReviewDate: string;
  difficultyLevel: string;
  createdAt: string;
  updatedAt?: string;

  // 新增圖片相關欄位
  exampleImages: ExampleImage[];
  hasExampleImage: boolean;
  primaryImageUrl?: string;
}

export interface CreateFlashcardRequest {
  word: string;
  translation: string;
  definition: string;
  pronunciation: string;
  partOfSpeech: string;
  example: string;
  exampleTranslation?: string;
  difficultyLevel?: string; // A1, A2, B1, B2, C1, C2
}

export interface ApiResponse<T> {
  success: boolean;
  data?: T;
  error?: string;
  message?: string;
}

class FlashcardsService {
  private readonly baseURL = `${process.env.NEXT_PUBLIC_API_URL || 'http://localhost:5008'}/api`;

  private async makeRequest<T>(endpoint: string, options: RequestInit = {}): Promise<T> {
    const token = localStorage.getItem('auth_token');

    const response = await fetch(`${this.baseURL}${endpoint}`, {
      headers: {
        'Content-Type': 'application/json',
        'Authorization': token ? `Bearer ${token}` : '',
        ...options.headers,
      },
      ...options,
    });

    if (!response.ok) {
      const errorData = await response.json().catch(() => ({ error: 'Network error' }));
      throw new Error(errorData.error || errorData.details || `HTTP ${response.status}`);
    }

    return response.json();
  }

  // 詞卡查詢方法 (支援進階篩選、排序和分頁)
  async getFlashcards(
    search?: string,
    favoritesOnly: boolean = false,
    cefrLevel?: string,
    partOfSpeech?: string,
    masteryLevel?: string,
    sortBy?: string,
    sortOrder?: 'asc' | 'desc',
    page?: number,
    limit?: number
  ): Promise<ApiResponse<{ flashcards: Flashcard[], count: number }>> {
    try {
      const params = new URLSearchParams();
      if (search) params.append('search', search);
      if (favoritesOnly) params.append('favoritesOnly', 'true');
      if (cefrLevel) params.append('cefrLevel', cefrLevel);
      if (partOfSpeech) params.append('partOfSpeech', partOfSpeech);
      if (masteryLevel) params.append('masteryLevel', masteryLevel);

      // 排序和分頁參數
      if (sortBy) params.append('sortBy', sortBy);
      if (sortOrder) params.append('sortOrder', sortOrder);
      if (page) params.append('page', page.toString());
      if (limit) params.append('limit', limit.toString());

      const queryString = params.toString();
      const endpoint = `/flashcards${queryString ? `?${queryString}` : ''}`;

      return await this.makeRequest<ApiResponse<{ flashcards: Flashcard[], count: number }>>(endpoint);
    } catch (error) {
      return {
        success: false,
        error: error instanceof Error ? error.message : 'Failed to fetch flashcards',
      };
    }
  }

  async createFlashcard(data: CreateFlashcardRequest): Promise<ApiResponse<Flashcard>> {
    try {
      return await this.makeRequest<ApiResponse<Flashcard>>('/flashcards', {
        method: 'POST',
        body: JSON.stringify(data),
      });
    } catch (error) {
      return {
        success: false,
        error: error instanceof Error ? error.message : 'Failed to create flashcard',
      };
    }
  }

  async deleteFlashcard(id: string): Promise<ApiResponse<void>> {
    try {
      return await this.makeRequest<ApiResponse<void>>(`/flashcards/${id}`, {
        method: 'DELETE',
      });
    } catch (error) {
      return {
        success: false,
        error: error instanceof Error ? error.message : 'Failed to delete flashcard',
      };
    }
  }

  async getFlashcard(id: string): Promise<ApiResponse<Flashcard>> {
    try {
      return await this.makeRequest<ApiResponse<Flashcard>>(`/flashcards/${id}`);
    } catch (error) {
      return {
        success: false,
        error: error instanceof Error ? error.message : 'Failed to get flashcard',
      };
    }
  }

  async updateFlashcard(id: string, data: CreateFlashcardRequest): Promise<ApiResponse<Flashcard>> {
    try {
      return await this.makeRequest<ApiResponse<Flashcard>>(`/flashcards/${id}`, {
        method: 'PUT',
        body: JSON.stringify(data),
      });
    } catch (error) {
      return {
        success: false,
        error: error instanceof Error ? error.message : 'Failed to update flashcard',
      };
    }
  }

  async toggleFavorite(id: string): Promise<ApiResponse<void>> {
    try {
      return await this.makeRequest<ApiResponse<void>>(`/flashcards/${id}/favorite`, {
        method: 'POST',
      });
    } catch (error) {
      return {
        success: false,
        error: error instanceof Error ? error.message : 'Failed to toggle favorite',
      };
    }
  }

  // =====================================================
  // 智能複習系統相關方法
  // =====================================================

  async getDueFlashcards(limit = 50): Promise<ApiResponse<Flashcard[]>> {
    try {
      console.log('🚀 API調用開始:', `/flashcards/due?limit=${limit}`);

      const response = await this.makeRequest<{ success: boolean; data: any[]; count: number }>(`/flashcards/due?limit=${limit}`);
      console.log('🔍 makeRequest回應:', response);
      console.log('📊 response.data類型:', typeof response.data, '長度:', response.data?.length);

      if (!response.data || !Array.isArray(response.data)) {
        console.log('❌ response.data不是數組:', response.data);
        return {
          success: false,
          error: 'Invalid response data format',
        };
      }

      // 轉換後端格式為前端期望格式
      const flashcards = response.data.map((card: any) => ({
        id: card.id,
        word: card.word,
        translation: card.translation,
        definition: card.definition,
        partOfSpeech: card.partOfSpeech,
        pronunciation: card.pronunciation,
        example: card.example,
        exampleTranslation: card.exampleTranslation,
        masteryLevel: card.masteryLevel || card.currentMasteryLevel || 0,
        timesReviewed: card.timesReviewed || 0,
        isFavorite: card.isFavorite || false,
        nextReviewDate: card.nextReviewDate,
        difficultyLevel: card.difficultyLevel || 'A2',
        createdAt: card.createdAt,
        updatedAt: card.updatedAt,
        // 智能複習擴展欄位 (數值欄位已移除，改用即時CEFR轉換)
        baseMasteryLevel: card.baseMasteryLevel || card.masteryLevel || 0,
        lastReviewDate: card.lastReviewDate || card.lastReviewedAt,
        currentInterval: card.currentInterval || card.intervalDays || 1,
        isOverdue: card.isOverdue || false,
        overdueDays: card.overdueDays || 0,
        // 圖片相關欄位
        exampleImages: card.exampleImages || [],
        hasExampleImage: card.hasExampleImage || false,
        primaryImageUrl: card.primaryImageUrl
      }));

      console.log('✅ 數據轉換完成:', flashcards.length, '張詞卡');

      return {
        success: true,
        data: flashcards
      };
    } catch (error) {
      console.error('💥 API request failed:', error);
      return {
        success: false,
        error: error instanceof Error ? error.message : 'Failed to get due flashcards',
      };
    }
  }

  async getNextReviewCard(): Promise<ApiResponse<Flashcard & { userLevel: number; wordLevel: number }>> {
    try {
      return await this.makeRequest<ApiResponse<Flashcard & { userLevel: number; wordLevel: number }>>('/flashcards/next-review');
    } catch (error) {
      return {
        success: false,
        error: error instanceof Error ? error.message : 'Failed to get next review card',
      };
    }
  }

  async getOptimalReviewMode(cardId: string, userCEFRLevel: string, wordCEFRLevel: string): Promise<ApiResponse<{ selectedMode: string }>> {
    try {
      const response = await this.makeRequest<{ success: boolean; data: any }>(`/flashcards/${cardId}/optimal-review-mode`, {
        method: 'POST',
        body: JSON.stringify({
          userCEFRLevel,
          wordCEFRLevel,
          includeHistory: true
        }),
      });

      return {
        success: response.success,
        data: {
          selectedMode: response.data.selectedMode
        }
      };
    } catch (error) {
      console.error('Optimal review mode API failed, using fallback:', error);
      return {
        success: false,
        error: error instanceof Error ? error.message : 'Failed to get optimal review mode',
      };
    }
  }

  async submitReview(id: string, reviewData: {
    isCorrect: boolean;
    confidenceLevel?: number;
    questionType: string;
    userAnswer?: string;
    timeTaken?: number;
  }): Promise<ApiResponse<{ newInterval: number; nextReviewDate: string; masteryLevel: number }>> {
    try {
      const response = await this.makeRequest<{ success: boolean; data: any }>(`/flashcards/${id}/review`, {
        method: 'POST',
        body: JSON.stringify({
          ...reviewData,
          timestamp: Date.now()
        }),
      });

      return {
        success: response.success,
        data: {
          newInterval: response.data.newInterval || response.data.newIntervalDays || 1,
          nextReviewDate: response.data.nextReviewDate,
          masteryLevel: response.data.masteryLevel || response.data.newMasteryLevel || 0
        }
      };
    } catch (error) {
      console.error('Submit review API failed, using fallback:', error);
      return {
        success: false,
        error: error instanceof Error ? error.message : 'Failed to submit review',
      };
    }
  }

  async generateQuestionOptions(cardId: string, questionType: string): Promise<ApiResponse<{
    options?: string[];
    correctAnswer: string;
    audioUrl?: string;
    sentence?: string;
    blankedSentence?: string;
    scrambledWords?: string[];
  }>> {
    try {
      return await this.makeRequest<ApiResponse<any>>(`/flashcards/${cardId}/question`, {
        method: 'POST',
        body: JSON.stringify({ questionType }),
      });
    } catch (error) {
      return {
        success: false,
        error: error instanceof Error ? error.message : 'Failed to generate question options',
      };
    }
  }

  /**
   * 獲取已完成的測驗記錄
   */
  async getCompletedTests(cardIds?: string[]): Promise<{
    success: boolean;
    data: Array<{
      flashcardId: string;
      testType: string;
      isCorrect: boolean;
      completedAt: string;
      userAnswer?: string;
    }> | null;
    error?: string;
  }> {
    try {
      const params = cardIds && cardIds.length > 0 ? `?cardIds=${cardIds.join(',')}` : '';
      const result = await this.makeRequest(`/study/completed-tests${params}`);

      return {
        success: true,
        data: result.data || [],
        error: undefined
      };
    } catch (error) {
      console.warn('Failed to get completed tests:', error);
      return {
        success: false,
        data: [],
        error: error instanceof Error ? error.message : 'Failed to get completed tests'
      };
    }
  }

  /**
   * 記錄測驗完成狀態 (立即保存到StudyRecord表)
   */
  async recordTestCompletion(request: {
    flashcardId: string;
    testType: string;
    isCorrect: boolean;
    userAnswer?: string;
    confidenceLevel?: number;
    responseTimeMs?: number;
  }): Promise<{ success: boolean; data: any | null; error?: string }> {
    try {
      const result = await this.makeRequest('/study/record-test', {
        method: 'POST',
        body: JSON.stringify({
          flashcardId: request.flashcardId,
          testType: request.testType,
          isCorrect: request.isCorrect,
          userAnswer: request.userAnswer,
          confidenceLevel: request.confidenceLevel,
          responseTimeMs: request.responseTimeMs || 2000
        })
      });

      return {
        success: true,
        data: result.data || result,
        error: undefined
      };
    } catch (error) {
      console.warn('Failed to record test completion:', error);
      return {
        success: false,
        data: null,
        error: error instanceof Error ? error.message : 'Failed to record test completion'
      };
    }
  }
}

export const flashcardsService = new FlashcardsService();