import {
  Injectable,
  NotFoundException,
  ForbiddenException,
  BadRequestException,
  Logger,
} from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { ConfigService } from '@nestjs/config';
import { ChatOpenAI } from '@langchain/openai';
import { SystemMessage, HumanMessage } from '@langchain/core/messages';
import { QuestionBank, QuestionBankStatus } from '../entities/question-bank.entity';
import {
  QuestionBankItem,
  QuestionBankItemStatus,
  QuestionType,
  QuestionDifficulty,
  QuestionDimension,
} from '../entities/question-bank-item.entity';
import { ModelConfigService } from '../../model-config/model-config.service';
import { ModelType } from '../../types';
import { safeParseJson } from '../../common/json-utils';

export interface CreateQuestionBankDto {
  templateId?: string;
  name: string;
  description?: string;
}

export interface UpdateQuestionBankDto {
  name?: string;
  description?: string;
  status?: QuestionBankStatus;
}

export interface CreateQuestionBankItemDto {
  questionText: string;
  questionType?: QuestionType;
  options?: string[];
  correctAnswer?: string;
  keyPoints: string[];
  difficulty?: QuestionDifficulty;
  dimension?: QuestionDimension;
  basis?: string;
}

export interface UpdateQuestionBankItemDto {
  questionText?: string;
  questionType?: QuestionType;
  options?: string[];
  correctAnswer?: string;
  keyPoints?: string[];
  difficulty?: QuestionDifficulty;
  dimension?: QuestionDimension;
  basis?: string;
}

export interface ReviewDto {
  approved: boolean;
  comment?: string;
}

const DIMENSIONS = [
  QuestionDimension.PROMPT,
  QuestionDimension.LLM,
  QuestionDimension.IDE,
  QuestionDimension.DEV_PATTERN,
  QuestionDimension.WORK_CAPABILITY,
];

@Injectable()
export class QuestionBankService {
  private readonly logger = new Logger(QuestionBankService.name);

  constructor(
    @InjectRepository(QuestionBank)
    private readonly bankRepository: Repository<QuestionBank>,
    @InjectRepository(QuestionBankItem)
    private readonly itemRepository: Repository<QuestionBankItem>,
    private readonly modelConfigService: ModelConfigService,
    private readonly configService: ConfigService,
  ) {}

  async create(
    createDto: CreateQuestionBankDto,
    userId: string,
    tenantId: string | null,
  ): Promise<QuestionBank> {
    if (!createDto.name || !createDto.name.trim()) {
      throw new BadRequestException('Question bank name is required');
    }
    if (createDto.templateId) {
      const existing = await this.bankRepository.findOne({
        where: { templateId: createDto.templateId, tenantId: tenantId as any },
      });
      if (existing) {
        if (existing.status === QuestionBankStatus.DRAFT || existing.status === QuestionBankStatus.REJECTED) {
          await this.bankRepository.remove(existing);
        } else {
          throw new BadRequestException('该模板已关联有效题库，请编辑已有题库');
        }
      }
    }
    const bankData: any = {
      name: createDto.name,
      description: createDto.description || '',
      createdBy: userId,
      tenantId: tenantId || null,
      status: QuestionBankStatus.DRAFT,
    };
    if (createDto.templateId) {
      bankData.templateId = createDto.templateId;
    }
    const bank = this.bankRepository.create(bankData as any);
    return this.bankRepository.save(bank as unknown as QuestionBank);
  }

  async findAll(
    userId: string,
    tenantId: string | null,
    page?: number,
    limit?: number,
  ): Promise<{ data: QuestionBank[]; total: number } | QuestionBank[]> {
    console.log('[QuestionBank findAll] userId:', userId, 'tenantId:', tenantId);
    const queryBuilder = this.bankRepository
      .createQueryBuilder('bank')
      .leftJoinAndSelect('bank.template', 'template');

    if (tenantId === null) {
      queryBuilder.where('bank.tenantId IS NULL');
    } else {
      queryBuilder.where('bank.tenantId = :tenantId', { tenantId });
    }

    queryBuilder.orderBy('bank.createdAt', 'DESC');

    if (page !== undefined && limit !== undefined) {
      const [data, total] = await queryBuilder
        .skip((page - 1) * limit)
        .take(limit)
        .getManyAndCount();
      return { data, total };
    }

    return queryBuilder.getMany();
  }

  async findByTemplateId(templateId: string): Promise<QuestionBank | null> {
    return this.bankRepository.findOne({
      where: { templateId },
      relations: ['template', 'items'],
    });
  }

  async findOne(id: string): Promise<QuestionBank> {
    const bank = await this.bankRepository.findOne({
      where: { id },
      relations: ['template', 'items'],
    });
    if (!bank) {
      throw new NotFoundException(`QuestionBank with ID "${id}" not found`);
    }
    return bank;
  }

  async update(
    id: string,
    updateDto: UpdateQuestionBankDto,
  ): Promise<QuestionBank> {
    const bank = await this.findOne(id);
    Object.assign(bank, updateDto);
    return this.bankRepository.save(bank);
  }

  async remove(id: string): Promise<void> {
    const bank = await this.findOne(id);
    await this.bankRepository.remove(bank);
  }

  async submitForReview(id: string, userId: string): Promise<QuestionBank> {
    const bank = await this.findOne(id);
    if (bank.status !== QuestionBankStatus.DRAFT) {
      throw new ForbiddenException(
        'Only DRAFT status can be submitted for review',
      );
    }
    bank.status = QuestionBankStatus.PENDING_REVIEW;
    return this.bankRepository.save(bank);
  }

  async review(
    id: string,
    reviewDto: ReviewDto,
    reviewerId: string,
  ): Promise<QuestionBank> {
    const bank = await this.findOne(id);
    if (bank.status !== QuestionBankStatus.PENDING_REVIEW) {
      throw new ForbiddenException(
        'Only PENDING_REVIEW status can be reviewed',
      );
    }
    bank.reviewedBy = reviewerId;
    bank.reviewedAt = new Date();
    bank.reviewComment = reviewDto.comment || null;
    bank.status = reviewDto.approved
      ? QuestionBankStatus.PUBLISHED
      : QuestionBankStatus.REJECTED;
    return this.bankRepository.save(bank);
  }

  async publish(id: string): Promise<QuestionBank> {
    const bank = await this.findOne(id);
    if (bank.status === QuestionBankStatus.PUBLISHED) {
      return bank;
    }
    if (bank.status !== QuestionBankStatus.REJECTED) {
      throw new ForbiddenException(
        'Only REJECTED status can be re-published',
      );
    }
    bank.status = QuestionBankStatus.PUBLISHED;
    this.logger.log(`QuestionBank ${id} published`);
    return this.bankRepository.save(bank);
  }

  async addItem(
    bankId: string,
    createDto: CreateQuestionBankItemDto,
  ): Promise<QuestionBankItem> {
    if (!createDto.questionText || !createDto.questionText.trim()) {
      throw new BadRequestException('Question text is required');
    }
    await this.findOne(bankId);
    const item = this.itemRepository.create({
      ...createDto,
      bankId,
      questionType: createDto.questionType || QuestionType.SHORT_ANSWER,
      difficulty: createDto.difficulty || QuestionDifficulty.STANDARD,
      dimension: createDto.dimension || QuestionDimension.PROMPT,
      status: QuestionBankItemStatus.PENDING_REVIEW,
    });
    return this.itemRepository.save(item);
  }

  async updateItem(
    bankId: string,
    itemId: string,
    updateDto: UpdateQuestionBankItemDto,
  ): Promise<QuestionBankItem> {
    await this.findOne(bankId);
    const item = await this.itemRepository.findOne({
      where: { id: itemId, bankId },
    });
    if (!item) {
      throw new NotFoundException(`QuestionBankItem with ID "${itemId}" not found`);
    }
    Object.assign(item, updateDto);
    return this.itemRepository.save(item);
  }

  async removeItem(bankId: string, itemId: string): Promise<void> {
    await this.findOne(bankId);
    const item = await this.itemRepository.findOne({
      where: { id: itemId, bankId },
    });
    if (!item) {
      throw new NotFoundException(`QuestionBankItem with ID "${itemId}" not found`);
    }
    await this.itemRepository.remove(item);
  }

  async generateQuestions(
    bankId: string,
    count: number,
    knowledgeBaseContent: string,
    tenantId: string,
  ): Promise<QuestionBankItem[]> {
    const bank = await this.findOne(bankId);

    if (count <= 0 || count > 50) {
      throw new BadRequestException('生成数量必须在 1-50 之间');
    }

    if (!knowledgeBaseContent || knowledgeBaseContent.trim().length < 10) {
      throw new BadRequestException('知识库内容太短，无法生成有效题目');
    }

    this.logger.log(`[generateQuestions] Starting AI generation for bank ${bankId}, count: ${count}`);

    const modelConfig = await this.modelConfigService.findDefaultByType(
      tenantId,
      ModelType.LLM,
    );
    const model = new ChatOpenAI({
      apiKey: modelConfig.apiKey || 'ollama',
      modelName: modelConfig.modelId,
      temperature: 0.7,
      configuration: {
        baseURL: modelConfig.baseUrl || 'https://api.deepseek.com/v1',
      },
    });

    const systemPrompt = `你是一位专业的知识评估专家。请根据提供的知识库片段生成 ${count} 个唯一的测试题目。

### 强制性语言规则：
**必须使用中文 (Simplified Chinese) 进行回复**。即使知识库内容是英文或其他语言，问题(question_text)和关键点(key_points)也必须使用中文。

### 多样性规则：
1. 禁止重复：绝对禁止生成相似的题目
2. 深度挖掘：从不同的角度出题，如流程、限制、优缺点、具体参数等
3. 随机扰动：从不同的逻辑链条出发

### 任务：
请以 JSON 数组格式返回 ${count} 个问题：
[
  {
    "question_text": "问题内容",
    "key_points": ["要点1", "要点2"],
    "difficulty": "STANDARD|ADVANCED|SPECIALIST",
    "dimension": "prompt|llm|ide|devPattern|workCapability",
    "basis": "[n] 引用原文..."
  }
]`;

    const humanMsg = `请使用中文基于以下内容生成题目：\n\n${knowledgeBaseContent}`;

    try {
      const response = await model.invoke([
        new SystemMessage(systemPrompt),
        new HumanMessage(humanMsg),
      ]);

      let parsedQuestions = safeParseJson<any>(response.content as string);
      if (!parsedQuestions) {
        this.logger.error('[generateQuestions] Failed to parse JSON from AI response');
        throw new BadRequestException('Invalid JSON format from AI');
      }

      if (!Array.isArray(parsedQuestions)) {
        parsedQuestions = [parsedQuestions];
      }

      const dimensionMap: Record<string, string> = {
        'prompt': 'PROMPT',
        'llm': 'LLM',
        'ide': 'IDE',
        'devPattern': 'DEV_PATTERN',
        'workCapability': 'WORK_CAPABILITY',
      };

      const difficultyMap: Record<string, string> = {
        'STANDARD': 'STANDARD',
        'ADVANCED': 'ADVANCED',
        'SPECIALIST': 'SPECIALIST',
      };

      const items: QuestionBankItem[] = [];
      for (const q of parsedQuestions) {
        const dimension = dimensionMap[q.dimension?.toLowerCase()] || 'WORK_CAPABILITY';
        const difficulty = difficultyMap[q.difficulty?.toUpperCase()] || 'STANDARD';

        const item = this.itemRepository.create({
          bankId,
          questionText: q.question_text,
          questionType: QuestionType.SHORT_ANSWER,
          keyPoints: q.key_points || [],
          difficulty: difficulty as QuestionDifficulty,
          dimension: dimension as QuestionDimension,
          basis: q.basis,
          status: QuestionBankItemStatus.PENDING_REVIEW,
        });
        items.push(item);
      }

      const savedItems = await this.itemRepository.save(items);

      this.logger.log(`[generateQuestions] Generated ${savedItems.length} questions for bank ${bankId}`);
      return savedItems;
    } catch (error) {
      this.logger.error('[generateQuestions] Error generating questions:', error);
      throw error;
    }
  }

  async selectQuestions(
    bankId: string,
    count: number,
  ): Promise<QuestionBankItem[]> {
    const bank = await this.findOne(bankId);
    if (bank.status !== QuestionBankStatus.PUBLISHED) {
      throw new ForbiddenException(
        'Only PUBLISHED banks can be used for selection',
      );
    }

    const allItems = await this.itemRepository.find({
      where: { bankId },
    });

    if (allItems.length === 0) {
      this.logger.warn(`[selectQuestions] No items found for bank ${bankId}`);
      return [];
    }

    const usedIds = new Set<string>();
    const selected: QuestionBankItem[] = [];
    const availableItems = [...allItems];

    let dimIdx = 0;
    while (selected.length < count && availableItems.length > 0) {
      const dim = DIMENSIONS[dimIdx % DIMENSIONS.length];
      dimIdx++;

      const available = availableItems.filter(
        (i) => i.dimension === dim && !usedIds.has(i.id),
      );

      if (available.length > 0) {
        const idx = Math.floor(Math.random() * available.length);
        const item = available[idx];
        selected.push(item);
        usedIds.add(item.id);
        const actualIdx = availableItems.findIndex(i => i.id === item.id);
        if (actualIdx > -1) {
          availableItems.splice(actualIdx, 1);
        }
      }

      if (dimIdx >= DIMENSIONS.length * 3) {
        break;
      }
    }

    if (selected.length < count && availableItems.length > 0) {
      const shuffled = this.shuffleArray([...availableItems]);
      for (const item of shuffled) {
        if (selected.length >= count) break;
        if (!usedIds.has(item.id)) {
          selected.push(item);
          usedIds.add(item.id);
        }
      }
    }

    if (selected.length < count) {
      const remaining = allItems.filter((i) => !usedIds.has(i.id));
      const shuffled = remaining.sort(() => Math.random() - 0.5);
      for (const item of shuffled) {
        if (selected.length >= count) break;
        selected.push(item);
        usedIds.add(item.id);
      }
    }

    this.logger.log(
      `[selectQuestions] Selected ${selected.length} questions from bank ${bankId}`,
    );
    return selected;
  }

  async batchReviewItems(
    bankId: string,
    itemIds: string[],
    approved: boolean,
    comment?: string,
  ): Promise<QuestionBankItem[]> {
    await this.findOne(bankId);
    
    const items = await this.itemRepository.find({
      where: itemIds.map(id => ({ id, bankId })),
    });

    if (items.length !== itemIds.length) {
      throw new NotFoundException('Some items not found');
    }

    const newStatus = approved 
      ? QuestionBankItemStatus.PUBLISHED 
      : QuestionBankItemStatus.PENDING_REVIEW;

    for (const item of items) {
      item.status = newStatus;
      if (comment) {
        item.basis = item.basis 
          ? `${item.basis}\n[审核意见]: ${comment}` 
          : `[审核意见]: ${comment}`;
      }
    }

    await this.itemRepository.save(items);
    this.logger.log(`[batchReview] ${items.length} items ${approved ? 'approved' : 'rejected'}`);
    return items;
  }

  private shuffleArray<T>(array: T[]): T[] {
    const result = [...array];
    for (let i = result.length - 1; i > 0; i--) {
      const j = Math.floor(Math.random() * (i + 1));
      [result[i], result[j]] = [result[j], result[i]];
    }
    return result;
  }
}