import { Injectable, NotFoundException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { Question } from './entity/question.entity';
import { CreateQuestionDto } from './dto/create-question.dto';
import { UpdateQuestionDto } from './dto/update-question.dto';

@Injectable()
export class QuestionService {
  constructor(
    @InjectRepository(Question)
    private readonly questionRepo: Repository<Question>,
  ) {}

  async create(data: CreateQuestionDto): Promise<Question> {
    const question = this.questionRepo.create(data);
    return this.questionRepo.save(question);
  }

  async findAll(page = 1, limit = 10) {
    const [docs, totalDocs] = await this.questionRepo.findAndCount({
      skip: (page - 1) * limit,
      take: limit,
    });

    const totalPages = Math.ceil(totalDocs / limit);
    return {
      docs,
      totalDocs,
      limit,
      page,
      totalPages,
      hasNextPage: page < totalPages,
      hasPrevPage: page > 1,
      nextPage: page < totalPages ? page + 1 : null,
      prevPage: page > 1 ? page - 1 : null,
    };
  }

  async findById(id: string): Promise<Question | null> {
    const question = await this.questionRepo.findOneBy({ id });
    if (!question) {
      throw new NotFoundException(`Question with ID "${id}" not found`);
    }
    return question;
  }

  async update(id: string, data: UpdateQuestionDto): Promise<Question | null> {
    await this.questionRepo.update(id, data);
    return this.findById(id);
  }

  async remove(id: string): Promise<void> {
    const result = await this.questionRepo.delete(id);
    if (result.affected === 0) {
      throw new NotFoundException(`Question with ID "${id}" not found`);
    }
  }
}