import { Injectable, NotFoundException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { Form } from './entity/form.entity';
import { CreateFormDto } from './dto/create-form.dto';
import { UpdateFormDto } from './dto/update-form.dto';

@Injectable()
export class FormService {
  constructor(
    @InjectRepository(Form)
    private readonly formRepo: Repository<Form>,
  ) {}

  async create(data: CreateFormDto): Promise<Form> {
    const form = this.formRepo.create({
      ...data,
    });
    return await this.formRepo.save(form);
  }

  async findAll(
    page = 1,
    limit = 10,
  ): Promise<{
    docs: Form[];
    totalDocs: number;
    limit: number;
    page: number;
    totalPages: number;
    hasNextPage: boolean;
    hasPrevPage: boolean;
    nextPage: number | null;
    prevPage: number | null;
  }> {
    const [docs, totalDocs] = await this.formRepo.findAndCount({
      skip: (page - 1) * limit,
      take: limit,
      relations: [
        'pages',
        'pages.formSections',
        'pages.formSections.attachments',
        'pages.formSections.questions',
        'pages.formSections.questions.options',
        'pages.formSections.questions.answers',
        'participants', // Load participants
      ], // Load nested relations
    });

    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<Form | null> {
    const form = await this.formRepo.findOne({
      where: { id },
      relations: [
        'pages',
        'pages.formSections',
        'pages.formSections.attachments',
        'pages.formSections.questions',
        'pages.formSections.questions.options',
        'pages.formSections.questions.answers',
        'participants',
      ], // Load nested relations
    });
    if (!form) {
      throw new NotFoundException(`Form with ID "${id}" not found`);
    }
    return form;
  }

  async update(
    id: string,
    data: UpdateFormDto,
  ): Promise<Form | null> {
    const result = await this.formRepo.update(
      { id },
      { ...data, updatedAt: new Date() },
    );

    if (result.affected === 0) {
      throw new NotFoundException(`Form with ID "${id}" not found`);
    }
    return await this.findById(id);
  }

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