import { Injectable, NotFoundException } from '@nestjs/common';
import { InjectModel } from '@nestjs/mongoose';
import { Model } from 'mongoose';
import { Form, FormDocument } from './entity/form.entity';
import { CreateFormDto } from './dto/create-form.dto';
import { UpdateFormDto } from './dto/update-form.dto';
import { PaginateModel } from '../participant/participant.service';

@Injectable()
export class FormService {
  constructor(
    @InjectModel(Form.name)
    private readonly formModel: PaginateModel<FormDocument>,
  ) {}

  async create(data: CreateFormDto): Promise<Form> {
    const form = new this.formModel({
      ...data,
      id: data.id || undefined, // Let BaseEntity generate UUID if not provided
      metadata: data.metadata || { entries: [] },
    });
    return form.save();
  }

  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;
  }> {
    // Selects all fields from the Form entity for the response
    return this.formModel.paginate(
      {},
      { page, limit, lean: true },
    );
  }

  async findById(id: string): Promise<Form | null> {
    const form = await this.formModel
      .findOne({ id })
      .lean()
      .exec();
    if (!form) {
      throw new NotFoundException(`Form with ID "${id}" not found`);
    }
    return form;
  }

  async update(
    id: string,
    data: UpdateFormDto,
  ): Promise<Form | null> {
    const updatedForm = await this.formModel
      .findOneAndUpdate(
        { id },
        { $set: { ...data, updatedAt: new Date() } },
        { new: true },
      )
      .lean()
      .exec();

    if (!updatedForm) {
      throw new NotFoundException(`Form with ID "${id}" not found`);
    }
    return updatedForm;
  }

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