import { Injectable } from '@nestjs/common';
import { AuthUser } from '../../auth/interfaces/auth-user.interface';
import { UserRole } from '../../users/enums/user-role.enum';
import { UpdateReserveDto } from '../../reserves/dto/update-reserve.dto';
import { Reserve } from '../../reserves/entities/reserve.entity';
import { ReserveStatus } from '../../reserves/enums/reserve-status.enum';
import { AuthorizationService } from '../authorization.service';

@Injectable()
export class ReservePolicy {
  constructor(private readonly authorizationService: AuthorizationService) {}

  canCreate(
    user: AuthUser,
    reserve: Pick<Reserve, 'salon' | 'customer'>,
  ): boolean {
    if (this.authorizationService.isAdmin(user)) {
      return true;
    }
    if (user.role === UserRole.SALON) {
      return reserve.salon.ownerId === user.id;
    }
    if (user.role === UserRole.CUSTOMER) {
      return reserve.customer.userId === user.id;
    }
    return false;
  }

  canRead(user: AuthUser, reserve: Reserve): boolean {
    if (this.authorizationService.isAdmin(user)) {
      return true;
    }
    if (user.role === UserRole.SALON) {
      return reserve.salon.ownerId === user.id;
    }
    if (user.role === UserRole.CUSTOMER) {
      return reserve.customer.userId === user.id;
    }
    return false;
  }

  canUpdate(
    user: AuthUser,
    reserve: Reserve,
    updateDto: UpdateReserveDto,
  ): boolean {
    if (!this.canRead(user, reserve)) {
      return false;
    }

    if (this.authorizationService.isAdmin(user)) {
      return true;
    }

    if (user.role === UserRole.SALON) {
      return true;
    }

    if (user.role === UserRole.CUSTOMER) {
      return this.isCustomerCancellationUpdate(updateDto);
    }

    return false;
  }

  private isCustomerCancellationUpdate(updateDto: UpdateReserveDto): boolean {
    const providedFields = (
      Object.keys(updateDto) as (keyof UpdateReserveDto)[]
    ).filter((key) => updateDto[key] !== undefined);

    if (providedFields.length === 0) {
      return false;
    }

    const allowedFields: (keyof UpdateReserveDto)[] = [
      'status',
      'cancellationReason',
    ];

    if (!providedFields.every((field) => allowedFields.includes(field))) {
      return false;
    }

    if (
      updateDto.status !== undefined &&
      updateDto.status !== ReserveStatus.CANCELLED
    ) {
      return false;
    }

    return updateDto.status === ReserveStatus.CANCELLED;
  }
}