import { ApiPropertyOptional } from '@nestjs/swagger';
import { IsOptional, IsString, MaxLength } from 'class-validator';

/**
 * Edit a departure's operational run identifiers. Both fields are optional so
 * either can be corrected alone; the service rejects a body carrying neither,
 * so an empty request cannot write an audit row for a no-op.
 *
 * Sending an empty string clears the field; omitting it leaves it unchanged.
 */
export class UpdateScheduleTrainNumberDto {
  @ApiPropertyOptional({
    example: '9201',
    description: "Run number for this departure. Empty string clears it.",
    maxLength: 20,
  })
  @IsOptional()
  @IsString()
  @MaxLength(20)
  trainNumber?: string;

  @ApiPropertyOptional({
    example: 'V-2026-014',
    description: 'Voyage (sailing) number for this departure. Empty string clears it.',
    maxLength: 20,
  })
  @IsOptional()
  @IsString()
  @MaxLength(20)
  voyageNumber?: string;

  @ApiPropertyOptional({
    description: 'Why the numbers changed — kept on the audit trail.',
    maxLength: 500,
  })
  @IsOptional()
  @IsString()
  @MaxLength(500)
  reason?: string;
}