import { plainToInstance, Type } from 'class-transformer';
import {
  IsEnum,
  IsInt,
  IsNotEmpty,
  IsOptional,
  IsString,
  Max,
  Min,
  validateSync,
} from 'class-validator';

export enum NodeEnv {
  Development = 'development',
  Production = 'production',
  Test = 'test',
}

/**
 * Schéma des variables d'environnement. Validé au démarrage via `validateEnv`
 * (branché sur `ConfigModule.forRoot({ validate })`) : l'app refuse de démarrer
 * si une variable requise manque ou est mal typée, plutôt que d'utiliser
 * silencieusement des valeurs par défaut (ex. credentials DB).
 */
export class EnvironmentVariables {
  @IsEnum(NodeEnv)
  @IsOptional()
  NODE_ENV: NodeEnv = NodeEnv.Development;

  @IsString()
  @IsNotEmpty()
  DATABASE_HOST!: string;

  @Type(() => Number)
  @IsInt()
  @Min(1)
  @Max(65535)
  DATABASE_PORT!: number;

  @IsString()
  @IsNotEmpty()
  DATABASE_USER!: string;

  @IsString()
  @IsNotEmpty()
  DATABASE_PASSWORD!: string;

  @IsString()
  @IsNotEmpty()
  DATABASE_NAME!: string;

  @Type(() => Number)
  @IsInt()
  @Min(1)
  @Max(65535)
  @IsOptional()
  PORT = 3000;

  @IsString()
  @IsOptional()
  DOCS_OUTPUT_DIR?: string;
}

export function validateEnv(config: Record<string, unknown>): EnvironmentVariables {
  const validated = plainToInstance(EnvironmentVariables, config, {
    enableImplicitConversion: true,
  });
  const errors = validateSync(validated, { skipMissingProperties: false });
  if (errors.length > 0) {
    const details = errors
      .map((e) => Object.values(e.constraints ?? {}).join(', '))
      .join('\n  - ');
    throw new Error(`Configuration d'environnement invalide:\n  - ${details}`);
  }
  return validated;
}