import { plainToInstance } from 'class-transformer';
import {
  IsString,
  IsUrl,
  IsInt,
  Min,
  Max,
  IsOptional,
  validateSync,
  IsEnum,
  IsNumber,
  IsBoolean,
} from 'class-validator';

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

class EnvironmentVariables {
  @IsEnum(NodeEnv)
  @IsOptional()
  NODE_ENV: NodeEnv = NodeEnv.Development;

  // @IsString()
  // MYSQL_URL!: string;

  @IsString()
  MONGO_URL!: string;

  @IsString()
  JWT_SECRET!: string;

  @IsInt()
  @Min(60)
  @Max(86400)
  @IsOptional()
  JWT_EXPIRES_IN_SECONDS: number = 43200; // 12 hours

  @IsString()
  @IsOptional()
  ENCRYPTION_KEY?: string;

  @IsInt()
  @Min(1024)
  @Max(65535)
  @IsOptional()
  PORT: number = 3000;

  // ===== Redis Config =====

  @IsString()
  REDIS_HOST!: string;

  @IsNumber()
  REDIS_PORT!: number;

  @IsOptional()
  @IsString()
  REDIS_PASSWORD?: string; // empty string is allowed

  @IsOptional()
  @IsNumber()
  REDIS_DB?: number;

  @IsOptional()
  @IsString()
  REDIS_KEY_PREFIX?: string;

  // If you later add TLS:
  @IsOptional()
  @IsBoolean()
  REDIS_TLS?: boolean;
}

export function validateEnvironment(config: Record<string, unknown>) {
  const validatedConfig = plainToInstance(EnvironmentVariables, config, {
    enableImplicitConversion: true,
  });

  const errors = validateSync(validatedConfig, {
    skipMissingProperties: false,
  });

  if (errors.length > 0) {
    const messages = errors
      .map((error) => {
        const constraints = error.constraints;
        return constraints ? Object.values(constraints).join(', ') : '';
      })
      .filter(Boolean);

    throw new Error(`Environment validation failed:\n${messages.join('\n')}`);
  }

  return validatedConfig;
}