export async function main()

in packages/aws-cdk-lib/region-info/build-tools/generate-static-data.ts [26:140]
88 lines of code
21 McCabe index (conditional complexity)

export async function main(): Promise<void> {
  checkRegions(APPMESH_ECR_ACCOUNTS);
  checkRegions(DLC_REPOSITORY_ACCOUNTS);
  checkRegions(ELBV2_ACCOUNTS);
  checkRegions(FIREHOSE_CIDR_BLOCKS);
  checkRegions(ROUTE_53_BUCKET_WEBSITE_ZONE_IDS);
  checkRegionsSubMap(CLOUDWATCH_LAMBDA_INSIGHTS_ARNS);
  checkRegionsSubMap(APPCONFIG_LAMBDA_LAYER_ARNS);

  const lines = [
    "import { Fact, FactName } from './fact';",
    '',
    '/* eslint-disable quote-props */',
    '/* eslint-disable max-len */',
    '',
    '/**',
    ' * Built-in regional information, re-generated by `npm run build`.',
    ' *',
    ` * @generated ${new Date().toISOString()}`,
    ' */',
    'export class BuiltIns {',
    '  /**',
    '   * Registers all the built in regional data in the RegionInfo database.',
    '   */',
    '  public static register(): void {',
  ];

  const defaultMap = 'default';

  for (const region of AWS_REGIONS) {
    let partition = PARTITION_MAP[defaultMap].partition;
    let domainSuffix = PARTITION_MAP[defaultMap].domainSuffix;

    for (const key in PARTITION_MAP) {
      if (region.startsWith(key)) {
        partition = PARTITION_MAP[key].partition;
        domainSuffix = PARTITION_MAP[key].domainSuffix;
      }
    }

    registerFact(region, 'PARTITION', partition);
    registerFact(region, 'DOMAIN_SUFFIX', domainSuffix);

    registerFact(region, 'CDK_METADATA_RESOURCE_AVAILABLE', AWS_CDK_METADATA.has(region) ? 'YES' : 'NO');

    registerFact(region, 'IS_OPT_IN_REGION', partition === 'aws' && after(region, RULE_CLASSIC_PARTITION_BECOMES_OPT_IN) ? 'YES' : 'NO');

    registerFact(region, 'S3_STATIC_WEBSITE_ENDPOINT', before(region, RULE_S3_WEBSITE_REGIONAL_SUBDOMAIN)
      ? `s3-website-${region}.${domainSuffix}`
      : `s3-website.${region}.${domainSuffix}`);

    registerFact(region, 'S3_STATIC_WEBSITE_ZONE_53_HOSTED_ZONE_ID', ROUTE_53_BUCKET_WEBSITE_ZONE_IDS[region] || '');

    registerFact(region, 'EBS_ENV_ENDPOINT_HOSTED_ZONE_ID', EBS_ENV_ENDPOINT_HOSTED_ZONE_IDS[region] || '');

    registerFact(region, 'ELBV2_ACCOUNT', ELBV2_ACCOUNTS[region]);

    registerFact(region, 'DLC_REPOSITORY_ACCOUNT', DLC_REPOSITORY_ACCOUNTS[region]);

    registerFact(region, 'APPMESH_ECR_ACCOUNT', APPMESH_ECR_ACCOUNTS[region]);

    registerFact(region, 'SAML_SIGN_ON_URL', PARTITION_SAML_SIGN_ON_URL[partition] || '');

    registerFact(region, 'LATEST_NODE_RUNTIME', LATEST_NODE_RUNTIME_MAP[partition]);

    const firehoseCidrBlock = FIREHOSE_CIDR_BLOCKS[region];
    if (firehoseCidrBlock) {
      registerFact(region, 'FIREHOSE_CIDR_BLOCK', `${FIREHOSE_CIDR_BLOCKS[region]}/27`);
    }

    const vpcEndpointServiceNamePrefix = `${domainSuffix.split('.').reverse().join('.')}.vpce`;
    registerFact(region, 'VPC_ENDPOINT_SERVICE_NAME_PREFIX', vpcEndpointServiceNamePrefix);

    for (const version in CLOUDWATCH_LAMBDA_INSIGHTS_ARNS) {
      for (const arch in CLOUDWATCH_LAMBDA_INSIGHTS_ARNS[version]) {
        registerFact(region, ['cloudwatchLambdaInsightsVersion', version, arch], CLOUDWATCH_LAMBDA_INSIGHTS_ARNS[version][arch][region]);
      }
    }

    for (const version in APPCONFIG_LAMBDA_LAYER_ARNS) {
      for (const arch in APPCONFIG_LAMBDA_LAYER_ARNS[version]) {
        registerFact(region, ['appConfigLambdaLayerVersion', version, arch], APPCONFIG_LAMBDA_LAYER_ARNS[version][arch][region]);
      }
    }

    for (const type in ADOT_LAMBDA_LAYER_ARNS) {
      for (const version in ADOT_LAMBDA_LAYER_ARNS[type]) {
        for (const arch in ADOT_LAMBDA_LAYER_ARNS[type][version]) {
          registerFact(
            region,
            ['adotLambdaLayer', type, version, arch],
            ADOT_LAMBDA_LAYER_ARNS[type][version][arch][region],
          );
        }
      }
    }

    for (const version in PARAMS_AND_SECRETS_LAMBDA_LAYER_ARNS) {
      for (const arch in PARAMS_AND_SECRETS_LAMBDA_LAYER_ARNS[version]) {
        registerFact(region, ['paramsAndSecretsLambdaLayer', version, arch], PARAMS_AND_SECRETS_LAMBDA_LAYER_ARNS[version][arch][region]);
      }
    }
  }
  lines.push('  }');
  lines.push('');
  lines.push('  private constructor() {}');
  lines.push('}');

  await fs.writeFile(path.resolve(__dirname, '..', 'lib', 'built-ins.generated.ts'), lines.join('\n'));

  function registerFact(region: string, name: string | string[], value: string) {
    const factName = typeof name === 'string' ? name : `${name[0]}(${name.slice(1).map(s => JSON.stringify(s)).join(', ')})`;
    lines.push(`    Fact.register({ region: ${JSON.stringify(region)}, name: FactName.${factName}, value: ${JSON.stringify(value)} });`);
  }
}