ntts/lib/code-refactor/exports-refactor/helpers/export-validator.ts

A CLI tool for refactoring an existing NodeJs application to a fully functional TypeScript application.

import { BinaryExpression, Identifier, SyntaxKind } from 'ts-morph';
import ExportParser from './export-parser';

class ExportValidator {
  private static isExport = (identifiers: (Identifier | null)[]): Identifier[] | undefined => this.isDefaultExport(identifiers)
    || this.isNamedExport(identifiers)
    || this.isElementAccessExport(identifiers);

  static isExportAssigment = (binary: BinaryExpression): Identifier[] | undefined => {
    const left = binary.getLeft().asKind(SyntaxKind.Identifier)
      || binary.getLeft().asKind(SyntaxKind.PropertyAccessExpression)
      || binary.getLeft().asKind(SyntaxKind.ElementAccessExpression);
    if (!binary.getOperatorToken().asKind(SyntaxKind.EqualsToken) || !left) {
      return undefined;
    }
    const identifiers = this.isExport(ExportParser.flatten(left));
    if (identifiers && identifiers[0]) {
      return identifiers;
    }
    return undefined;
  };

  static isNamedExport = (identifiers: (Identifier | null)[]): Identifier[] | undefined => {
    if (identifiers.length > 2
      && identifiers[0] && identifiers[0].getText() === 'module'
      && identifiers[1] && identifiers[1].getText() === 'exports'
      && identifiers[2]
    ) {
      return [identifiers[0], identifiers[1], identifiers[2]];
    }
    if (
      identifiers.length > 1
      && identifiers[0] && identifiers[0].getText() === 'exports'
      && identifiers[1]
    ) {
      return [identifiers[0], identifiers[1]];
    }
    return undefined;
  };

  static isDefaultExport = (identifiers: (Identifier | null)[]): Identifier[] | undefined => {
    if (identifiers.length === 2
      && identifiers[0] && identifiers[0].getText() === 'module'
      && identifiers[1] && identifiers[1].getText() === 'exports'
    ) {
      return [identifiers[0], identifiers[1]];
    }
    if (
      identifiers.length === 1
      && identifiers[0] && identifiers[0].getText() === 'exports'
    ) {
      return [identifiers[0]];
    }
    return undefined;
  };

  static isElementAccessExport = (identifiers: (Identifier | null)[]): Identifier[] | undefined => {
    if (identifiers.length > 2
      && identifiers[0] && identifiers[0].getText() === 'module'
      && identifiers[1] && identifiers[1].getText() === 'exports'
      && !identifiers[2]
    ) {
      return [identifiers[0], identifiers[1]];
    }
    if (identifiers.length > 1
      && identifiers[0] && identifiers[0].getText() === 'exports'
      && !identifiers[1]
    ) {
      return [identifiers[0]];
    }
    return undefined;
  };
}

export default ExportValidator;