ntts/lib/code-refactor/imports-refactor/import-clause-refactor/import-clause-refactor.ts

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

import {
  ImportDeclaration, ImportSpecifier, SourceFile, VariableDeclarationKind,
} from 'ts-morph';
import ImportCreator from '../../helpers/import-creator/import-creator';
import VariableNameGenerator from '../../helpers/variable-name-generator/variable-name-generator';

class ImportClauseRefactor {
  static refactorImportClause = (
    importStatement: ImportDeclaration,
    usedImportNames: string[],
    sourceFile: SourceFile,
  ): string[] => {
    const moduleSpecifier = importStatement.getModuleSpecifierValue();
    const importedSourceFile = importStatement.isModuleSpecifierRelative() && importStatement.getModuleSpecifierSourceFile();
    if (importedSourceFile) {
      this.refactorDefaultImport(importStatement, moduleSpecifier, importedSourceFile, sourceFile);
      return this.refactorNamedImports(importStatement, usedImportNames, importedSourceFile, sourceFile);
    }
    return usedImportNames;
  };

  private static refactorDefaultImport = (
    importStatement: ImportDeclaration,
    moduleSpecifier: string,
    importedSourceFile: SourceFile,
    sourceFile: SourceFile,
  ) => {
    const defaultImport = importStatement.getDefaultImport()?.getText();
    if (defaultImport && !this.hasDefaultExport(importedSourceFile)) {
      if (importStatement.getNamedImports().length > 0) {
        ImportCreator.addNamespaceImport(defaultImport, moduleSpecifier, sourceFile);
        importStatement.removeDefaultImport();
      } else {
        importStatement.removeDefaultImport().setNamespaceImport(defaultImport);
      }
    }
  };

  private static refactorNamedImports = (
    importStatement: ImportDeclaration,
    usedImportNames: string[],
    importedSourceFile: SourceFile,
    sourceFile: SourceFile,
  ): string[] => {
    const namedImports = importStatement.getNamedImports();
    if (namedImports.length > 0) {
      const exportedList = this.getExportedList(importedSourceFile);
      const defaultImports = namedImports.filter((namedImport) => !exportedList.includes(namedImport.getName()));
      const defaultImportName = importStatement.getDefaultImport()?.getText();

      if (defaultImportName && defaultImports.length > 0) {
        this.createObjectDestructuring(importStatement, defaultImports, defaultImportName, sourceFile);
        defaultImports.forEach((d) => d.remove());
      }
      if (!defaultImportName && defaultImports.length > 0) {
        const importName = VariableNameGenerator.variableNameFromImportId(importStatement.getModuleSpecifierValue());
        const initializer = VariableNameGenerator.getUsableVariableName(importName, usedImportNames);
        importStatement.setDefaultImport(initializer);
        this.createObjectDestructuring(importStatement, defaultImports, initializer, sourceFile);
        defaultImports.forEach((d) => d.remove());
        return usedImportNames.concat(importName);
      }
    }
    return usedImportNames;
  };

  private static getExportedList = (importedSourceFile: SourceFile): string[] => importedSourceFile
    .getExportDeclarations()
    .reduce((exportedNames: string[], exportDeclaration) => {
      const names = exportDeclaration
        .getNamedExports()
        .map((named) => named.getAliasNode()?.getText() || named.getName());
      return exportedNames.concat(...names);
    }, []);

  private static createObjectDestructuring = (
    importStatement: ImportDeclaration,
    defaultImports: ImportSpecifier[],
    initializer: string,
    sourceFile: SourceFile,
  ) => {
    const index = importStatement.getChildIndex();
    const objectDestructuring = defaultImports.map((i) => (i.getAliasNode() ? `${i.getName()}: ${i.getAliasNode()}` : i.getName())).join(', ');
    sourceFile.insertVariableStatement(index + 1, {
      declarationKind: VariableDeclarationKind.Const,
      declarations: [{ name: `{ ${objectDestructuring} }`, initializer }],
    });
  };

  private static hasDefaultExport = (sourceFile: SourceFile): boolean => !!sourceFile.getDefaultExportSymbol();
}

export default ImportClauseRefactor;