transformer.ts

import ts from 'typescript';
import path from 'path';
import { DynamodbRecordTransformer } from './lib/dynamodb_record_transformer';
import { FromDynamodbRecordTransformer } from './lib/from_dynamodb_record_transformer';

export default function transformer(program: ts.Program): ts.TransformerFactory<ts.SourceFile> {
  return (context: ts.TransformationContext) => (file: ts.SourceFile) => visitNodeAndChildren(file, program, context);
}

function visitNodeAndChildren(
  node: ts.SourceFile,
  program: ts.Program,
  context: ts.TransformationContext,
): ts.SourceFile;
function visitNodeAndChildren(
  node: ts.Node,
  program: ts.Program,
  context: ts.TransformationContext,
): ts.Node | undefined;
function visitNodeAndChildren(
  node: ts.Node,
  program: ts.Program,
  context: ts.TransformationContext,
): ts.Node | undefined {
  return ts.visitEachChild(
    visitNode(node, program),
    childNode => visitNodeAndChildren(childNode, program, context),
    context,
  );
}

function visitNode(node: ts.SourceFile, program: ts.Program): ts.SourceFile;
function visitNode(node: ts.Node, program: ts.Program): ts.Node | undefined;
function visitNode(node: ts.Node, program: ts.Program): ts.Node | undefined {
  const typeChecker = program.getTypeChecker();
  if (isDynamodbRecordImportExpression(node)) {
    // remove import expression from transformed code
    return undefined;
  }

  if (isFunctionCallExpression(DynamodbRecordTransformer.funcName, node, typeChecker)) {
    return DynamodbRecordTransformer.visitNode(node, typeChecker);
  }

  if (isFunctionCallExpression(FromDynamodbRecordTransformer.funcName, node, typeChecker)) {
    return FromDynamodbRecordTransformer.visitNode(node, typeChecker);
  }

  return node;
}

const indexJs = path.join(__dirname, 'index.js');
function isDynamodbRecordImportExpression(node: ts.Node): node is ts.ImportDeclaration {
  if (!ts.isImportDeclaration(node)) {
    return false;
  }
  const module = (node.moduleSpecifier as ts.StringLiteral).text;
  try {
    return (
      indexJs ===
      (module.startsWith('.')
        ? require.resolve(path.resolve(path.dirname(node.getSourceFile().fileName), module))
        : require.resolve(module))
    );
  } catch (e) {
    return false;
  }
}

const indexTs = path.join(__dirname, 'index.d.ts');

function isFunctionCallExpression(
  functionName: string,
  node: ts.Node,
  typeChecker: ts.TypeChecker,
): node is ts.CallExpression {
  if (!ts.isCallExpression(node)) {
    return false;
  }
  const declaration = typeChecker.getResolvedSignature(node)?.declaration;
  if (!declaration || ts.isJSDocSignature(declaration) || declaration.name?.getText() !== functionName) {
    return false;
  }
  try {
    // require.resolve is required to resolve symlink.
    // https://github.com/kimamula/ts-transformer-keys/issues/4#issuecomment-643734716
    return require.resolve(declaration.getSourceFile().fileName) === indexTs;
  } catch {
    // declaration.getSourceFile().fileName may not be in Node.js require stack and require.resolve may result in an error.
    // https://github.com/kimamula/ts-transformer-keys/issues/47
    return false;
  }
}