Flatten TS Interface chain to string map

flatten.ts

import * as ts from 'typescript';
import * as path from 'path';

function getFlattenedKeys(
  typeChecker: ts.TypeChecker,
  type: ts.Type,
  prefix: string = ''
): string[] {
  const keys: string[] = [];

  const properties = type.getProperties();
  for (const property of properties) {
    const propertyName = property.getName();
    const propertyType = typeChecker.getTypeOfSymbolAtLocation(property, property.valueDeclaration!);

    if (typeChecker.isArrayType(propertyType)) {
      const elementType = typeChecker.getTypeArguments(propertyType as ts.TypeReference)[0];
      const nestedKeys = getFlattenedKeys(
        typeChecker,
        elementType,
        `${prefix}${propertyName}[].`
      );
      keys.push(...nestedKeys);
    } else if (propertyType.isClassOrInterface()) {
      const nestedKeys = getFlattenedKeys(
        typeChecker,
        propertyType,
        `${prefix}${propertyName}.`
      );
      keys.push(...nestedKeys);
    } else {
      keys.push(`${prefix}${propertyName}`);
    }
  }

  return keys;
}

function getAllFlattenedKeys(rootDir: string, rootInterface: string): string[] {
  const program = ts.createProgram([path.join(rootDir, 'dataModel.ts')], {
    target: ts.ScriptTarget.ES2020,
    module: ts.ModuleKind.CommonJS,
  });

  const typeChecker = program.getTypeChecker();
  const sourceFile = program.getSourceFile(path.join(rootDir, 'dataModel.ts'));

  if (!sourceFile) {
    throw new Error('Source file not found');
  }

  const symbol = typeChecker.getSymbolAtLocation(sourceFile);
  if (!symbol) {
    throw new Error('Symbol not found');
  }

  const exportedSymbols = typeChecker.getExportsOfModule(symbol);
  const rootInterfaceSymbol = exportedSymbols.find(s => s.getName() === rootInterface);

  if (!rootInterfaceSymbol) {
    throw new Error(`Root interface '${rootInterface}' not found`);
  }

  const rootType = typeChecker.getDeclaredTypeOfSymbol(rootInterfaceSymbol);
  return getFlattenedKeys(typeChecker, rootType);
}

// Usage
const rootDir = './src/models/';
const flattenedKeys = getAllFlattenedKeys(rootDir, 'DataModel');

const resultMap: any = {};
flattenedKeys.forEach(key => {
  resultMap[key] = null;
});

console.log(resultMap);