import { dirname } from 'path';
import * as ts from 'typescript';
import defaultResolver from 'jest-resolve/build/default_resolver';

interface ResolveOptions {
  rootDir: string;
  basedir: string;
  paths: string[];
  moduleDirectory: string[];
  browser: boolean;
  extensions: string[];
}

function getCompilerSetup(rootDir: string) {
  const tsConfigPath =
    ts.findConfigFile(rootDir, ts.sys.fileExists, 'tsconfig.spec.json') ||
    ts.findConfigFile(rootDir, ts.sys.fileExists, 'tsconfig.test.json') ||
    ts.findConfigFile(rootDir, ts.sys.fileExists, 'tsconfig.jest.json');

  if (!tsConfigPath) {
    console.error(
      `Cannot locate a tsconfig.spec.json. Please create one at ${rootDir}/tsconfig.spec.json`
    );
  }

  const readResult = ts.readConfigFile(tsConfigPath, ts.sys.readFile);
  const config = ts.parseJsonConfigFileContent(
    readResult.config,
    ts.sys,
    dirname(tsConfigPath)
  );
  const compilerOptions = config.options;
  const host = ts.createCompilerHost(compilerOptions, true);
  return { compilerOptions, host };
}

let compilerSetup;

module.exports = function(path: string, options: ResolveOptions) {
  // Try to use the defaultResolver
  try {
    return defaultResolver(path, options);
  } catch (e) {
    // Fallback to using typescript
    compilerSetup = compilerSetup || getCompilerSetup(options.rootDir);
    const { compilerOptions, host } = compilerSetup;
    return ts.resolveModuleName(path, options.basedir, compilerOptions, host)
      .resolvedModule.resolvedFileName;
  }
};