resolver-functions.ts

import { resolve } from 'path';
import type { TSCommon, TSInternal } from './ts-compiler-types';
import type { ProjectLocalResolveHelper } from './util';

/**
 * @internal
 * In a factory because these are shared across both CompilerHost and LanguageService codepaths
 */
export function createResolverFunctions(kwargs: {
  ts: TSCommon;
  host: TSCommon.ModuleResolutionHost;
  cwd: string;
  getCanonicalFileName: (filename: string) => string;
  config: TSCommon.ParsedCommandLine;
  projectLocalResolveHelper: ProjectLocalResolveHelper;
}) {
  const {
    host,
    ts,
    config,
    cwd,
    getCanonicalFileName,
    projectLocalResolveHelper,
  } = kwargs;
  const moduleResolutionCache = ts.createModuleResolutionCache(
    cwd,
    getCanonicalFileName,
    config.options
  );
  const knownInternalFilenames = new Set<string>();
  /** "Buckets" (module directories) whose contents should be marked "internal" */
  const internalBuckets = new Set<string>();

  // Get bucket for a source filename.  Bucket is the containing `./node_modules/*/` directory
  // For '/project/node_modules/foo/node_modules/bar/lib/index.js' bucket is '/project/node_modules/foo/node_modules/bar/'
  // For '/project/node_modules/foo/node_modules/@scope/bar/lib/index.js' bucket is '/project/node_modules/foo/node_modules/@scope/bar/'
  const moduleBucketRe = /.*\/node_modules\/(?:@[^\/]+\/)?[^\/]+\//;
  function getModuleBucket(filename: string) {
    const find = moduleBucketRe.exec(filename);
    if (find) return find[0];
    return '';
  }

  // Mark that this file and all siblings in its bucket should be "internal"
  function markBucketOfFilenameInternal(filename: string) {
    internalBuckets.add(getModuleBucket(filename));
  }

  function isFileInInternalBucket(filename: string) {
    return internalBuckets.has(getModuleBucket(filename));
  }

  function isFileKnownToBeInternal(filename: string) {
    return knownInternalFilenames.has(filename);
  }

  /**
   * If we need to emit JS for a file, force TS to consider it non-external
   */
  const fixupResolvedModule = (
    resolvedModule:
      | TSCommon.ResolvedModule
      | TSCommon.ResolvedTypeReferenceDirective
  ) => {
    const { resolvedFileName } = resolvedModule;
    if (resolvedFileName === undefined) return;
    // [MUST_UPDATE_FOR_NEW_FILE_EXTENSIONS]
    // .ts,.mts,.cts is always switched to internal
    // .js is switched on-demand
    if (
      resolvedModule.isExternalLibraryImport &&
      ((resolvedFileName.endsWith('.ts') &&
        !resolvedFileName.endsWith('.d.ts')) ||
        (resolvedFileName.endsWith('.cts') &&
          !resolvedFileName.endsWith('.d.cts')) ||
        (resolvedFileName.endsWith('.mts') &&
          !resolvedFileName.endsWith('.d.mts')) ||
        isFileKnownToBeInternal(resolvedFileName) ||
        isFileInInternalBucket(resolvedFileName))
    ) {
      resolvedModule.isExternalLibraryImport = false;
    }
    if (!resolvedModule.isExternalLibraryImport) {
      knownInternalFilenames.add(resolvedFileName);
    }
  };
  /*
   * NOTE:
   * Older ts versions do not pass `redirectedReference` nor `options`.
   * We must pass `redirectedReference` to newer ts versions, but cannot rely on `options`, hence the weird argument name
   */
  const resolveModuleNames: TSCommon.LanguageServiceHost['resolveModuleNames'] =
    (
      moduleNames: string[],
      containingFile: string,
      reusedNames: string[] | undefined,
      redirectedReference: TSCommon.ResolvedProjectReference | undefined,
      optionsOnlyWithNewerTsVersions: TSCommon.CompilerOptions,
      containingSourceFile?: TSCommon.SourceFile
    ): (TSCommon.ResolvedModule | undefined)[] => {
      return moduleNames.map((moduleName, i) => {
        const mode = containingSourceFile
          ? (ts as any as TSInternal).getModeForResolutionAtIndex?.(
              containingSourceFile,
              i
            )
          : undefined;
        const { resolvedModule } = ts.resolveModuleName(
          moduleName,
          containingFile,
          config.options,
          host,
          moduleResolutionCache,
          redirectedReference,
          mode
        );
        if (resolvedModule) {
          fixupResolvedModule(resolvedModule);
        }
        return resolvedModule;
      });
    };

  // language service never calls this, but TS docs recommend that we implement it
  const getResolvedModuleWithFailedLookupLocationsFromCache: TSCommon.LanguageServiceHost['getResolvedModuleWithFailedLookupLocationsFromCache'] =
    (
      moduleName,
      containingFile,
      resolutionMode?: TSCommon.ModuleKind.CommonJS | TSCommon.ModuleKind.ESNext
    ): TSCommon.ResolvedModuleWithFailedLookupLocations | undefined => {
      const ret = ts.resolveModuleNameFromCache(
        moduleName,
        containingFile,
        moduleResolutionCache,
        resolutionMode
      );
      if (ret && ret.resolvedModule) {
        fixupResolvedModule(ret.resolvedModule);
      }
      return ret;
    };

  const resolveTypeReferenceDirectives: TSCommon.LanguageServiceHost['resolveTypeReferenceDirectives'] =
    (
      typeDirectiveNames: string[] | readonly TSCommon.FileReference[],
      containingFile: string,
      redirectedReference: TSCommon.ResolvedProjectReference | undefined,
      options: TSCommon.CompilerOptions,
      containingFileMode?: TSCommon.SourceFile['impliedNodeFormat'] | undefined // new impliedNodeFormat is accepted by compilerHost
    ): (TSCommon.ResolvedTypeReferenceDirective | undefined)[] => {
      // Note: seems to be called with empty typeDirectiveNames array for all files.
      // TODO consider using `ts.loadWithTypeDirectiveCache`
      return typeDirectiveNames.map((typeDirectiveName) => {
        // Copy-pasted from TS source:
        const nameIsString = typeof typeDirectiveName === 'string';
        const mode = nameIsString
          ? undefined
          : (ts as any as TSInternal).getModeForFileReference!(
              typeDirectiveName,
              containingFileMode
            );
        const strName = nameIsString
          ? typeDirectiveName
          : typeDirectiveName.fileName.toLowerCase();
        let { resolvedTypeReferenceDirective } =
          ts.resolveTypeReferenceDirective(
            strName,
            containingFile,
            config.options,
            host,
            redirectedReference,
            undefined,
            mode
          );
        if (typeDirectiveName === 'node' && !resolvedTypeReferenceDirective) {
          // Resolve @types/node relative to project first, then __dirname (copy logic from elsewhere / refactor into reusable function)
          let typesNodePackageJsonPath: string | undefined;
          try {
            typesNodePackageJsonPath = projectLocalResolveHelper(
              '@types/node/package.json',
              true
            );
          } catch {} // gracefully do nothing when @types/node is not installed for any reason
          if (typesNodePackageJsonPath) {
            const typeRoots = [resolve(typesNodePackageJsonPath, '../..')];
            ({ resolvedTypeReferenceDirective } =
              ts.resolveTypeReferenceDirective(
                typeDirectiveName,
                containingFile,
                {
                  ...config.options,
                  typeRoots,
                },
                host,
                redirectedReference
              ));
          }
        }
        if (resolvedTypeReferenceDirective) {
          fixupResolvedModule(resolvedTypeReferenceDirective);
        }
        return resolvedTypeReferenceDirective;
      });
    };

  return {
    resolveModuleNames,
    getResolvedModuleWithFailedLookupLocationsFromCache,
    resolveTypeReferenceDirectives,
    isFileKnownToBeInternal,
    markBucketOfFilenameInternal,
  };
}