createWatchProgram.ts

import debug from 'debug';
import fs from 'fs';
import * as ts from 'typescript';
import { Extra } from '../parser-options';
import { WatchCompilerHostOfConfigFile } from './WatchCompilerHostOfConfigFile';
import {
  canonicalDirname,
  CanonicalPath,
  getTsconfigPath,
  DEFAULT_COMPILER_OPTIONS,
  getCanonicalFileName,
} from './shared';

const log = debug('typescript-eslint:typescript-estree:createWatchProgram');

/**
 * Maps tsconfig paths to their corresponding file contents and resulting watches
 */
const knownWatchProgramMap = new Map<
  CanonicalPath,
  ts.WatchOfConfigFile<ts.SemanticDiagnosticsBuilderProgram>
>();

/**
 * Maps file/folder paths to their set of corresponding watch callbacks
 * There may be more than one per file/folder if a file/folder is shared between projects
 */
const fileWatchCallbackTrackingMap = new Map<
  CanonicalPath,
  Set<ts.FileWatcherCallback>
>();
const folderWatchCallbackTrackingMap = new Map<
  CanonicalPath,
  Set<ts.FileWatcherCallback>
>();

/**
 * Stores the list of known files for each program
 */
const programFileListCache = new Map<CanonicalPath, Set<CanonicalPath>>();

/**
 * Caches the last modified time of the tsconfig files
 */
const tsconfigLastModifiedTimestampCache = new Map<CanonicalPath, number>();

const parsedFilesSeenHash = new Map<CanonicalPath, string>();

/**
 * Clear all of the parser caches.
 * This should only be used in testing to ensure the parser is clean between tests.
 */
function clearCaches(): void {
  knownWatchProgramMap.clear();
  fileWatchCallbackTrackingMap.clear();
  folderWatchCallbackTrackingMap.clear();
  parsedFilesSeenHash.clear();
  programFileListCache.clear();
  tsconfigLastModifiedTimestampCache.clear();
}

function saveWatchCallback(
  trackingMap: Map<string, Set<ts.FileWatcherCallback>>,
) {
  return (
    fileName: string,
    callback: ts.FileWatcherCallback,
  ): ts.FileWatcher => {
    const normalizedFileName = getCanonicalFileName(fileName);
    const watchers = ((): Set<ts.FileWatcherCallback> => {
      let watchers = trackingMap.get(normalizedFileName);
      if (!watchers) {
        watchers = new Set();
        trackingMap.set(normalizedFileName, watchers);
      }
      return watchers;
    })();
    watchers.add(callback);

    return {
      close: (): void => {
        watchers.delete(callback);
      },
    };
  };
}

/**
 * Holds information about the file currently being linted
 */
const currentLintOperationState: { code: string; filePath: CanonicalPath } = {
  code: '',
  filePath: '' as CanonicalPath,
};

/**
 * Appropriately report issues found when reading a config file
 * @param diagnostic The diagnostic raised when creating a program
 */
function diagnosticReporter(diagnostic: ts.Diagnostic): void {
  throw new Error(
    ts.flattenDiagnosticMessageText(diagnostic.messageText, ts.sys.newLine),
  );
}

/**
 * Hash content for compare content.
 * @param content hashed contend
 * @returns hashed result
 */
function createHash(content: string): string {
  // No ts.sys in browser environments.
  if (ts.sys && ts.sys.createHash) {
    return ts.sys.createHash(content);
  }
  return content;
}

/**
 * Calculate project environments using options provided by consumer and paths from config
 * @param code The code being linted
 * @param filePathIn The path of the file being parsed
 * @param extra.tsconfigRootDir The root directory for relative tsconfig paths
 * @param extra.projects Provided tsconfig paths
 * @returns The programs corresponding to the supplied tsconfig paths
 */
function getProgramsForProjects(
  code: string,
  filePathIn: string,
  extra: Extra,
): ts.Program[] {
  const filePath = getCanonicalFileName(filePathIn);
  const results = [];

  // preserve reference to code and file being linted
  currentLintOperationState.code = code;
  currentLintOperationState.filePath = filePath;

  // Update file version if necessary
  const fileWatchCallbacks = fileWatchCallbackTrackingMap.get(filePath);
  const codeHash = createHash(code);
  if (
    parsedFilesSeenHash.get(filePath) !== codeHash &&
    fileWatchCallbacks &&
    fileWatchCallbacks.size > 0
  ) {
    fileWatchCallbacks.forEach(cb =>
      cb(filePath, ts.FileWatcherEventKind.Changed),
    );
  }

  /*
   * before we go into the process of attempting to find and update every program
   * see if we know of a program that contains this file
   */
  for (const rawTsconfigPath of extra.projects) {
    const tsconfigPath = getTsconfigPath(rawTsconfigPath, extra);
    const existingWatch = knownWatchProgramMap.get(tsconfigPath);
    if (!existingWatch) {
      continue;
    }

    let fileList = programFileListCache.get(tsconfigPath);
    let updatedProgram: ts.Program | null = null;
    if (!fileList) {
      updatedProgram = existingWatch.getProgram().getProgram();
      fileList = new Set(
        updatedProgram.getRootFileNames().map(f => getCanonicalFileName(f)),
      );
      programFileListCache.set(tsconfigPath, fileList);
    }

    if (fileList.has(filePath)) {
      log('Found existing program for file. %s', filePath);

      updatedProgram =
        updatedProgram ?? existingWatch.getProgram().getProgram();
      // sets parent pointers in source files
      updatedProgram.getTypeChecker();

      return [updatedProgram];
    }
  }
  log(
    'File did not belong to any existing programs, moving to create/update. %s',
    filePath,
  );

  /*
   * We don't know of a program that contains the file, this means that either:
   * - the required program hasn't been created yet, or
   * - the file is new/renamed, and the program hasn't been updated.
   */
  for (const rawTsconfigPath of extra.projects) {
    const tsconfigPath = getTsconfigPath(rawTsconfigPath, extra);

    const existingWatch = knownWatchProgramMap.get(tsconfigPath);

    if (existingWatch) {
      const updatedProgram = maybeInvalidateProgram(
        existingWatch,
        filePath,
        tsconfigPath,
      );
      if (!updatedProgram) {
        continue;
      }

      // sets parent pointers in source files
      updatedProgram.getTypeChecker();
      results.push(updatedProgram);

      continue;
    }

    const programWatch = createWatchProgram(tsconfigPath, extra);
    const program = programWatch.getProgram().getProgram();

    // cache watch program and return current program
    knownWatchProgramMap.set(tsconfigPath, programWatch);
    results.push(program);
  }

  return results;
}

function createWatchProgram(
  tsconfigPath: string,
  extra: Extra,
): ts.WatchOfConfigFile<ts.SemanticDiagnosticsBuilderProgram> {
  log('Creating watch program for %s.', tsconfigPath);

  // create compiler host
  const watchCompilerHost = ts.createWatchCompilerHost(
    tsconfigPath,
    DEFAULT_COMPILER_OPTIONS,
    ts.sys,
    ts.createSemanticDiagnosticsBuilderProgram,
    diagnosticReporter,
    /*reportWatchStatus*/ () => {},
  ) as WatchCompilerHostOfConfigFile<ts.SemanticDiagnosticsBuilderProgram>;

  // ensure readFile reads the code being linted instead of the copy on disk
  const oldReadFile = watchCompilerHost.readFile;
  watchCompilerHost.readFile = (filePathIn, encoding): string | undefined => {
    const filePath = getCanonicalFileName(filePathIn);
    const fileContent =
      filePath === currentLintOperationState.filePath
        ? currentLintOperationState.code
        : oldReadFile(filePath, encoding);
    if (fileContent) {
      parsedFilesSeenHash.set(filePath, createHash(fileContent));
    }
    return fileContent;
  };

  // ensure process reports error on failure instead of exiting process immediately
  watchCompilerHost.onUnRecoverableConfigFileDiagnostic = diagnosticReporter;

  // ensure process doesn't emit programs
  watchCompilerHost.afterProgramCreate = (program): void => {
    // report error if there are any errors in the config file
    const configFileDiagnostics = program
      .getConfigFileParsingDiagnostics()
      .filter(
        diag =>
          diag.category === ts.DiagnosticCategory.Error && diag.code !== 18003,
      );
    if (configFileDiagnostics.length > 0) {
      diagnosticReporter(configFileDiagnostics[0]);
    }
  };

  /*
   * From the CLI, the file watchers won't matter, as the files will be parsed once and then forgotten.
   * When running from an IDE, these watchers will let us tell typescript about changes.
   *
   * ESLint IDE plugins will send us unfinished file content as the user types (before it's saved to disk).
   * We use the file watchers to tell typescript about this latest file content.
   *
   * When files are created (or renamed), we won't know about them because we have no filesystem watchers attached.
   * We use the folder watchers to tell typescript it needs to go and find new files in the project folders.
   */
  watchCompilerHost.watchFile = saveWatchCallback(fileWatchCallbackTrackingMap);
  watchCompilerHost.watchDirectory = saveWatchCallback(
    folderWatchCallbackTrackingMap,
  );

  // allow files with custom extensions to be included in program (uses internal ts api)
  const oldOnDirectoryStructureHostCreate =
    watchCompilerHost.onCachedDirectoryStructureHostCreate;
  watchCompilerHost.onCachedDirectoryStructureHostCreate = (host): void => {
    const oldReadDirectory = host.readDirectory;
    host.readDirectory = (
      path,
      extensions,
      exclude,
      include,
      depth,
    ): string[] =>
      oldReadDirectory(
        path,
        !extensions ? undefined : extensions.concat(extra.extraFileExtensions),
        exclude,
        include,
        depth,
      );
    oldOnDirectoryStructureHostCreate(host);
  };

  /*
   * The watch change callbacks TS provides us all have a 250ms delay before firing
   * https://github.com/microsoft/TypeScript/blob/b845800bdfcc81c8c72e2ac6fdc2c1df0cdab6f9/src/compiler/watch.ts#L1013
   *
   * We live in a synchronous world, so we can't wait for that.
   * This is a bit of a hack, but it lets us immediately force updates when we detect a tsconfig or directory change
   */
  const oldSetTimeout = watchCompilerHost.setTimeout;
  watchCompilerHost.setTimeout = (cb, ms, ...args): unknown => {
    if (ms === 250) {
      cb();
      return null;
    }

    return oldSetTimeout?.(cb, ms, ...args);
  };

  return ts.createWatchProgram(watchCompilerHost);
}

function hasTSConfigChanged(tsconfigPath: CanonicalPath): boolean {
  const stat = fs.statSync(tsconfigPath);
  const lastModifiedAt = stat.mtimeMs;
  const cachedLastModifiedAt = tsconfigLastModifiedTimestampCache.get(
    tsconfigPath,
  );

  tsconfigLastModifiedTimestampCache.set(tsconfigPath, lastModifiedAt);

  if (cachedLastModifiedAt === undefined) {
    return false;
  }

  return Math.abs(cachedLastModifiedAt - lastModifiedAt) > Number.EPSILON;
}

function maybeInvalidateProgram(
  existingWatch: ts.WatchOfConfigFile<ts.SemanticDiagnosticsBuilderProgram>,
  filePath: CanonicalPath,
  tsconfigPath: CanonicalPath,
): ts.Program | null {
  /*
   * By calling watchProgram.getProgram(), it will trigger a resync of the program based on
   * whatever new file content we've given it from our input.
   */
  let updatedProgram = existingWatch.getProgram().getProgram();

  // In case this change causes problems in larger real world codebases
  // Provide an escape hatch so people don't _have_ to revert to an older version
  if (process.env.TSESTREE_NO_INVALIDATION === 'true') {
    return updatedProgram;
  }

  if (hasTSConfigChanged(tsconfigPath)) {
    /*
     * If the stat of the tsconfig has changed, that could mean the include/exclude/files lists has changed
     * We need to make sure typescript knows this so it can update appropriately
     */
    log('tsconfig has changed - triggering program update. %s', tsconfigPath);
    fileWatchCallbackTrackingMap
      .get(tsconfigPath)!
      .forEach(cb => cb(tsconfigPath, ts.FileWatcherEventKind.Changed));

    // tsconfig change means that the file list more than likely changed, so clear the cache
    programFileListCache.delete(tsconfigPath);
  }

  let sourceFile = updatedProgram.getSourceFile(filePath);
  if (sourceFile) {
    return updatedProgram;
  }
  /*
   * Missing source file means our program's folder structure might be out of date.
   * So we need to tell typescript it needs to update the correct folder.
   */
  log('File was not found in program - triggering folder update. %s', filePath);

  // Find the correct directory callback by climbing the folder tree
  const currentDir = canonicalDirname(filePath);
  let current: CanonicalPath | null = null;
  let next = currentDir;
  let hasCallback = false;
  while (current !== next) {
    current = next;
    const folderWatchCallbacks = folderWatchCallbackTrackingMap.get(current);
    if (folderWatchCallbacks) {
      folderWatchCallbacks.forEach(cb => {
        cb(currentDir, ts.FileWatcherEventKind.Changed);
        cb(current!, ts.FileWatcherEventKind.Changed);
      });
      hasCallback = true;
      break;
    }

    next = canonicalDirname(current);
  }
  if (!hasCallback) {
    /*
     * No callback means the paths don't matchup - so no point returning any program
     * this will signal to the caller to skip this program
     */
    log('No callback found for file, not part of this program. %s', filePath);
    return null;
  }

  // directory update means that the file list more than likely changed, so clear the cache
  programFileListCache.delete(tsconfigPath);

  // force the immediate resync
  updatedProgram = existingWatch.getProgram().getProgram();
  sourceFile = updatedProgram.getSourceFile(filePath);
  if (sourceFile) {
    return updatedProgram;
  }

  /*
   * At this point we're in one of two states:
   * - The file isn't supposed to be in this program due to exclusions
   * - The file is new, and was renamed from an old, included filename
   *
   * For the latter case, we need to tell typescript that the old filename is now deleted
   */
  log(
    'File was still not found in program after directory update - checking file deletions. %s',
    filePath,
  );

  const rootFilenames = updatedProgram.getRootFileNames();
  // use find because we only need to "delete" one file to cause typescript to do a full resync
  const deletedFile = rootFilenames.find(file => !fs.existsSync(file));
  if (!deletedFile) {
    // There are no deleted files, so it must be the former case of the file not belonging to this program
    return null;
  }

  const fileWatchCallbacks = fileWatchCallbackTrackingMap.get(
    getCanonicalFileName(deletedFile),
  );
  if (!fileWatchCallbacks) {
    // shouldn't happen, but just in case
    log('Could not find watch callbacks for root file. %s', deletedFile);
    return updatedProgram;
  }

  log('Marking file as deleted. %s', deletedFile);
  fileWatchCallbacks.forEach(cb =>
    cb(deletedFile, ts.FileWatcherEventKind.Deleted),
  );

  // deleted files means that the file list _has_ changed, so clear the cache
  programFileListCache.delete(tsconfigPath);

  updatedProgram = existingWatch.getProgram().getProgram();
  sourceFile = updatedProgram.getSourceFile(filePath);
  if (sourceFile) {
    return updatedProgram;
  }

  log(
    'File was still not found in program after deletion check, assuming it is not part of this program. %s',
    filePath,
  );
  return null;
}

export { clearCaches, createWatchProgram, getProgramsForProjects };