TypeScript/src/compiler/watch.ts

import {
    addRange,
    BuilderProgram,
    CancellationToken,
    chainDiagnosticMessages,
    CharacterCodes,
    combinePaths,
    CompilerHost,
    CompilerOptions,
    contains,
    convertToRelativePath,
    copyProperties,
    countWhere,
    createCompilerDiagnostic,
    createEmitAndSemanticDiagnosticsBuilderProgram,
    createGetCanonicalFileName,
    createGetSourceFile,
    createIncrementalCompilerHost,
    createIncrementalProgram,
    CreateProgram,
    createWriteFileMeasuringIO,
    CustomTransformers,
    Debug,
    Diagnostic,
    DiagnosticAndArguments,
    DiagnosticCategory,
    DiagnosticMessage,
    DiagnosticMessageChain,
    DiagnosticReporter,
    Diagnostics,
    DirectoryStructureHost,
    EmitAndSemanticDiagnosticsBuilderProgram,
    EmitResult,
    emptyArray,
    endsWith,
    ExitStatus,
    ExtendedConfigCacheEntry,
    Extension,
    externalHelpersModuleNameText,
    FileExtensionInfo,
    fileExtensionIs,
    FileIncludeKind,
    FileIncludeReason,
    FileWatcher,
    filter,
    find,
    findIndex,
    flattenDiagnosticMessageText,
    forEach,
    ForegroundColorEscapeSequences,
    formatColorAndReset,
    formatDiagnostic,
    FormatDiagnosticsHost,
    formatDiagnosticsWithColorAndContext,
    generateDjb2Hash,
    getDefaultLibFileName,
    getDirectoryPath,
    getEmitDeclarations,
    getEmitScriptTarget,
    getImpliedNodeFormatForEmitWorker,
    getLineAndCharacterOfPosition,
    getNameOfScriptTarget,
    getNewLineCharacter,
    getNormalizedAbsolutePath,
    getParsedCommandLineOfConfigFile,
    getPatternFromSpec,
    getReferencedFileLocation,
    getRegexFromPattern,
    getRelativePathFromDirectory,
    getWatchFactory,
    HasCurrentDirectory,
    isExternalOrCommonJsModule,
    isLineBreak,
    isReferencedFile,
    isReferenceFileLocation,
    isString,
    last,
    maxBy,
    maybeBind,
    memoize,
    ModuleKind,
    noop,
    normalizePath,
    packageIdToString,
    ParseConfigFileHost,
    ParsedCommandLine,
    pathIsAbsolute,
    Program,
    ProgramHost,
    ProjectReference,
    ReportEmitErrorSummary,
    ReportFileInError,
    sortAndDeduplicateDiagnostics,
    SortedReadonlyArray,
    SourceFile,
    sourceMapCommentRegExp,
    sourceMapCommentRegExpDontCareLineStart,
    sys,
    System,
    WatchCompilerHost,
    WatchCompilerHostOfConfigFile,
    WatchCompilerHostOfFilesAndCompilerOptions,
    WatchFactory,
    WatchFactoryHost,
    WatchHost,
    WatchLogLevel,
    WatchOptions,
    WatchStatusReporter,
    whitespaceOrMapCommentRegExp,
    WriteFileCallback,
} from "./_namespaces/ts.js";

const sysFormatDiagnosticsHost: FormatDiagnosticsHost | undefined = sys ? {
    getCurrentDirectory: () => sys.getCurrentDirectory(),
    getNewLine: () => sys.newLine,
    getCanonicalFileName: createGetCanonicalFileName(sys.useCaseSensitiveFileNames),
} : undefined;

/**
 * Create a function that reports error by writing to the system and handles the formatting of the diagnostic
 *
 * @internal
 */
export function createDiagnosticReporter(system: System, pretty?: boolean): DiagnosticReporter {
    const host: FormatDiagnosticsHost = system === sys && sysFormatDiagnosticsHost ? sysFormatDiagnosticsHost : {
        getCurrentDirectory: () => system.getCurrentDirectory(),
        getNewLine: () => system.newLine,
        getCanonicalFileName: createGetCanonicalFileName(system.useCaseSensitiveFileNames),
    };
    if (!pretty) {
        return diagnostic => system.write(formatDiagnostic(diagnostic, host));
    }

    const diagnostics: Diagnostic[] = new Array(1);
    return diagnostic => {
        diagnostics[0] = diagnostic;
        system.write(formatDiagnosticsWithColorAndContext(diagnostics, host) + host.getNewLine());
        diagnostics[0] = undefined!; // TODO: GH#18217
    };
}

/**
 * @returns Whether the screen was cleared.
 */
function clearScreenIfNotWatchingForFileChanges(system: System, diagnostic: Diagnostic, options: CompilerOptions): boolean {
    if (
        system.clearScreen &&
        !options.preserveWatchOutput &&
        !options.extendedDiagnostics &&
        !options.diagnostics &&
        contains(screenStartingMessageCodes, diagnostic.code)
    ) {
        system.clearScreen();
        return true;
    }

    return false;
}

const screenStartingMessageCodes: number[] = [
    Diagnostics.Starting_compilation_in_watch_mode.code,
    Diagnostics.File_change_detected_Starting_incremental_compilation.code,
];

function getPlainDiagnosticFollowingNewLines(diagnostic: Diagnostic, newLine: string): string {
    return contains(screenStartingMessageCodes, diagnostic.code)
        ? newLine + newLine
        : newLine;
}

/**
 * Get locale specific time based on whether we are in test mode
 *
 * @internal
 */
export function getLocaleTimeString(system: System): string {
    return !system.now ?
        new Date().toLocaleTimeString() :
        // On some systems / builds of Node, there's a non-breaking space between the time and AM/PM.
        // This branch is solely for testing, so just switch it to a normal space for baseline stability.
        // See:
        //     - https://github.com/nodejs/node/issues/45171
        //     - https://github.com/nodejs/node/issues/45753
        system.now().toLocaleTimeString("en-US", { timeZone: "UTC" }).replace("\u202f", " ");
}

/**
 * Create a function that reports watch status by writing to the system and handles the formatting of the diagnostic
 *
 * @internal
 */
export function createWatchStatusReporter(system: System, pretty?: boolean): WatchStatusReporter {
    return pretty ?
        (diagnostic, newLine, options) => {
            clearScreenIfNotWatchingForFileChanges(system, diagnostic, options);
            let output = `[${formatColorAndReset(getLocaleTimeString(system), ForegroundColorEscapeSequences.Grey)}] `;
            output += `${flattenDiagnosticMessageText(diagnostic.messageText, system.newLine)}${newLine + newLine}`;
            system.write(output);
        } :
        (diagnostic, newLine, options) => {
            let output = "";

            if (!clearScreenIfNotWatchingForFileChanges(system, diagnostic, options)) {
                output += newLine;
            }

            output += `${getLocaleTimeString(system)} - `;
            output += `${flattenDiagnosticMessageText(diagnostic.messageText, system.newLine)}${getPlainDiagnosticFollowingNewLines(diagnostic, newLine)}`;

            system.write(output);
        };
}

/**
 * Parses config file using System interface
 *
 * @internal
 */
export function parseConfigFileWithSystem(configFileName: string, optionsToExtend: CompilerOptions, extendedConfigCache: Map<string, ExtendedConfigCacheEntry> | undefined, watchOptionsToExtend: WatchOptions | undefined, system: System, reportDiagnostic: DiagnosticReporter): ParsedCommandLine | undefined {
    const host: ParseConfigFileHost = system as any;
    host.onUnRecoverableConfigFileDiagnostic = diagnostic => reportUnrecoverableDiagnostic(system, reportDiagnostic, diagnostic);
    const result = getParsedCommandLineOfConfigFile(configFileName, optionsToExtend, host, extendedConfigCache, watchOptionsToExtend);
    host.onUnRecoverableConfigFileDiagnostic = undefined!; // TODO: GH#18217
    return result;
}

/** @internal */
export function getErrorCountForSummary(diagnostics: readonly Diagnostic[]): number {
    return countWhere(diagnostics, diagnostic => diagnostic.category === DiagnosticCategory.Error);
}

/** @internal */
export function getFilesInErrorForSummary(diagnostics: readonly Diagnostic[]): (ReportFileInError | undefined)[] {
    const filesInError = filter(diagnostics, diagnostic => diagnostic.category === DiagnosticCategory.Error)
        .map(
            errorDiagnostic => {
                if (errorDiagnostic.file === undefined) return;
                return `${errorDiagnostic.file.fileName}`;
            },
        );
    return filesInError.map(fileName => {
        if (fileName === undefined) {
            return undefined;
        }

        const diagnosticForFileName = find(diagnostics, diagnostic => diagnostic.file !== undefined && diagnostic.file.fileName === fileName);

        if (diagnosticForFileName !== undefined) {
            const { line } = getLineAndCharacterOfPosition(diagnosticForFileName.file!, diagnosticForFileName.start!);
            return {
                fileName,
                line: line + 1,
            };
        }
    });
}

/** @internal */
export function getWatchErrorSummaryDiagnosticMessage(errorCount: number): DiagnosticMessage {
    return errorCount === 1 ?
        Diagnostics.Found_1_error_Watching_for_file_changes :
        Diagnostics.Found_0_errors_Watching_for_file_changes;
}

function prettyPathForFileError(error: ReportFileInError, cwd: string) {
    const line = formatColorAndReset(":" + error.line, ForegroundColorEscapeSequences.Grey);
    if (pathIsAbsolute(error.fileName) && pathIsAbsolute(cwd)) {
        return getRelativePathFromDirectory(cwd, error.fileName, /*ignoreCase*/ false) + line;
    }

    return error.fileName + line;
}

/** @internal */
export function getErrorSummaryText(
    errorCount: number,
    filesInError: readonly (ReportFileInError | undefined)[],
    newLine: string,
    host: HasCurrentDirectory,
): string {
    if (errorCount === 0) return "";
    const nonNilFiles = filesInError.filter(fileInError => fileInError !== undefined);
    const distinctFileNamesWithLines = nonNilFiles.map(fileInError => `${fileInError.fileName}:${fileInError.line}`)
        .filter((value, index, self) => self.indexOf(value) === index);

    const firstFileReference = nonNilFiles[0] && prettyPathForFileError(nonNilFiles[0], host.getCurrentDirectory());

    let messageAndArgs: DiagnosticAndArguments;
    if (errorCount === 1) {
        messageAndArgs = filesInError[0] !== undefined ? [Diagnostics.Found_1_error_in_0, firstFileReference] : [Diagnostics.Found_1_error];
    }
    else {
        messageAndArgs = distinctFileNamesWithLines.length === 0 ? [Diagnostics.Found_0_errors, errorCount] :
            distinctFileNamesWithLines.length === 1 ? [Diagnostics.Found_0_errors_in_the_same_file_starting_at_Colon_1, errorCount, firstFileReference] :
            [Diagnostics.Found_0_errors_in_1_files, errorCount, distinctFileNamesWithLines.length];
    }

    const d = createCompilerDiagnostic(...messageAndArgs);
    const suffix = distinctFileNamesWithLines.length > 1 ? createTabularErrorsDisplay(nonNilFiles, host) : "";
    return `${newLine}${flattenDiagnosticMessageText(d.messageText, newLine)}${newLine}${newLine}${suffix}`;
}

function createTabularErrorsDisplay(filesInError: (ReportFileInError | undefined)[], host: HasCurrentDirectory) {
    const distinctFiles = filesInError.filter((value, index, self) => index === self.findIndex(file => file?.fileName === value?.fileName));
    if (distinctFiles.length === 0) return "";

    const numberLength = (num: number) => Math.log(num) * Math.LOG10E + 1;
    const fileToErrorCount = distinctFiles.map(file => ([file, countWhere(filesInError, fileInError => fileInError!.fileName === file!.fileName)] as const));
    const maxErrors = maxBy(fileToErrorCount, 0, value => value[1]);

    const headerRow = Diagnostics.Errors_Files.message;
    const leftColumnHeadingLength = headerRow.split(" ")[0].length;
    const leftPaddingGoal = Math.max(leftColumnHeadingLength, numberLength(maxErrors));
    const headerPadding = Math.max(numberLength(maxErrors) - leftColumnHeadingLength, 0);

    let tabularData = "";
    tabularData += " ".repeat(headerPadding) + headerRow + "\n";
    fileToErrorCount.forEach(row => {
        const [file, errorCount] = row;
        const errorCountDigitsLength = Math.log(errorCount) * Math.LOG10E + 1 | 0;
        const leftPadding = errorCountDigitsLength < leftPaddingGoal ?
            " ".repeat(leftPaddingGoal - errorCountDigitsLength)
            : "";

        const fileRef = prettyPathForFileError(file!, host.getCurrentDirectory());
        tabularData += `${leftPadding}${errorCount}  ${fileRef}\n`;
    });

    return tabularData;
}

/** @internal */
export function isBuilderProgram<T extends BuilderProgram>(program: Program | BuilderProgram): program is T {
    return !!(program as T).state;
}

function listFiles<T extends BuilderProgram>(program: Program | T, write: (s: string) => void) {
    const options = program.getCompilerOptions();
    if (options.explainFiles) {
        explainFiles(isBuilderProgram(program) ? program.getProgram() : program, write);
    }
    else if (options.listFiles || options.listFilesOnly) {
        forEach(program.getSourceFiles(), file => {
            write(file.fileName);
        });
    }
}

/** @internal */
export function explainFiles(program: Program, write: (s: string) => void): void {
    const reasons = program.getFileIncludeReasons();
    const relativeFileName = (fileName: string) => convertToRelativePath(fileName, program.getCurrentDirectory(), program.getCanonicalFileName);
    for (const file of program.getSourceFiles()) {
        write(`${toFileName(file, relativeFileName)}`);
        reasons.get(file.path)?.forEach(reason => write(`  ${fileIncludeReasonToDiagnostics(program, reason, relativeFileName).messageText}`));
        explainIfFileIsRedirectAndImpliedFormat(file, program.getCompilerOptionsForFile(file), relativeFileName)?.forEach(d => write(`  ${d.messageText}`));
    }
}

/** @internal */
export function explainIfFileIsRedirectAndImpliedFormat(
    file: SourceFile,
    options: CompilerOptions,
    fileNameConvertor?: (fileName: string) => string,
): DiagnosticMessageChain[] | undefined {
    let result: DiagnosticMessageChain[] | undefined;
    if (file.path !== file.resolvedPath) {
        (result ??= []).push(chainDiagnosticMessages(
            /*details*/ undefined,
            Diagnostics.File_is_output_of_project_reference_source_0,
            toFileName(file.originalFileName, fileNameConvertor),
        ));
    }
    if (file.redirectInfo) {
        (result ??= []).push(chainDiagnosticMessages(
            /*details*/ undefined,
            Diagnostics.File_redirects_to_file_0,
            toFileName(file.redirectInfo.redirectTarget, fileNameConvertor),
        ));
    }
    if (isExternalOrCommonJsModule(file)) {
        switch (getImpliedNodeFormatForEmitWorker(file, options)) {
            case ModuleKind.ESNext:
                if (file.packageJsonScope) {
                    (result ??= []).push(chainDiagnosticMessages(
                        /*details*/ undefined,
                        Diagnostics.File_is_ECMAScript_module_because_0_has_field_type_with_value_module,
                        toFileName(last(file.packageJsonLocations!), fileNameConvertor),
                    ));
                }
                break;
            case ModuleKind.CommonJS:
                if (file.packageJsonScope) {
                    (result ??= []).push(chainDiagnosticMessages(
                        /*details*/ undefined,
                        file.packageJsonScope.contents.packageJsonContent.type ?
                            Diagnostics.File_is_CommonJS_module_because_0_has_field_type_whose_value_is_not_module :
                            Diagnostics.File_is_CommonJS_module_because_0_does_not_have_field_type,
                        toFileName(last(file.packageJsonLocations!), fileNameConvertor),
                    ));
                }
                else if (file.packageJsonLocations?.length) {
                    (result ??= []).push(chainDiagnosticMessages(
                        /*details*/ undefined,
                        Diagnostics.File_is_CommonJS_module_because_package_json_was_not_found,
                    ));
                }
                break;
        }
    }
    return result;
}

/** @internal */
export function getMatchedFileSpec(program: Program, fileName: string): string | undefined {
    const configFile = program.getCompilerOptions().configFile;
    if (!configFile?.configFileSpecs?.validatedFilesSpec) return undefined;

    const filePath = program.getCanonicalFileName(fileName);
    const basePath = getDirectoryPath(getNormalizedAbsolutePath(configFile.fileName, program.getCurrentDirectory()));
    const index = findIndex(configFile.configFileSpecs.validatedFilesSpec, fileSpec => program.getCanonicalFileName(getNormalizedAbsolutePath(fileSpec, basePath)) === filePath);
    return index !== -1 ? configFile.configFileSpecs.validatedFilesSpecBeforeSubstitution![index] : undefined;
}

/** @internal */
export function getMatchedIncludeSpec(program: Program, fileName: string): string | true | undefined {
    const configFile = program.getCompilerOptions().configFile;
    if (!configFile?.configFileSpecs?.validatedIncludeSpecs) return undefined;

    // Return true if its default include spec
    if (configFile.configFileSpecs.isDefaultIncludeSpec) return true;

    const isJsonFile = fileExtensionIs(fileName, Extension.Json);
    const basePath = getDirectoryPath(getNormalizedAbsolutePath(configFile.fileName, program.getCurrentDirectory()));
    const useCaseSensitiveFileNames = program.useCaseSensitiveFileNames();
    const index = findIndex(configFile?.configFileSpecs?.validatedIncludeSpecs, includeSpec => {
        if (isJsonFile && !endsWith(includeSpec, Extension.Json)) return false;
        const pattern = getPatternFromSpec(includeSpec, basePath, "files");
        return !!pattern && getRegexFromPattern(`(?:${pattern})$`, useCaseSensitiveFileNames).test(fileName);
    });
    return index !== -1 ? configFile.configFileSpecs.validatedIncludeSpecsBeforeSubstitution![index] : undefined;
}

/** @internal */
export function fileIncludeReasonToDiagnostics(program: Program, reason: FileIncludeReason, fileNameConvertor?: (fileName: string) => string): DiagnosticMessageChain {
    const options = program.getCompilerOptions();
    if (isReferencedFile(reason)) {
        const referenceLocation = getReferencedFileLocation(program, reason);
        const referenceText = isReferenceFileLocation(referenceLocation) ? referenceLocation.file.text.substring(referenceLocation.pos, referenceLocation.end) : `"${referenceLocation.text}"`;
        let message: DiagnosticMessage;
        Debug.assert(isReferenceFileLocation(referenceLocation) || reason.kind === FileIncludeKind.Import, "Only synthetic references are imports");
        switch (reason.kind) {
            case FileIncludeKind.Import:
                if (isReferenceFileLocation(referenceLocation)) {
                    message = referenceLocation.packageId ?
                        Diagnostics.Imported_via_0_from_file_1_with_packageId_2 :
                        Diagnostics.Imported_via_0_from_file_1;
                }
                else if (referenceLocation.text === externalHelpersModuleNameText) {
                    message = referenceLocation.packageId ?
                        Diagnostics.Imported_via_0_from_file_1_with_packageId_2_to_import_importHelpers_as_specified_in_compilerOptions :
                        Diagnostics.Imported_via_0_from_file_1_to_import_importHelpers_as_specified_in_compilerOptions;
                }
                else {
                    message = referenceLocation.packageId ?
                        Diagnostics.Imported_via_0_from_file_1_with_packageId_2_to_import_jsx_and_jsxs_factory_functions :
                        Diagnostics.Imported_via_0_from_file_1_to_import_jsx_and_jsxs_factory_functions;
                }
                break;
            case FileIncludeKind.ReferenceFile:
                Debug.assert(!referenceLocation.packageId);
                message = Diagnostics.Referenced_via_0_from_file_1;
                break;
            case FileIncludeKind.TypeReferenceDirective:
                message = referenceLocation.packageId ?
                    Diagnostics.Type_library_referenced_via_0_from_file_1_with_packageId_2 :
                    Diagnostics.Type_library_referenced_via_0_from_file_1;
                break;
            case FileIncludeKind.LibReferenceDirective:
                Debug.assert(!referenceLocation.packageId);
                message = Diagnostics.Library_referenced_via_0_from_file_1;
                break;
            default:
                Debug.assertNever(reason);
        }
        return chainDiagnosticMessages(
            /*details*/ undefined,
            message,
            referenceText,
            toFileName(referenceLocation.file, fileNameConvertor),
            (referenceLocation.packageId && packageIdToString(referenceLocation.packageId))!,
        );
    }
    switch (reason.kind) {
        case FileIncludeKind.RootFile:
            if (!options.configFile?.configFileSpecs) return chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Root_file_specified_for_compilation);
            const fileName = getNormalizedAbsolutePath(program.getRootFileNames()[reason.index], program.getCurrentDirectory());
            const matchedByFiles = getMatchedFileSpec(program, fileName);
            if (matchedByFiles) return chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Part_of_files_list_in_tsconfig_json);
            const matchedByInclude = getMatchedIncludeSpec(program, fileName);
            return isString(matchedByInclude) ?
                chainDiagnosticMessages(
                    /*details*/ undefined,
                    Diagnostics.Matched_by_include_pattern_0_in_1,
                    matchedByInclude,
                    toFileName(options.configFile, fileNameConvertor),
                ) :
                // Could be additional files specified as roots or matched by default include
                chainDiagnosticMessages(
                    /*details*/ undefined,
                    matchedByInclude ?
                        Diagnostics.Matched_by_default_include_pattern_Asterisk_Asterisk_Slash_Asterisk :
                        Diagnostics.Root_file_specified_for_compilation,
                );
        case FileIncludeKind.SourceFromProjectReference:
        case FileIncludeKind.OutputFromProjectReference:
            const isOutput = reason.kind === FileIncludeKind.OutputFromProjectReference;
            const referencedResolvedRef = Debug.checkDefined(program.getResolvedProjectReferences()?.[reason.index]);
            return chainDiagnosticMessages(
                /*details*/ undefined,
                options.outFile ?
                    isOutput ?
                        Diagnostics.Output_from_referenced_project_0_included_because_1_specified :
                        Diagnostics.Source_from_referenced_project_0_included_because_1_specified :
                    isOutput ?
                    Diagnostics.Output_from_referenced_project_0_included_because_module_is_specified_as_none :
                    Diagnostics.Source_from_referenced_project_0_included_because_module_is_specified_as_none,
                toFileName(referencedResolvedRef.sourceFile.fileName, fileNameConvertor),
                options.outFile ? "--outFile" : "--out",
            );
        case FileIncludeKind.AutomaticTypeDirectiveFile: {
            const messageAndArgs: DiagnosticAndArguments = options.types?.includes("*") ?
                reason.packageId ?
                    [Diagnostics.Entry_point_for_implicit_type_library_0_with_packageId_1, reason.typeReference, packageIdToString(reason.packageId)] :
                    [Diagnostics.Entry_point_for_implicit_type_library_0, reason.typeReference] :
                reason.packageId ?
                [Diagnostics.Entry_point_of_type_library_0_specified_in_compilerOptions_with_packageId_1, reason.typeReference, packageIdToString(reason.packageId)] :
                [Diagnostics.Entry_point_of_type_library_0_specified_in_compilerOptions, reason.typeReference];

            return chainDiagnosticMessages(/*details*/ undefined, ...messageAndArgs);
        }
        case FileIncludeKind.LibFile: {
            if (reason.index !== undefined) return chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Library_0_specified_in_compilerOptions, options.lib![reason.index]);
            const target = getNameOfScriptTarget(getEmitScriptTarget(options));
            const messageAndArgs: DiagnosticAndArguments = target ? [Diagnostics.Default_library_for_target_0, target] : [Diagnostics.Default_library];
            return chainDiagnosticMessages(/*details*/ undefined, ...messageAndArgs);
        }
        default:
            Debug.assertNever(reason);
    }
}

function toFileName(file: SourceFile | string, fileNameConvertor?: (fileName: string) => string) {
    const fileName = isString(file) ? file : file.fileName;
    return fileNameConvertor ? fileNameConvertor(fileName) : fileName;
}

/**
 * Helper that emit files, report diagnostics and lists emitted and/or source files depending on compiler options
 *
 * @internal
 */
export function emitFilesAndReportErrors<T extends BuilderProgram>(
    program: Program | T,
    reportDiagnostic: DiagnosticReporter,
    write?: (s: string) => void,
    reportSummary?: ReportEmitErrorSummary,
    writeFile?: WriteFileCallback,
    cancellationToken?: CancellationToken,
    emitOnlyDtsFiles?: boolean,
    customTransformers?: CustomTransformers,
): {
    emitResult: EmitResult;
    diagnostics: SortedReadonlyArray<Diagnostic>;
} {
    const options = program.getCompilerOptions();

    // First get and report any syntactic errors.
    const allDiagnostics = program.getConfigFileParsingDiagnostics().slice();
    const configFileParsingDiagnosticsLength = allDiagnostics.length;
    addRange(allDiagnostics, program.getSyntacticDiagnostics(/*sourceFile*/ undefined, cancellationToken));

    // If we didn't have any syntactic errors, then also try getting the global and
    // semantic errors.
    if (allDiagnostics.length === configFileParsingDiagnosticsLength) {
        addRange(allDiagnostics, program.getOptionsDiagnostics(cancellationToken));

        if (!options.listFilesOnly) {
            addRange(allDiagnostics, program.getGlobalDiagnostics(cancellationToken));

            if (allDiagnostics.length === configFileParsingDiagnosticsLength) {
                addRange(allDiagnostics, program.getSemanticDiagnostics(/*sourceFile*/ undefined, cancellationToken));
            }

            if (
                options.noEmit &&
                getEmitDeclarations(options) &&
                allDiagnostics.length === configFileParsingDiagnosticsLength
            ) {
                addRange(allDiagnostics, program.getDeclarationDiagnostics(/*sourceFile*/ undefined, cancellationToken));
            }
        }
    }

    // Emit and report any errors we ran into.
    const emitResult = options.listFilesOnly
        ? { emitSkipped: true, diagnostics: emptyArray }
        : program.emit(/*targetSourceFile*/ undefined, writeFile, cancellationToken, emitOnlyDtsFiles, customTransformers);
    addRange(allDiagnostics, emitResult.diagnostics);

    const diagnostics = sortAndDeduplicateDiagnostics(allDiagnostics);
    diagnostics.forEach(reportDiagnostic);
    if (write) {
        const currentDir = program.getCurrentDirectory();
        forEach(emitResult.emittedFiles, file => {
            const filepath = getNormalizedAbsolutePath(file, currentDir);
            write(`TSFILE: ${filepath}`);
        });
        listFiles(program, write);
    }

    if (reportSummary) {
        reportSummary(getErrorCountForSummary(diagnostics), getFilesInErrorForSummary(diagnostics));
    }

    return {
        emitResult,
        diagnostics,
    };
}

/** @internal */
export function emitFilesAndReportErrorsAndGetExitStatus<T extends BuilderProgram>(
    program: Program | T,
    reportDiagnostic: DiagnosticReporter,
    write?: (s: string) => void,
    reportSummary?: ReportEmitErrorSummary,
    writeFile?: WriteFileCallback,
    cancellationToken?: CancellationToken,
    emitOnlyDtsFiles?: boolean,
    customTransformers?: CustomTransformers,
): ExitStatus {
    const { emitResult, diagnostics } = emitFilesAndReportErrors(
        program,
        reportDiagnostic,
        write,
        reportSummary,
        writeFile,
        cancellationToken,
        emitOnlyDtsFiles,
        customTransformers,
    );

    if (emitResult.emitSkipped && diagnostics.length > 0) {
        // If the emitter didn't emit anything, then pass that value along.
        return ExitStatus.DiagnosticsPresent_OutputsSkipped;
    }
    else if (diagnostics.length > 0) {
        // The emitter emitted something, inform the caller if that happened in the presence
        // of diagnostics or not.
        return ExitStatus.DiagnosticsPresent_OutputsGenerated;
    }
    return ExitStatus.Success;
}

/** @internal */
export const noopFileWatcher: FileWatcher = { close: noop };
/** @internal */
export const returnNoopFileWatcher = (): FileWatcher => noopFileWatcher;

/** @internal */
export function createWatchHost(system: System = sys, reportWatchStatus?: WatchStatusReporter): WatchHost {
    const onWatchStatusChange = reportWatchStatus || createWatchStatusReporter(system);
    return {
        onWatchStatusChange,
        watchFile: maybeBind(system, system.watchFile) || returnNoopFileWatcher,
        watchDirectory: maybeBind(system, system.watchDirectory) || returnNoopFileWatcher,
        setTimeout: maybeBind(system, system.setTimeout) || noop,
        clearTimeout: maybeBind(system, system.clearTimeout) || noop,
        preferNonRecursiveWatch: system.preferNonRecursiveWatch,
    };
}

/** @internal */
export type WatchType = WatchTypeRegistry[keyof WatchTypeRegistry];
/** @internal */
export const WatchType: WatchTypeRegistry = {
    ConfigFile: "Config file",
    ExtendedConfigFile: "Extended config file",
    SourceFile: "Source file",
    MissingFile: "Missing file",
    WildcardDirectory: "Wild card directory",
    FailedLookupLocations: "Failed Lookup Locations",
    AffectingFileLocation: "File location affecting resolution",
    TypeRoots: "Type roots",
    ConfigFileOfReferencedProject: "Config file of referened project",
    ExtendedConfigOfReferencedProject: "Extended config file of referenced project",
    WildcardDirectoryOfReferencedProject: "Wild card directory of referenced project",
    PackageJson: "package.json file",
    ClosedScriptInfo: "Closed Script info",
    ConfigFileForInferredRoot: "Config file for the inferred project root",
    NodeModules: "node_modules for closed script infos and package.jsons affecting module specifier cache",
    MissingSourceMapFile: "Missing source map file",
    NoopConfigFileForInferredRoot: "Noop Config file for the inferred project root",
    MissingGeneratedFile: "Missing generated file",
    NodeModulesForModuleSpecifierCache: "node_modules for module specifier cache invalidation",
    TypingInstallerLocationFile: "File location for typing installer",
    TypingInstallerLocationDirectory: "Directory location for typing installer",
};

/** @internal */
export interface WatchTypeRegistry {
    ConfigFile: "Config file";
    ExtendedConfigFile: "Extended config file";
    SourceFile: "Source file";
    MissingFile: "Missing file";
    WildcardDirectory: "Wild card directory";
    FailedLookupLocations: "Failed Lookup Locations";
    AffectingFileLocation: "File location affecting resolution";
    TypeRoots: "Type roots";
    ConfigFileOfReferencedProject: "Config file of referened project";
    ExtendedConfigOfReferencedProject: "Extended config file of referenced project";
    WildcardDirectoryOfReferencedProject: "Wild card directory of referenced project";
    PackageJson: "package.json file";

    // Additional tsserver specific watch information
    ClosedScriptInfo: "Closed Script info";
    ConfigFileForInferredRoot: "Config file for the inferred project root";
    NodeModules: "node_modules for closed script infos and package.jsons affecting module specifier cache";
    MissingSourceMapFile: "Missing source map file";
    NoopConfigFileForInferredRoot: "Noop Config file for the inferred project root";
    MissingGeneratedFile: "Missing generated file";
    NodeModulesForModuleSpecifierCache: "node_modules for module specifier cache invalidation";
    TypingInstallerLocationFile: "File location for typing installer";
    TypingInstallerLocationDirectory: "Directory location for typing installer";
}

/** @internal */
export interface WatchFactoryWithLog<X, Y = undefined> extends WatchFactory<X, Y> {
    writeLog: (s: string) => void;
}

/** @internal */
export function createWatchFactory<Y = undefined>(host: WatchFactoryHost & { trace?(s: string): void; }, options: { extendedDiagnostics?: boolean; diagnostics?: boolean; }): WatchFactoryWithLog<WatchType, Y> {
    const watchLogLevel = host.trace ? options.extendedDiagnostics ? WatchLogLevel.Verbose : options.diagnostics ? WatchLogLevel.TriggerOnly : WatchLogLevel.None : WatchLogLevel.None;
    const writeLog: (s: string) => void = watchLogLevel !== WatchLogLevel.None ? (s => host.trace!(s)) : noop;
    const result = getWatchFactory<WatchType, Y>(host, watchLogLevel, writeLog) as WatchFactoryWithLog<WatchType, Y>;
    result.writeLog = writeLog;
    return result;
}

/** @internal */
export function createCompilerHostFromProgramHost(host: ProgramHost<any>, getCompilerOptions: () => CompilerOptions, directoryStructureHost: DirectoryStructureHost = host): CompilerHost {
    const useCaseSensitiveFileNames = host.useCaseSensitiveFileNames();
    const compilerHost: CompilerHost = {
        getSourceFile: createGetSourceFile(
            (fileName, encoding) => !encoding ? compilerHost.readFile(fileName) : host.readFile(fileName, encoding),
            /*setParentNodes*/ undefined,
        ),
        getDefaultLibLocation: maybeBind(host, host.getDefaultLibLocation),
        getDefaultLibFileName: options => host.getDefaultLibFileName(options),
        writeFile: createWriteFileMeasuringIO(
            (path, data, writeByteOrderMark) => host.writeFile!(path, data, writeByteOrderMark),
            path => host.createDirectory!(path),
            path => host.directoryExists!(path),
        ),
        getCurrentDirectory: memoize(() => host.getCurrentDirectory()),
        useCaseSensitiveFileNames: () => useCaseSensitiveFileNames,
        getCanonicalFileName: createGetCanonicalFileName(useCaseSensitiveFileNames),
        getNewLine: () => getNewLineCharacter(getCompilerOptions()),
        fileExists: f => host.fileExists(f),
        readFile: f => host.readFile(f),
        trace: maybeBind(host, host.trace),
        directoryExists: maybeBind(directoryStructureHost, directoryStructureHost.directoryExists),
        getDirectories: maybeBind(directoryStructureHost, directoryStructureHost.getDirectories),
        realpath: maybeBind(host, host.realpath),
        getEnvironmentVariable: maybeBind(host, host.getEnvironmentVariable) || (() => ""),
        createHash: maybeBind(host, host.createHash),
        readDirectory: maybeBind(host, host.readDirectory),
        storeSignatureInfo: host.storeSignatureInfo,
        jsDocParsingMode: host.jsDocParsingMode,
    };
    return compilerHost;
}

/** @internal */
export function getSourceFileVersionAsHashFromText(host: Pick<CompilerHost, "createHash">, text: string): string {
    // If text can contain the sourceMapUrl ignore sourceMapUrl for calcualting hash
    if (text.match(sourceMapCommentRegExpDontCareLineStart)) {
        let lineEnd = text.length;
        let lineStart = lineEnd;
        for (let pos = lineEnd - 1; pos >= 0; pos--) {
            const ch = text.charCodeAt(pos);
            switch (ch) {
                case CharacterCodes.lineFeed:
                    if (pos && text.charCodeAt(pos - 1) === CharacterCodes.carriageReturn) {
                        pos--;
                    }
                // falls through
                case CharacterCodes.carriageReturn:
                    break;
                default:
                    if (ch < CharacterCodes.maxAsciiCharacter || !isLineBreak(ch)) {
                        lineStart = pos;
                        continue;
                    }
                    break;
            }
            // This is start of the line
            const line = text.substring(lineStart, lineEnd);
            if (line.match(sourceMapCommentRegExp)) {
                text = text.substring(0, lineStart);
                break;
            }
            // If we see a non-whitespace/map comment-like line, break, to avoid scanning up the entire file
            else if (!line.match(whitespaceOrMapCommentRegExp)) {
                break;
            }
            lineEnd = lineStart;
        }
    }
    return (host.createHash || generateDjb2Hash)(text);
}

/** @internal */
export function setGetSourceFileAsHashVersioned(compilerHost: CompilerHost): void {
    const originalGetSourceFile = compilerHost.getSourceFile;
    compilerHost.getSourceFile = (...args) => {
        const result = originalGetSourceFile.call(compilerHost, ...args);
        if (result) {
            result.version = getSourceFileVersionAsHashFromText(compilerHost, result.text);
        }
        return result;
    };
}

/**
 * Creates the watch compiler host that can be extended with config file or root file names and options host
 *
 * @internal
 */
export function createProgramHost<T extends BuilderProgram = EmitAndSemanticDiagnosticsBuilderProgram>(system: System, createProgram: CreateProgram<T> | undefined): ProgramHost<T> {
    const getDefaultLibLocation = memoize(() => getDirectoryPath(normalizePath(system.getExecutingFilePath())));
    return {
        useCaseSensitiveFileNames: () => system.useCaseSensitiveFileNames,
        getNewLine: () => system.newLine,
        getCurrentDirectory: memoize(() => system.getCurrentDirectory()),
        getDefaultLibLocation,
        getDefaultLibFileName: options => combinePaths(getDefaultLibLocation(), getDefaultLibFileName(options)),
        fileExists: path => system.fileExists(path),
        readFile: (path, encoding) => system.readFile(path, encoding),
        directoryExists: path => system.directoryExists(path),
        getDirectories: path => system.getDirectories(path),
        readDirectory: (path, extensions, exclude, include, depth) => system.readDirectory(path, extensions, exclude, include, depth),
        realpath: maybeBind(system, system.realpath),
        getEnvironmentVariable: maybeBind(system, system.getEnvironmentVariable),
        trace: s => system.write(s + system.newLine),
        createDirectory: path => system.createDirectory(path),
        writeFile: (path, data, writeByteOrderMark) => system.writeFile(path, data, writeByteOrderMark),
        createHash: maybeBind(system, system.createHash),
        createProgram: createProgram || createEmitAndSemanticDiagnosticsBuilderProgram as any as CreateProgram<T>,
        storeSignatureInfo: system.storeSignatureInfo,
        now: maybeBind(system, system.now),
    };
}

/**
 * Creates the watch compiler host that can be extended with config file or root file names and options host
 */
function createWatchCompilerHost<T extends BuilderProgram = EmitAndSemanticDiagnosticsBuilderProgram>(system = sys, createProgram: CreateProgram<T> | undefined, reportDiagnostic: DiagnosticReporter, reportWatchStatus?: WatchStatusReporter): WatchCompilerHost<T> {
    const write = (s: string) => system.write(s + system.newLine);
    const result = createProgramHost(system, createProgram) as WatchCompilerHost<T>;
    copyProperties(result, createWatchHost(system, reportWatchStatus));
    result.afterProgramCreate = builderProgram => {
        const compilerOptions = builderProgram.getCompilerOptions();
        const newLine = getNewLineCharacter(compilerOptions);

        emitFilesAndReportErrors(
            builderProgram,
            reportDiagnostic,
            write,
            errorCount =>
                result.onWatchStatusChange!(
                    createCompilerDiagnostic(getWatchErrorSummaryDiagnosticMessage(errorCount), errorCount),
                    newLine,
                    compilerOptions,
                    errorCount,
                ),
        );
    };
    return result;
}

/**
 * Report error and exit
 */
function reportUnrecoverableDiagnostic(system: System, reportDiagnostic: DiagnosticReporter, diagnostic: Diagnostic) {
    reportDiagnostic(diagnostic);
    system.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
}

/** @internal */
export interface CreateWatchCompilerHostInput<T extends BuilderProgram> {
    system: System;
    createProgram?: CreateProgram<T>;
    reportDiagnostic?: DiagnosticReporter;
    reportWatchStatus?: WatchStatusReporter;
}

/** @internal */
export interface CreateWatchCompilerHostOfConfigFileInput<T extends BuilderProgram> extends CreateWatchCompilerHostInput<T> {
    configFileName: string;
    optionsToExtend?: CompilerOptions;
    watchOptionsToExtend?: WatchOptions;
    extraFileExtensions?: readonly FileExtensionInfo[];
}
/**
 * Creates the watch compiler host from system for config file in watch mode
 *
 * @internal
 */
export function createWatchCompilerHostOfConfigFile<T extends BuilderProgram = EmitAndSemanticDiagnosticsBuilderProgram>({
    configFileName,
    optionsToExtend,
    watchOptionsToExtend,
    extraFileExtensions,
    system,
    createProgram,
    reportDiagnostic,
    reportWatchStatus,
}: CreateWatchCompilerHostOfConfigFileInput<T>): WatchCompilerHostOfConfigFile<T> {
    const diagnosticReporter = reportDiagnostic || createDiagnosticReporter(system);
    const host = createWatchCompilerHost(system, createProgram, diagnosticReporter, reportWatchStatus) as WatchCompilerHostOfConfigFile<T>;
    host.onUnRecoverableConfigFileDiagnostic = diagnostic => reportUnrecoverableDiagnostic(system, diagnosticReporter, diagnostic);
    host.configFileName = configFileName;
    host.optionsToExtend = optionsToExtend;
    host.watchOptionsToExtend = watchOptionsToExtend;
    host.extraFileExtensions = extraFileExtensions;
    return host;
}

/** @internal */
export interface CreateWatchCompilerHostOfFilesAndCompilerOptionsInput<T extends BuilderProgram> extends CreateWatchCompilerHostInput<T> {
    rootFiles: string[];
    options: CompilerOptions;
    watchOptions: WatchOptions | undefined;
    projectReferences?: readonly ProjectReference[];
}
/**
 * Creates the watch compiler host from system for compiling root files and options in watch mode
 *
 * @internal
 */
export function createWatchCompilerHostOfFilesAndCompilerOptions<T extends BuilderProgram = EmitAndSemanticDiagnosticsBuilderProgram>({
    rootFiles,
    options,
    watchOptions,
    projectReferences,
    system,
    createProgram,
    reportDiagnostic,
    reportWatchStatus,
}: CreateWatchCompilerHostOfFilesAndCompilerOptionsInput<T>): WatchCompilerHostOfFilesAndCompilerOptions<T> {
    const host = createWatchCompilerHost(system, createProgram, reportDiagnostic || createDiagnosticReporter(system), reportWatchStatus) as WatchCompilerHostOfFilesAndCompilerOptions<T>;
    host.rootFiles = rootFiles;
    host.options = options;
    host.watchOptions = watchOptions;
    host.projectReferences = projectReferences;
    return host;
}

/** @internal */
export interface IncrementalCompilationOptions {
    rootNames: readonly string[];
    options: CompilerOptions;
    configFileParsingDiagnostics?: readonly Diagnostic[];
    projectReferences?: readonly ProjectReference[];
    host?: CompilerHost;
    reportDiagnostic?: DiagnosticReporter;
    reportErrorSummary?: ReportEmitErrorSummary;
    afterProgramEmitAndDiagnostics?(program: EmitAndSemanticDiagnosticsBuilderProgram): void;
    system?: System;
}

/** @internal */
export function performIncrementalCompilation(input: IncrementalCompilationOptions): ExitStatus {
    const system = input.system || sys;
    const host = input.host || (input.host = createIncrementalCompilerHost(input.options, system));
    const builderProgram = createIncrementalProgram(input);
    const exitStatus = emitFilesAndReportErrorsAndGetExitStatus(
        builderProgram,
        input.reportDiagnostic || createDiagnosticReporter(system),
        s => host.trace && host.trace(s),
        input.reportErrorSummary || input.options.pretty ? (errorCount, filesInError) => system.write(getErrorSummaryText(errorCount, filesInError, system.newLine, host)) : undefined,
    );
    if (input.afterProgramEmitAndDiagnostics) input.afterProgramEmitAndDiagnostics(builderProgram);
    return exitStatus;
}