import {
    arrayToMap,
    binarySearch,
    BuilderProgram,
    clearMap,
    closeFileWatcher,
    compareStringsCaseSensitive,
    CompilerOptions,
    createGetCanonicalFileName,
    Debug,
    DirectoryWatcherCallback,
    emptyArray,
    emptyFileSystemEntries,
    ensureTrailingDirectorySeparator,
    ExtendedConfigCacheEntry,
    Extension,
    FileExtensionInfo,
    fileExtensionIsOneOf,
    FileSystemEntries,
    FileWatcher,
    FileWatcherCallback,
    FileWatcherEventKind,
    find,
    forEachAncestorDirectory,
    getAllowJSCompilerOption,
    getBaseFileName,
    getDirectoryPath,
    getNormalizedAbsolutePath,
    getResolveJsonModule,
    hasExtension,
    identity,
    insertSorted,
    isArray,
    isBuilderProgram,
    isDeclarationFileName,
    isExcludedFile,
    isSupportedSourceFileName,
    map,
    MapLike,
    matchesExclude,
    matchFiles,
    mutateMap,
    noop,
    normalizePath,
    Path,
    PollingInterval,
    Program,
    removeFileExtension,
    removeIgnoredPath,
    returnNoopFileWatcher,
    ScriptKind,
    setSysLog,
    SortedArray,
    SortedReadonlyArray,
    supportedJSExtensionsFlat,
    timestamp,
    toPath as ts_toPath,
    WatchDirectoryFlags,
    WatchFileKind,
    WatchOptions,
} from "./_namespaces/ts.js";

/**
 * Partial interface of the System thats needed to support the caching of directory structure
 *
 * @internal
 */
export interface DirectoryStructureHost {
    fileExists(path: string): boolean;
    readFile(path: string, encoding?: string): string | undefined;

    // TODO: GH#18217 Optional methods are frequently used as non-optional
    directoryExists?(path: string): boolean;
    getDirectories?(path: string): string[];
    readDirectory?(path: string, extensions?: readonly string[], exclude?: readonly string[], include?: readonly string[], depth?: number): string[];
    realpath?(path: string): string;

    createDirectory?(path: string): void;
    writeFile?(path: string, data: string, writeByteOrderMark?: boolean): void;
}

/** @internal */
export interface FileAndDirectoryExistence {
    fileExists: boolean;
    directoryExists: boolean;
}

/** @internal */
export interface CachedDirectoryStructureHost extends DirectoryStructureHost {
    useCaseSensitiveFileNames: boolean;

    getDirectories(path: string): string[];
    readDirectory(path: string, extensions?: readonly string[], exclude?: readonly string[], include?: readonly string[], depth?: number): string[];

    /** Returns the queried result for the file exists and directory exists if at all it was done */
    addOrDeleteFileOrDirectory(fileOrDirectory: string, fileOrDirectoryPath: Path): FileAndDirectoryExistence | undefined;
    addOrDeleteFile(fileName: string, filePath: Path, eventKind: FileWatcherEventKind): void;
    clearCache(): void;
}

type Canonicalized = string & { __canonicalized: void; };

interface MutableFileSystemEntries {
    readonly files: string[];
    readonly directories: string[];
    sortedAndCanonicalizedFiles?: SortedArray<Canonicalized>;
    sortedAndCanonicalizedDirectories?: SortedArray<Canonicalized>;
}

interface SortedAndCanonicalizedMutableFileSystemEntries {
    readonly files: string[];
    readonly directories: string[];
    readonly sortedAndCanonicalizedFiles: SortedArray<Canonicalized>;
    readonly sortedAndCanonicalizedDirectories: SortedArray<Canonicalized>;
}

/** @internal */
export function createCachedDirectoryStructureHost(host: DirectoryStructureHost, currentDirectory: string, useCaseSensitiveFileNames: boolean): CachedDirectoryStructureHost | undefined {
    if (!host.getDirectories || !host.readDirectory) {
        return undefined;
    }

    const cachedReadDirectoryResult = new Map<string, MutableFileSystemEntries | false>();
    const getCanonicalFileName = createGetCanonicalFileName(useCaseSensitiveFileNames) as ((name: string) => Canonicalized);
    return {
        useCaseSensitiveFileNames,
        fileExists,
        readFile: (path, encoding) => host.readFile(path, encoding),
        directoryExists: host.directoryExists && directoryExists,
        getDirectories,
        readDirectory,
        createDirectory: host.createDirectory && createDirectory,
        writeFile: host.writeFile && writeFile,
        addOrDeleteFileOrDirectory,
        addOrDeleteFile,
        clearCache,
        realpath: host.realpath && realpath,
    };

    function toPath(fileName: string) {
        return ts_toPath(fileName, currentDirectory, getCanonicalFileName);
    }

    function getCachedFileSystemEntries(rootDirPath: Path) {
        return cachedReadDirectoryResult.get(ensureTrailingDirectorySeparator(rootDirPath));
    }

    function getCachedFileSystemEntriesForBaseDir(path: Path) {
        const entries = getCachedFileSystemEntries(getDirectoryPath(path));
        if (!entries) {
            return entries;
        }

        // If we're looking for the base directory, we're definitely going to search the entries
        if (!entries.sortedAndCanonicalizedFiles) {
            entries.sortedAndCanonicalizedFiles = entries.files.map(getCanonicalFileName).sort() as SortedArray<Canonicalized>;
            entries.sortedAndCanonicalizedDirectories = entries.directories.map(getCanonicalFileName).sort() as SortedArray<Canonicalized>;
        }
        return entries as SortedAndCanonicalizedMutableFileSystemEntries;
    }

    function getBaseNameOfFileName(fileName: string) {
        return getBaseFileName(normalizePath(fileName));
    }

    function createCachedFileSystemEntries(rootDir: string, rootDirPath: Path) {
        if (!host.realpath || ensureTrailingDirectorySeparator(toPath(host.realpath(rootDir))) === rootDirPath) {
            const resultFromHost: MutableFileSystemEntries = {
                files: map(host.readDirectory!(rootDir, /*extensions*/ undefined, /*exclude*/ undefined, /*include*/ ["*.*"]), getBaseNameOfFileName) || [],
                directories: host.getDirectories!(rootDir) || [],
            };

            cachedReadDirectoryResult.set(ensureTrailingDirectorySeparator(rootDirPath), resultFromHost);
            return resultFromHost;
        }

        // If the directory is symlink do not cache the result
        if (host.directoryExists?.(rootDir)) {
            cachedReadDirectoryResult.set(rootDirPath, false);
            return false;
        }

        // Non existing directory
        return undefined;
    }

    /**
     * If the readDirectory result was already cached, it returns that
     * Otherwise gets result from host and caches it.
     * The host request is done under try catch block to avoid caching incorrect result
     */
    function tryReadDirectory(rootDir: string, rootDirPath: Path) {
        rootDirPath = ensureTrailingDirectorySeparator(rootDirPath);
        const cachedResult = getCachedFileSystemEntries(rootDirPath);
        if (cachedResult) {
            return cachedResult;
        }

        try {
            return createCachedFileSystemEntries(rootDir, rootDirPath);
        }
        catch {
            // If there is exception to read directories, dont cache the result and direct the calls to host
            Debug.assert(!cachedReadDirectoryResult.has(ensureTrailingDirectorySeparator(rootDirPath)));
            return undefined;
        }
    }

    function hasEntry(entries: SortedReadonlyArray<Canonicalized>, name: Canonicalized) {
        // Case-sensitive comparison since already canonicalized
        const index = binarySearch(entries, name, identity, compareStringsCaseSensitive);
        return index >= 0;
    }

    function writeFile(fileName: string, data: string, writeByteOrderMark?: boolean): void {
        const path = toPath(fileName);
        const result = getCachedFileSystemEntriesForBaseDir(path);
        if (result) {
            updateFilesOfFileSystemEntry(result, getBaseNameOfFileName(fileName), /*fileExists*/ true);
        }
        return host.writeFile!(fileName, data, writeByteOrderMark);
    }

    function fileExists(fileName: string): boolean {
        const path = toPath(fileName);
        const result = getCachedFileSystemEntriesForBaseDir(path);
        return result && hasEntry(result.sortedAndCanonicalizedFiles, getCanonicalFileName(getBaseNameOfFileName(fileName))) ||
            host.fileExists(fileName);
    }

    function directoryExists(dirPath: string): boolean {
        const path = toPath(dirPath);
        return cachedReadDirectoryResult.has(ensureTrailingDirectorySeparator(path)) || host.directoryExists!(dirPath);
    }

    function createDirectory(dirPath: string) {
        const path = toPath(dirPath);
        const result = getCachedFileSystemEntriesForBaseDir(path);
        if (result) {
            const baseName = getBaseNameOfFileName(dirPath);
            const canonicalizedBaseName = getCanonicalFileName(baseName);
            const canonicalizedDirectories = result.sortedAndCanonicalizedDirectories;
            // Case-sensitive comparison since already canonicalized
            if (insertSorted(canonicalizedDirectories, canonicalizedBaseName, compareStringsCaseSensitive)) {
                result.directories.push(baseName);
            }
        }
        host.createDirectory!(dirPath);
    }

    function getDirectories(rootDir: string): string[] {
        const rootDirPath = toPath(rootDir);
        const result = tryReadDirectory(rootDir, rootDirPath);
        if (result) {
            return result.directories.slice();
        }
        return host.getDirectories!(rootDir);
    }

    function readDirectory(rootDir: string, extensions?: readonly string[], excludes?: readonly string[], includes?: readonly string[], depth?: number): string[] {
        const rootDirPath = toPath(rootDir);
        const rootResult = tryReadDirectory(rootDir, rootDirPath);
        let rootSymLinkResult: FileSystemEntries | undefined;
        if (rootResult !== undefined) {
            return matchFiles(rootDir, extensions, excludes, includes, useCaseSensitiveFileNames, currentDirectory, depth, getFileSystemEntries, realpath);
        }
        return host.readDirectory!(rootDir, extensions, excludes, includes, depth);

        function getFileSystemEntries(dir: string): FileSystemEntries {
            const path = toPath(dir);
            if (path === rootDirPath) {
                return rootResult || getFileSystemEntriesFromHost(dir, path);
            }
            const result = tryReadDirectory(dir, path);
            return result !== undefined ?
                result || getFileSystemEntriesFromHost(dir, path) :
                emptyFileSystemEntries;
        }

        function getFileSystemEntriesFromHost(dir: string, path: Path): FileSystemEntries {
            if (rootSymLinkResult && path === rootDirPath) return rootSymLinkResult;
            const result: FileSystemEntries = {
                files: map(host.readDirectory!(dir, /*extensions*/ undefined, /*exclude*/ undefined, /*include*/ ["*.*"]), getBaseNameOfFileName) || emptyArray,
                directories: host.getDirectories!(dir) || emptyArray,
            };
            if (path === rootDirPath) rootSymLinkResult = result;
            return result;
        }
    }

    function realpath(s: string) {
        return host.realpath ? host.realpath(s) : s;
    }

    function clearFirstAncestorEntry(fileOrDirectoryPath: Path) {
        forEachAncestorDirectory(
            getDirectoryPath(fileOrDirectoryPath),
            ancestor => cachedReadDirectoryResult.delete(ensureTrailingDirectorySeparator(ancestor)) ? true : undefined,
        );
    }

    function addOrDeleteFileOrDirectory(fileOrDirectory: string, fileOrDirectoryPath: Path) {
        const existingResult = getCachedFileSystemEntries(fileOrDirectoryPath);
        if (existingResult !== undefined) {
            // Just clear the cache for now
            // For now just clear the cache, since this could mean that multiple level entries might need to be re-evaluated
            clearCache();
            return undefined;
        }

        const parentResult = getCachedFileSystemEntriesForBaseDir(fileOrDirectoryPath);
        if (!parentResult) {
            clearFirstAncestorEntry(fileOrDirectoryPath);
            return undefined;
        }

        // This was earlier a file (hence not in cached directory contents)
        // or we never cached the directory containing it

        if (!host.directoryExists) {
            // Since host doesnt support directory exists, clear the cache as otherwise it might not be same
            clearCache();
            return undefined;
        }

        const baseName = getBaseNameOfFileName(fileOrDirectory);
        const fsQueryResult: FileAndDirectoryExistence = {
            fileExists: host.fileExists(fileOrDirectory),
            directoryExists: host.directoryExists(fileOrDirectory),
        };
        if (fsQueryResult.directoryExists || hasEntry(parentResult.sortedAndCanonicalizedDirectories, getCanonicalFileName(baseName))) {
            // Folder added or removed, clear the cache instead of updating the folder and its structure
            clearCache();
        }
        else {
            // No need to update the directory structure, just files
            updateFilesOfFileSystemEntry(parentResult, baseName, fsQueryResult.fileExists);
        }
        return fsQueryResult;
    }

    function addOrDeleteFile(fileName: string, filePath: Path, eventKind: FileWatcherEventKind) {
        if (eventKind === FileWatcherEventKind.Changed) {
            return;
        }

        const parentResult = getCachedFileSystemEntriesForBaseDir(filePath);
        if (parentResult) {
            updateFilesOfFileSystemEntry(parentResult, getBaseNameOfFileName(fileName), eventKind === FileWatcherEventKind.Created);
        }
        else {
            clearFirstAncestorEntry(filePath);
        }
    }

    function updateFilesOfFileSystemEntry(parentResult: SortedAndCanonicalizedMutableFileSystemEntries, baseName: string, fileExists: boolean): void {
        const canonicalizedFiles = parentResult.sortedAndCanonicalizedFiles;
        const canonicalizedBaseName = getCanonicalFileName(baseName);
        if (fileExists) {
            // Case-sensitive comparison since already canonicalized
            if (insertSorted(canonicalizedFiles, canonicalizedBaseName, compareStringsCaseSensitive)) {
                parentResult.files.push(baseName);
            }
        }
        else {
            // Case-sensitive comparison since already canonicalized
            const sortedIndex = binarySearch(canonicalizedFiles, canonicalizedBaseName, identity, compareStringsCaseSensitive);
            if (sortedIndex >= 0) {
                canonicalizedFiles.splice(sortedIndex, 1);
                const unsortedIndex = parentResult.files.findIndex(entry => getCanonicalFileName(entry) === canonicalizedBaseName);
                parentResult.files.splice(unsortedIndex, 1);
            }
        }
    }

    function clearCache() {
        cachedReadDirectoryResult.clear();
    }
}

export enum ProgramUpdateLevel {
    /** Program is updated with same root file names and options */
    Update,
    /** Loads program after updating root file names from the disk */
    RootNamesAndUpdate,
    /**
     * Loads program completely, including:
     *  - re-reading contents of config file from disk
     *  - calculating root file names for the program
     *  - Updating the program
     */

    Full,
}

/** @internal */
export interface SharedExtendedConfigFileWatcher<T> extends FileWatcher {
    watcher: FileWatcher;
    projects: Set<T>;
}

/**
 * Updates the map of shared extended config file watches with a new set of extended config files from a base config file of the project
 *
 * @internal
 */
export function updateSharedExtendedConfigFileWatcher<T>(
    projectPath: T,
    options: CompilerOptions | undefined,
    extendedConfigFilesMap: Map<Path, SharedExtendedConfigFileWatcher<T>>,
    createExtendedConfigFileWatch: (extendedConfigPath: string, extendedConfigFilePath: Path) => FileWatcher,
    toPath: (fileName: string) => Path,
): void {
    const extendedConfigs = arrayToMap(options?.configFile?.extendedSourceFiles || emptyArray, toPath);
    // remove project from all unrelated watchers
    extendedConfigFilesMap.forEach((watcher, extendedConfigFilePath) => {
        if (!extendedConfigs.has(extendedConfigFilePath)) {
            watcher.projects.delete(projectPath);
            watcher.close();
        }
    });
    // Update the extended config files watcher
    extendedConfigs.forEach((extendedConfigFileName, extendedConfigFilePath) => {
        const existing = extendedConfigFilesMap.get(extendedConfigFilePath);
        if (existing) {
            existing.projects.add(projectPath);
        }
        else {
            // start watching previously unseen extended config
            extendedConfigFilesMap.set(extendedConfigFilePath, {
                projects: new Set([projectPath]),
                watcher: createExtendedConfigFileWatch(extendedConfigFileName, extendedConfigFilePath),
                close: () => {
                    const existing = extendedConfigFilesMap.get(extendedConfigFilePath);
                    if (!existing || existing.projects.size !== 0) return;
                    existing.watcher.close();
                    extendedConfigFilesMap.delete(extendedConfigFilePath);
                },
            });
        }
    });
}

/**
 * Remove the project from the extended config file watchers and close not needed watches
 *
 * @internal
 */
export function clearSharedExtendedConfigFileWatcher<T>(
    projectPath: T,
    extendedConfigFilesMap: Map<Path, SharedExtendedConfigFileWatcher<T>>,
): void {
    extendedConfigFilesMap.forEach(watcher => {
        if (watcher.projects.delete(projectPath)) watcher.close();
    });
}

/**
 * Clean the extendsConfigCache when extended config file has changed
 *
 * @internal
 */
export function cleanExtendedConfigCache(
    extendedConfigCache: Map<string, ExtendedConfigCacheEntry>,
    extendedConfigFilePath: Path,
    toPath: (fileName: string) => Path,
): void {
    if (!extendedConfigCache.delete(extendedConfigFilePath)) return;
    extendedConfigCache.forEach(({ extendedResult }, key) => {
        if (extendedResult.extendedSourceFiles?.some(extendedFile => toPath(extendedFile) === extendedConfigFilePath)) {
            cleanExtendedConfigCache(extendedConfigCache, key as Path, toPath);
        }
    });
}

/**
 * Updates the existing missing file watches with the new set of missing files after new program is created
 *
 * @internal
 */
export function updateMissingFilePathsWatch(
    program: Program,
    missingFileWatches: Map<Path, FileWatcher>,
    createMissingFileWatch: (missingFilePath: Path, missingFileName: string) => FileWatcher,
): void {
    // Update the missing file paths watcher
    mutateMap(
        missingFileWatches,
        program.getMissingFilePaths(),
        {
            // Watch the missing files
            createNewValue: createMissingFileWatch,
            // Files that are no longer missing (e.g. because they are no longer required)
            // should no longer be watched.
            onDeleteValue: closeFileWatcher,
        },
    );
}

/** @internal */
export interface WildcardDirectoryWatcher<T extends FileWatcher = FileWatcher> {
    watcher: T;
    flags: WatchDirectoryFlags;
}

/**
 * Updates the existing wild card directory watches with the new set of wild card directories from the config file
 * after new program is created because the config file was reloaded or program was created first time from the config file
 * Note that there is no need to call this function when the program is updated with additional files without reloading config files,
 * as wildcard directories wont change unless reloading config file
 *
 * @internal
 */
export function updateWatchingWildcardDirectories<T extends FileWatcher>(
    existingWatchedForWildcards: Map<string, WildcardDirectoryWatcher<T>>,
    wildcardDirectories: MapLike<WatchDirectoryFlags> | undefined,
    watchDirectory: (directory: string, flags: WatchDirectoryFlags) => T,
): void {
    if (wildcardDirectories) {
        mutateMap(
            existingWatchedForWildcards,
            new Map(Object.entries(wildcardDirectories)),
            {
                // Create new watch and recursive info
                createNewValue: createWildcardDirectoryWatcher,
                // Close existing watch thats not needed any more
                onDeleteValue: closeFileWatcherOf,
                // Close existing watch that doesnt match in the flags
                onExistingValue: updateWildcardDirectoryWatcher,
            },
        );
    }
    else {
        clearMap(existingWatchedForWildcards, closeFileWatcherOf);
    }

    function createWildcardDirectoryWatcher(directory: string, flags: WatchDirectoryFlags): WildcardDirectoryWatcher<T> {
        // Create new watch and recursive info
        return {
            watcher: watchDirectory(directory, flags),
            flags,
        };
    }

    function updateWildcardDirectoryWatcher(existingWatcher: WildcardDirectoryWatcher<T>, flags: WatchDirectoryFlags, directory: string) {
        // Watcher needs to be updated if the recursive flags dont match
        if (existingWatcher.flags === flags) {
            return;
        }

        existingWatcher.watcher.close();
        existingWatchedForWildcards.set(directory, createWildcardDirectoryWatcher(directory, flags));
    }
}

/** @internal */
export interface IsIgnoredFileFromWildCardWatchingInput {
    watchedDirPath: Path;
    fileOrDirectory: string;
    fileOrDirectoryPath: Path;
    configFileName: string;
    options: CompilerOptions;
    program: BuilderProgram | Program | readonly string[] | undefined;
    extraFileExtensions?: readonly FileExtensionInfo[];
    currentDirectory: string;
    useCaseSensitiveFileNames: boolean;
    writeLog: (s: string) => void;
    toPath: (fileName: string) => Path;
    getScriptKind?: (fileName: string) => ScriptKind;
}
/** @internal */
export function isIgnoredFileFromWildCardWatching({
    watchedDirPath,
    fileOrDirectory,
    fileOrDirectoryPath,
    configFileName,
    options,
    program,
    extraFileExtensions,
    currentDirectory,
    useCaseSensitiveFileNames,
    writeLog,
    toPath,
    getScriptKind,
}: IsIgnoredFileFromWildCardWatchingInput): boolean {
    const newPath = removeIgnoredPath(fileOrDirectoryPath);
    if (!newPath) {
        writeLog(`Project: ${configFileName} Detected ignored path: ${fileOrDirectory}`);
        return true;
    }

    fileOrDirectoryPath = newPath;
    if (fileOrDirectoryPath === watchedDirPath) return false;

    // If the the added or created file or directory is not supported file name, ignore the file
    if (
        hasExtension(fileOrDirectoryPath) && !(
            isSupportedSourceFileName(fileOrDirectory, options, extraFileExtensions) ||
            isSupportedScriptKind()
        )
    ) {
        writeLog(`Project: ${configFileName} Detected file add/remove of non supported extension: ${fileOrDirectory}`);
        return true;
    }

    if (isExcludedFile(fileOrDirectory, options.configFile!.configFileSpecs!, getNormalizedAbsolutePath(getDirectoryPath(configFileName), currentDirectory), useCaseSensitiveFileNames, currentDirectory)) {
        writeLog(`Project: ${configFileName} Detected excluded file: ${fileOrDirectory}`);
        return true;
    }

    if (!program) return false;

    // We want to ignore emit file check if file is not going to be emitted next to source file
    // In that case we follow config file inclusion rules
    if (options.outFile || options.outDir) return false;

    // File if emitted next to input needs to be ignored
    if (isDeclarationFileName(fileOrDirectoryPath)) {
        // If its declaration directory: its not ignored if not excluded by config
        if (options.declarationDir) return false;
    }
    else if (!fileExtensionIsOneOf(fileOrDirectoryPath, supportedJSExtensionsFlat)) {
        return false;
    }

    // just check if sourceFile with the name exists
    const filePathWithoutExtension = removeFileExtension(fileOrDirectoryPath);
    const realProgram = isArray(program) ? undefined : isBuilderProgram(program) ? program.getProgramOrUndefined() : program;
    const builderProgram = !realProgram && !isArray(program) ? program as BuilderProgram : undefined;
    if (
        hasSourceFile((filePathWithoutExtension + Extension.Ts) as Path) ||
        hasSourceFile((filePathWithoutExtension + Extension.Tsx) as Path)
    ) {
        writeLog(`Project: ${configFileName} Detected output file: ${fileOrDirectory}`);
        return true;
    }
    return false;

    function hasSourceFile(file: Path): boolean {
        return realProgram ?
            !!realProgram.getSourceFileByPath(file) :
            builderProgram ?
            builderProgram.state.fileInfos.has(file) :
            !!find(program as readonly string[], rootFile => toPath(rootFile) === file);
    }

    function isSupportedScriptKind() {
        if (!getScriptKind) return false;
        const scriptKind = getScriptKind(fileOrDirectory);
        switch (scriptKind) {
            case ScriptKind.TS:
            case ScriptKind.TSX:
            case ScriptKind.Deferred:
            case ScriptKind.External:
                return true;
            case ScriptKind.JS:
            case ScriptKind.JSX:
                return getAllowJSCompilerOption(options);
            case ScriptKind.JSON:
                return getResolveJsonModule(options);
            case ScriptKind.Unknown:
                return false;
        }
    }
}

/** @internal */
export function isEmittedFileOfProgram(program: Program | undefined, file: string): boolean {
    if (!program) {
        return false;
    }

    return program.isEmittedFile(file);
}

/** @internal */
export enum WatchLogLevel {
    None,
    TriggerOnly,
    Verbose,
}

/** @internal */
export interface WatchFactoryHost {
    watchFile(path: string, callback: FileWatcherCallback, pollingInterval?: number, options?: WatchOptions): FileWatcher;
    watchDirectory(path: string, callback: DirectoryWatcherCallback, recursive?: boolean, options?: WatchOptions): FileWatcher;
    getCurrentDirectory?(): string;
    useCaseSensitiveFileNames: boolean | (() => boolean);
}

/** @internal */
export interface WatchFactory<X, Y = undefined> {
    watchFile: (file: string, callback: FileWatcherCallback, pollingInterval: PollingInterval, options: WatchOptions | undefined, detailInfo1: X, detailInfo2?: Y) => FileWatcher;
    watchDirectory: (directory: string, callback: DirectoryWatcherCallback, flags: WatchDirectoryFlags, options: WatchOptions | undefined, detailInfo1: X, detailInfo2?: Y) => FileWatcher;
}

/** @internal */
export type GetDetailWatchInfo<X, Y> = (detailInfo1: X, detailInfo2: Y | undefined) => string;
/** @internal */
export function getWatchFactory<X, Y = undefined>(host: WatchFactoryHost, watchLogLevel: WatchLogLevel, log: (s: string) => void, getDetailWatchInfo?: GetDetailWatchInfo<X, Y>): WatchFactory<X, Y> {
    setSysLog(watchLogLevel === WatchLogLevel.Verbose ? log : noop);
    const plainInvokeFactory: WatchFactory<X, Y> = {
        watchFile: (file, callback, pollingInterval, options) => host.watchFile(file, callback, pollingInterval, options),
        watchDirectory: (directory, callback, flags, options) => host.watchDirectory(directory, callback, (flags & WatchDirectoryFlags.Recursive) !== 0, options),
    };
    const triggerInvokingFactory: WatchFactory<X, Y> | undefined = watchLogLevel !== WatchLogLevel.None ?
        {
            watchFile: createTriggerLoggingAddWatch("watchFile"),
            watchDirectory: createTriggerLoggingAddWatch("watchDirectory"),
        } :
        undefined;
    const factory = watchLogLevel === WatchLogLevel.Verbose ?
        {
            watchFile: createFileWatcherWithLogging,
            watchDirectory: createDirectoryWatcherWithLogging,
        } :
        triggerInvokingFactory || plainInvokeFactory;
    const excludeWatcherFactory = watchLogLevel === WatchLogLevel.Verbose ?
        createExcludeWatcherWithLogging :
        returnNoopFileWatcher;

    return {
        watchFile: createExcludeHandlingAddWatch("watchFile"),
        watchDirectory: createExcludeHandlingAddWatch("watchDirectory"),
    };

    function createExcludeHandlingAddWatch<T extends keyof WatchFactory<X, Y>>(key: T): WatchFactory<X, Y>[T] {
        return (
            file: string,
            cb: FileWatcherCallback | DirectoryWatcherCallback,
            flags: PollingInterval | WatchDirectoryFlags,
            options: WatchOptions | undefined,
            detailInfo1: X,
            detailInfo2?: Y,
        ) => !matchesExclude(file, key === "watchFile" ? options?.excludeFiles : options?.excludeDirectories, useCaseSensitiveFileNames(), host.getCurrentDirectory?.() || "") ?
            factory[key].call(/*thisArgs*/ undefined, file, cb, flags, options, detailInfo1, detailInfo2) :
            excludeWatcherFactory(file, flags, options, detailInfo1, detailInfo2);
    }

    function useCaseSensitiveFileNames() {
        return typeof host.useCaseSensitiveFileNames === "boolean" ?
            host.useCaseSensitiveFileNames :
            host.useCaseSensitiveFileNames();
    }

    function createExcludeWatcherWithLogging(
        file: string,
        flags: PollingInterval | WatchDirectoryFlags,
        options: WatchOptions | undefined,
        detailInfo1: X,
        detailInfo2?: Y,
    ) {
        log(`ExcludeWatcher:: Added:: ${getWatchInfo(file, flags, options, detailInfo1, detailInfo2, getDetailWatchInfo)}`);
        return {
            close: () => log(`ExcludeWatcher:: Close:: ${getWatchInfo(file, flags, options, detailInfo1, detailInfo2, getDetailWatchInfo)}`),
        };
    }

    function createFileWatcherWithLogging(
        file: string,
        cb: FileWatcherCallback,
        flags: PollingInterval,
        options: WatchOptions | undefined,
        detailInfo1: X,
        detailInfo2?: Y,
    ): FileWatcher {
        log(`FileWatcher:: Added:: ${getWatchInfo(file, flags, options, detailInfo1, detailInfo2, getDetailWatchInfo)}`);
        const watcher = triggerInvokingFactory!.watchFile(file, cb, flags, options, detailInfo1, detailInfo2);
        return {
            close: () => {
                log(`FileWatcher:: Close:: ${getWatchInfo(file, flags, options, detailInfo1, detailInfo2, getDetailWatchInfo)}`);
                watcher.close();
            },
        };
    }

    function createDirectoryWatcherWithLogging(
        file: string,
        cb: DirectoryWatcherCallback,
        flags: WatchDirectoryFlags,
        options: WatchOptions | undefined,
        detailInfo1: X,
        detailInfo2?: Y,
    ): FileWatcher {
        const watchInfo = `DirectoryWatcher:: Added:: ${getWatchInfo(file, flags, options, detailInfo1, detailInfo2, getDetailWatchInfo)}`;
        log(watchInfo);
        const start = timestamp();
        const watcher = triggerInvokingFactory!.watchDirectory(file, cb, flags, options, detailInfo1, detailInfo2);
        const elapsed = timestamp() - start;
        log(`Elapsed:: ${elapsed}ms ${watchInfo}`);
        return {
            close: () => {
                const watchInfo = `DirectoryWatcher:: Close:: ${getWatchInfo(file, flags, options, detailInfo1, detailInfo2, getDetailWatchInfo)}`;
                log(watchInfo);
                const start = timestamp();
                watcher.close();
                const elapsed = timestamp() - start;
                log(`Elapsed:: ${elapsed}ms ${watchInfo}`);
            },
        };
    }

    function createTriggerLoggingAddWatch<T extends keyof WatchFactory<X, Y>>(key: T): WatchFactory<X, Y>[T] {
        return (
            file: string,
            cb: FileWatcherCallback | DirectoryWatcherCallback,
            flags: PollingInterval | WatchDirectoryFlags,
            options: WatchOptions | undefined,
            detailInfo1: X,
            detailInfo2?: Y,
        ) => plainInvokeFactory[key].call(
            /*thisArgs*/ undefined,
            file,
            (...args: any[]) => {
                const triggerredInfo = `${key === "watchFile" ? "FileWatcher" : "DirectoryWatcher"}:: Triggered with ${args[0]} ${args[1] !== undefined ? args[1] : ""}:: ${getWatchInfo(file, flags, options, detailInfo1, detailInfo2, getDetailWatchInfo)}`;
                log(triggerredInfo);
                const start = timestamp();
                cb.call(/*thisArg*/ undefined, ...args);
                const elapsed = timestamp() - start;
                log(`Elapsed:: ${elapsed}ms ${triggerredInfo}`);
            },
            flags,
            options,
            detailInfo1,
            detailInfo2,
        );
    }

    function getWatchInfo<T>(file: string, flags: T, options: WatchOptions | undefined, detailInfo1: X, detailInfo2: Y | undefined, getDetailWatchInfo: GetDetailWatchInfo<X, Y> | undefined) {
        return `WatchInfo: ${file} ${flags} ${JSON.stringify(options)} ${getDetailWatchInfo ? getDetailWatchInfo(detailInfo1, detailInfo2) : detailInfo2 === undefined ? detailInfo1 : `${detailInfo1} ${detailInfo2}`}`;
    }
}

/** @internal */
export function getFallbackOptions(options: WatchOptions | undefined): WatchOptions {
    const fallbackPolling = options?.fallbackPolling;
    return {
        watchFile: fallbackPolling !== undefined ?
            fallbackPolling as unknown as WatchFileKind :
            WatchFileKind.PriorityPollingInterval,
    };
}

/** @internal */
export function closeFileWatcherOf<T extends { watcher: FileWatcher; }>(objWithWatcher: T): void {
    objWithWatcher.watcher.close();
}