declare module "zlib" {
    import * as stream from "stream";

    interface ZlibOptions {
        flush?: number; // default: zlib.constants.Z_NO_FLUSH
        finishFlush?: number; // default: zlib.constants.Z_FINISH
        chunkSize?: number; // default: 16*1024
        windowBits?: number;
        level?: number; // compression only
        memLevel?: number; // compression only
        strategy?: number; // compression only
        dictionary?: Buffer | NodeJS.TypedArray | DataView | ArrayBuffer; // deflate/inflate only, empty dictionary by default
    }

    interface Zlib {
        /** @deprecated Use bytesWritten instead. */
        readonly bytesRead: number;
        readonly bytesWritten: number;
        shell?: boolean | string;
        close(callback?: () => void): void;
        flush(kind?: number | (() => void), callback?: () => void): void;
    }

    interface ZlibParams {
        params(level: number, strategy: number, callback: () => void): void;
    }

    interface ZlibReset {
        reset(): void;
    }

    interface Gzip extends stream.Transform, Zlib { }
    interface Gunzip extends stream.Transform, Zlib { }
    interface Deflate extends stream.Transform, Zlib, ZlibReset, ZlibParams { }
    interface Inflate extends stream.Transform, Zlib, ZlibReset { }
    interface DeflateRaw extends stream.Transform, Zlib, ZlibReset, ZlibParams { }
    interface InflateRaw extends stream.Transform, Zlib, ZlibReset { }
    interface Unzip extends stream.Transform, Zlib { }

    function createGzip(options?: ZlibOptions): Gzip;
    function createGunzip(options?: ZlibOptions): Gunzip;
    function createDeflate(options?: ZlibOptions): Deflate;
    function createInflate(options?: ZlibOptions): Inflate;
    function createDeflateRaw(options?: ZlibOptions): DeflateRaw;
    function createInflateRaw(options?: ZlibOptions): InflateRaw;
    function createUnzip(options?: ZlibOptions): Unzip;

    type InputType = string | Buffer | DataView | ArrayBuffer | NodeJS.TypedArray;
    function deflate(buf: InputType, callback: (error: Error | null, result: Buffer) => void): void;
    function deflate(buf: InputType, options: ZlibOptions, callback: (error: Error | null, result: Buffer) => void): void;
    function deflateSync(buf: InputType, options?: ZlibOptions): Buffer;
    function deflateRaw(buf: InputType, callback: (error: Error | null, result: Buffer) => void): void;
    function deflateRaw(buf: InputType, options: ZlibOptions, callback: (error: Error | null, result: Buffer) => void): void;
    function deflateRawSync(buf: InputType, options?: ZlibOptions): Buffer;
    function gzip(buf: InputType, callback: (error: Error | null, result: Buffer) => void): void;
    function gzip(buf: InputType, options: ZlibOptions, callback: (error: Error | null, result: Buffer) => void): void;
    function gzipSync(buf: InputType, options?: ZlibOptions): Buffer;
    function gunzip(buf: InputType, callback: (error: Error | null, result: Buffer) => void): void;
    function gunzip(buf: InputType, options: ZlibOptions, callback: (error: Error | null, result: Buffer) => void): void;
    function gunzipSync(buf: InputType, options?: ZlibOptions): Buffer;
    function inflate(buf: InputType, callback: (error: Error | null, result: Buffer) => void): void;
    function inflate(buf: InputType, options: ZlibOptions, callback: (error: Error | null, result: Buffer) => void): void;
    function inflateSync(buf: InputType, options?: ZlibOptions): Buffer;
    function inflateRaw(buf: InputType, callback: (error: Error | null, result: Buffer) => void): void;
    function inflateRaw(buf: InputType, options: ZlibOptions, callback: (error: Error | null, result: Buffer) => void): void;
    function inflateRawSync(buf: InputType, options?: ZlibOptions): Buffer;
    function unzip(buf: InputType, callback: (error: Error | null, result: Buffer) => void): void;
    function unzip(buf: InputType, options: ZlibOptions, callback: (error: Error | null, result: Buffer) => void): void;
    function unzipSync(buf: InputType, options?: ZlibOptions): Buffer;

    namespace constants {
        // Allowed flush values.

        const Z_NO_FLUSH: number;
        const Z_PARTIAL_FLUSH: number;
        const Z_SYNC_FLUSH: number;
        const Z_FULL_FLUSH: number;
        const Z_FINISH: number;
        const Z_BLOCK: number;
        const Z_TREES: number;

        // Return codes for the compression/decompression functions. Negative values are errors, positive values are used for special but normal events.

        const Z_OK: number;
        const Z_STREAM_END: number;
        const Z_NEED_DICT: number;
        const Z_ERRNO: number;
        const Z_STREAM_ERROR: number;
        const Z_DATA_ERROR: number;
        const Z_MEM_ERROR: number;
        const Z_BUF_ERROR: number;
        const Z_VERSION_ERROR: number;

        // Compression levels.

        const Z_NO_COMPRESSION: number;
        const Z_BEST_SPEED: number;
        const Z_BEST_COMPRESSION: number;
        const Z_DEFAULT_COMPRESSION: number;

        // Compression strategy.

        const Z_FILTERED: number;
        const Z_HUFFMAN_ONLY: number;
        const Z_RLE: number;
        const Z_FIXED: number;
        const Z_DEFAULT_STRATEGY: number;
    }

    // Constants
    const Z_NO_FLUSH: number;
    const Z_PARTIAL_FLUSH: number;
    const Z_SYNC_FLUSH: number;
    const Z_FULL_FLUSH: number;
    const Z_FINISH: number;
    const Z_BLOCK: number;
    const Z_TREES: number;
    const Z_OK: number;
    const Z_STREAM_END: number;
    const Z_NEED_DICT: number;
    const Z_ERRNO: number;
    const Z_STREAM_ERROR: number;
    const Z_DATA_ERROR: number;
    const Z_MEM_ERROR: number;
    const Z_BUF_ERROR: number;
    const Z_VERSION_ERROR: number;
    const Z_NO_COMPRESSION: number;
    const Z_BEST_SPEED: number;
    const Z_BEST_COMPRESSION: number;
    const Z_DEFAULT_COMPRESSION: number;
    const Z_FILTERED: number;
    const Z_HUFFMAN_ONLY: number;
    const Z_RLE: number;
    const Z_FIXED: number;
    const Z_DEFAULT_STRATEGY: number;
    const Z_BINARY: number;
    const Z_TEXT: number;
    const Z_ASCII: number;
    const Z_UNKNOWN: number;
    const Z_DEFLATED: number;
}