{ stdenv, lib
, src, patches, version, qtCompatVersion

, coreutils, bison, flex, gdb, gperf, lndir, perl, pkg-config, python3
, which
  # darwin support
, darwinMinVersionHook, apple-sdk, apple-sdk_10_14, apple-sdk_14, xcbuild

, dbus, fontconfig, freetype, glib, harfbuzz, icu, libdrm, libX11, libXcomposite
, libXcursor, libXext, libXi, libXrender, libinput, libjpeg, libpng , libxcb
, libxkbcommon, libxml2, libxslt, openssl, pcre2, sqlite, udev, xcbutil
, xcbutilimage, xcbutilkeysyms, xcbutilrenderutil, xcbutilwm , zlib, at-spi2-core

  # optional dependencies
, cups ? null, postgresql ? null
, withGtk3 ? false, dconf, gtk3
, withQttranslation ? true, qttranslations ? null

  # options
, libGLSupported ? !stdenv.hostPlatform.isDarwin
, libGL
  # qmake detection for libmysqlclient does not seem to work when cross compiling
, mysqlSupport ? stdenv.hostPlatform == stdenv.buildPlatform
, libmysqlclient
, buildExamples ? false
, buildTests ? false
, debug ? false
, developerBuild ? false
, decryptSslTraffic ? false
, testers
, buildPackages
}:

let
  debugSymbols = debug || developerBuild;
  qtPlatformCross = plat: with plat;
    if isLinux
    then "linux-generic-g++"
    else throw "Please add a qtPlatformCross entry for ${plat.config}";

  # Per https://doc.qt.io/qt-5/macos.html#supported-versions: deployment target = 10.13, build SDK = 14.x.
  # Note that Qt propagates the 10.14 SDK instead of the 10.13 SDK to make sure that applications linked to Qt
  # support automatic dark mode on x86_64-darwin (see: https://developer.apple.com/documentation/appkit/nsappearancecustomization/choosing_a_specific_appearance_for_your_macos_app).
  propagatedAppleSDK = if lib.versionOlder (lib.getVersion apple-sdk) "10.14" then apple-sdk_10_14 else apple-sdk;
  propagatedMinVersionHook = darwinMinVersionHook "10.13";
  buildAppleSDK = apple-sdk_14;
in

stdenv.mkDerivation (finalAttrs: ({
  pname = "qtbase";
  inherit qtCompatVersion src version;
  debug = debugSymbols;

  propagatedBuildInputs = [
    libxml2 libxslt openssl sqlite zlib

    # Text rendering
    harfbuzz icu

    # Image formats
    libjpeg libpng
    pcre2
  ] ++ (
    if stdenv.hostPlatform.isDarwin then [
      propagatedAppleSDK
      propagatedMinVersionHook
    ] else [
      dbus glib udev

      # Text rendering
      fontconfig freetype

      libdrm

      # X11 libs
      libX11 libXcomposite libXext libXi libXrender libxcb libxkbcommon xcbutil
      xcbutilimage xcbutilkeysyms xcbutilrenderutil xcbutilwm
    ] ++ lib.optional libGLSupported libGL
  );

  buildInputs = [ python3 at-spi2-core ]
    ++ lib.optionals (!stdenv.hostPlatform.isDarwin)
    (
      [ libinput ]
      ++ lib.optional withGtk3 gtk3
    )
    ++ lib.optional stdenv.isDarwin buildAppleSDK
    ++ lib.optional developerBuild gdb
    ++ lib.optional (cups != null) cups
    ++ lib.optional (mysqlSupport) libmysqlclient
    ++ lib.optional (postgresql != null) postgresql;

  nativeBuildInputs = [ bison flex gperf lndir perl pkg-config which ]
    ++ lib.optionals stdenv.hostPlatform.isDarwin [ xcbuild ];

  } // lib.optionalAttrs (stdenv.buildPlatform != stdenv.hostPlatform) {
    # `qtbase` expects to find `cc` (with no prefix) in the
    # `$PATH`, so the following is needed even if
    # `stdenv.buildPlatform.canExecute stdenv.hostPlatform`
    depsBuildBuild = [ buildPackages.stdenv.cc ];
  } // {

  propagatedNativeBuildInputs = [ lndir ];

  # libQt5Core links calls CoreFoundation APIs that call into the system ICU. Binaries linked
  # against it will crash during build unless they can access `/usr/share/icu/icudtXXl.dat`.
  propagatedSandboxProfile = lib.optionalString stdenv.hostPlatform.isDarwin ''
    (allow file-read* (subpath "/usr/share/icu"))
  '';

  enableParallelBuilding = true;

  outputs = [ "bin" "dev" "out" ];

  inherit patches;

  fix_qt_builtin_paths = ../hooks/fix-qt-builtin-paths.sh;
  fix_qt_module_paths = ../hooks/fix-qt-module-paths.sh;
  preHook = ''
    . "$fix_qt_builtin_paths"
    . "$fix_qt_module_paths"
    . ${../hooks/move-qt-dev-tools.sh}
    . ${../hooks/fix-qmake-libtool.sh}
  '';

  postPatch = ''
    for prf in qml_plugin.prf qt_plugin.prf qt_docs.prf qml_module.prf create_cmake.prf; do
        substituteInPlace "mkspecs/features/$prf" \
            --subst-var qtPluginPrefix \
            --subst-var qtQmlPrefix \
            --subst-var qtDocPrefix
    done

    substituteInPlace configure --replace /bin/pwd pwd
    substituteInPlace src/corelib/global/global.pri --replace /bin/ls ${coreutils}/bin/ls
    sed -e 's@/\(usr\|opt\)/@/var/empty/@g' -i mkspecs/*/*.conf

    sed -i '/PATHS.*NO_DEFAULT_PATH/ d' src/corelib/Qt5Config.cmake.in
    sed -i '/PATHS.*NO_DEFAULT_PATH/ d' src/corelib/Qt5CoreMacros.cmake
    sed -i 's/NO_DEFAULT_PATH//' src/gui/Qt5GuiConfigExtras.cmake.in
    sed -i '/PATHS.*NO_DEFAULT_PATH/ d' mkspecs/features/data/cmake/Qt5BasicConfig.cmake.in

    # https://bugs.gentoo.org/803470
    sed -i 's/-lpthread/-pthread/' mkspecs/common/linux.conf src/corelib/configure.json

    patchShebangs ./bin
  '' + (
    if stdenv.hostPlatform.isDarwin then ''
      substituteInPlace configure \
        --replace-fail '/usr/bin/xcode-select' '${lib.getBin xcbuild}/bin/xcode-select' \
        --replace-fail '/usr/bin/xcrun' '${lib.getBin xcbuild}/bin/xcrun' \
        --replace-fail '/System/Library/Frameworks/Cocoa.framework' "$SDKROOT/System/Library/Frameworks/Cocoa.framework"
      substituteInPlace ./mkspecs/common/mac.conf \
        --replace-fail "/System/Library/Frameworks/OpenGL.framework/" "$SDKROOT/System/Library/Frameworks/OpenGL.framework/" \
        --replace-fail "/System/Library/Frameworks/AGL.framework/" "$SDKROOT/System/Library/Frameworks/AGL.framework/"
    '' else lib.optionalString libGLSupported ''
      sed -i mkspecs/common/linux.conf \
          -e "/^QMAKE_INCDIR_OPENGL/ s|$|${lib.getDev libGL}/include|" \
          -e "/^QMAKE_LIBDIR_OPENGL/ s|$|${lib.getLib libGL}/lib|"
    '' + lib.optionalString (stdenv.hostPlatform.isx86_32 && stdenv.cc.isGNU) ''
      sed -i mkspecs/common/gcc-base-unix.conf \
          -e "/^QMAKE_LFLAGS_SHLIB/ s/-shared/-shared -static-libgcc/"
    ''
  );

  qtPluginPrefix = "lib/qt-${qtCompatVersion}/plugins";
  qtQmlPrefix = "lib/qt-${qtCompatVersion}/qml";
  qtDocPrefix = "share/doc/qt-${qtCompatVersion}";

  setOutputFlags = false;
  preConfigure = ''
    export LD_LIBRARY_PATH="$PWD/lib:$PWD/plugins/platforms''${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH"

    NIX_CFLAGS_COMPILE+=" -DNIXPKGS_QT_PLUGIN_PREFIX=\"$qtPluginPrefix\""

    # paralellize compilation of qtmake, which happens within ./configure
    export MAKEFLAGS+=" -j$NIX_BUILD_CORES"

    ./bin/syncqt.pl -version $version
  '' + lib.optionalString (!stdenv.buildPlatform.canExecute stdenv.hostPlatform) ''
    # QT's configure script will refuse to use pkg-config unless these two environment variables are set
    export PKG_CONFIG_SYSROOT_DIR=/
    export PKG_CONFIG_LIBDIR=${lib.getLib pkg-config}/lib
    echo "QMAKE_LFLAGS=''${LDFLAGS}" >> mkspecs/devices/${qtPlatformCross stdenv.hostPlatform}/qmake.conf
    echo "QMAKE_CFLAGS=''${CFLAGS}" >> mkspecs/devices/${qtPlatformCross stdenv.hostPlatform}/qmake.conf
    echo "QMAKE_CXXFLAGS=''${CXXFLAGS}" >> mkspecs/devices/${qtPlatformCross stdenv.hostPlatform}/qmake.conf
  '';

  postConfigure = ''
    qmakeCacheInjectNixOutputs() {
        local cache="$1/.qmake.stash"
        echo "qmakeCacheInjectNixOutputs: $cache"
        if ! [ -f "$cache" ]; then
            echo >&2 "qmakeCacheInjectNixOutputs: WARNING: $cache does not exist"
        fi
        cat >>"$cache" <<EOF
    NIX_OUTPUT_BIN = $bin
    NIX_OUTPUT_DEV = $dev
    NIX_OUTPUT_OUT = $out
    NIX_OUTPUT_DOC = $dev/$qtDocPrefix
    NIX_OUTPUT_QML = $bin/$qtQmlPrefix
    NIX_OUTPUT_PLUGIN = $bin/$qtPluginPrefix
    EOF
    }

    find . -name '.qmake.conf' | while read conf; do
        qmakeCacheInjectNixOutputs "$(dirname $conf)"
    done
  '';

  env = {
    NIX_CFLAGS_COMPILE = toString ([
      "-Wno-error=sign-compare" # freetype-2.5.4 changed signedness of some struct fields
    ] ++ lib.optionals (stdenv.buildPlatform != stdenv.hostPlatform) [
      "-Wno-warn=free-nonheap-object"
      "-Wno-free-nonheap-object"
      "-w"
    ] ++ [
      ''-DNIXPKGS_QTCOMPOSE="${libX11.out}/share/X11/locale"''
      ''-DLIBRESOLV_SO="${stdenv.cc.libc.out}/lib/libresolv"''
      ''-DNIXPKGS_LIBXCURSOR="${libXcursor.out}/lib/libXcursor"''
    ] ++ lib.optional libGLSupported ''-DNIXPKGS_MESA_GL="${libGL.out}/lib/libGL"''
    ++ lib.optional stdenv.hostPlatform.isLinux "-DUSE_X11"
    ++ lib.optionals (stdenv.hostPlatform.system == "x86_64-darwin") [
      # ignore "is only available on macOS 10.12.2 or newer" in obj-c code
      "-Wno-error=unguarded-availability"
    ]
    ++ lib.optionals withGtk3 [
      ''-DNIXPKGS_QGTK3_XDG_DATA_DIRS="${gtk3}/share/gsettings-schemas/${gtk3.name}"''
      ''-DNIXPKGS_QGTK3_GIO_EXTRA_MODULES="${dconf.lib}/lib/gio/modules"''
    ] ++ lib.optional decryptSslTraffic "-DQT_DECRYPT_SSL_TRAFFIC");
  } // lib.optionalAttrs (stdenv.buildPlatform != stdenv.hostPlatform) {
    NIX_CFLAGS_COMPILE_FOR_BUILD = toString ([
      "-Wno-warn=free-nonheap-object"
      "-Wno-free-nonheap-object"
      "-w"
    ]);
  };

  prefixKey = "-prefix ";

  # PostgreSQL autodetection fails sporadically because Qt omits the "-lpq" flag
  # if dependency paths contain the string "pq", which can occur in the hash.
  # To prevent these failures, we need to override PostgreSQL detection.
  PSQL_LIBS = lib.optionalString (postgresql != null) "-L${postgresql.lib}/lib -lpq";

  } // lib.optionalAttrs (stdenv.buildPlatform != stdenv.hostPlatform) {
  configurePlatforms = [ ];
  } // {
  # TODO Remove obsolete and useless flags once the build will be totally mastered
  configureFlags = [
    "-plugindir $(out)/$(qtPluginPrefix)"
    "-qmldir $(out)/$(qtQmlPrefix)"
    "-docdir $(out)/$(qtDocPrefix)"

    "-verbose"
    "-confirm-license"
    "-opensource"

    "-release"
    "-shared"
    "-accessibility"
    "-optimized-qmake"
    # for separateDebugInfo
    "-no-strip"
    "-system-proxies"
    "-pkg-config"

    "-gui"
    "-widgets"
    "-opengl desktop"
    "-icu"
    "-L" "${icu.out}/lib"
    "-I" "${icu.dev}/include"
    "-pch"
  ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
    "-device ${qtPlatformCross stdenv.hostPlatform}"
    "-device-option CROSS_COMPILE=${stdenv.cc.targetPrefix}"
  ]
  ++ lib.optional debugSymbols "-debug"
  ++ lib.optionals developerBuild [
    "-developer-build"
    "-no-warnings-are-errors"
  ] ++ lib.optionals (stdenv.buildPlatform != stdenv.hostPlatform) [
    "-no-warnings-are-errors"
  ] ++ (if (!stdenv.hostPlatform.isx86_64) then [
    "-no-sse2"
  ] else [
    "-sse2"
    "${lib.optionalString (!stdenv.hostPlatform.sse3Support)   "-no"}-sse3"
    "${lib.optionalString (!stdenv.hostPlatform.ssse3Support)  "-no"}-ssse3"
    "${lib.optionalString (!stdenv.hostPlatform.sse4_1Support) "-no"}-sse4.1"
    "${lib.optionalString (!stdenv.hostPlatform.sse4_2Support) "-no"}-sse4.2"
    "${lib.optionalString (!stdenv.hostPlatform.avxSupport)    "-no"}-avx"
    "${lib.optionalString (!stdenv.hostPlatform.avx2Support)   "-no"}-avx2"
    ]
  ) ++ [
    "-no-mips_dsp"
    "-no-mips_dspr2"
  ] ++ [
    "-system-zlib"
    "-L" "${zlib.out}/lib"
    "-I" "${zlib.dev}/include"
    "-system-libjpeg"
    "-L" "${libjpeg.out}/lib"
    "-I" "${libjpeg.dev}/include"
    "-system-harfbuzz"
    "-L" "${harfbuzz.out}/lib"
    "-I" "${harfbuzz.dev}/include"
    "-system-pcre"
    "-openssl-linked"
    "-L" "${lib.getLib openssl}/lib"
    "-I" "${openssl.dev}/include"
    "-system-sqlite"
    ''-${if mysqlSupport then "plugin" else "no"}-sql-mysql''
    ''-${if postgresql != null then "plugin" else "no"}-sql-psql''

    "-make libs"
    "-make tools"
    ''-${lib.optionalString (!buildExamples) "no"}make examples''
    ''-${lib.optionalString (!buildTests) "no"}make tests''
  ]
    ++ (
      if stdenv.hostPlatform.isDarwin then [
      "-no-fontconfig"
      "-qt-freetype"
      "-qt-libpng"
      "-no-framework"
    ] else [
      "-rpath"
    ] ++ [
      "-xcb"
      "-qpa xcb"
      "-L" "${libX11.out}/lib"
      "-I" "${libX11.out}/include"
      "-L" "${libXext.out}/lib"
      "-I" "${libXext.out}/include"
      "-L" "${libXrender.out}/lib"
      "-I" "${libXrender.out}/include"

      "-libinput"

      ''-${lib.optionalString (cups == null) "no-"}cups''
      "-dbus-linked"
      "-glib"
    ] ++ [
      "-system-libpng"
    ] ++ lib.optional withGtk3 "-gtk"
      ++ [
        "-inotify"
    ] ++ lib.optionals (cups != null) [
      "-L" "${cups.lib}/lib"
      "-I" "${cups.dev}/include"
    ] ++ lib.optionals (mysqlSupport) [
      "-L" "${libmysqlclient}/lib"
      "-I" "${libmysqlclient}/include"
    ] ++ lib.optional (withQttranslation && (qttranslations != null)) [
      # depends on x11
      "-translationdir" "${qttranslations}/translations"
    ]
  );

  # Move selected outputs.
  postInstall = ''
    moveToOutput "mkspecs" "$dev"
  '';

  devTools = [
    "bin/fixqt4headers.pl"
    "bin/moc"
    "bin/qdbuscpp2xml"
    "bin/qdbusxml2cpp"
    "bin/qlalr"
    "bin/qmake"
    "bin/rcc"
    "bin/syncqt.pl"
    "bin/uic"
  ];

  postFixup = ''
    # Don't retain build-time dependencies like gdb.
    sed '/QMAKE_DEFAULT_.*DIRS/ d' -i $dev/mkspecs/qconfig.pri
    fixQtModulePaths "''${!outputDev}/mkspecs/modules"
    fixQtBuiltinPaths "''${!outputDev}" '*.pr?'

    # Move development tools to $dev
    moveQtDevTools
    moveToOutput bin "$dev"

    # fixup .pc file (where to find 'moc' etc.)
    sed -i "$dev/lib/pkgconfig/Qt5Core.pc" \
      -e "/^host_bins=/ c host_bins=$dev/bin"
  '';

  dontStrip = debugSymbols;

  setupHook = ../hooks/qtbase-setup-hook.sh;

  passthru.tests.pkg-config = testers.testMetaPkgConfig finalAttrs.finalPackage;

  meta = with lib; {
    homepage = "https://www.qt.io/";
    description = "Cross-platform application framework for C++";
    license = with licenses; [ fdl13Plus gpl2Plus lgpl21Plus lgpl3Plus ];
    maintainers = with maintainers; [ qknight ttuegel periklis bkchr ];
    pkgConfigModules = [
      "Qt5Concurrent"
      "Qt5Core"
      "Qt5DBus"
      "Qt5Gui"
      "Qt5Network"
      "Qt5OpenGL"
      "Qt5OpenGLExtensions"
      "Qt5PrintSupport"
      #"Qt5Qml"
      #"Qt5QmlModels"
      #"Qt5Quick"
      #"Qt5QuickTest"
      #"Qt5QuickWidgets"
      "Qt5Sql"
      "Qt5Test"
      "Qt5Widgets"
      "Qt5Xml"
    ];
    platforms = platforms.unix;
  };

}))