{ stdenv, fetchurl, xar, cpio, pkgs, python3, pbzx, lib, darwin-stubs, print-reexports }:

let version = "10.12"; in

# Ensure appleSdkVersion is up to date.
assert stdenv.isDarwin -> stdenv.appleSdkVersion == version;

let
  # sadly needs to be exported because security_tool needs it
  sdk = stdenv.mkDerivation rec {
    pname = "MacOS_SDK";
    inherit version;

    # This URL comes from https://swscan.apple.com/content/catalogs/others/index-10.12.merged-1.sucatalog, which we found by:
    #  1. Google: site:swscan.apple.com and look for a name that seems appropriate for your version
    #  2. In the resulting file, search for a file called DevSDK ending in .pkg
    #  3. ???
    #  4. Profit
    src = fetchurl {
      url    = "http://swcdn.apple.com/content/downloads/33/36/041-90419-A_7JJ4H9ZHO2/xs88ob5wjz6riz7g6764twblnvksusg4ps/DevSDK_OSX1012.pkg";
      sha256 = "13xq34sb7383b37hwy076gnhf96prpk1b4087p87xnwswxbrisih";
    };

    nativeBuildInputs = [ xar cpio python3 pbzx ];

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

    unpackPhase = ''
      xar -x -f $src
    '';

    installPhase = ''
      start="$(pwd)"
      mkdir -p $out
      cd $out
      pbzx -n $start/Payload | cpio -idm

      mv usr/* .
      rmdir usr

      mv System/* .
      rmdir System

      pushd lib
      cp ${darwin-stubs}/usr/lib/libcups*.tbd .
      ln -s libcups.2.tbd      libcups.tbd
      ln -s libcupscgi.1.tbd   libcupscgi.tbd
      ln -s libcupsimage.2.tbd libcupsimage.tbd
      ln -s libcupsmime.1.tbd  libcupsmime.tbd
      ln -s libcupsppdc.1.tbd  libcupsppdc.tbd
      popd
    '';

    meta = with lib; {
      description = "Apple SDK ${version}";
      maintainers = with maintainers; [ copumpkin ];
      platforms   = platforms.darwin;
    };
  };

  mkFrameworkSubs = name: deps:
  let
    deps' = deps // { "${name}" = placeholder "out"; };
    substArgs = lib.concatMap (x: [ "--subst-var-by" x deps'."${x}" ]) (lib.attrNames deps');
  in lib.escapeShellArgs substArgs;

  framework = name: deps: stdenv.mkDerivation {
    name = "apple-framework-${name}";

    dontUnpack = true;

    # because we copy files from the system
    preferLocalBuild = true;

    disallowedRequisites = [ sdk ];

    nativeBuildInputs = [ print-reexports ];

    extraTBDFiles = [];

    installPhase = ''
      linkFramework() {
        local path="$1"
        local nested_path="$1"
        if [ "$path" == "JavaNativeFoundation.framework" ]; then
          local nested_path="JavaVM.framework/Versions/A/Frameworks/JavaNativeFoundation.framework"
        fi
        if [ "$path" == "JavaRuntimeSupport.framework" ]; then
          local nested_path="JavaVM.framework/Versions/A/Frameworks/JavaRuntimeSupport.framework"
        fi
        local name="$(basename "$path" .framework)"
        local current="$(readlink "/System/Library/Frameworks/$nested_path/Versions/Current")"
        if [ -z "$current" ]; then
          current=A
        fi

        local dest="$out/Library/Frameworks/$path"

        mkdir -p "$dest/Versions/$current"
        pushd "$dest/Versions/$current" >/dev/null

        if [ -d "${sdk.out}/Library/Frameworks/$nested_path/Versions/$current/Headers" ]; then
          cp -R "${sdk.out}/Library/Frameworks/$nested_path/Versions/$current/Headers" .
        elif [ -d "${sdk.out}/Library/Frameworks/$name.framework/Versions/$current/Headers" ]; then
          current="$(readlink "/System/Library/Frameworks/$name.framework/Versions/Current")"
          cp -R "${sdk.out}/Library/Frameworks/$name.framework/Versions/$current/Headers" .
        fi

        local tbd_source=${darwin-stubs}/System/Library/Frameworks/$nested_path/Versions/$current
        if [ "${name}" != "Kernel" ]; then
          # The Kernel.framework has headers but no actual library component.
          cp -v $tbd_source/*.tbd .
        fi

        if [ -d "$tbd_source/Libraries" ]; then
          mkdir Libraries
          cp -v $tbd_source/Libraries/*.tbd Libraries/
        fi

        ln -s -L "/System/Library/Frameworks/$nested_path/Versions/$current/Resources"

        if [ -f "/System/Library/Frameworks/$nested_path/module.map" ]; then
          ln -s "/System/Library/Frameworks/$nested_path/module.map"
        fi

        pushd "${sdk.out}/Library/Frameworks/$nested_path/Versions/$current" >/dev/null
        local children=$(echo Frameworks/*.framework)
        popd >/dev/null

        for child in $children; do
          childpath="$path/Versions/$current/$child"
          linkFramework "$childpath"
        done

        pushd ../.. >/dev/null
        ln -s "$current" Versions/Current
        ln -s Versions/Current/* .
        popd >/dev/null

        popd >/dev/null
      }

      linkFramework "${name}.framework"

      # linkFramework is recursive, the rest of the processing is not.

      local tbd_source=${darwin-stubs}/System/Library/Frameworks/${name}.framework
      for tbd in $extraTBDFiles; do
        local tbd_dest_dir=$out/Library/Frameworks/${name}.framework/$(dirname "$tbd")
        mkdir -p "$tbd_dest_dir"
        cp -v "$tbd_source/$tbd" "$tbd_dest_dir"
      done

      # Fix and check tbd re-export references
      find $out -name '*.tbd' | while read tbd; do
        echo "Fixing re-exports in $tbd"
        substituteInPlace "$tbd" ${mkFrameworkSubs name deps}

        echo "Checking re-exports in $tbd"
        print-reexports "$tbd" | while read target; do
          local expected="''${target%.dylib}.tbd"
          if ! [ -e "$expected" ]; then
            echo -e "Re-export missing:\n\t$target\n\t(expected $expected)"
            echo -e "While processing\n\t$tbd"
            exit 1
          else
            echo "Re-exported target $target ok"
          fi
        done
      done
    '';

    propagatedBuildInputs = builtins.attrValues deps;

    # don't use pure CF for dylibs that depend on frameworks
    setupHook = ./framework-setup-hook.sh;

    # Not going to be more specific than this for now
    __propagatedImpureHostDeps = lib.optionals (name != "Kernel") [
      # The setup-hook ensures that everyone uses the impure CoreFoundation who uses these SDK frameworks, so let's expose it
      "/System/Library/Frameworks/CoreFoundation.framework"
      "/System/Library/Frameworks/${name}.framework"
      "/System/Library/Frameworks/${name}.framework/${name}"
    ];

    meta = with lib; {
      description = "Apple SDK framework ${name}";
      maintainers = with maintainers; [ copumpkin ];
      platforms   = platforms.darwin;
    };
  };

  tbdOnlyFramework = name: { private ? true }: stdenv.mkDerivation {
    name = "apple-framework-${name}";
    dontUnpack = true;
    installPhase = ''
      mkdir -p $out/Library/Frameworks/
      cp -r ${darwin-stubs}/System/Library/${lib.optionalString private "Private"}Frameworks/${name}.framework \
        $out/Library/Frameworks
      # NOTE there's no re-export checking here, this is probably wrong
    '';
  };
in rec {
  libs = {
    xpc = stdenv.mkDerivation {
      name   = "apple-lib-xpc";
      dontUnpack = true;

      installPhase = ''
        mkdir -p $out/include
        pushd $out/include >/dev/null
        cp -r "${lib.getDev sdk}/include/xpc" $out/include/xpc
        cp "${lib.getDev sdk}/include/launch.h" $out/include/launch.h
        popd >/dev/null
      '';
    };

    Xplugin = stdenv.mkDerivation {
      name   = "apple-lib-Xplugin";
      dontUnpack = true;

      # Not enough
      __propagatedImpureHostDeps = [ "/usr/lib/libXplugin.1.dylib" ];

      propagatedBuildInputs = with frameworks; [
        OpenGL ApplicationServices Carbon IOKit CoreGraphics CoreServices CoreText
      ];

      installPhase = ''
        mkdir -p $out/include $out/lib
        ln -s "${lib.getDev sdk}/include/Xplugin.h" $out/include/Xplugin.h
        cp ${darwin-stubs}/usr/lib/libXplugin.1.tbd $out/lib
        ln -s libXplugin.1.tbd $out/lib/libXplugin.tbd
      '';
    };

    utmp = stdenv.mkDerivation {
      name   = "apple-lib-utmp";
      dontUnpack = true;

      installPhase = ''
        mkdir -p $out/include
        pushd $out/include >/dev/null
        ln -s "${lib.getDev sdk}/include/utmp.h"
        ln -s "${lib.getDev sdk}/include/utmpx.h"
        popd >/dev/null
      '';
    };
  };

  overrides = super: {
    AppKit = lib.overrideDerivation super.AppKit (drv: {
      __propagatedImpureHostDeps = drv.__propagatedImpureHostDeps ++ [
        "/System/Library/PrivateFrameworks/"
      ];
    });

    Carbon = lib.overrideDerivation super.Carbon (drv: {
      extraTBDFiles = [ "Versions/A/Frameworks/HTMLRendering.framework/Versions/A/HTMLRendering.tbd" ];
    });

    CoreFoundation = lib.overrideDerivation super.CoreFoundation (drv: {
      setupHook = ./cf-setup-hook.sh;
    });

    CoreMedia = lib.overrideDerivation super.CoreMedia (drv: {
      __propagatedImpureHostDeps = drv.__propagatedImpureHostDeps ++ [
        "/System/Library/Frameworks/CoreImage.framework"
      ];
    });

    CoreMIDI = lib.overrideDerivation super.CoreMIDI (drv: {
      __propagatedImpureHostDeps = drv.__propagatedImpureHostDeps ++ [
        "/System/Library/PrivateFrameworks/"
      ];
      setupHook = ./private-frameworks-setup-hook.sh;
    });

    IMServicePlugIn = lib.overrideDerivation super.IMServicePlugIn (drv: {
      extraTBDFiles = [ "Versions/A/Frameworks/IMServicePlugInSupport.framework/Versions/A/IMServicePlugInSupport.tbd" ];
    });

    Security = lib.overrideDerivation super.Security (drv: {
      setupHook = ./security-setup-hook.sh;
    });

    QuartzCore = lib.overrideDerivation super.QuartzCore (drv: {
      installPhase = drv.installPhase + ''
        f="$out/Library/Frameworks/QuartzCore.framework/Headers/CoreImage.h"
        substituteInPlace "$f" \
          --replace "QuartzCore/../Frameworks/CoreImage.framework/Headers" "CoreImage"
      '';
    });

    MetalKit = lib.overrideDerivation super.MetalKit (drv: {
      installPhase = drv.installPhase + ''
        mkdir -p $out/include/simd
        cp ${lib.getDev sdk}/include/simd/*.h $out/include/simd/
      '';
    });

    WebKit = lib.overrideDerivation super.WebKit (drv: {
      extraTBDFiles = [
        "Versions/A/Frameworks/WebCore.framework/Versions/A/WebCore.tbd"
        "Versions/A/Frameworks/WebKitLegacy.framework/Versions/A/WebKitLegacy.tbd"
      ];
    });
  } // lib.genAttrs [ "ContactsPersistence" "UIFoundation" "GameCenter" ] (x: tbdOnlyFramework x {});

  bareFrameworks = lib.mapAttrs framework (import ./frameworks.nix {
    inherit frameworks libs;
    inherit (pkgs.darwin) libobjc;
  });

  frameworks = bareFrameworks // overrides bareFrameworks;

  inherit sdk;
}