class Vtk < Formula
  desc "Toolkit for 3D computer graphics, image processing, and visualization."
  homepage "http://www.vtk.org"
  url "http://www.vtk.org/files/release/7.1/VTK-7.1.0.tar.gz"
  mirror "https://fossies.org/linux/misc/VTK-7.1.0.tar.gz"
  sha256 "5f3ea001204d4f714be972a810a62c0f2277fbb9d8d2f8df39562988ca37497a"
  revision 1

  head "https://github.com/Kitware/VTK.git"

  bottle do
    sha256 "ea7e0d67acaeae418f5a523f87e34a4a3e7765739811f655b50277b48664472a" => :sierra
    sha256 "30afadc288f71f1fbdd12097c7f1cb584945157052e286f1b3c1a088cab550af" => :el_capitan
    sha256 "7fcddb90cf72a5e83f94a6248dd72387e1cc20b2beb9c880b484dd8545b54fc1" => :yosemite
  end

  deprecated_option "examples" => "with-examples"
  deprecated_option "qt-extern" => "with-qt-extern"
  deprecated_option "tcl" => "with-tcl"
  deprecated_option "remove-legacy" => "without-legacy"

  option :cxx11
  option "with-examples",   "Compile and install various examples"
  option "with-qt-extern",  "Enable Qt4 extension via non-Homebrew external Qt4"
  option "with-tcl",        "Enable Tcl wrapping of VTK classes"
  option "with-matplotlib", "Enable matplotlib support"
  option "without-legacy",  "Disable legacy APIs"
  option "without-python",  "Build without python2 support"

  depends_on "cmake" => :build
  depends_on :x11 => :optional
  depends_on "qt5" => :optional

  depends_on :python => :recommended if MacOS.version <= :snow_leopard
  depends_on :python3 => :optional

  depends_on "boost" => :recommended
  depends_on "fontconfig" => :recommended
  depends_on "hdf5" => :recommended
  depends_on "jpeg" => :recommended
  depends_on "libpng" => :recommended
  depends_on "libtiff" => :recommended
  depends_on "matplotlib" => :python if build.with?("matplotlib") && build.with?("python")

  # If --with-qt and --with-python, then we automatically use PyQt, too!
  if build.with? "qt5"
    if build.with? "python"
      depends_on "sip"
      depends_on "pyqt5" => ["with-python", "without-python3"]
    elsif build.with? "python3"
      depends_on "sip"   => ["with-python3", "without-python"]
      depends_on "pyqt5"
    end
  end

  def install
    args = std_cmake_args + %W[
      -DVTK_REQUIRED_OBJCXX_FLAGS=''
      -DBUILD_SHARED_LIBS=ON
      -DCMAKE_INSTALL_RPATH:STRING=#{lib}
      -DCMAKE_INSTALL_NAME_DIR:STRING=#{lib}
      -DVTK_USE_SYSTEM_EXPAT=ON
      -DVTK_USE_SYSTEM_LIBXML2=ON
      -DVTK_USE_SYSTEM_ZLIB=ON
    ]

    args << "-DBUILD_EXAMPLES=" + ((build.with? "examples") ? "ON" : "OFF")

    if build.with? "examples"
      args << "-DBUILD_TESTING=ON"
    else
      args << "-DBUILD_TESTING=OFF"
    end

    if build.with?("qt5")
      args << "-DVTK_QT_VERSION:STRING=5"
      args << "-DVTK_Group_Qt=ON"
    end

    args << "-DVTK_WRAP_TCL=ON" if build.with? "tcl"

    # Cocoa for everything except x11
    if build.with? "x11"
      args << "-DVTK_USE_COCOA=OFF"
      args << "-DVTK_USE_X=ON"
      args << "-DOPENGL_INCLUDE_DIR:PATH=/usr/X11R6/include"
      args << "-DOPENGL_gl_LIBRARY:STRING=/usr/X11R6/lib/libGL.dylib"
      args << "-DOPENGL_glu_LIBRARY:STRING=/usr/X11R6/lib/libGLU.dylib"
    else
      args << "-DVTK_USE_COCOA=ON"
    end

    unless MacOS::CLT.installed?
      # We are facing an Xcode-only installation, and we have to keep
      # vtk from using its internal Tk headers (that differ from OSX's).
      args << "-DTK_INCLUDE_PATH:PATH=#{MacOS.sdk_path}/System/Library/Frameworks/Tk.framework/Headers"
      args << "-DTK_INTERNAL_PATH:PATH=#{MacOS.sdk_path}/System/Library/Frameworks/Tk.framework/Headers/tk-private"
    end

    args << "-DModule_vtkInfovisBoost=ON" << "-DModule_vtkInfovisBoostGraphAlgorithms=ON" if build.with? "boost"
    args << "-DModule_vtkRenderingFreeTypeFontConfig=ON" if build.with? "fontconfig"
    args << "-DVTK_USE_SYSTEM_HDF5=ON" if build.with? "hdf5"
    args << "-DVTK_USE_SYSTEM_JPEG=ON" if build.with? "jpeg"
    args << "-DVTK_USE_SYSTEM_PNG=ON" if build.with? "libpng"
    args << "-DVTK_USE_SYSTEM_TIFF=ON" if build.with? "libtiff"
    args << "-DModule_vtkRenderingMatplotlib=ON" if build.with? "matplotlib"
    args << "-DVTK_LEGACY_REMOVE=ON" if build.without? "legacy"

    ENV.cxx11 if build.cxx11?

    mkdir "build" do
      if build.with?("python3") && build.with?("python")
        # VTK Does not support building both python 2 and 3 versions
        odie "VTK: Does not support building both python 2 and 3 wrappers"
      elsif build.with?("python") || build.with?("python3")
        python_executable = `which python`.strip if build.with? "python"
        python_executable = `which python3`.strip if build.with? "python3"

        python_prefix = `#{python_executable} -c 'import sys;print(sys.prefix)'`.chomp
        python_include = `#{python_executable} -c 'from distutils import sysconfig;print(sysconfig.get_python_inc(True))'`.chomp
        python_version = "python" + `#{python_executable} -c 'import sys;print(sys.version[:3])'`.chomp
        py_site_packages = "#{lib}/#{python_version}/site-packages"

        args << "-DVTK_WRAP_PYTHON=ON"
        args << "-DPYTHON_EXECUTABLE='#{python_executable}'"
        args << "-DPYTHON_INCLUDE_DIR='#{python_include}'"
        # CMake picks up the system's python dylib, even if we have a brewed one.
        if File.exist? "#{python_prefix}/Python"
          args << "-DPYTHON_LIBRARY='#{python_prefix}/Python'"
        elsif File.exist? "#{python_prefix}/lib/lib#{python_version}.a"
          args << "-DPYTHON_LIBRARY='#{python_prefix}/lib/lib#{python_version}.a'"
        else
          args << "-DPYTHON_LIBRARY='#{python_prefix}/lib/lib#{python_version}.dylib'"
        end
        # Set the prefix for the python bindings to the Cellar
        args << "-DVTK_INSTALL_PYTHON_MODULE_DIR='#{py_site_packages}/'"
      end

      if build.with?("qt5")
        args << "-DVTK_WRAP_PYTHON_SIP=ON"
        args << "-DSIP_PYQT_DIR='#{Formula["pyqt5"].opt_share}/sip'"
      end

      args << ".."
      system "cmake", *args
      system "make"
      system "make", "install"
    end

    pkgshare.install "Examples" if build.with? "examples"
  end

  def post_install
    # This is a horrible, horrible hack because VTK's build system links
    # directly against libpython, breaking all installs for users of brewed
    # Python. See tracking issues:
    #
    # https://github.com/Homebrew/homebrew-science/pull/3811
    # https://github.com/Homebrew/homebrew-science/issues/3401
    # https://gitlab.kitware.com/vtk/vtk/merge_requests/1713
    #
    # This postinstall block should be removed once upstream issues a fix.
    return unless OS.mac? && build.with?("python")
    # Detect if we are using brewed Python 2
    python = Formula["python"]
    brewed_python = python.opt_frameworks/"Python.framework"
    system_python = "/System/Library/Frameworks/Python.framework"
    if python.linked_keg.exist?
      ohai "Patching VTK to use Homebrew's Python 2"
      from = system_python
      to = brewed_python
    else
      ohai "Patching VTK to use system Python 2"
      from = brewed_python
      to = system_python
    end

    # Patch it all up
    keg = Keg.new(prefix)
    keg.mach_o_files.each do |file|
      file.ensure_writable do
        keg.each_install_name_for(file) do |old_name|
          next unless old_name.start_with? from
          new_name = old_name.sub(from, to)
          puts "#{file}:\n  #{old_name} => #{new_name}" if ARGV.verbose?
          keg.change_install_name(old_name, new_name, file)
        end
      end
    end
  end

  def caveats
    s = ""
    s += <<-EOS.undent
        Even without the --with-qt5 option, you can display native VTK render windows
        from python. Alternatively, you can integrate the RenderWindowInteractor
        in PyQt4, Tk or Wx at runtime. Read more:
            import vtk.qt5; help(vtk.qt5) or import vtk.wx; help(vtk.wx)
    EOS

    if build.with? "examples"
      s += <<-EOS.undent

        The scripting examples are stored in #{HOMEBREW_PREFIX}/share/vtk
      EOS
    end

    if build.with? "python"
      s += <<-EOS.undent

        VTK was linked against #{Formula["python"].linked_keg.exist? ? "Homebrew's" : "your system"} copy of Python.
        If you later decide to change Python installations, relink VTK with:

          brew postinstall vtk
      EOS
    end
    s.empty? ? nil : s
  end

  test do
    (testpath/"Version.cpp").write <<-EOS
        #include <vtkVersion.h>
        #include <assert.h>
        int main(int, char *[])
        {
          assert (vtkVersion::GetVTKMajorVersion()==7);
          assert (vtkVersion::GetVTKMinorVersion()==1);
          return EXIT_SUCCESS;
        }
      EOS

    system ENV.cxx, "Version.cpp", "-I#{opt_include}/vtk-7.1"
    system "./a.out"
    system "#{bin}/vtkpython", "-c", "exit()"
  end
end