class Llvm < Formula
  desc "Next-gen compiler infrastructure"
  homepage "https://llvm.org/"

  stable do
    url "https://releases.llvm.org/8.0.0/llvm-8.0.0.src.tar.xz"
    sha256 "8872be1b12c61450cacc82b3d153eab02be2546ef34fa3580ed14137bb26224c"

    resource "clang" do
      url "https://releases.llvm.org/8.0.0/cfe-8.0.0.src.tar.xz"
      sha256 "084c115aab0084e63b23eee8c233abb6739c399e29966eaeccfc6e088e0b736b"
    end

    resource "clang-extra-tools" do
      url "https://releases.llvm.org/8.0.0/clang-tools-extra-8.0.0.src.tar.xz"
      sha256 "4f00122be408a7482f2004bcf215720d2b88cf8dc78b824abb225da8ad359d4b"
    end

    resource "compiler-rt" do
      url "https://releases.llvm.org/8.0.0/compiler-rt-8.0.0.src.tar.xz"
      sha256 "b435c7474f459e71b2831f1a4e3f1d21203cb9c0172e94e9d9b69f50354f21b1"
    end

    resource "libcxx" do
      url "https://releases.llvm.org/8.0.0/libcxx-8.0.0.src.tar.xz"
      sha256 "c2902675e7c84324fb2c1e45489220f250ede016cc3117186785d9dc291f9de2"
    end

    resource "libunwind" do
      url "https://releases.llvm.org/8.0.0/libunwind-8.0.0.src.tar.xz"
      sha256 "ff243a669c9cef2e2537e4f697d6fb47764ea91949016f2d643cb5d8286df660"
    end

    resource "lld" do
      url "https://releases.llvm.org/8.0.0/lld-8.0.0.src.tar.xz"
      sha256 "9caec8ec922e32ffa130f0fb08e4c5a242d7e68ce757631e425e9eba2e1a6e37"
    end

    resource "openmp" do
      url "https://releases.llvm.org/8.0.0/openmp-8.0.0.src.tar.xz"
      sha256 "f7b1705d2f16c4fc23d6531f67d2dd6fb78a077dd346b02fed64f4b8df65c9d5"
    end

    resource "polly" do
      url "https://releases.llvm.org/8.0.0/polly-8.0.0.src.tar.xz"
      sha256 "e3f5a3d6794ef8233af302c45ceb464b74cdc369c1ac735b6b381b21e4d89df4"
    end
  end

  bottle do
    cellar :any
    sha256 "28494073b3d20b22668ca82af68fef01c59708547acec2f6b86ff5e3e152e8dc" => :mojave
    sha256 "a2bf6ec0b51b56541c40d31ec7677b700764850e93f29474f54333b96355bc0d" => :high_sierra
    sha256 "b827b266bcbca04ea70b362b452aa0c903403e14847665c0ce59b6b11273a21f" => :sierra
  end

  # Clang cannot find system headers if Xcode CLT is not installed
  pour_bottle? do
    reason "The bottle needs the Xcode CLT to be installed."
    satisfy { MacOS::CLT.installed? }
  end

  head do
    url "https://git.llvm.org/git/llvm.git"

    resource "clang" do
      url "https://git.llvm.org/git/clang.git"
    end

    resource "clang-extra-tools" do
      url "https://git.llvm.org/git/clang-tools-extra.git"
    end

    resource "compiler-rt" do
      url "https://git.llvm.org/git/compiler-rt.git"
    end

    resource "libcxx" do
      url "https://git.llvm.org/git/libcxx.git"
    end

    resource "libunwind" do
      url "https://git.llvm.org/git/libunwind.git"
    end

    resource "lld" do
      url "https://git.llvm.org/git/lld.git"
    end

    resource "openmp" do
      url "https://git.llvm.org/git/openmp.git"
    end

    resource "polly" do
      url "https://git.llvm.org/git/polly.git"
    end
  end

  keg_only :provided_by_macos

  # https://llvm.org/docs/GettingStarted.html#requirement
  depends_on "cmake" => :build
  depends_on :xcode => :build
  depends_on "libffi"

  def install
    # Apple's libstdc++ is too old to build LLVM
    ENV.libcxx if ENV.compiler == :clang

    (buildpath/"tools/clang").install resource("clang")
    (buildpath/"tools/clang/tools/extra").install resource("clang-extra-tools")
    (buildpath/"projects/openmp").install resource("openmp")
    (buildpath/"projects/libcxx").install resource("libcxx")
    (buildpath/"projects/libunwind").install resource("libunwind")
    (buildpath/"tools/lld").install resource("lld")
    (buildpath/"tools/polly").install resource("polly")
    (buildpath/"projects/compiler-rt").install resource("compiler-rt")

    # compiler-rt has some iOS simulator features that require i386 symbols
    # I'm assuming the rest of clang needs support too for 32-bit compilation
    # to work correctly, but if not, perhaps universal binaries could be
    # limited to compiler-rt. llvm makes this somewhat easier because compiler-rt
    # can almost be treated as an entirely different build from llvm.
    ENV.permit_arch_flags

    args = %W[
      -DLIBOMP_ARCH=x86_64
      -DLINK_POLLY_INTO_TOOLS=ON
      -DLLVM_BUILD_EXTERNAL_COMPILER_RT=ON
      -DLLVM_BUILD_LLVM_DYLIB=ON
      -DLLVM_ENABLE_EH=ON
      -DLLVM_ENABLE_FFI=ON
      -DLLVM_ENABLE_LIBCXX=ON
      -DLLVM_ENABLE_RTTI=ON
      -DLLVM_INCLUDE_DOCS=OFF
      -DLLVM_INSTALL_UTILS=ON
      -DLLVM_OPTIMIZED_TABLEGEN=ON
      -DLLVM_TARGETS_TO_BUILD=all
      -DWITH_POLLY=ON
      -DFFI_INCLUDE_DIR=#{Formula["libffi"].opt_lib}/libffi-#{Formula["libffi"].version}/include
      -DFFI_LIBRARY_DIR=#{Formula["libffi"].opt_lib}
      -DLLVM_CREATE_XCODE_TOOLCHAIN=ON
    ]

    mkdir "build" do
      system "cmake", "-G", "Unix Makefiles", "..", *(std_cmake_args + args)
      system "make"
      system "make", "install"
      system "make", "install-xcode-toolchain"
    end

    (share/"clang/tools").install Dir["tools/clang/tools/scan-{build,view}"]
    (share/"cmake").install "cmake/modules"
    inreplace "#{share}/clang/tools/scan-build/bin/scan-build", "$RealBin/bin/clang", "#{bin}/clang"
    bin.install_symlink share/"clang/tools/scan-build/bin/scan-build", share/"clang/tools/scan-view/bin/scan-view"
    man1.install_symlink share/"clang/tools/scan-build/man/scan-build.1"

    # install llvm python bindings
    (lib/"python2.7/site-packages").install buildpath/"bindings/python/llvm"
    (lib/"python2.7/site-packages").install buildpath/"tools/clang/bindings/python/clang"
  end

  def caveats; <<~EOS
    To use the bundled libc++ please add the following LDFLAGS:
      LDFLAGS="-L#{opt_lib} -Wl,-rpath,#{opt_lib}"
  EOS
  end

  test do
    assert_equal prefix.to_s, shell_output("#{bin}/llvm-config --prefix").chomp

    (testpath/"omptest.c").write <<~EOS
      #include <stdlib.h>
      #include <stdio.h>
      #include <omp.h>

      int main() {
          #pragma omp parallel num_threads(4)
          {
            printf("Hello from thread %d, nthreads %d\\n", omp_get_thread_num(), omp_get_num_threads());
          }
          return EXIT_SUCCESS;
      }
    EOS

    clean_version = version.to_s[/(\d+\.?)+/]

    system "#{bin}/clang", "-L#{lib}", "-fopenmp", "-nobuiltininc",
                           "-I#{lib}/clang/#{clean_version}/include",
                           "omptest.c", "-o", "omptest"
    testresult = shell_output("./omptest")

    sorted_testresult = testresult.split("\n").sort.join("\n")
    expected_result = <<~EOS
      Hello from thread 0, nthreads 4
      Hello from thread 1, nthreads 4
      Hello from thread 2, nthreads 4
      Hello from thread 3, nthreads 4
    EOS
    assert_equal expected_result.strip, sorted_testresult.strip

    (testpath/"test.c").write <<~EOS
      #include <stdio.h>

      int main()
      {
        printf("Hello World!\\n");
        return 0;
      }
    EOS

    (testpath/"test.cpp").write <<~EOS
      #include <iostream>

      int main()
      {
        std::cout << "Hello World!" << std::endl;
        return 0;
      }
    EOS

    # Testing Command Line Tools
    if MacOS::CLT.installed?
      libclangclt = Dir["/Library/Developer/CommandLineTools/usr/lib/clang/#{MacOS::CLT.version.to_i}*"].last { |f| File.directory? f }

      system "#{bin}/clang++", "-v", "-nostdinc",
              "-I/Library/Developer/CommandLineTools/usr/include/c++/v1",
              "-I#{libclangclt}/include",
              "-I/usr/include", # need it because /Library/.../usr/include/c++/v1/iosfwd refers to <wchar.h>, which CLT installs to /usr/include
              "test.cpp", "-o", "testCLT++"
      assert_includes MachO::Tools.dylibs("testCLT++"), "/usr/lib/libc++.1.dylib"
      assert_equal "Hello World!", shell_output("./testCLT++").chomp

      system "#{bin}/clang", "-v", "-nostdinc",
              "-I/usr/include", # this is where CLT installs stdio.h
              "test.c", "-o", "testCLT"
      assert_equal "Hello World!", shell_output("./testCLT").chomp
    end

    # Testing Xcode
    if MacOS::Xcode.installed?
      libclangxc = Dir["#{MacOS::Xcode.toolchain_path}/usr/lib/clang/#{DevelopmentTools.clang_version}*"].last { |f| File.directory? f }

      system "#{bin}/clang++", "-v", "-nostdinc",
              "-I#{MacOS::Xcode.toolchain_path}/usr/include/c++/v1",
              "-I#{libclangxc}/include",
              "-I#{MacOS.sdk_path}/usr/include",
              "test.cpp", "-o", "testXC++"
      assert_includes MachO::Tools.dylibs("testXC++"), "/usr/lib/libc++.1.dylib"
      assert_equal "Hello World!", shell_output("./testXC++").chomp

      system "#{bin}/clang", "-v", "-nostdinc",
              "-I#{MacOS.sdk_path}/usr/include",
              "test.c", "-o", "testXC"
      assert_equal "Hello World!", shell_output("./testXC").chomp
    end

    # link against installed libc++
    # related to https://github.com/Homebrew/legacy-homebrew/issues/47149
    system "#{bin}/clang++", "-v", "-nostdinc",
            "-std=c++11", "-stdlib=libc++",
            "-I#{MacOS::Xcode.toolchain_path}/usr/include/c++/v1",
            "-I#{libclangxc}/include",
            "-I#{MacOS.sdk_path}/usr/include",
            "-L#{lib}",
            "-Wl,-rpath,#{lib}", "test.cpp", "-o", "test"
    assert_includes MachO::Tools.dylibs("test"), "#{opt_lib}/libc++.1.dylib"
    assert_equal "Hello World!", shell_output("./test").chomp
  end
end