#!/bin/bash

set -ex

if [ -n "$CLANG_VERSION" ]; then

  if [[ $UBUNTU_VERSION == 22.04 ]]; then
    # work around ubuntu apt-get conflicts
    sudo apt-get -y -f install
    wget --no-check-certificate -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
    if [[ $CLANG_VERSION == 18 ]]; then
      apt-add-repository "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-18 main"
    fi
  fi

  sudo apt-get update
  if [[ $CLANG_VERSION -ge 18 ]]; then
    apt-get install -y libomp-${CLANG_VERSION}-dev libclang-rt-${CLANG_VERSION}-dev clang-"$CLANG_VERSION" llvm-"$CLANG_VERSION"
  else
    apt-get install -y --no-install-recommends clang-"$CLANG_VERSION" llvm-"$CLANG_VERSION"
  fi

  # Install dev version of LLVM.
  if [ -n "$LLVMDEV" ]; then
    sudo apt-get install -y --no-install-recommends llvm-"$CLANG_VERSION"-dev
  fi

  # Use update-alternatives to make this version the default
  update-alternatives --install /usr/bin/clang clang /usr/bin/clang-"$CLANG_VERSION" 50
  update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-"$CLANG_VERSION" 50
  # Override cc/c++ to clang as well
  update-alternatives --install /usr/bin/cc cc /usr/bin/clang 50
  update-alternatives --install /usr/bin/c++ c++ /usr/bin/clang++ 50

  # clang's packaging is a little messed up (the runtime libs aren't
  # added into the linker path), so give it a little help
  clang_lib=("/usr/lib/llvm-$CLANG_VERSION/lib/clang/"*"/lib/linux")
  echo "$clang_lib" >/etc/ld.so.conf.d/clang.conf
  ldconfig

  # Cleanup package manager
  apt-get autoclean && apt-get clean
  rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

fi