#!/usr/bin/env bash
#
# This file detects the C/C++ compiler and exports it to the CC/CXX environment variables
#

if [[ "$#" -lt 2 ]]; then
  echo "Usage..."
  echo "detect-compiler.sh <Architecture> <compiler> <compiler major version> <compiler minor version>"
  echo "Specify the target architecture."
  echo "Specify the name of compiler (clang or gcc)."
  echo "Specify the major version of compiler."
  echo "Specify the minor version of compiler."
  exit 1
fi

build_arch="$1"
compiler="$2"
cxxCompiler="$compiler++"
majorVersion="$3"
minorVersion="$4"

# clear the existing CC and CXX from environment
CC=
CXX=

if [[ "$compiler" == "gcc" ]]; then cxxCompiler="g++"; fi

check_version_exists() {
    desired_version=-1

    # Set up the environment to be used for building with the desired compiler.
    if command -v "$compiler-$1.$2" > /dev/null; then
        desired_version="-$1.$2"
    elif command -v "$compiler$1$2" > /dev/null; then
        desired_version="$1$2"
    elif command -v "$compiler-$1$2" > /dev/null; then
        desired_version="-$1$2"
    fi

    echo "$desired_version"
}

if [[ -z "$CLR_CC" ]]; then

    # Set default versions
    if [[ -z "$majorVersion" ]]; then
        # note: gcc (all versions) and clang versions higher than 6 do not have minor version in file name, if it is zero.
        if [[ "$compiler" == "clang" ]]; then versions=( 9 8 7 6.0 5.0 4.0 3.9 3.8 3.7 3.6 3.5 )
        elif [[ "$compiler" == "gcc" ]]; then versions=( 9 8 7 6 5 4.9 ); fi

        for version in "${versions[@]}"; do
            parts=(${version//./ })
            desired_version="$(check_version_exists "${parts[0]}" "${parts[1]}")"
            if [[ "$desired_version" != "-1" ]]; then majorVersion="${parts[0]}"; break; fi
        done

        if [[ -z "$majorVersion" ]]; then
            if command -v "$compiler" > /dev/null; then
                if [[ "$(uname)" != "Darwin" ]]; then
                    echo "WARN: Specific version of $compiler not found, falling back to use the one in PATH."
                fi
                CC="$(command -v "$compiler")"
                CXX="$(command -v "$cxxCompiler")"
            else
                echo "ERROR: No usable version of $compiler found."
                exit 1
            fi
        else
            if [[ "$compiler" == "clang" && "$majorVersion" -lt 5 ]]; then
                if [[ "$build_arch" == "arm" || "$build_arch" == "armel" ]]; then
                    if command -v "$compiler" > /dev/null; then
                        echo "WARN: Found clang version $majorVersion which is not supported on arm/armel architectures, falling back to use clang from PATH."
                        CC="$(command -v "$compiler")"
                        CXX="$(command -v "$cxxCompiler")"
                    else
                        echo "ERROR: Found clang version $majorVersion which is not supported on arm/armel architectures, and there is no clang in PATH."
                        exit 1
                    fi
                fi
            fi
        fi
    else
        desired_version="$(check_version_exists "$majorVersion" "$minorVersion")"
        if [[ "$desired_version" == "-1" ]]; then
            echo "ERROR: Could not find specific version of $compiler: $majorVersion $minorVersion."
            exit 1
        fi
    fi

    if [[ -z "$CC" ]]; then
        CC="$(command -v "$compiler$desired_version")"
        CXX="$(command -v "$cxxCompiler$desired_version")"
        if [[ -z "$CXX" ]]; then CXX="$(command -v "$cxxCompiler")"; fi
    fi
else
    if [[ ! -f "$CLR_CC" ]]; then
        echo "ERROR: CLR_CC is set but path '$CLR_CC' does not exist"
        exit 1
    fi
    CC="$CLR_CC"
    CXX="$CLR_CXX"
fi

if [[ -z "$CC" ]]; then
    echo "ERROR: Unable to find $compiler."
    exit 1
fi

SCAN_BUILD_COMMAND="$(command -v "scan-build$desired_version")"

export CC CXX SCAN_BUILD_COMMAND
