#!/bin/bash -e
#
#   This script allows CMAKE_CXX_COMPILER to be a standard
#   C++ compiler and hosttrace sets RULE_LAUNCH_COMPILE and
#   RULE_LAUNCH_LINK in CMake so that all compiler and link
#   commands are prefixed with this script followed by the
#   C++ compiler. Thus if $1 == $2 then we know the command
#   was intended for the C++ compiler and we discard both
#   $1 and $2 and redirect the command to linker.
#   If $1 != $2 then we know that the command was not intended
#   for the C++ compiler and we just discard $1 and launch
#   the original command. Examples of when $2 will not equal
#   $1 are 'ar', 'cmake', etc. during the linking phase
#

# emit a message about the underlying command executed
: ${DEBUG:=0}
: ${HOSTTRACE_DEBUG_LAUNCH_COMPILER:=${DEBUG}}

debug-message()
{
    if [ "${HOSTTRACE_DEBUG_LAUNCH_COMPILER}" -ne 0 ]; then
        echo -e "##### $(basename ${BASH_SOURCE[0]}) executing: \"$@\"... #####"
    fi
}

# if hosttrace compiler is not passed, someone is probably trying to invoke it directly
if [ -z "${1}" ]; then
    echo -e "\n${BASH_SOURCE[0]} was invoked without the hosttrace compiler as the first argument."
    echo "This script is not indended to be directly invoked by any mechanism other"
    echo -e "than through a RULE_LAUNCH_COMPILE or RULE_LAUNCH_LINK property set in CMake.\n"
    exit 1
fi

# if hosttrace compiler is not passed, someone is probably trying to invoke it directly
if [ -z "${2}" ]; then
    echo -e "\n${BASH_SOURCE[0]} was invoked without the C++ compiler as the second argument."
    echo "This script is not indended to be directly invoked by any mechanism other"
    echo -e "than through a RULE_LAUNCH_COMPILE or RULE_LAUNCH_LINK property set in CMake.\n"
    exit 1
fi

# if there aren't two args, this isn't necessarily invalid, just a bit strange
if [ -z "${3}" ]; then exit 0; fi

# store the hosttrace compiler
HOSTTRACE_COMPILER=${1}

# remove the hosttrace compiler from the arguments
shift

# store the expected C++ compiler
CXX_COMPILER=${1}

# remove the expected C++ compiler from the arguments
shift

if [[ "${CXX_COMPILER}" != "${1}" ]]; then
    debug-message $@
    # the command does not depend on hosttrace so just execute the command w/o re-directing to ${HOSTTRACE_COMPILER}
    eval $@
else
    # the executable is the C++ compiler, so we need to re-direct to ${HOSTTRACE_COMPILER}
    if [ ! -f "${HOSTTRACE_COMPILER}" ]; then
        echo -e "\nError: the compiler redirect for hosttrace was not found at ${HOSTTRACE_COMPILER}\n"
        exit 1
    fi

    # discard the compiler from the command
    shift

    debug-message ${HOSTTRACE_COMPILER} $@
    # execute ${HOSTTRACE_COMPILER} (again, usually nvcc_wrapper)
    ${HOSTTRACE_COMPILER} $@
fi