## Parses the VERSION_STRING variable and places
## the first, second and third number values in
## the major, minor and patch variables.
function( parse_version VERSION_STRING )

    string ( FIND ${VERSION_STRING} "-" STRING_INDEX )

    if ( ${STRING_INDEX} GREATER -1 )
        math ( EXPR STRING_INDEX "${STRING_INDEX} + 1" )
        string ( SUBSTRING ${VERSION_STRING} ${STRING_INDEX} -1 VERSION_BUILD )
    endif ()

    string ( REGEX MATCHALL "[0123456789]+" VERSIONS ${VERSION_STRING} )
    list ( LENGTH VERSIONS VERSION_COUNT )

    if ( ${VERSION_COUNT} GREATER 0)
        list ( GET VERSIONS 0 MAJOR )
        set ( VERSION_MAJOR ${MAJOR} PARENT_SCOPE )
        set ( TEMP_VERSION_STRING "${MAJOR}" )
    endif ()

    if ( ${VERSION_COUNT} GREATER 1 )
        list ( GET VERSIONS 1 MINOR )
        set ( VERSION_MINOR ${MINOR} PARENT_SCOPE )
        set ( TEMP_VERSION_STRING "${TEMP_VERSION_STRING}.${MINOR}" )
    endif ()

    if ( ${VERSION_COUNT} GREATER 2 )
        list ( GET VERSIONS 2 PATCH )
        set ( VERSION_PATCH ${PATCH} PARENT_SCOPE )
        set ( TEMP_VERSION_STRING "${TEMP_VERSION_STRING}.${PATCH}" )
    endif ()

    if ( DEFINED VERSION_BUILD )
        set ( VERSION_BUILD "${VERSION_BUILD}" PARENT_SCOPE )
    endif ()

    set ( VERSION_STRING "${TEMP_VERSION_STRING}" PARENT_SCOPE )

endfunction ()

## Gets the current version of the repository
## using versioning tags and git describe.
## Passes back a packaging version string
## and a library version string.
function ( get_version DEFAULT_VERSION_STRING )

    parse_version ( ${DEFAULT_VERSION_STRING} )

    find_program ( GIT NAMES git )

    if ( GIT )

        execute_process ( COMMAND "git describe --dirty --long --match [0-9]* 2>/dev/null"
                          WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
                          OUTPUT_VARIABLE GIT_TAG_STRING
                          OUTPUT_STRIP_TRAILING_WHITESPACE
                          RESULT_VARIABLE RESULT )

        if ( ${RESULT} EQUAL 0 )

            parse_version ( ${GIT_TAG_STRING} )

        endif ()

    endif ()

    set( VERSION_STRING "${VERSION_STRING}" PARENT_SCOPE )
    set( VERSION_MAJOR  "${VERSION_MAJOR}" PARENT_SCOPE )
    set( VERSION_MINOR  "${VERSION_MINOR}" PARENT_SCOPE )
    set( VERSION_PATCH  "${VERSION_PATCH}" PARENT_SCOPE )
    set( VERSION_BUILD  "${VERSION_BUILD}" PARENT_SCOPE )

endfunction()

function(get_git_rev GIT_REVISION_OUT)
    find_package(Git)

    if(Git_FOUND)
        execute_process(
            COMMAND ${GIT_EXECUTABLE} describe --tags
            OUTPUT_VARIABLE GIT_DESCRIBE
            OUTPUT_STRIP_TRAILING_WHITESPACE
            RESULT_VARIABLE _GIT_DESCRIBE_RESULT
            ERROR_QUIET)
        if(NOT _GIT_DESCRIBE_RESULT EQUAL 0)
            execute_process(
                COMMAND ${GIT_EXECUTABLE} describe
                OUTPUT_VARIABLE GIT_DESCRIBE
                OUTPUT_STRIP_TRAILING_WHITESPACE
                RESULT_VARIABLE _GIT_DESCRIBE_RESULT
                ERROR_QUIET)
        endif()

        execute_process(
            COMMAND ${GIT_EXECUTABLE} rev-parse HEAD
            WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
            OUTPUT_VARIABLE GIT_REVISION
            OUTPUT_STRIP_TRAILING_WHITESPACE ERROR_QUIET)
        set(${GIT_REVISION_OUT} "${GIT_REVISION}" PARENT_SCOPE)
    else()
        set(${GIT_REVISION_OUT} "" PARENT_SCOPE)
    endif()
endfunction()