#
# CMake build script to determine project version number.
#
# this will set PROJECT_VERSION to a string
#
FUNCTION (FindProjectVersion project_path)
    # Mercurial
    if (EXISTS ${project_path}/.hg)
        # first, determine tag
        EXECUTE_PROCESS (
            COMMAND hg identify --tag
            WORKING_DIRECTORY "${project_path}"
            RESULT_VARIABLE hg_error_code 
            OUTPUT_VARIABLE hg_tag
            OUTPUT_STRIP_TRAILING_WHITESPACE
        )
        
        if (hg_error_code)
            MESSAGE (FATAL_ERROR "`hg identify --tag` failed")
        endif (hg_error_code)

        # if tag is other than tip, use that
        if ("${hg_tag}" STREQUAL "tip")
            # use the revision hash
            EXECUTE_PROCESS (
                COMMAND hg identify --id
                WORKING_DIRECTORY "${project_path}"
                RESULT_VARIABLE hg_error_code 
                OUTPUT_VARIABLE hg_id
                OUTPUT_STRIP_TRAILING_WHITESPACE
            )

            if (hg_error_code)
                MESSAGE (FATAL_ERROR "`hg identify --id` failed")
            endif (hg_error_code)

            SET (PROJECT_VERSION "${hg_id}" PARENT_SCOPE)
            MESSAGE (STATUS "Version: mercurial tip id: ${hg_id}")

        else ("${hg_tag}" STREQUAL "tip")
            SET (PROJECT_VERSION "${hg_tag}" PARENT_SCOPE)
            MESSAGE (STATUS "Version: mercurial tag: ${hg_tag}")

        endif ("${hg_tag}" STREQUAL "tip")

    else (EXISTS ${project_path}/.hg)
        SET (PROJECT_VERSION "???" PARENT_SCOPE)
        MESSAGE (STATUS "No version information available")

    endif (EXISTS ${project_path}/.hg)
ENDFUNCTION (FindProjectVersion)