# Add a file to be compiled.
#
# add_files([file1 ...] CONDITION condition [condition ...])
#
# CONDITION is a complete statement that can be evaluated with if().
# If it evaluates true, the source files will be added; otherwise not.
# For example: ADD_IF SDL_FOUND AND Allegro_FOUND
#
function(add_files)
    cmake_parse_arguments(PARAM "" "" "CONDITION" ${ARGN})
    set(PARAM_FILES "${PARAM_UNPARSED_ARGUMENTS}")

    if(PARAM_CONDITION)
        if(NOT (${PARAM_CONDITION}))
            return()
        endif()
    endif()

    foreach(FILE IN LISTS PARAM_FILES)
        target_sources(openttd PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/${FILE})
    endforeach()
endfunction()

# This function works around an 'issue' with CMake, where
# set_source_files_properties() only works in the scope of the file. We want
# to set properties for the source file on a more global level. To solve this,
# this function records the flags you want, and a macro adds them in the root
# CMakeLists.txt.
# See this URL for more information on the issue:
# http://cmake.3232098.n2.nabble.com/scope-of-set-source-files-properties-td4766111.html
#
# set_compile_flags([file1 ...] COMPILE_FLAGS cflag [cflag ...])
#
function(set_compile_flags)
    cmake_parse_arguments(PARAM "" "" "COMPILE_FLAGS" ${ARGN})
    set(PARAM_FILES "${PARAM_UNPARSED_ARGUMENTS}")

    get_property(SOURCE_PROPERTIES GLOBAL PROPERTY source_properties)

    foreach(FILE IN LISTS PARAM_FILES)
        list(APPEND SOURCE_PROPERTIES "${CMAKE_CURRENT_SOURCE_DIR}/${FILE}::${PARAM_COMPILE_FLAGS}")
    endforeach()

    set_property(GLOBAL PROPERTY source_properties "${SOURCE_PROPERTIES}")
endfunction()

# Call this macro in the same CMakeLists.txt and after add_executable().
# This makes sure all the COMPILE_FLAGS of set_compile_flags() are set
# correctly.
#
# process_compile_flags()
#
function(process_compile_flags)
    get_property(SOURCE_PROPERTIES GLOBAL PROPERTY source_properties)

    foreach(ENTRY ${SOURCE_PROPERTIES})
        string(REPLACE "::" ";" ENTRY "${ENTRY}")
        list(GET ENTRY 0 FILE)
        list(GET ENTRY 1 PROPERTIES)

        set_source_files_properties(${FILE} PROPERTIES COMPILE_FLAGS ${PROPERTIES})
    endforeach()
endfunction()