# sw_load_sources - Uses the glob approach to building source files
# allows for platform specific folders to be automatically excluded/included
# depending on the current platform.
# For example, in the following project layout:
#
#   MyProj\*.cpp
#       win\*.cpp
#       lin\*.cpp
#       mac\*.cpp
#
# Only the win, and MyProject paths will be scanned, excluding lin/mac folders
# automatically.
#
# Usage:
#   sw_load_sources(VarName
#       NO_RECURSE
#       EXCLUDE "SomeValue"
#       LIST_ONLY_EXTS "json;pem"
#       *.hpp
#       *.cpp
#       *.c
#       *.json
#       *.pem
#       ...
#   )
#
# Options:
#   NO_RECURSE - If specified will prevent scanning recursively in paths.
#
# Arguments:
#   EXCLUDE        - Defines a string to exclude, will be matched on with regex.
#   ARGN           - One or more paths with wildcards, e.g. ${CMAKE_CURRENT_SOURCE_DIR}/*.cpp
#   LIST_ONLY_EXTS - Defines one or more file extensions (separated by semicolon) which should not be compiled.
#                    This is useful for displaying configuration files or
#                    resources in the project envs.
function(sw_load_sources output_var)
    set(options NO_RECURSE)
    set(oneValueArgs EXCLUDE LIST_ONLY_EXTS)

    cmake_parse_arguments(sw_load_sources
        "${options}" "${oneValueArgs}" "${multiArgs}" ${ARGN})

    foreach(pattern ${ARGN})
        file(GLOB_RECURSE _source_files [LIST_DIRECTORIES false] ${pattern})
        set(source_files ${source_files} ${_source_files})
    endforeach()

    if (NOT source_files)
        message(FATAL_ERROR "No sources loaded for filter: ${ARGN}")
    endif()

    # Exclude platform folders that do not match our own
    if (SW_PLAT_WIN)
        list(FILTER source_files EXCLUDE REGEX "\/unx|mac|lin\/")
    elseif (SW_PLAT_LIN)
        list(FILTER source_files EXCLUDE REGEX "\/mac|win|win32\/")
    elseif (SW_PLAT_MAC)
        list(FILTER source_files EXCLUDE REGEX "\/lin|win32|win\/")
    else()
        message(FATAL_ERROR "Unknown platform")
    endif()

    # Exclude, excludes
    if (sw_load_sources_EXCLUDE)
        list(FILTER _output_var EXCLUDE REGEX "${sw_load_sources_EXCLUDE}")
    endif()

    # Now strip out any list only extensions so we can group them differently from the rest
    if (sw_load_sources_LIST_ONLY_EXTS)
        # Convert it to a list
        separate_arguments(list_only_exts UNIX_COMMAND ${sw_load_sources_LIST_ONLY_EXTS})
        message("List only extensions: ${list_only_exts}")
        message("List only extensions: ${sw_load_sources_LIST_ONLY_EXTS}")
        foreach(source_file ${source_files})
            get_filename_component(source_file_ext ${source_file} EXT)

            if (source_file_ext)
                foreach(list_only_ext ${list_only_exts})
                    message("Matching ${list_only_ext}")
                    if (".${list_only_ext}" STREQUAL ${source_file_ext})
                        set_source_files_properties(${source_file} PROPERTIES HEADER_FILE_ONLY TRUE)
                        list(REMOVE_ITEM source_files ${source_file})
                        set(list_only_files ${list_only_files} ${source_file})
                    endif()
                endforeach()
            endif()
        endforeach()
    endif()

    # Sort the dependencies in visual studio
    if (SW_PLAT_WIN)
        source_group(TREE ${CMAKE_CURRENT_LIST_DIR} PREFIX "Sources" FILES ${source_files})
        source_group(TREE ${CMAKE_CURRENT_LIST_DIR} PREFIX "/" FILES ${list_only_files})
    endif()

    # Now set this in the callers scope and combine both list only and source files
    set(${output_var} ${source_files} ${list_only_files} PARENT_SCOPE)

endfunction()