# add custom command to output compiled shader
function(add_shader_command)
    cmake_parse_arguments(ARGS "" "FILENAME;OUT;LANG" "" ${ARGN})

    cmake_path(REMOVE_EXTENSION ARGS_FILENAME LAST_ONLY OUTPUT_VARIABLE FILENAME_WITHOUT_EXT)

    set(SRC_FILENAME ${CMAKE_CURRENT_SOURCE_DIR}/${ARGS_FILENAME})
    set(OUTPUT_FILENAME ${CMAKE_BINARY_DIR}/bin/${FILENAME_WITHOUT_EXT}.${ARGS_LANG})

    message(${SRC_FILENAME})
    message("new output filename " .. ${OUTPUT_FILENAME})

    if(NEEDS_HOSTED_SHADER_COMPILER)
        set(SHADER_COMPILER_COMMAND ${SHADER_COMPILER_LOCATION})
    else()
        set(SHADER_COMPILER_COMMAND $<TARGET_FILE:ShaderCompilerTool>)
    endif()

    add_custom_command(
        OUTPUT ${OUTPUT_FILENAME}
        COMMAND ${SHADER_COMPILER_COMMAND} ${SRC_FILENAME} ${OUTPUT_FILENAME} ${ARGS_LANG} ${EXTRA_PLATFORM_ARG}
        DEPENDS ${SRC_FILENAME}
        WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/shaders)

    # return the actual filename
    set(${ARGS_OUT} ${OUTPUT_FILENAME} PARENT_SCOPE)
endfunction()

# add shaders to target
function(add_shaders)
    cmake_parse_arguments(ARGS "" "TARGET" "SHADERS" ${ARGN})

    foreach(SHADER_LANG ${SHADER_LANGUAGES})
        message(${SHADER_LANG})
        foreach(SHADER_FILENAME ${ARGS_SHADERS})
            cmake_path(REMOVE_EXTENSION SHADER_FILENAME LAST_ONLY OUTPUT_VARIABLE FILENAME_WITHOUT_EXT)

            # we want to remove the .nocompile extension just like the tool does, if it exists
            cmake_path(GET FILENAME_WITHOUT_EXT EXTENSION LAST_ONLY LAST_EXT)

            set(NEW_SHADER_LANG ${SHADER_LANG})
            if(LAST_EXT STREQUAL ".nocompile")
                set(NEW_SHADER_LANG glsl)
                cmake_path(REPLACE_EXTENSION FILENAME_WITHOUT_EXT LAST_ONLY glsl)
            endif()

            add_shader_command(FILENAME ${SHADER_FILENAME} OUT DST_FILENAME LANG ${NEW_SHADER_LANG})

            list(APPEND SRC_FILES ${CMAKE_CURRENT_SOURCE_DIR}/${SHADER_FILENAME})
            list(APPEND DST_FILES ${DST_FILENAME})
        endforeach()
    endforeach()

    if(NOT NEEDS_HOSTED_SHADER_COMPILER)
        add_custom_target(BuildShaders DEPENDS ShaderCompilerTool ${DST_FILES})
    else()
        add_custom_target(BuildShaders DEPENDS ${DST_FILES})
    endif()

    add_dependencies(${ARGS_TARGET} BuildShaders)
endfunction()

# make the shader directory if it doesnt exist already
file(MAKE_DIRECTORY ${CMAKE_BINARY_DIR}/bin/shaders)