function(engine_read_shader_includes shaderpath include_dirs includes_list_out)
	file(READ "${shaderpath}" contents)
	string(REGEX REPLACE ";" "\\\\;" contents "${contents}")
	string(REGEX REPLACE "\r" "" contents "${contents}")
	string(REGEX REPLACE "\n" ";" contents "${contents}")
	set(_local_list "${${includes_list_out}}")
	foreach (line ${contents})
		string(FIND "${line}" "#include" out)
		if("${out}" EQUAL 0)
			string(SUBSTRING ${line} 8 -1 include_file)
			string(REPLACE " " "" include_file ${include_file})
			string(REPLACE "\"" "" include_file ${include_file})
			foreach (dir ${include_dirs})
				if (EXISTS "${dir}/${include_file}")
					list(APPEND _local_list "${dir}/${include_file}")
					break()
				endif()
			endforeach()
		endif()
	endforeach()
	list(REMOVE_DUPLICATES _local_list)
	set(${includes_list_out} ${_local_list} PARENT_SCOPE)
endfunction()

function(engine_generate_shaders TARGET)
	if (NOT DEFINED video_SOURCE_DIR)
		message(FATAL_ERROR "video project not found")
	endif()

	set(SHADERTOOL_INCLUDE_DIRS)
	list(APPEND SHADERTOOL_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR}/shaders)
	set(DEPENDENCIES)
	engine_resolve_dependencies(${TARGET} DEPENDENCIES)
	foreach (D ${DEPENDENCIES})
		if (EXISTS ${${D}_SOURCE_DIR}/shaders)
			list(APPEND SHADERTOOL_INCLUDE_DIRS "${${D}_SOURCE_DIR}/shaders")
		endif()
	endforeach()
	list(REMOVE_DUPLICATES SHADERTOOL_INCLUDE_DIRS)
	set(SHADERTOOL_INCLUDE_DIRS_PARAM)
	foreach (IDIR ${SHADERTOOL_INCLUDE_DIRS})
		list(APPEND SHADERTOOL_INCLUDE_DIRS_PARAM "-I")
		list(APPEND SHADERTOOL_INCLUDE_DIRS_PARAM "${IDIR}")
	endforeach()

	set(GEN_DIR ${GENERATE_DIR}/shaders/${TARGET}/)
	engine_generated_library(${TARGET}-shaders)
	target_include_directories(${TARGET}-shaders PUBLIC ${GEN_DIR})
	target_link_libraries(${TARGET}-shaders PUBLIC video)
	foreach (SHADER ${ARGN})
		generate_shader(${TARGET}-shaders ${SHADER} ${GEN_DIR} ${SHADERTOOL_INCLUDE_DIRS})
	endforeach()
	target_link_libraries(${TARGET} PUBLIC ${TARGET}-shaders)
endfunction()

function(generate_shader TARGET SHADER GEN_DIR SHADERTOOL_INCLUDE_DIRS)
	set(SRC_DIR ${ROOT_DIR}/src/tools/shadertool)
	set(SHADER_TEMPLATE_HDR_FILE ${SRC_DIR}/ShaderTemplate.h.in)
	set(SHADER_TEMPLATE_CPP_FILE ${SRC_DIR}/ShaderTemplate.cpp.in)
	set(SHADER_TEMPLATE_CONST_FILE ${SRC_DIR}/ShaderConstantsTemplate.h.in)
	set(SHADER_TEMPLATE_UB_FILE ${SRC_DIR}/UniformBufferTemplate.h.in)
	set(SHADER_SEARCH_DIR ${CMAKE_CURRENT_SOURCE_DIR}/shaders)
	set(FOUND_SHADER_FILES)

	if (EXISTS ${SHADER_SEARCH_DIR}/${SHADER}.frag AND EXISTS ${SHADER_SEARCH_DIR}/${SHADER}.vert)
		list(APPEND FOUND_SHADER_FILES ${SHADER_SEARCH_DIR}/${SHADER}.frag ${SHADER_SEARCH_DIR}/${SHADER}.vert)
		if (EXISTS ${SHADER_SEARCH_DIR}/${SHADER}.geom)
			list(APPEND FOUND_SHADER_FILES ${SHADER_SEARCH_DIR}/${SHADER}.geom)
		endif()
	endif()
	if (EXISTS ${SHADER_SEARCH_DIR}/${SHADER}.comp)
		list(APPEND FOUND_SHADER_FILES ${SHADER_SEARCH_DIR}/${SHADER}.comp)
	endif()
	if (FOUND_SHADER_FILES)
		set(SHADER_DEPENDENCIES)
		foreach (FOUND_SHADER_FILE ${FOUND_SHADER_FILES})
			engine_read_shader_includes(${FOUND_SHADER_FILE} "${SHADERTOOL_INCLUDE_DIRS}" SHADER_DEPENDENCIES)
		endforeach()
		convert_to_camel_case(${SHADER} SHADER_NAME_CAMEL_CASE)
		set(SHADER_TARGET_HDR_FILE "${GEN_DIR}${SHADER_NAME_CAMEL_CASE}Shader.h")
		set(SHADER_TARGET_CPP_FILE "${GEN_DIR}${SHADER_NAME_CAMEL_CASE}Shader.cpp")
		set(SHADER_TARGET_CONST_FILE "${GEN_DIR}${SHADER_NAME_CAMEL_CASE}ShaderConstants.h")
		set(MD5_VAR "")
		string(MD5 MD5_VAR ${SHADER_TARGET_HDR_FILE})
		if (NOT CMAKE_CROSSCOMPILING)
			set(_args
				${SHADERTOOL_INCLUDE_DIRS_PARAM}
				--shader ${SHADER_SEARCH_DIR}/${SHADER}
				--constantstemplate ${SHADER_TEMPLATE_CONST_FILE}
				--headertemplate ${SHADER_TEMPLATE_HDR_FILE}
				--sourcetemplate ${SHADER_TEMPLATE_CPP_FILE}
				--buffertemplate ${SHADER_TEMPLATE_UB_FILE}
				--sourcedir ${GEN_DIR}
			)
			if (USE_GLSLANG_VALIDATOR AND GLSLANG_EXECUTABLE)
				list(APPEND _args --glslang ${GLSLANG_EXECUTABLE})
			endif()
			add_custom_command(
				OUTPUT ${SHADER_TARGET_HDR_FILE} ${SHADER_TARGET_CPP_FILE} ${SHADER_TARGET_CONST_FILE}
				IMPLICIT_DEPENDS C ${FOUND_SHADER_FILES}
				COMMENT "Validate ${SHADER}"
				COMMAND ${CMAKE_COMMAND} -E env "APP_HOMEPATH=${CMAKE_CURRENT_BINARY_DIR}/" "LSAN_OPTIONS=exitcode=0"
					$<TARGET_FILE:shadertool>
					${_args}
				DEPENDS shadertool ${FOUND_SHADER_FILES} ${SHADER_DEPENDENCIES} ${SHADER_TEMPLATE_HDR_FILE} ${SHADER_TEMPLATE_CPP_FILE} ${SHADER_TEMPLATE_UB_FILE} ${SHADER_TEMPLATE_CONST_FILE}
			)
		elseif (NOT EXISTS "${SHADER_TARGET_HDR_FILE}")
			message(WARNING "Source code generation must be done by native toolchain")
		else()
			set_source_files_properties(${SHADER_TARGET_HDR_FILE} ${SHADER_TARGET_CPP_FILE} ${SHADER_TARGET_CONST_FILE} PROPERTIES GENERATED TRUE)
		endif()
		target_sources(${TARGET} PRIVATE ${SHADER_TARGET_HDR_FILE} ${SHADER_TARGET_CPP_FILE} ${SHADER_TARGET_CONST_FILE})
	else()
		message(FATAL_ERROR "Could not find any shader files for ${SHADER} and target '${TARGET}'")
	endif()

endfunction()