# glslc.cmake
# Compiles GLSL shaders to SPV files

find_package(Vulkan COMPONENTS glslc REQUIRED)
find_program(glslc_EXECUTABLE NAMES glslc HINTS Vulkan::glslc)

macro (get_target_property_or var target prop default)
    get_property(__is_set TARGET ${target} PROPERTY ${prop} SET)
    if (__is_set)
        get_property(${var} TARGET ${target} PROPERTY ${prop})
    else()
        set(${var} "${default}")
    endif()
    unset(__is_set)
endmacro()

function (target_glsl_shaders)
    set(target "")

    foreach (word ${ARGV})
        # First argument is target name
        if (target STREQUAL "")
            set(target ${word})
            get_target_property_or(glsl_shaders ${target} GLSL_SHADERS "")
        else()
            list(APPEND glsl_shaders ${word})
        endif()
    endforeach()

    set_target_properties(${target} PROPERTIES GLSL_SHADERS "${glsl_shaders}")
endfunction()

file(MAKE_DIRECTORY "${generated}/compiled_glsl_shaders")

function(compile_glsl target)
    get_target_property(glsl_shaders ${target} GLSL_SHADERS)

    foreach (source_path ${glsl_shaders})
        get_filename_component(source_basename ${source_path} NAME)
        set(spv_path
            "${generated}/compiled_glsl_shaders/${source_basename}.spv")

        add_custom_command(
            OUTPUT ${spv_path}
            DEPENDS ${source_path}
            COMMAND ${glslc_EXECUTABLE}
                    -o ${spv_path}
                    ${CMAKE_CURRENT_SOURCE_DIR}/${source_path}
            COMMENT "Compiling shader ${source_path}"
        )
        target_embeds(${target} ${spv_path} AS "${source_basename}.spv")
    endforeach()
endfunction()


## Global variables. Yikes. FIXME
#set(tools ${PROJECT_SOURCE_DIR}/tools)
#set(generated ${PROJECT_BINARY_DIR}/generated)
#set(assets_to_embed "")
#set(assets_to_embed_args "")
#
#file(MAKE_DIRECTORY ${generated})
#
#find_package(Vulkan COMPONENTS glslc REQUIRED)
#find_program(glslc_executable NAMES glslc HINTS Vulkan::glslc)
#set(shaders ${generated}/shaders)
#file(MAKE_DIRECTORY ${shaders})
#
## Shedules compilation of shaders
## Adapted from https://stackoverflow.com/a/60472877/4463352
#macro(compile_shader)
#    foreach(source ${ARGV})
#        get_filename_component(source_basename ${source} NAME)
#        set(tmp "${shaders}/${source_basename}.spv")
#        add_custom_command(
#            OUTPUT ${tmp}
#            DEPENDS ${source}
#            COMMAND ${glslc_executable}
#                    -o ${tmp}
#                    ${CMAKE_CURRENT_SOURCE_DIR}/${source}
#            COMMENT "Compiling shader ${source}"
#        )
#        list(APPEND assets_to_embed_args "${tmp};as;${source_basename}.spv")
#        list(APPEND assets_to_embed "${tmp}")
#        unset(tmp)
#        unset(source_basename)
#    endforeach()
#endmacro()
#
#compile_shader(
#    desktop/graphics/shaders/shader.frag
#    desktop/graphics/shaders/shader.vert
#)
#
## Generate embed files
#add_custom_command(
#    OUTPUT ${generated}/embedded_resources.cpp
#           ${generated}/embedded_resources.h
#
#    COMMAND ${tools}/embed/embed.py
#            --cpp    ${generated}/embedded_resources.cpp
#            --header ${generated}/embedded_resources.h
#            --
#            ${assets_to_embed_args}
#
#    DEPENDS "${assets_to_embed}"
#            ${tools}/embed/embed.py
#
#    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
#    COMMENT "Embedding assets"
#)
#