# embed.cmake
# Generates embedded_resources.h and embedded_resources.cpp

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

find_package(Python3 COMPONENTS Interpreter REQUIRED)

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_embeds)
    set(expecting_name FALSE)
    set(target "")
    set(current_asset "")

    foreach (word ${ARGV})

        # First argument is target name
        if (target STREQUAL "")
            set(target "${word}")
            get_target_property_or(script_args "${target}" EMBED_ARGS "")
            get_target_property_or(embeds "${target}" EMBEDS "")
            continue()
        endif()

        if (current_asset STREQUAL "")
            # Beginning of asset declaration (1/2)
            set(current_asset "${word}")

        elseif (expecting_name)
            # End of "asset AS asset_name"
            list(APPEND script_args "${current_asset};as;${word}")
            list(APPEND embeds ${current_asset})
            set(current_asset "")
            set(expecting_name FALSE)

        elseif ("${word}" STREQUAL "AS")
            # Keyword AS in "asset AS asset_name"
            set(expecting_name TRUE)

        else()
            # End of asset without AS, beginning of asset declaration (2/2)
            list(APPEND script_args "${current_asset};as;${current_asset}")
            list(APPEND embeds ${current_asset})
            set(current_asset "${word}")
        endif()

    endforeach()

    if (expecting_name)
        message(FATAL_ERROR "No name given for asset \"${current_asset}\"")
    endif()

    if (NOT current_asset STREQUAL "")
        list(APPEND script_args "${current_asset};as;${current_asset}")
    endif()

    set_target_properties("${target}" PROPERTIES EMBED_ARGS "${script_args}")
    set_target_properties("${target}" PROPERTIES EMBEDS "${embeds}")
endfunction()

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

function(compile_embeds target)
    get_target_property(script_args "${target}" EMBED_ARGS)
    get_target_property(embeds "${target}" EMBEDS)

    add_custom_command(
        OUTPUT  ${generated}/embedded_resources/embedded_resources.cpp
                ${generated}/embedded_resources/embedded_resources.h

        COMMAND ${Python3_EXECUTABLE} ${tools}/embed/embed.py
                --cpp    ${generated}/embedded_resources/embedded_resources.cpp
                --header ${generated}/embedded_resources/embedded_resources.h
                --
                ${script_args}

        DEPENDS ${embeds}
                ${tools}/embed/embed.py

        WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
        COMMENT "Embedding assets"
    )
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"
#)
#