# Building for desktop (WebGPU-native) with Dawn:
#  1. git clone https://github.com/google/dawn dawn
#  2. cmake -B build -DIMGUI_DAWN_DIR=dawn
#  3. cmake --build build
# The resulting binary will be found at one of the following locations:
#   * build/Debug/example_sdl2_wgpu[.exe]
#   * build/example_sdl2_wgpu[.exe]

# Building for desktop (WGPU-Native) with WGPU-Native:
#  1. download WGPU-Native autogenerated binary modules for your platform/compiler from: https://github.com/gfx-rs/wgpu-native/releases
#  2. unzip the downloaded file in your_preferred_folder
#  3. move into your_preferred_folder (e.g. typing: `cd your_preferred_folder`)
#  4. cmake -B build -DIMGUI_WGPU_DIR=your_preferred_folder  ("full path" or "relative" starting from current directory)
#  5. cmake --build build
# The resulting binary will be found at one of the following locations:
#   * build/Debug/example_sdl2_wgpu[.exe]
#   * build/example_sdl2_wgpu[.exe]

# Building for Emscripten:
#  1. Install Emscripten SDK following the instructions: https://emscripten.org/docs/getting_started/downloads.html
#  2. Install Ninja build system
#  3. emcmake cmake -G Ninja -B build
#  3. cmake --build build
#  4. emrun build/index.html

cmake_minimum_required(VERSION 3.10.2)
project(imgui_example_sdl2_wgpu C CXX)

set(IMGUI_EXECUTABLE example_sdl2_wgpu)

if(NOT CMAKE_BUILD_TYPE)
  set(CMAKE_BUILD_TYPE Debug CACHE STRING "" FORCE)
endif()

set(CMAKE_CXX_STANDARD 17) # Dawn requires C++17

# Dear ImGui
set(IMGUI_DIR ../../)

# ImGui example commons source files
set(IMGUI_EXAMPLE_SOURCE_FILES
    main.cpp
    # backend files
    ${IMGUI_DIR}/backends/imgui_impl_sdl2.cpp
    ${IMGUI_DIR}/backends/imgui_impl_wgpu.cpp
    # Dear ImGui files
    ${IMGUI_DIR}/imgui.cpp
    ${IMGUI_DIR}/imgui_draw.cpp
    ${IMGUI_DIR}/imgui_demo.cpp
    ${IMGUI_DIR}/imgui_tables.cpp
    ${IMGUI_DIR}/imgui_widgets.cpp)

# SDL_MAIN_HANDLED
    find_package(SDL2 REQUIRED)

# Libraries
if(EMSCRIPTEN)
  if(EMSCRIPTEN_VERSION VERSION_GREATER_EQUAL "4.0.10")
    set(IMGUI_EMSCRIPTEN_WEBGPU_FLAG "--use-port=emdawnwebgpu" CACHE STRING "Choose between --use-port=emdawnwebgpu (Dawn implementation of EMSCRIPTEN) and -sUSE_WEBGPU=1 (WGPU implementation of EMSCRIPTEN, deprecated in 4.0.10): default to --use-port=emdawnwebgpu for EMSCRIPTEN >= 4.0.10")
  else()
    set(IMGUI_EMSCRIPTEN_WEBGPU_FLAG "-sUSE_WEBGPU=1" CACHE STRING "Use -sUSE_WEBGPU=1 for EMSCRIPTEN WGPU implementation" FORCE)
  endif()

  add_compile_options(-sDISABLE_EXCEPTION_CATCHING=1 -DIMGUI_DISABLE_FILE_FUNCTIONS=1)
else()
  # if it's Native/Desktop build, IMGUI_DAWN_DIR or IMGUI_WGPU_DIR must be specified
  if (NOT IMGUI_DAWN_DIR AND NOT IMGUI_WGPU_DIR)
    message(FATAL_ERROR "Please specify the Dawn or WGPU base directory")
  endif()

  # IMGUI_DAWN_DIR and IMGUI_WGPU_DIR both cannot be set
  if (IMGUI_DAWN_DIR AND IMGUI_WGPU_DIR)
    message(FATAL_ERROR "Please specify only one of Dawn / WGPU base directory")
  endif()

  # Add SDL2 module to get Surface, with libs and file property for MacOS build
  if(APPLE)
    set_source_files_properties(${IMGUI_DIR}/backends/imgui_impl_sdl2.cpp PROPERTIES COMPILE_FLAGS "-x objective-c++")
    set(OS_LIBRARIES "-framework CoreFoundation -framework QuartzCore -framework Metal -framework MetalKit -framework Cocoa")
  endif()

  # Native DAWN build settings
  if(IMGUI_DAWN_DIR)
    # Dawn wgpu desktop
    set(DAWN_FETCH_DEPENDENCIES ON)
    set(IMGUI_DAWN_DIR CACHE PATH "Path to Dawn repository")
    if (NOT IMGUI_DAWN_DIR)
      message(FATAL_ERROR "Please specify the Dawn repository by setting IMGUI_DAWN_DIR")
    endif()

    option(DAWN_FETCH_DEPENDENCIES "Use fetch_dawn_dependencies.py as an alternative to using depot_tools" ON)

    # disable buildin GLFW in DAWN when we use SDL2 / SDL3 build
    option(DAWN_USE_GLFW OFF)

    # Dawn builds many things by default - disable things we don't need
    option(DAWN_BUILD_SAMPLES "Enables building Dawn's samples" OFF)
    option(TINT_BUILD_CMD_TOOLS "Build the Tint command line tools" OFF)
    option(TINT_BUILD_DOCS "Build documentation" OFF)
    option(TINT_BUILD_TESTS "Build tests" OFF)
    if (NOT APPLE)
      option(TINT_BUILD_MSL_WRITER "Build the MSL output writer" OFF)
    endif()
    if(WIN32)
      option(TINT_BUILD_SPV_READER "Build the SPIR-V input reader" OFF)
      option(TINT_BUILD_WGSL_READER "Build the WGSL input reader" ON)
      option(TINT_BUILD_GLSL_WRITER "Build the GLSL output writer" OFF)
      option(TINT_BUILD_GLSL_VALIDATOR "Build the GLSL output validator" OFF)
      option(TINT_BUILD_SPV_WRITER "Build the SPIR-V output writer" OFF)
      option(TINT_BUILD_WGSL_WRITER "Build the WGSL output writer" ON)
    endif()
    # check if WAYLAND is the current Session Type and enable DAWN_USE_WAYLAND Wayland option @compile time
    # You can override this using: cmake -DDAWN_USE_WAYLAND=X (X = ON | OFF)
    if(LINUX)
      if ($ENV{XDG_SESSION_TYPE} MATCHES wayland)
        option(DAWN_USE_WAYLAND "Enable support for Wayland surface" ON)
      endif()
    endif()

    add_subdirectory("${IMGUI_DAWN_DIR}" "${CMAKE_CURRENT_BINARY_DIR}/dawn" EXCLUDE_FROM_ALL)

    set(LIBRARIES webgpu_dawn webgpu_cpp ${OS_LIBRARIES})
  else()
    # Native WGPU build settings

    set(WGPU_NATIVE_LIB_DIR ${IMGUI_WGPU_DIR}/lib)
    find_library(WGPU_LIBRARY NAMES libwgpu_native.a wgpu_native.lib wgpu_native
                 HINTS ${WGPU_NATIVE_LIB_DIR} REQUIRED)
    if (WIN32)
      set(OS_LIBRARIES d3dcompiler ws2_32 userenv bcrypt ntdll opengl32 Propsys RuntimeObject)
    elseif(UNIX AND NOT APPLE)
      set(OS_LIBRARIES "-lm -ldl")
    endif()

    set(LIBRARIES ${WGPU_LIBRARY} ${OS_LIBRARIES})

  endif()
endif()

add_executable(${IMGUI_EXECUTABLE} ${IMGUI_EXAMPLE_SOURCE_FILES})

target_include_directories(${IMGUI_EXECUTABLE} PUBLIC
  ${IMGUI_DIR}
  ${IMGUI_DIR}/backends
  ${SDL2_INCLUDE_DIRS}
)

target_link_libraries(${IMGUI_EXECUTABLE} PUBLIC ${LIBRARIES} ${SDL2_LIBRARIES})

target_compile_definitions(${IMGUI_EXECUTABLE} PUBLIC "IMGUI_EXAMPLE_SDL2_WGPU")

# IMGUI_IMPL_WEBGPU_BACKEND_DAWN/WGPU internal define is set according to:
#   EMSCRIPTEN: by used FLAG
#     --use-port=emdawnwebgpu --> IMGUI_IMPL_WEBGPU_BACKEND_DAWN enabled (+EMSCRIPTEN)
#     -sUSE_WEBGPU=1          --> IMGUI_IMPL_WEBGPU_BACKEND_WGPU enabled (+EMSCRIPTEN)
#   NATIVE: by used SDK installation directory
#     if IMGUI_DAWN_DIR is valid --> IMGUI_IMPL_WEBGPU_BACKEND_DAWN enabled
#     if IMGUI_WGPU_DIR is valid --> IMGUI_IMPL_WEBGPU_BACKEND_WGPU enabled

# Native settings
IF(NOT EMSCRIPTEN)
  if(IMGUI_DAWN_DIR)
    target_compile_definitions(${IMGUI_EXECUTABLE} PUBLIC "IMGUI_IMPL_WEBGPU_BACKEND_DAWN")
  else()
    target_compile_definitions(${IMGUI_EXECUTABLE} PUBLIC "IMGUI_IMPL_WEBGPU_BACKEND_WGPU")
    target_include_directories(${IMGUI_EXECUTABLE} PUBLIC ${IMGUI_WGPU_DIR}/include)
  endif()
# Emscripten settings
else()
  set(CMAKE_EXECUTABLE_SUFFIX ".html")

  if("${IMGUI_EMSCRIPTEN_WEBGPU_FLAG}" STREQUAL "--use-port=emdawnwebgpu")
    target_compile_options(${IMGUI_EXECUTABLE} PUBLIC "${IMGUI_EMSCRIPTEN_WEBGPU_FLAG}")
    target_compile_definitions(${IMGUI_EXECUTABLE} PUBLIC "IMGUI_IMPL_WEBGPU_BACKEND_DAWN")
  else()
    target_compile_definitions(${IMGUI_EXECUTABLE} PUBLIC "IMGUI_IMPL_WEBGPU_BACKEND_WGPU")
  endif()
  message(STATUS "Using ${IMGUI_EMSCRIPTEN_WEBGPU_FLAG} WebGPU implementation")

  target_compile_options(${IMGUI_EXECUTABLE} PUBLIC "-sUSE_SDL=2" )
  target_link_options(${IMGUI_EXECUTABLE} PRIVATE
    "${IMGUI_EMSCRIPTEN_WEBGPU_FLAG}"
    "-sUSE_SDL=2"
    "-sWASM=1"
    "-sASYNCIFY=1"
    "-sALLOW_MEMORY_GROWTH=1"
    "-sNO_EXIT_RUNTIME=0"
    "-sASSERTIONS=1"
    "-sDISABLE_EXCEPTION_CATCHING=1"
    "-sNO_FILESYSTEM=1"
    "--shell-file=${CMAKE_CURRENT_LIST_DIR}/../libs/emscripten/shell_minimal.html"
  )
  set_target_properties(${IMGUI_EXECUTABLE} PROPERTIES OUTPUT_NAME "index")
endif()