# Usage:
# cccl_generate_header_tests(<target_name> <project_include_path>
#                            [cccl_configure_target options]
#                            [LANGUAGE <CXX|CUDA>]
#                            [HEADER_TEMPLATE <template>]
#                            [GLOBS <glob1> [glob2 ...]]
#                            [EXCLUDES <glob1> [glob2 ...]]
#                            [HEADERS <header1> [header2 ...]]
#                            [PER_HEADER_DEFINES
#                               DEFINE <definition> <regex> [<regex> ...]
#                              [DEFINE <definition> <regex> [<regex> ...]] ...]
# )
#
# Options:
# target_name: The name of the meta-target that will build this set of header tests.
# project_include_path: The path to the project's include directory, relative to <CCCL_SOURCE_DIR>.
# cccl_configure_target options: Options to pass to cccl_configure_target. Must appear before any other named arguments.
# LANGUAGE: The language to use for the header tests. Defaults to CUDA.
# HEADER_TEMPLATE: A file that will be used as a template for each header test. The template will be configured for each header.
# GLOBS: All files that match these globbing patterns will be included in the header tests, unless they also match EXCLUDES.
# EXCLUDES: Files that match these globbing patterns will be excluded from the header tests.
# HEADERS: An explicit list of headers to include in the header tests.
# PER_HEADER_DEFINES: A list of definitions to add to specific headers. Each definition is followed by one or more regexes that match the headers it should be applied to.
# NO_METATARGETS: If specified, metatargets will not be created for the header test targets.
#
# Notes:
# - The header globs are applied relative to <project_include_path>.
# - If no HEADER_TEMPLATE is provided, a default template will be used.
# - The HEADER_TEMPLATE will be configured for each header, with the following variables:
#   - @header@: The path to the target header, relative to <project_include_path>.
option(
  CCCL_COMPILE_TIME_SAVE_PREPROCESSED_TUS
  "Save preprocessed generated one-include CUDA TUs for compile-time benchmarks."
  OFF
)
option(
  CCCL_COMPILE_TIME_GENERATE_DEVICE_TIME_TRACES
  "Emit NVCC device time traces for compile-time benchmarks."
  OFF
)
mark_as_advanced(
  CCCL_COMPILE_TIME_SAVE_PREPROCESSED_TUS
  CCCL_COMPILE_TIME_GENERATE_DEVICE_TIME_TRACES
)

function(cccl_generate_header_tests target_name project_include_path)
  set(options NO_METATARGETS)
  set(oneValueArgs LANGUAGE HEADER_TEMPLATE)
  set(multiValueArgs GLOBS EXCLUDES HEADERS PER_HEADER_DEFINES)
  cmake_parse_arguments(
    CGHT
    "${options}"
    "${oneValueArgs}"
    "${multiValueArgs}"
    ${ARGN}
  )

  if (CGHT_UNPARSED_ARGUMENTS)
    message(FATAL_ERROR "Unrecognized arguments: ${CGHT_UNPARSED_ARGUMENTS}")
  endif()

  # Setup defaults
  if (NOT DEFINED CGHT_LANGUAGE)
    set(CGHT_LANGUAGE CUDA)
  endif()

  if (NOT DEFINED CGHT_HEADER_TEMPLATE)
    set(CGHT_HEADER_TEMPLATE "${CCCL_SOURCE_DIR}/cmake/header_test.cu.in")
  endif()

  # Derived vars:
  if (${CGHT_LANGUAGE} STREQUAL "C")
    set(extension "c")
  elseif (${CGHT_LANGUAGE} STREQUAL "CXX")
    set(extension "cpp")
  elseif (${CGHT_LANGUAGE} STREQUAL "CUDA")
    set(extension "cu")
  else()
    message(FATAL_ERROR "Unsupported language: ${CGHT_LANGUAGE}")
  endif()

  set(cccl_configure_target_options ${CGHT_UNPARSED_ARGUMENTS})
  set(base_path "${CCCL_SOURCE_DIR}/${project_include_path}")

  # Prepend the basepath to all globbing expressions:
  if (DEFINED CGHT_GLOBS)
    set(globs)
    foreach (glob IN LISTS CGHT_GLOBS)
      list(APPEND globs "${base_path}/${glob}")
    endforeach()
    set(CGHT_GLOBS ${globs})
  endif()
  if (DEFINED CGHT_EXCLUDES)
    set(excludes)
    foreach (exclude IN LISTS CGHT_EXCLUDES)
      list(APPEND excludes "${base_path}/${exclude}")
    endforeach()
    set(CGHT_EXCLUDES ${excludes})
  endif()

  # Determine header list
  set(headers)

  # Add globs:
  if (DEFINED CGHT_GLOBS)
    file(
      GLOB_RECURSE headers
      RELATIVE "${base_path}"
      CONFIGURE_DEPENDS
      ${CGHT_GLOBS}
    )
  endif()

  # Remove excludes:
  if (DEFINED CGHT_EXCLUDES)
    file(
      GLOB_RECURSE header_excludes
      RELATIVE "${base_path}"
      CONFIGURE_DEPENDS
      ${CGHT_EXCLUDES}
    )
    list(REMOVE_ITEM headers ${header_excludes})
  endif()

  # Add explicit headers:
  if (DEFINED CGHT_HEADERS)
    list(APPEND headers ${CGHT_HEADERS})
  endif()

  # Cleanup:
  list(REMOVE_DUPLICATES headers)

  # Helper function for applying per-header defines:
  # header: The original header filepath
  # src: The generated source file for the header test
  function(cght_apply_per_header_defines header src)
    if (NOT DEFINED CGHT_PER_HEADER_DEFINES)
      return()
    endif()
    set(current_definition)
    foreach (item IN LISTS CGHT_PER_HEADER_DEFINES)
      if (item STREQUAL "DEFINE")
        # New definition
        set(current_definition)
      elseif (NOT current_definition)
        # First item after DEFINE is the definition
        set(current_definition "${item}")
      else()
        # Subsequent items are regexes to match against the header
        if (header MATCHES ${item})
          set_property(
            SOURCE "${src}"
            APPEND
            PROPERTY COMPILE_DEFINITIONS "${current_definition}"
          )
        endif()
      endif()
    endforeach()
  endfunction()

  # Configure header templates:
  set(header_srcs)
  foreach (header IN LISTS headers)
    set(
      header_src
      "${CMAKE_CURRENT_BINARY_DIR}/headers/${target_name}/${header}.${extension}"
    )
    configure_file("${CGHT_HEADER_TEMPLATE}" "${header_src}" @ONLY)
    cght_apply_per_header_defines("${header}" "${header_src}")

    # Compile-time benchmark workflows can ask generated one-include CUDA TUs to
    # preserve preprocessed artifacts and/or emit NVCC device time traces.
    if (
      (
        CCCL_COMPILE_TIME_SAVE_PREPROCESSED_TUS
        OR CCCL_COMPILE_TIME_GENERATE_DEVICE_TIME_TRACES
      )
      AND CGHT_LANGUAGE STREQUAL "CUDA"
    )
      get_filename_component(header_src_dir "${header_src}" DIRECTORY)
      if ("${CMAKE_CUDA_COMPILER_ID}" STREQUAL "NVIDIA")
        if (CCCL_COMPILE_TIME_SAVE_PREPROCESSED_TUS)
          set_property(
            SOURCE "${header_src}"
            APPEND
            PROPERTY COMPILE_OPTIONS "--keep" "--keep-dir=${header_src_dir}"
          )
        endif()
        if (CCCL_COMPILE_TIME_GENERATE_DEVICE_TIME_TRACES)
          set(trace_id "${header}")
          string(REPLACE "/" "__" trace_id "${trace_id}")
          string(REPLACE "." "_" trace_id "${trace_id}")
          set(
            trace_dir
            "${CMAKE_BINARY_DIR}/compile_time/raw_traces/${target_name}"
          )
          file(MAKE_DIRECTORY "${trace_dir}")
          set_property(
            SOURCE "${header_src}"
            APPEND
            PROPERTY
              COMPILE_OPTIONS "--fdevice-time-trace=${trace_dir}/${trace_id}"
          )
        endif()
      elseif (
        CCCL_COMPILE_TIME_SAVE_PREPROCESSED_TUS
        AND "${CMAKE_CUDA_COMPILER_ID}" STREQUAL "Clang"
      )
        set_property(
          SOURCE "${header_src}"
          APPEND
          PROPERTY COMPILE_OPTIONS "-save-temps=obj"
        )
      endif()
    endif()
    list(APPEND header_srcs "${header_src}")
  endforeach()

  # Object library that compiles each header:
  add_library(${target_name} OBJECT ${header_srcs})
  cccl_configure_target(${target_name} ${cccl_configure_target_options})
  if (NOT CGHT_NO_METATARGETS)
    cccl_ensure_metatargets(${target_name})
  endif()

  # Check that all functions in headers are either template functions or inline:
  set(link_target ${target_name}.link_check)
  cccl_add_executable(
    ${link_target}
    SOURCES "${CCCL_SOURCE_DIR}/cmake/link_check_main.cpp"
    NO_METATARGETS
  )
  # Linking both ${target_name} and $<TARGET_OBJECTS:${target_name}> forces CMake to
  # link the same objects twice. The compiler will complain about duplicate symbols if
  # any functions are missing inline markup.
  target_link_libraries(
    ${link_target}
    PRIVATE #
      ${target_name}
      $<TARGET_OBJECTS:${target_name}>
  )
endfunction()