include(CMakeParseArguments)

# Resolve a dependency in this order:
# 1) already-defined target(s)
# 2) find_package() system package(s)
# 3) FetchContent fallback
function(hdk_resolve_dependency)
  set(_opts "")
  set(_one_value NAME MIN_VERSION USE_SYSTEM FETCH_FALLBACK GIT_REPOSITORY GIT_TAG FETCHCONTENT_NAME OUT_VAR)
  set(_multi_value TARGETS PACKAGE_NAMES)
  cmake_parse_arguments(HDK_DEP "${_opts}" "${_one_value}" "${_multi_value}" ${ARGN})

  if(NOT HDK_DEP_NAME)
    message(FATAL_ERROR "hdk_resolve_dependency requires NAME")
  endif()
  if(NOT HDK_DEP_TARGETS)
    message(FATAL_ERROR "hdk_resolve_dependency(${HDK_DEP_NAME}) requires TARGETS")
  endif()
  if(NOT HDK_DEP_FETCHCONTENT_NAME)
    message(FATAL_ERROR "hdk_resolve_dependency(${HDK_DEP_NAME}) requires FETCHCONTENT_NAME")
  endif()

  set(_hdk_dep_resolved_target "")
  foreach(_target IN LISTS HDK_DEP_TARGETS)
    if(TARGET ${_target})
      set(_hdk_dep_resolved_target ${_target})
      break()
    endif()
  endforeach()

  if(NOT _hdk_dep_resolved_target AND HDK_DEP_USE_SYSTEM)
    foreach(_pkg IN LISTS HDK_DEP_PACKAGE_NAMES)
      if(HDK_DEP_MIN_VERSION)
        find_package(${_pkg} ${HDK_DEP_MIN_VERSION} QUIET CONFIG)
      else()
        find_package(${_pkg} QUIET CONFIG)
      endif()

      foreach(_target IN LISTS HDK_DEP_TARGETS)
        if(TARGET ${_target})
          set(_hdk_dep_resolved_target ${_target})
          break()
        endif()
      endforeach()

      if(_hdk_dep_resolved_target)
        break()
      endif()
    endforeach()
  endif()

  if(NOT _hdk_dep_resolved_target)
    if(NOT HDK_DEP_FETCH_FALLBACK)
      if(HDK_DEP_MIN_VERSION)
        message(FATAL_ERROR "${HDK_DEP_NAME} >= ${HDK_DEP_MIN_VERSION} not found and fallback is disabled")
      else()
        message(FATAL_ERROR "${HDK_DEP_NAME} not found and fallback is disabled")
      endif()
    endif()

    if(NOT HDK_DEP_GIT_REPOSITORY)
      message(FATAL_ERROR "hdk_resolve_dependency(${HDK_DEP_NAME}) fallback requires GIT_REPOSITORY")
    endif()
    if(NOT HDK_DEP_GIT_TAG)
      message(FATAL_ERROR "hdk_resolve_dependency(${HDK_DEP_NAME}) fallback requires GIT_TAG")
    endif()

    include(FetchContent)
    FetchContent_Declare(
      ${HDK_DEP_FETCHCONTENT_NAME}
      GIT_REPOSITORY ${HDK_DEP_GIT_REPOSITORY}
      GIT_TAG ${HDK_DEP_GIT_TAG}
    )
    FetchContent_MakeAvailable(${HDK_DEP_FETCHCONTENT_NAME})

    foreach(_target IN LISTS HDK_DEP_TARGETS)
      if(TARGET ${_target})
        set(_hdk_dep_resolved_target ${_target})
        break()
      endif()
    endforeach()
  endif()

  if(NOT _hdk_dep_resolved_target)
    message(FATAL_ERROR "${HDK_DEP_NAME} could not be resolved to any expected target: ${HDK_DEP_TARGETS}")
  endif()

  if(HDK_DEP_OUT_VAR)
    set(${HDK_DEP_OUT_VAR} ${_hdk_dep_resolved_target} PARENT_SCOPE)
  endif()
endfunction()