cmake_minimum_required(VERSION 3.10)
project(toplevel LANGUAGES C)

add_subdirectory(libraries)

set(ALL_MY_PROJECT_TARGETS "" CACHE INTERNAL "Global list")

# Function to recursively collect all targets
function(get_all_project_targets _target_list_var _current_dir)
    # Get targets defined directly in the current directory
    get_property(_targets_in_dir DIRECTORY "${_current_dir}" PROPERTY BUILDSYSTEM_TARGETS)
	message("_targets_in_dir: ${_targets_in_dir}")
	list(APPEND _ALL_MY_PROJECT_TARGETS ${ALL_MY_PROJECT_TARGETS} ${_targets_in_dir})
	set(ALL_MY_PROJECT_TARGETS ${_ALL_MY_PROJECT_TARGETS} "" CACHE INTERNAL "")
	message("ALL_MY_PROJECT_TARGETS: ${ALL_MY_PROJECT_TARGETS}")

	message("current_dir: ${_current_dir}")
	get_filename_component(CURRENT_DIR_NAME "${_current_dir}" NAME)
	message("  - NAME: ${CURRENT_DIR_NAME}")

    # Get subdirectories of the current directory
    get_property(_subdirs DIRECTORY "${_current_dir}" PROPERTY SUBDIRECTORIES)
    foreach(_subdir IN LISTS _subdirs)
        # Recursively call for each subdirectory
		message("_subdir: ${_subdir}")
        get_all_project_targets(${_target_list_var} "${_subdir}")
    endforeach()
endfunction()

# Call the function from the top-level CMakeLists.txt
get_all_project_targets(ALL_MY_PROJECT_TARGETS "${CMAKE_CURRENT_SOURCE_DIR}")

# Print the list of all targets
message("All CMake Targets in this project:")
foreach(target_name IN LISTS ALL_MY_PROJECT_TARGETS)
    message("- ${target_name}")
endforeach()

# Do stuff
add_executable(${PROJECT_NAME}-exe main.c)
target_link_libraries(${PROJECT_NAME}-exe library_a-lib library_b-lib)