# Build a Python extension module using pybind11
#   pybindings_add_module(<module>)
# Here <module> should be the fully qualified name for the module,
# e.g. pybindings_add_module(foo.bar._baz)
# <module> becomes the target name in case you wish to do something to it later
# The source for the binding *must* be placed in src/pybindings/{relpath}/py{name}.cc
# E.g. for module=foo.bar._baz -> src/pybindings/bar/py_baz.cc
function(pybindings_add_module module)
    set(target_name ${module})
    string(REPLACE "." "/" modpath ${module})
    string(REPLACE "." ";" modlist ${module})

    # The module name is the last entry
    list(GET modlist -1 modname)

    # Remove everything that is not the root or the module name
    #list(REMOVE_AT modlist 0)
    list(REMOVE_AT modlist -1)

    # Get the relative path
    if(modlist)
        string(REPLACE ";" "/" relpath "${modlist}")
    else()
        set(relpath "")
    endif()

    # Define the binding source file
    set(sources src/pybindings/${relpath}/py${modname}.cc)

    # Invoke pybind11 and set where the library should go, and what it is called
    pybind11_add_module(${target_name} ${sources})
    set(outdir ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${relpath})
    set_target_properties(${target_name} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${outdir})
    set_target_properties(${target_name} PROPERTIES OUTPUT_NAME ${modname})
endfunction()