private class JavaExtraFilesPhase
	super Phase

	redef fun process_annotated_node(nmoduledecl, nat)
	do
		# Skip if we are not interested
		var annot_name = "extra_java_files"
		if nat.name != annot_name then return

		# Do some validity checks and print errors if the annotation is used incorrectly
		var modelbuilder = toolcontext.modelbuilder

		if not nmoduledecl isa AModuledecl then
			modelbuilder.error(nat, "Syntax Error: only the declaration of modules may use `{annot_name}`.")
			return
		end

		var args = nat.n_args
		if args.is_empty then
			modelbuilder.error(nat, "Syntax Error: `{annot_name}` expects at least one argument.")
			return
		end

		# retrieve module
		var nmodule = nmoduledecl.parent.as(AModule)
		var mmodule = nmodule.mmodule.as(not null)
		var java_files = mmodule.extra_java_files
		if java_files == null then
			java_files = new Array[ExtraJavaFile]
			mmodule.extra_java_files = java_files
		end

		var format_error = "Syntax Error: `{annot_name}` expects its arguments to be paths to java files."
		for arg in args do
			var name = arg.as_string
			if name == null or name.is_empty then
				modelbuilder.error(arg, format_error)
				return
			end

			var path = name.split(".").last + ".java"

			# Append specified path to directory of the Nit source file
			var source_file = nat.location.file
			if source_file != null then path = "{source_file.filename.dirname}/{path}"

			if not path.file_exists then
				modelbuilder.error(nat, "FFI with Java Error: file `{path}` not found.")
				continue
			end

			var file = new ExtraJavaFile(name, path)
			mmodule.ffi_files.add file
			java_files.add file
		end
	end
end