PROTOC ?= protoc
PROTOC_GEN_NANOPB ?= $(PKGDIRBASE)/nanopb/generator/protoc-gen-nanopb

PROTOBUF_FILES ?= $(wildcard *.proto)

# remove duplicates
PROTOBUF_FILES := $(sort $(PROTOBUF_FILES))

NANOPB_OUT_DIR := $(BINDIR)/nanopb

ifneq (,$(PROTOBUF_FILES))
  INCLUDES += -I$(NANOPB_OUT_DIR)
endif

PROTOBUF_FILES_BASENAMES = $(notdir $(PROTOBUF_FILES))

GENSRC   += $(PROTOBUF_FILES_BASENAMES:%.proto=$(NANOPB_OUT_DIR)/%.pb.c)

# workaround for old protoc
PROTO_INCLUDES += -I.
# add nanopb specific includes
PROTO_INCLUDES += -I$(PKGDIRBASE)/nanopb/generator/proto

# We need to filter all protobuf files for source generation as pattern
# matching won't work due to the potentially different directory
# prefixes.

nanopb_select_proto_from_target = $(firstword $(filter %$(notdir $(basename $(basename $(1)))).proto,$(PROTOBUF_FILES)))

$(NANOPB_OUT_DIR)/%.pb.c: $(PROTOBUF_FILES)
# We have to create the output directory here because properly chaining
# with the clean target is currently not possible.
	-$(Q)mkdir -p $(NANOPB_OUT_DIR)
# Change of directory is required here because of protoc shortcomings.
# Setting --proto_path to the same value will fail under certain
# conditions.
	$(Q)cd "$(dir $(call nanopb_select_proto_from_target,$@))" \
	&& protoc --plugin=protoc-gen-nanopb=$(PROTOC_GEN_NANOPB) \
	    --proto_path=. \
	    --nanopb_out="$(NANOPB_OUT_DIR)" $(PROTO_INCLUDES) \
	    $(notdir $(call nanopb_select_proto_from_target,$@))