## @defgroup    utils_blob Blob file module
## @ingroup     utils
## @brief       Include any file content as binary data in a RIOT application
##
## makes any file in BLOBS available via an include directive in the C code.
##
## # Usage:
##
## Add this to an application or module Makefile:
##
## ```
## BLOBS += foo.ext
## ```
##
## Then include in C file or header:
##
## ```
## #include "blob/foo.ext.h"
## ```
##
## The blob can then be accessed using the symbols "foo_ext" and "foo_ext_len".
##
## # Subfolders
##
## It is possible to add files from subfolders to BLOBS:
##
##     BLOBS += subfolder/my_file.foo
##
## The subfolder will be part of the generated header's path, but *not* of the
## generated symbols. E.g., above blob would be made available by including
## "blobs/subfolder/my_file.ext.h", which would define the symbols "my_file_ext"
## and "my_file_ext_len". Beware possible symbol name clashes.
##

# use "blobs/blob" so the headers can be included as "blob/foo.h", but
# we don't have to add $(BINDIR)/$(MODULE) to the include path.
BLOB_HDR_DIR ?= $(BINDIR)/$(MODULE)/blobs/blob
BLOB_H := $(BLOBS:%=$(BLOB_HDR_DIR)/%.h)

ifneq (, $(BLOB_H))
  # add $(BINDIR)/$(MODULE)/blobs to include path
  CFLAGS += -I$(dir $(BLOB_HDR_DIR))
endif

# In order to allow automatic folder creation in subtrees,
# this Makefile makes use SECONDEXPANSION, PRECIOUS and
# order only prerequisites.
# Folder targets are "tagged" by appending "/."
# The final recipe uses "| $$(@D)/." to create necessary trees.
#
# Inspiration from:
# http://ismail.badawi.io/blog/2017/03/28/automatic-directory-creation-in-make/
#
.PRECIOUS: $(BLOB_HDR_DIR)/. $(BLOB_HDR_DIR)%/.

$(BLOB_HDR_DIR)/.:
	@mkdir -p $@

$(BLOB_HDR_DIR)%/.:
	@mkdir -p $@

XXD ?= xxd

$(BLOB_H): $(BLOB_HDR_DIR)/%.h: % $(BLOBS) | $$(@D)/.
	@command -v $(XXD) > /dev/null 2>&1 || ( \
	  echo "error: xxd binary '$(XXD)' not found! (Maybe install vim package?)"; exit 1)

	${Q}cd $(dir $<); xxd -i $(notdir $<) | sed 's/^unsigned/const unsigned/g'> $@

# make C and C++ objects of this module depend on generated headers, so they
# get re-build on changes to the blob files.
$(OBJC) $(OBJCXX): $(BLOB_H)