# call once recursively so we get rid of default rules and variables
ifndef RECURSIVE

all:

Makefile: ;

%:
	@$(MAKE) -rR --no-print-directory RECURSIVE=1 $(MAKECMDGOALS)

else

# default target
all: libs progs
	@:

.SECONDEXPANSION:

# default directories
DESTDIR		?=
SBINDIR		?= /usr/sbin
CONFDIR		?= /etc/$(PACKAGE)
MANDIR		?= /usr/share/man
DOCDIR		?= /usr/share/doc/$(PACKAGE)
STATEDIR	?= /var/run

# utilities and default flags for them.
CROSS_COMPILE	?=
CC		:= $(CROSS_COMPILE)gcc
AR		:= $(CROSS_COMPILE)ar
RANLIB		:= $(CROSS_COMPILE)ranlib
LD		:= $(CROSS_COMPILE)ld
INSTALL		:= install
INSTALLDIR	:= $(INSTALL) -d

CFLAGS		:= -Wall -Wstrict-prototypes -D_GNU_SOURCE -std=gnu99
CFLAGS_ALL	?= -g -O2
LDFLAGS		:= $(LDFLAGS)
LDFLAGS_ALL	?= -g

# some helpers
PHONY:=all libs progs allobjdirs arguments-changed
build-prologue:=$(TFBUILD)TFbuild.prologue
build-epilogue:=$(TFBUILD)TFbuild.epilogue
comma:=,
squote:='
empty:=
space:=$(empty) $(empty)
separator:=--

ifdef V
  ifeq ("$(origin V)", "command line")
    VERBOSE = $(V)
  endif
endif
ifndef VERBOSE
  VERBOSE = 0
endif
ifeq ($(VERBOSE),1)
  quiet =
  Q =
else
  quiet=quiet_
  Q = @
endif
ifneq ($(findstring s,$(MAKEFLAGS)),)
  quiet=silent_
endif

# recursion related stuff
srctree			:=
objtree			:= obj/
current-dir		:=
current-dirc		:=
recursion-level		= $(words $(current-dirc))
next-recursion-level	= $(words $(current-dirc) dummy)
objdir			= $(objtree)$(current-dir)

# globals
all-progs		:=
all-libs		:=
local-vars		:= CFLAGS LDFLAGS LIBS

# helper macros for targets
escsq = $(subst $(squote),'\$(squote)',$1)
printable-target = $(patsubst $(objtree)%,%,$@)
depfile = $(subst $(comma),_,$(@).d)
#arg-check-prereq = $(if $(arg-check),arguments-changed \
	#$(warning arg-check $(arg-check))\
	#$(warning old $@ - $(cmd_$(@)))\
	#$(warning new $1 - $(cmd_$(1)))\
	#)
arg-check-prereq = $(if $(arg-check),arguments-changed)
arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$(@))) \
                    $(filter-out $(cmd_$(@)), $(cmd_$(1))) )
echo-cmd = $(if $($(quiet)cmd_$(1)),\
	echo '  $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
make-cmd = $(subst \#,\\\#,$(subst $$,$$$$,$(call escsq,$(cmd_$(1)))))
cmd = @$(echo-cmd) $(cmd_$(1))
primary_source = $(firstword $^)

#target-objects2=$(addprefix $(objdir),$(if $(filter-out $(origin $(1)-objs-y),undefined),$($(1)-objs-y),$(1).o))
#target-objects=$(warning target-objects $(1)=$(target-objects2))$(target-objects2)
target-objects=$(addprefix $(objdir),$(if $(filter-out $(origin $(1)-objs-y),undefined),$($(1)-objs-y),$(1).o))

# why - tell all prerequisites that have changed
ifeq ($(VERBOSE),2)
why = - due to $(filter-out $(PHONY),$?) $(filter $(PHONY),$^)
echo-why = $(call escsq, $(strip $(why)))
endif

# rules for targets
define CreateDirectory
ifeq ($(filter createdir-$(1),$(PHONY)),)
PHONY+=createdir-$(1)
ifneq ($(shell [ -d $(1) ] && echo yes), yes)
createdir-$(1):
	$(Q)mkdir -p $(1)
allobjdirs: createdir-$(1)
endif
endif
endef

define CallRule
	@set -e;							\
	$(rule_$(1))
endef

define ExecuteCommand
	@set -e;							\
	$(echo-cmd) $(cmd_$(1));					\
	echo 'cmd_$@ := $(make-cmd)' > $(@).cmd
endef

define MemoizeVariable
ifneq ($($(1)),)
$(current-dir)--$(1):=$($(1))
$(1):=
endif
endef

define PushVariable
inherit-$(1)-$(recursion-level):=$($(1))
endef

define PopVariable
$(current-dir)--$(1):=$($(1))
$(1):=$(inherit-$(1)-$(recursion-level))
endef

define MemoizeAndPopVariable
$(current-dir)--$(1):=$($(1))
$(1):=$(inherit-$(1)-$(recursion-level))
endef

# GCC C-compiler
c_flags		= -Wp,-MD,$(depfile),-MT,$@ $(CFLAGS_ALL) \
	$($(dir $(printable-target))--CFLAGS) \
	$($(dir $(printable-target))--CFLAGS_$(notdir $(primary_source)))

quiet_cmd_cc_o_c = CC      $(printable-target)
      cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $(primary_source)

define rule_cc_o_c
	$(call echo-cmd,cc_o_c) $(cmd_cc_o_c);			\
	(echo 'cmd_$@ := $(call make-cmd,cc_o_c)';		\
	 echo; cat $(depfile) ; echo ;				\
	 sed -e 's/#.*//' -e 's/^[^:]*: *//' -e 's/ *\\$$//'	\
	     -e '/^$$/ d' -e 's/$$/ :/' < $(depfile) )		\
		> $@.cmd ;					\
	rm $(depfile)
endef

$(objtree)%.o: $(srctree)%.c $$(call arg-check-prereq,cc_o_c) |allobjdirs
	$(call CallRule,cc_o_c)

# AR static library archiver
quiet_cmd_ar	= AR      $(printable-target)
      cmd_ar	= $(AR) -r $@ $? 2> /dev/null && \
		  $(RANLIB) $@

define CreateLibrary
all-libs += $(objdir)$(1).a

$(objdir)$(1).a: $(target-objects) $(LIBS) | createdir-$(objdir)

-include $(addsuffix .cmd,$(target-objects))

$(call CreateDirectory,$(objdir))
endef

# Linker
ld_flags	= $(LDFLAGS_ALL) \
	$($(dir $(printable-target))--LDFLAGS) \
	$($(dir $(printable-target))--LDFLAGS_$(notdir $(primary_source)))

quiet_cmd_ld	= LD      $(printable-target)
      cmd_ld	= $(CC) $(ld_flags) -o $@ $(filter-out $(PHONY),$^) $($(@D)--LIBS) $($@--LIBS)

define CreateProgram
all-progs += $(objdir)$(1)

$(objdir)$(1): $(target-objects) $(LIBS) | createdir-$(objdir)

-include $(addsuffix .cmd,$(objdir)$(1) $(target-objects))

$(call CreateDirectory,$(objdir))
endef

# version string
GIT_REV := $(shell test -d .git && git describe 2> /dev/null || echo exported)
ifneq ($(GIT_REV), exported)
FULL_VERSION	:= $(patsubst v%,%,$(GIT_REV))
else
FULL_VERSION	:= $(VERSION)
endif

# include the main directory's TFbuild
include $(build-prologue) TFbuild $(build-epilogue)

# debug dump all variables
#$(foreach VAR,$(sort $(.VARIABLES)),$(warning $(VAR)=$($(VAR))))

progs: $(all-progs)
libs: $(all-libs)

$(all-libs): %:
	$(call ExecuteCommand,ar)

$(all-progs): %: $$(call arg-check-prereq,ld)
	$(call ExecuteCommand,ld)

.PHONY: $(PHONY)
$(PHONY):

endif