# Main makefile, alternative implementation to project.mk
# Simplified, according to these design goals:
#  (1) no recursive make[1]
#  (2) all build targets and intermediates go into separate build
#  (3) one platform per make invokation (parameterized)
#  (4) collect all code in a single .a to avoid .a order problems
#  (5) a build can have multiple output targets, which all link against the main .a
#  (6) shun phony targets ("make clean" should be just "rm -rf build")
#  (7) allow a simple "list of modules" approach

# Recursive make is not a good approach[1].  For multiple target
# platforms, it is simpler to parameterize the makefile over the
# target platform, instead of including multiple target rules in the
# main makefile.  Supporting simple individual target builts

# [1] http://miller.emu.id.au/pmiller/books/rmch/

# Disable all implicit rules
MAKEFLAGS += --no-builtin-rules
.SUFFIXES:
BUILD_ID := $(shell date +%Y%m%d-%H%M%S)

.DELETE_ON_ERROR:

# These are overridden in the Makefile generated by configure.
SRC      = $(shell readlink -f ..)
BUILD    = $(shell readlink -f .)
TARGET 	 = Linux

LDFLAGS  :=
CFLAGS   := -g -O0 -Wall -std=gnu99 -fPIC # -Wno-deprecated-declarations
CPPFLAGS := \
	-I$(BUILD) \
	-I$(SRC) \
	-DBUILD_ID=\"$(BUILD_ID)\" \
	-DTARGET=\"$(TARGET)\" \
	-DPRIM_HOME=\"$(SRC)/\" \
	-DHAVE_LEAF

# To use the libprim build system with libprim source tree embedded in
# a larger tree, this variable needs to be set.  Note that $(SRC) then
# refers to the larger source tree.

-include $(SRC)/target/$(TARGET).mk


# $(TARGET).mk can define LIBPRIM_SUBTREE, which allows libprim
# extensions, re-using the libprim build system.
LIBPRIM_SRC   := $(SRC)/$(LIBPRIM_SUBTREE)
LIBPRIM_BUILD := $(BUILD)/$(LIBPRIM_SUBTREE)
CPPFLAGS      += -I$(LIBPRIM_SRC) -I$(LIBPRIM_BUILD)

GCC      := $(TOOL_PREFIX)gcc
AS       := $(TOOL_PREFIX)as
AR       := $(TOOL_PREFIX)ar
LD       := $(TOOL_PREFIX)ld
CC       := $(GCC)

MZSCHEME := mzscheme -S $(LIBPRIM_SRC)/rkt


.PHONY: all
all: g_OUT swig

# Makefile template for the module.mk context. Once expanded, it
# gathers module-specific data from the local m_ variables and
# collects info in global g_ variables.  Note that '$' varrefs are
# expanded at template expansion-time, while '$$' varrefs survive as
# '$' refs in the expanded code.
define module_template
m_C        :=
m_O        :=
m_D        :=
m_H        :=
m_ELF      :=
m_TEST     :=
m_SO       :=
m_SRC      := $(SRC)/$(1)
m_BUILD	   := $(BUILD)/$(1)
m_LDFLAGS  :=
include  $$(m_SRC)/module.mk
g_C        += $$(addprefix $$(m_SRC)/,$$(m_C))
g_O	   += $$(addprefix $$(m_BUILD)/,$$(m_C:.c=.o))
g_D        += $$(addprefix $$(m_BUILD)/,$$(m_C:.c=.d))
g_H	   += $$(addprefix $$(m_BUILD)/,$$(m_H))
g_ELF	   += $$(addprefix $$(m_BUILD)/,$$(m_ELF))
g_TEST	   += $$(addprefix $$(m_BUILD)/,$$(m_TEST))
g_SO	   += $$(addprefix $$(m_BUILD)/,$$(m_SO))
g_LDFLAGS  += $$(m_LDFLAGS)
endef

# Expand template for each module and include the dependency files.
# Note that initialization of the g_ accumulators is necessary to turn
# them into simply expanded variables, since the default is recursive
# expanding variables.
g_C        :=
g_O        :=
g_D        :=
g_H        :=
g_ELF      :=
g_TEST     :=
g_SO       :=
g_LDFLAGS  := 
g_MISC     :=
$(foreach prog,$(MODULES),$(eval $(call module_template,$(prog))))

# g_D / g_O is only for the .o in lib.a
g_OUT_D := $(g_ELF:.elf=.d) $(g_SO:.so=.d) $(g_TEST:.test=.d)
g_OUT_O := $(g_OUT_D:.d=.o)

g_ELF += $(g_TEST:.test=.elf)



.PHONY: g_OUT
g_OUT: $(g_ELF) $(g_SO) $(g_TEST) $(g_MISC)


-include $(g_D)
-include $(g_OUT_D)



# This is necessary to allow .d files to be generated properly.
GENERATED_H := $(g_H) $(BUILD)/config.h

# All build rules are shared for the project.  It is not worth the
# complexity to have sub-project dependent build flags.  If this is
# necessary, abstract the subproject in a library dependency.

# Remove the '@' character for more verbose compilation.
# compile = @mkdir -p $(dir $(1)) ; echo [$(2)] $(notdir $(1)) ; $(3)
compile = echo $(3); mkdir -p $(dir $(1)) ; echo [$(2)] $(notdir $(1)) ; $(3)

# Gather dependencies from .c file
depstx := sed -r 's,\s(\w+/), $(LIBPRIM_BUILD)/\1,g'
$(g_D) $(g_OUT_D): $(BUILD)/%.d: $(SRC)/%.c $(GENERATED_H)
	$(call compile,$@,d,$(CC) $(CPPFLAGS) -M -MG -MT $(@:.d=.o) $< | $(depstx) >$@)

_CC := $(CC) $(CPPFLAGS) $(CFLAGS)

# Intermediate object
$(g_O) $(g_OUT_O): $(BUILD)/%.o: $(SRC)/%.c $(BUILD)/%.d
	$(call compile,$@,o,$(_CC) -o $@ -c $<)



# Executable
$(g_ELF): $(BUILD)/%.elf: $(BUILD)/%.o $(BUILD)/lib.a
	$(call compile,$@,elf,$(_CC) $*.o $(BUILD)/lib.a $(g_LDFLAGS) -o $@)

# Shared library.
$(g_SO): $(BUILD)/%.so: $(BUILD)/%.o $(BUILD)/lib.a
	$(call compile,$@,so,$(_CC) $*.o $(BUILD)/lib.a $(g_LDFLAGS) -rdynamic -shared -o $@)

# Archive all object files from sources listed in m_C variables.
$(BUILD)/lib.a: $(g_O)
	$(call compile,$@,a,rm -f $@ ; $(AR) -r $@ $(g_O) 2>/dev/null)

# Generated header files
$(BUILD)/config.h:
	$(call compile,$@,h,echo '#include <target/$(TARGET).h>' > $@)
$(g_H): $(BUILD)/%.g.h: $(SRC)/%.c
	$(call compile,$@,h,$(MZSCHEME) $(dir $<)gen_prims.ss $< $@)

# Preprocess only
$(BUILD)/%.E.c: $(SRC)/%.c $(GENERATED_H)
	$(call compile,$@,c,$(CC) $(CPPFLAGS) -E $< -o $@)

# Test
$(g_TEST): $(BUILD)/%.test: $(BUILD)/%.elf
	$(call compile,$@,test,$(LIBPRIM_SRC)/bin/run_test $< $@)

# Swig
PYTHON_VER    := 3.5
PYTHON_SO     := $(BUILD)/swig/python/_libprim.so
PYTHON_O      := $(BUILD)/swig/python/_libprim.o
PYTHON_C      := $(BUILD)/swig/python/_libprim.c
PYTHON_CFLAGS := $(shell pkg-config python-$(PYTHON_VER) --cflags)
PYTHON_LIBS   := $(shell pkg-config python-$(PYTHON_VER) --libs)
$(PYTHON_C): $(SRC)/swig/libprim.i
	$(call compile,$@,i,cd $(SRC) ; swig -python -py3 -o $@ $<)
$(PYTHON_O): $(PYTHON_C)
	$(call compile,$@,o,$(_CC) $(PYTHON_CFLAGS) -o $@ -c $<)
$(PYTHON_SO): $(PYTHON_O) $(BUILD)/lib.a
	$(call compile,$@,so,$(_CC) $(PYTHON_O) $(BUILD)/lib.a $(g_LDFLAGS) $(PYTHON_LIBS) -rdynamic -shared -o $@)

swig: $(PYTHON_SO)




# Do not use .SECONDARY: enabled by default.
#
# While it useful to look at intermediate build resuilts, it also has
# some odd behaviors. If you want to build an intermediate, build it
# explicitly using absolute paths using:
#
#   make vars.sh ; . vars.sh
#   make $PROJECT_DIR/<thing>
#
# From [1]: "...one of the side effects of a target being declared
# secondary is that make doesn't consider it out of date when it
# doesn't exist."
#
# [1] http://www.mail-archive.com/bug-make@gnu.org/msg03942.html