#This program is free software: you can redistribute it and/or modify
#it under the terms of the GNU General Public License as published by
#the Free Software Foundation, either version 3 of the License, or
#(at your option) any later version.

#This program is distributed in the hope that it will be useful,
#but WITHOUT ANY WARRANTY; without even the implied warranty of
#MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#GNU General Public License for more details.

#You should have received a copy of the GNU General Public License
#along with this program. If not, see <http://www.gnu.org/licenses/>.

#Copyright 2021 rexy712

#Makefile to generate a single executable from rust source

ifeq ($(OS),Windows_NT)
	WINDOWS::=1
endif

MAIN_SOURCE_FILE::=src/hello.rs
DEPDIR::=dep
LIBDIRS::=lib
LDLIBS::=
LDFLAGS::=
RUSTFLAGS::=
DEBUG_RUSTFLAGS::=
MAIN_EXECUTABLE::=tester
RELEASE?=0
SAVEFLAGS?=1

RUSTC::=rustc

ifeq ($(WINDOWS),1)
	MAIN_EXECUTABLE::=$(MAIN_EXECUTABLE).exe
endif

.PHONY: all
#prerun targets
all::

#main target
all:: | flags-update $(MAIN_EXECUTABLE)

#postrun targets
all::

#custom clean targets
clean::

###########################################################################################################
#Everything past this point is internal BS, probably best not to touch it unless you know what you're doing

#set the default target as the default target, otherwise the topmost target will run
.DEFAULT_GOAL::=all

#system dependant bullshit
ifeq ($(OS),Windows_NT)
	#windows' cmd commands
	mkdir=mkdir $(subst /,\,$(1)) > NUL 2>&1
	rm=del /F $(1) > NUL 2>&1
	rmdir=rd /S /Q $(1) > NUL 2>&1
	move=move /Y $(subst /,\,$(1)) $(subst /,\,$(2)) > NUL 2>&1
	copy=copy /Y /B $(subst /,\,$(1)) $(subst /,\,$(2)) > NUL 2>&1
else
	#*nix terminal commands
	mkdir=mkdir -p $(1)
	rm=rm -f $(1)
	rmdir=rm -rf $(1)
	move=mv $(1) $(2)
	copy=cp $(1) $(2)
endif

#Rust is weird and should only need one depfile for a whole project since the compiler auto imports stuff
MAIN_DEP_FILE::=$(DEPDIR)/$(notdir $(addsuffix .d,$(MAIN_SOURCE_FILE)))

ALL_LDFLAGS+=$(LDFLAGS) $(foreach dir,$(LIBDIRS),-L'$(dir)') $(foreach lib,$(LDLIBS),"--extern $(lib)")

ifneq ($(RELEASE),1)
	RUSTFLAGS+=$(DEBUG_RUSTFLAGS)
endif
ifeq ($(RELEASE),1)
	RUSTFLAGS+=-O
else
	RUSTFLAGS+=-g
endif

COMPILER::=$(RUSTC)

#setup temp files for storing compile and link flags
ifeq ($(SAVEFLAGS),1)
	RUSTFLAGS_TMPFILE::=.rustflags.tmp
	LDFLAGS_TMPFILE::=.ldflags.tmp
	OLD_COMPILEFLAGS::=$(file <$(RUSTFLAGS_TMPFILE))
	OLD_LINKFLAGS::=$(file <$(LDFLAGS_TMPFILE))
endif

#Compile all the rust 'crates'
$(MAIN_EXECUTABLE): $(MAIN_SOURCE_FILE) $(MAIN_DEP_FILE) $(LDFLAGS_TMPFILE)
	$(COMPILER) $< $(RUSTFLAGS) -o $@ $(ALL_LDFLAGS)
#create a dependency tracking file so that the project rebuilds when any dep is updated
$(MAIN_DEP_FILE): $(MAIN_SOURCE_FILE) $(DEPDIR) $(RUSTFLAGS_TMPFILE)
	$(COMPILER) $< --emit dep-info $(RUSTFLAGS) -o $@

$(DEPDIR):
	$(call mkdir,"$(DEPDIR)")

.PHONY: flags-update
flags-update: rustflags-update ldflags-update

#Check if compile flags have changed since last build
.PHONY: rustflags-update
rustflags-update:
ifeq ($(SAVEFLAGS),1)
ifneq ($(OLD_COMPILEFLAGS),$(RUSTFLAGS))
	$(file >$(RUSTFLAGS_TMPFILE),$(RUSTFLAGS))
endif
$(RUSTFLAGS_TMPFILE): rustflags-update
endif
#Check if link flags have changed since last build
.PHONY: ldflags-update
ldflags-update:
ifeq ($(SAVEFLAGS),1)
ifneq ($(ALL_LDFLAGS),$(OLD_LINKFLAGS))
	$(file >$(LDFLAGS_TMPFILE),$(ALL_LDFLAGS))
endif
$(LDFLAGS_TMPFILE): ldflags-update
endif

.PHONY: clean
clean::
	$(call rm,"$(MAIN_EXECUTABLE)")
	$(call rm,"$(MAIN_EXECUTABLE).exe")
	$(call rmdir,"$(DEPDIR)")
ifeq ($(SAVEFLAGS),1)
	$(call rm,"$(RUSTFLAGS_TMPFILE)")
	$(call rm,"$(LDFLAGS_TMPFILE)")
endif

#include rules from generated depfiles
-include $(wildcard $(DEPDIR)/*.d)