ifeq ($(NDK),)
$(error Must export NDK location before building for Android)
endif
NDK_ROOT:=$(NDK)
#NDK_LOG:=1
include $(NDK)/build/core/init.mk

TOOLCHAIN_DIR:=$(foreach chain, $(NDK_ALL_TOOLCHAINS), $(if $(findstring aarch64, $(chain)), $(chain), ))
# Filter out clang
TEMP_LIST_DIR := $(foreach chain, $(TOOLCHAIN_DIR), $(if $(findstring clang, $(chain)), , $(chain)))
ifdef TEMP_LIST_DIR
	TOOLCHAIN_DIR := $(TEMP_LIST_DIR)
endif
# use freshmost compiler
TOOLCHAIN_DIR:=$(lastword $(TOOLCHAIN_DIR))

ifeq ($(HOST_TAG64),)
HOST_TAG64:=linux-x86
endif
NDK_TOOLCHAIN_VERSION:=$(shell echo $(TOOLCHAIN_DIR) | awk -F - '{print $$NF;}')

CROSS_PLATFORM:=$(NDK)/platforms/android-24/arch-arm64
CROSS_PREFIX:=$(NDK)/toolchains/$(TOOLCHAIN_DIR)/prebuilt/$(HOST_TAG64)/bin/aarch64-linux-android-

CXX:=$(CROSS_PREFIX)g++
CC:=$(CROSS_PREFIX)gcc
AR:=$(CROSS_PREFIX)ar
AS:=$(CROSS_PREFIX)as
LD:=$(CROSS_PREFIX)ld
NM:=$(CROSS_PREFIX)nm
OBJCOPY:=$(CROSS_PREFIX)objcopy
OBJDUMP:=$(CROSS_PREFIX)objdump
RANLIB:=$(CROSS_PREFIX)ranlib
STRIP:=$(CROSS_PREFIX)strip

COMMON_FLAGS=-ggdb -DFB_SEND_FLAGS=MSG_NOSIGNAL -DLINUX -DANDROID -DARM64 -pipe -MMD -fPIC -fmessage-length=0 \
			 -I$(ROOT)/extern/libtommath --sysroot=$(CROSS_PLATFORM) \
			 -I$(CROSS_PLATFORM)/usr/include -I$(ROOT)/gen/cross -fsigned-char \
			 -I$(NDK)/sources/cxx-stl/gnu-libstdc++/$(NDK_TOOLCHAIN_VERSION)/include \
			 -I$(NDK)/sources/cxx-stl/gnu-libstdc++/$(NDK_TOOLCHAIN_VERSION)/libs/arm64-v8a/include


OPTIMIZE_FLAGS=-fno-omit-frame-pointer
WARN_FLAGS=-Wall -Wno-switch -Wno-parentheses -Wno-unknown-pragmas -Wno-unused-variable

PROD_FLAGS=$(COMMON_FLAGS) $(OPTIMIZE_FLAGS)
DEV_FLAGS=$(COMMON_FLAGS) $(WARN_FLAGS)

CROSS_CONFIG=android.arm64

LDFLAGS += --sysroot=$(CROSS_PLATFORM) -L$(NDK)/sources/cxx-stl/gnu-libstdc++/$(NDK_TOOLCHAIN_VERSION)/libs/arm64-v8a \
	-L$(NDK)/sources/cxx-stl/gnu-libstdc++/libs/arm64-v8a
DroidLibs := -lm -ldl -lsupc++

LINK_LIBS = $(DroidLibs)
STATICLINK_LIBS = $(DroidLibs)
SO_LINK_LIBS = $(DroidLibs)

EXE_LINK_OPTIONS= $(LDFLAGS) $(UNDEF_FLAGS) $(LIB_PATH_OPTS) $(LINK_EMPTY_SYMBOLS) -pie
LIB_LINK_OPTIONS= $(LDFLAGS) -shared

UNICODE_DIR := $(shell dirname `find /usr/include -name ucnv.h`)
UNICODE_DIR := $(filter %unicode, $(UNICODE_DIR))
UNICODE_DIR := $(firstword $(UNICODE_DIR))
ifndef UNICODE_DIR
	$(error ERROR while locating ICU include directory, probably missing ucnv.h)
endif

.PHONY:	prerequisites
prerequisites: $(ROOT)/gen/cross/unicode

$(ROOT)/gen/cross/unicode:
	echo $(UNICODE_DIR)
	rm -rf $(ROOT)/gen/cross
	mkdir $(ROOT)/gen/cross
	ln -s $(UNICODE_DIR) cross/unicode