# builds opencv using want_var to create bld from src
# want_var set as: "" (empty) or "bld=typ" or "bld=typ,src=typ"
#   empty: defaults to bld=sys
#   bld=typ   sta,dyn,sys: sta=static, dyn=shared, sys=system libraries
#   src=typ   git,tar,git=url,tar=url: git (default git_url), tar (default: tar_url)
# once thirdparty/opencv is built, it will be reused.
# use target "mrclean" to remove thirdparty/opencv*
#
ifeq (no,$(shell [ -d $(THIRDPARTY) ] && echo yes || echo no))
$(error THIRDPARTY is not a directory: '$(THIRDPARTY)')
endif

blddir:=$(shell cd $(THIRDPARTY) && pwd)
srcdir:=$(blddir)/src
opencv:=$(blddir)/opencv
opencv_prefix:=$(opencv)/build/usr/local

# if previous build stamped, use that bld
ifneq (,$(wildcard $(opencv).sta))
bld:=sta
else ifneq (,$(wildcard $(opencv).dyn))
bld:=dyn
else ifneq (,$(wildcard $(opencv).sys))
bld:=sys
endif

comma=,
params:=$(subst $(comma), ,$(want_var))

# code: src=tar/tar=tar_url;git/git=git_url, build: bld=sta/dyn/sys
$(foreach p,$(params),\
 $(if $(bld),,$(eval var:=$(filter sta dyn sys,$(p)))\
  $(if $(var),$(eval bld:=$(var))))\
 $(if $(src),,$(eval var:=$(filter git tar,$(p)))\
  $(if $(var),$(eval src:=$(var)),\
   $(if $(filter git=%,$(p)),$(eval src:=git)$(eval git_url=$(patsubst git=%,%,$(p))),\
    $(if $(filter tar=%,$(p)),$(eval src:=tar)$(eval tar_url=$(patsubst tar=%,%,$(p))))))))

# defaults: src=git, bld=sys
src?=git
bld?=sys
git_url?=https://github.com/opencv
tar_url?=https://www.cinelerra-gg.org/download/opencv/opencv-20180401.tgz
opencv_tar:=$(notdir $(tar_url))

cpus:=$(shell grep -c "^proc" /proc/cpuinfo)
jobs:=-j$(shell echo $$(($(cpus) + $(cpus)/2 +2)))

#opencv4 breaks SIFT/SURF findobj
#CFLAGS += -I$(opencv_prefix)/include/opencv4
CFLAGS += -I$(opencv_prefix)/include

ifeq ($(src),git)
$(opencv).src:
	cd $(blddir) && rm -rf opencv opencv_contrib opencv.*
	git -C $(blddir) clone --depth 1 $(git_url)/opencv.git
	git -C $(blddir) clone --depth 1 $(git_url)/opencv_contrib.git
	touch $@
else ifeq ($(src),tar)
$(srcdir)/$(opencv_tar):
	cd $(srcdir) && rm -f $(opencv_tar)
	wget -P $(srcdir) "$(tar_url)"

$(opencv).src: $(srcdir)/$(opencv_tar)
	cd $(blddir) && rm -rf opencv opencv_contrib opencv.*
	tar -C $(blddir) -xzf $(srcdir)/$(opencv_tar);
	touch $@
else
$(error src not git/tar)
endif

ifeq ($(bld),sta)
$(opencv)/build: $(opencv).src
	mkdir -p $@
	cd $@ && cmake \
  -DCMAKE_BUILD_TYPE=RELEASE \
  -DWITH_IPP=OFF \
  -DBUILD_SHARED_LIBS=OFF \
  -DINSTALL_C_EXAMPLES=OFF \
  -DINSTALL_PYTHON_EXAMPLES=OFF \
  -DBUILD_EXAMPLES=OFF .. \
  -DBUILD_opencv_python3=no \
  -DCMAKE_INSTALL_PREFIX=/usr/local \
  -DOPENCV_EXTRA_MODULES_PATH="$(opencv)_contrib/modules/"

LFLAGS += -Wl,--start-group
LFLAGS += $(shell find $(opencv_prefix)/lib* -name "libopencv_*.a" 2> /dev/null)
#opencv4 breaks SIFT/SURF findobj
#LFLAGS += $(shell find $(opencv_prefix)/lib64/opencv4/3rdparty/lib* -name "lib*.a" 2> /dev/null)
LFLAGS += $(shell find $(opencv_prefix)/share/OpenCV/3rdparty/lib* -name "lib*.a" 2> /dev/null)
LFLAGS += -Wl,--end-group
else ifeq ($(bld),dyn)
$(opencv)/build: $(opencv).src
	mkdir -p $@
	cd $@ && cmake \
  -DCMAKE_BUILD_TYPE=RELEASE \
  -DWITH_IPP=OFF \
  -DBUILD_SHARED_LIBS=ON \
  -DINSTALL_C_EXAMPLES=ON \
  -DINSTALL_PYTHON_EXAMPLES=ON \
  -DBUILD_EXAMPLES=ON .. \
  -DBUILD_opencv_python3=no \
  -DCMAKE_INSTALL_PREFIX=/usr/local \
  -DOPENCV_EXTRA_MODULES_PATH="$(opencv)_contrib/modules/"

SYSLIB := $(lastword $(wildcard /usr/lib /usrlib32 /usr/lib64))
CVLIBS := $(dir (shell find $(opencv_prefix) -name libopencv_core.a))
LFLAGS += -L$(CVLIBS) $(patsubst $(CVLIBS)/lib%.so,-l%,$(wildcard $(CVLIBS)/libopencv_*.so))
LFLAGS += $(patsubst $(SYSLIB)/lib%.so,-l%,$(wildcard $(SYSLIB)/lib{Half,Imath,Ilm,Iex}*.so))
static_libs :=
static_incs :=
else ifeq ($(bld),sys)
$(opencv)/build:

SYSLIB := $(lastword $(wildcard /usr/lib /usrlib32 /usr/lib64))
LFLAGS += $(patsubst $(SYSLIB)/lib%.so,-l%,$(wildcard $(SYSLIB)/libopencv_*.so))
LFLAGS += $(patsubst $(SYSLIB)/lib%.so,-l%,$(wildcard $(SYSLIB)/lib{Half,Imath,Ilm,Iex}*.so))
static_libs :=
static_incs :=
else
$(error bld not sta/dyn/sys)
endif

$(opencv).sta $(opencv).dyn: $(opencv)/build
	cd $(opencv)/build && make $(jobs) 2>&1 | tee log
	cd $(opencv)/build && make install DESTDIR=`pwd`
	touch $@

$(opencv).sys:
	touch $@

mrclean:	clean
	rm -rf $(blddir)/opencv* $(srcdir)/$(opencv_tar)

opencv:	$(opencv).$(bld)