CC ?= cc
CFLAGS ?= -std=c11 -march=native -pipe -Wall -Wextra -Wpedantic
OPENMP_FLAGS ?= -fopenmp
LDLIBS ?= -lm
ENABLE_PNG ?= 1
SPACETIME ?= minkowski
BUILD_TYPE ?= Release
ENABLE_HDR ?= 0

ifeq ($(BUILD_TYPE),Release)
BUILD_CFLAGS := -O2 -DNDEBUG
BUILD_CPPFLAGS :=
else ifeq ($(BUILD_TYPE),Debug)
BUILD_CFLAGS := -O0 -g3
BUILD_CPPFLAGS := -DGR_DEBUG
else
$(error Unknown BUILD_TYPE '$(BUILD_TYPE)'; choose Release or Debug)
endif

ifeq ($(ENABLE_PNG),1)
CPPFLAGS += -DENABLE_PNG
LDLIBS += -lpng
IMAGE_EXT := png
else
IMAGE_EXT := ppm
endif

COMMON_SOURCES := $(filter-out src/main.c src/spacetime_minkowski.c src/spacetime_schwarzschild.c,$(wildcard src/*.c))
PROVIDER_SOURCE := src/spacetime_$(SPACETIME).c
BUILD_DIR := build/$(BUILD_TYPE)
TARGET_BASENAME := $(SPACETIME)_sky
OBJECT_DIR := $(BUILD_DIR)/obj/$(SPACETIME)
CORE_MINKOWSKI_SOURCES := $(COMMON_SOURCES) src/spacetime_minkowski.c
TEST_TARGET := $(BUILD_DIR)/test_geodesic
FRAME_TEST_TARGET := $(BUILD_DIR)/test_frame
SCHWARZSCHILD_TEST_TARGET := $(BUILD_DIR)/test_schwarzschild
OBSERVER_TRACK_TEST_TARGET := $(BUILD_DIR)/test_observer_track
CATALOG_PREFETCH_TEST_TARGET := $(BUILD_DIR)/test_catalog_prefetch

.PHONY: all backend clean run test minkowski schwarzschild FORCE

ifeq ($(SPACETIME),minkowski)
BACKEND_CPPFLAGS := -DSPACETIME_MINKOWSKI
else ifeq ($(SPACETIME),schwarzschild)
BACKEND_CPPFLAGS := -DSPACETIME_SCHWARZSCHILD
else
$(error Unknown SPACETIME '$(SPACETIME)'; choose minkowski or schwarzschild)
endif

ifeq ($(ENABLE_HDR),1)
HDR_CPPFLAGS := -DENABLE_HDR_OUTPUT $(shell pkg-config --cflags cfitsio)
HDR_LDLIBS := $(shell pkg-config --libs cfitsio)
HDR_BUILD_TAG := hdr
else ifeq ($(ENABLE_HDR),0)
HDR_BUILD_TAG := standard
else
$(error Unknown ENABLE_HDR '$(ENABLE_HDR)'; choose 0 or 1)
endif

TARGET := $(BUILD_DIR)/$(TARGET_BASENAME)
RENDER_SOURCES := $(COMMON_SOURCES) $(PROVIDER_SOURCE) src/main.c
RENDER_OBJECTS := $(patsubst %.c,$(OBJECT_DIR)/$(HDR_BUILD_TAG)/%.o,$(RENDER_SOURCES))
RENDER_DEPS := $(RENDER_OBJECTS:.o=.d)

# With no explicit backend choice, all means every currently supported
# production spacetime backend. An explicit SPACETIME selects that backend,
# so `make SPACETIME=schwarzschild` remains the direct build command.
ifneq ($(filter command\ line environment environment\ override,$(origin SPACETIME)),)
all: backend
else
all: minkowski schwarzschild
endif

minkowski:
	$(MAKE) SPACETIME=minkowski ENABLE_HDR=$(ENABLE_HDR) backend

schwarzschild:
	$(MAKE) SPACETIME=schwarzschild ENABLE_HDR=$(ENABLE_HDR) backend

# Build exactly the selected backend/configuration, e.g.
# make SPACETIME=schwarzschild ENABLE_HDR=1 backend
backend: $(TARGET)

$(TARGET): $(RENDER_OBJECTS) FORCE | $(BUILD_DIR)
	$(CC) $(BUILD_CFLAGS) $(OPENMP_FLAGS) $(RENDER_OBJECTS) $(LDLIBS) $(HDR_LDLIBS) -o $@

FORCE:

$(OBJECT_DIR)/$(HDR_BUILD_TAG)/%.o: %.c
	@mkdir -p $(dir $@)
	$(CC) $(CPPFLAGS) $(BUILD_CPPFLAGS) $(BACKEND_CPPFLAGS) $(HDR_CPPFLAGS) $(CFLAGS) $(BUILD_CFLAGS) $(OPENMP_FLAGS) -Isrc -MMD -MP -c $< -o $@

$(BUILD_DIR):
	mkdir -p $@

run: $(TARGET)
	mkdir -p output/imgs
	./$(TARGET) --catalog assets/sky_grid_5deg.csv --output output/imgs/$(SPACETIME)_sky.$(IMAGE_EXT)

$(TEST_TARGET): tests/test_geodesic.c $(CORE_MINKOWSKI_SOURCES) | $(BUILD_DIR)
	$(CC) $(CPPFLAGS) $(BUILD_CPPFLAGS) $(CFLAGS) $(BUILD_CFLAGS) $(OPENMP_FLAGS) -Isrc $^ $(LDLIBS) -o $@

$(FRAME_TEST_TARGET): tests/test_frame.c $(CORE_MINKOWSKI_SOURCES) | $(BUILD_DIR)
	$(CC) $(CPPFLAGS) $(BUILD_CPPFLAGS) $(CFLAGS) $(BUILD_CFLAGS) $(OPENMP_FLAGS) -Isrc $^ $(LDLIBS) -o $@

$(SCHWARZSCHILD_TEST_TARGET): tests/test_schwarzschild.c $(COMMON_SOURCES) src/spacetime_schwarzschild.c | $(BUILD_DIR)
	$(CC) $(CPPFLAGS) $(BUILD_CPPFLAGS) $(CFLAGS) $(BUILD_CFLAGS) $(OPENMP_FLAGS) -Isrc $^ $(LDLIBS) -o $@

$(OBSERVER_TRACK_TEST_TARGET): tests/test_observer_track.c $(COMMON_SOURCES) | $(BUILD_DIR)
	$(CC) $(CPPFLAGS) $(BUILD_CPPFLAGS) $(CFLAGS) $(BUILD_CFLAGS) $(OPENMP_FLAGS) -Isrc $^ $(LDLIBS) -o $@

$(CATALOG_PREFETCH_TEST_TARGET): tests/test_catalog_prefetch.c $(CORE_MINKOWSKI_SOURCES) | $(BUILD_DIR)
	$(CC) $(CPPFLAGS) $(BUILD_CPPFLAGS) $(CFLAGS) $(BUILD_CFLAGS) $(OPENMP_FLAGS) -Isrc $^ $(LDLIBS) -o $@

test: $(TEST_TARGET) $(FRAME_TEST_TARGET) $(SCHWARZSCHILD_TEST_TARGET) $(OBSERVER_TRACK_TEST_TARGET) $(CATALOG_PREFETCH_TEST_TARGET)
	./$(TEST_TARGET)
	./$(FRAME_TEST_TARGET)
	./$(SCHWARZSCHILD_TEST_TARGET)
	./$(OBSERVER_TRACK_TEST_TARGET)
	./$(CATALOG_PREFETCH_TEST_TARGET)

clean:
	rm -rf build

-include $(RENDER_DEPS)