set(SRCS
	backward.cpp
	backward.h
)

engine_add_library(
	LIB backward
	SRCS ${SRCS}
)

###############################################################################
# OPTIONS
###############################################################################

if (MSVC)
set(STACK_WALKING_UNWIND FALSE CACHE BOOL "Use compiler's unwind API")
else()
set(STACK_WALKING_UNWIND TRUE CACHE BOOL "Use compiler's unwind API")
endif()
set(STACK_WALKING_BACKTRACE FALSE CACHE BOOL "Use backtrace from (e)glibc for stack walking")
set(STACK_DETAILS_AUTO_DETECT TRUE CACHE BOOL "Auto detect backward's stack details dependencies")
set(STACK_DETAILS_BACKTRACE_SYMBOL FALSE CACHE BOOL "Use backtrace from (e)glibc for symbols resolution")
set(STACK_DETAILS_DW FALSE CACHE BOOL "Use libdw to read debug info")
set(STACK_DETAILS_BFD FALSE CACHE BOOL "Use libbfd to read debug info")
set(STACK_DETAILS_DWARF FALSE CACHE BOOL "Use libdwarf/libelf to read debug info")
unset(BACKWARD_LIBRARIES CACHE)
unset(BACKWARD_INCLUDE_DIRS CACHE)

###############################################################################
# CONFIGS
###############################################################################
if (${STACK_DETAILS_AUTO_DETECT})
	include(FindPackageHandleStandardArgs)

	# find libdw
	find_path(LIBDW_INCLUDE_DIR NAMES "elfutils/libdw.h" "elfutils/libdwfl.h")
	find_library(LIBDW_LIBRARY dw)
	set(LIBDW_INCLUDE_DIRS ${LIBDW_INCLUDE_DIR} )
	set(LIBDW_LIBRARIES ${LIBDW_LIBRARY} )
	find_package_handle_standard_args(libdw DEFAULT_MSG LIBDW_LIBRARY LIBDW_INCLUDE_DIR)
	mark_as_advanced(LIBDW_INCLUDE_DIR LIBDW_LIBRARY)

	# find libbfd
	find_path(LIBBFD_INCLUDE_DIR NAMES "bfd.h")
	find_path(LIBDL_INCLUDE_DIR NAMES "dlfcn.h")
	find_library(LIBBFD_LIBRARY bfd)
	find_library(LIBDL_LIBRARY dl)
	set(LIBBFD_INCLUDE_DIRS ${LIBBFD_INCLUDE_DIR} ${LIBDL_INCLUDE_DIR})
	set(LIBBFD_LIBRARIES ${LIBBFD_LIBRARY} ${LIBDL_LIBRARY})
	find_package_handle_standard_args(libbfd DEFAULT_MSG LIBBFD_LIBRARY LIBBFD_INCLUDE_DIR LIBDL_LIBRARY LIBDL_INCLUDE_DIR)
	mark_as_advanced(LIBBFD_INCLUDE_DIR LIBBFD_LIBRARY LIBDL_INCLUDE_DIR LIBDL_LIBRARY)

	# find libdwarf
	find_path(LIBDWARF_INCLUDE_DIR NAMES "libdwarf.h" PATH_SUFFIXES libdwarf)
	find_path(LIBELF_INCLUDE_DIR NAMES "libelf.h")
	find_path(LIBDL_INCLUDE_DIR NAMES "dlfcn.h")
	find_library(LIBDWARF_LIBRARY dwarf)
	find_library(LIBELF_LIBRARY elf)
	find_library(LIBDL_LIBRARY dl)
	set(LIBDWARF_INCLUDE_DIRS ${LIBDWARF_INCLUDE_DIR} ${LIBELF_INCLUDE_DIR} ${LIBDL_INCLUDE_DIR})
	set(LIBDWARF_LIBRARIES ${LIBDWARF_LIBRARY} ${LIBELF_LIBRARY} ${LIBDL_LIBRARY})
	find_package_handle_standard_args(libdwarf DEFAULT_MSG
		LIBDWARF_LIBRARY LIBDWARF_INCLUDE_DIR
		LIBELF_LIBRARY LIBELF_INCLUDE_DIR
		LIBDL_LIBRARY LIBDL_INCLUDE_DIR)
	mark_as_advanced(LIBDWARF_INCLUDE_DIR LIBDWARF_LIBRARY
		LIBELF_INCLUDE_DIR LIBELF_LIBRARY
		LIBDL_INCLUDE_DIR LIBDL_LIBRARY)

	if (LIBDW_FOUND)
		list(APPEND BACKWARD_INCLUDE_DIRS ${LIBDW_INCLUDE_DIRS})
		list(APPEND BACKWARD_LIBRARIES ${LIBDW_LIBRARIES})
		set(STACK_DETAILS_DW TRUE)
		set(STACK_DETAILS_BFD FALSE)
		set(STACK_DETAILS_DWARF FALSE)
		set(STACK_DETAILS_BACKTRACE_SYMBOL FALSE)
	elseif(LIBBFD_FOUND)
		list(APPEND BACKWARD_INCLUDE_DIRS ${LIBBFD_INCLUDE_DIRS})
		list(APPEND BACKWARD_LIBRARIES ${LIBBFD_LIBRARIES})

		# If we attempt to link against static bfd, make sure to link its dependencies, too
		get_filename_component(bfd_lib_ext "${LIBBFD_LIBRARY}" EXT)
		if (bfd_lib_ext STREQUAL "${CMAKE_STATIC_LIBRARY_SUFFIX}")
			list(APPEND BACKWARD_LIBRARIES iberty z)
		endif()

		set(STACK_DETAILS_DW FALSE)
		set(STACK_DETAILS_BFD TRUE)
		set(STACK_DETAILS_DWARF FALSE)
		set(STACK_DETAILS_BACKTRACE_SYMBOL FALSE)
	elseif(LIBDWARF_FOUND)
		list(APPEND BACKWARD_INCLUDE_DIRS ${LIBDWARF_INCLUDE_DIRS})
		list(APPEND BACKWARD_LIBRARIES ${LIBDWARF_LIBRARIES})
		set(STACK_DETAILS_DW FALSE)
		set(STACK_DETAILS_BFD FALSE)
		set(STACK_DETAILS_DWARF TRUE)
		set(STACK_DETAILS_BACKTRACE_SYMBOL FALSE)
	else()
		set(STACK_DETAILS_DW FALSE)
		set(STACK_DETAILS_BFD FALSE)
		set(STACK_DETAILS_DWARF FALSE)
		set(STACK_DETAILS_BACKTRACE_SYMBOL TRUE)
	endif()
else()
	if (STACK_DETAILS_DW)
		list(APPEND BACKWARD_LIBRARIES dw)
	endif()

	if (STACK_DETAILS_BFD)
		list(APPEND BACKWARD_LIBRARIES bfd dl)
	endif()

	if (STACK_DETAILS_DWARF)
		list(APPEND BACKWARD_LIBRARIES dwarf elf)
	endif()
endif()

macro(map_definitions var_prefix define_prefix)
	foreach(def ${ARGN})
		if (${${var_prefix}${def}})
			list(APPEND BACKWARD_DEFINITIONS "${define_prefix}${def}=1")
		else()
			list(APPEND BACKWARD_DEFINITIONS "${define_prefix}${def}=0")
		endif()
	endforeach()
endmacro()

map_definitions("STACK_WALKING_" "BACKWARD_HAS_" UNWIND BACKTRACE)
map_definitions("STACK_DETAILS_" "BACKWARD_HAS_" BACKTRACE_SYMBOL DW BFD DWARF)

foreach(def ${BACKWARD_DEFINITIONS})
	message(STATUS "${def}")
endforeach()

list(APPEND BACKWARD_INCLUDE_DIRS .)

target_include_directories(backward PUBLIC ${BACKWARD_INCLUDE_DIRS})
target_compile_definitions(backward PUBLIC ${BACKWARD_DEFINITIONS})
target_link_libraries(backward ${BACKWARD_LIBRARIES})
mark_as_advanced(BACKWARD_INCLUDE_DIRS BACKWARD_DEFINITIONS BACKWARD_LIBRARIES)

# Expand each definition in BACKWARD_DEFINITIONS to its own cmake var and export
# to outer scope
foreach(var ${BACKWARD_DEFINITIONS})
	string(REPLACE "=" ";" var_as_list ${var})
	list(GET var_as_list 0 var_name)
	list(GET var_as_list 1 var_value)
	set(${var_name} ${var_value})
	mark_as_advanced(${var_name})
endforeach()