set(DEPS_INSTALL_DIR "${CMAKE_BINARY_DIR}/usr")
set(DEPS_BIN_DIR "${DEPS_INSTALL_DIR}/bin")
set(DEPS_LIB_DIR "${DEPS_INSTALL_DIR}/lib")
set(DEPS_SHARE_DIR "${DEPS_INSTALL_DIR}/share/lua/5.1")

set(DEPS_BUILD_DIR "${CMAKE_BINARY_DIR}/build")
set(DEPS_DOWNLOAD_DIR "${DEPS_BUILD_DIR}/downloads")

set(DEPS_CMAKE_ARGS
  -D CMAKE_C_COMPILER=${CMAKE_C_COMPILER}
  -D CMAKE_C_STANDARD=99
  -D CMAKE_GENERATOR=${CMAKE_GENERATOR}
  -D CMAKE_GENERATOR_PLATFORM=${CMAKE_GENERATOR_PLATFORM}
  -D BUILD_SHARED_LIBS=OFF
  -D CMAKE_POSITION_INDEPENDENT_CODE=ON
  -D CMAKE_INSTALL_PREFIX=${DEPS_INSTALL_DIR})
if(APPLE)
  list(APPEND DEPS_CMAKE_ARGS -D CMAKE_FIND_FRAMEWORK=${CMAKE_FIND_FRAMEWORK})
endif()

find_program(CACHE_PRG NAMES ccache sccache)
mark_as_advanced(CACHE_PRG)
if(CACHE_PRG)
  set(CMAKE_C_COMPILER_LAUNCHER ${CMAKE_COMMAND} -E env CCACHE_SLOPPINESS=pch_defines,time_macros ${CACHE_PRG})
  list(APPEND DEPS_CMAKE_CACHE_ARGS -DCMAKE_C_COMPILER_LAUNCHER:STRING=${CMAKE_C_COMPILER_LAUNCHER})
endif()

# MAKE_PRG
if(UNIX)
  find_program(MAKE_PRG NAMES gmake make)
  mark_as_advanced(MAKE_PRG)
  if(NOT MAKE_PRG)
    message(FATAL_ERROR "GNU Make is required to build the dependencies.")
  else()
    message(STATUS "Found GNU Make at ${MAKE_PRG}")
  endif()
endif()
# When using make, use the $(MAKE) variable to avoid warning about the job
# server.
if(CMAKE_GENERATOR MATCHES "Makefiles")
  set(MAKE_PRG "$(MAKE)")
endif()
if(MINGW AND CMAKE_GENERATOR MATCHES "Ninja")
  find_program(MAKE_PRG NAMES mingw32-make)
  if(NOT MAKE_PRG)
    message(FATAL_ERROR "GNU Make for mingw32 is required to build the dependencies.")
  else()
    message(STATUS "Found GNU Make for mingw32: ${MAKE_PRG}")
  endif()
endif()

# DEPS_C_COMPILER
set(DEPS_C_COMPILER "${CMAKE_C_COMPILER}")
if(CMAKE_OSX_SYSROOT)
  set(DEPS_C_COMPILER "${DEPS_C_COMPILER} -isysroot${CMAKE_OSX_SYSROOT}")
endif()

get_filename_component(rootdir ${PROJECT_SOURCE_DIR} NAME)
if(${rootdir} MATCHES "cmake.deps")
  set(depsfile ${PROJECT_SOURCE_DIR}/deps.txt)
else()
  set(depsfile ${PROJECT_SOURCE_DIR}/cmake.deps/deps.txt)
endif()

set_directory_properties(PROPERTIES
  EP_PREFIX "${DEPS_BUILD_DIR}"
  CMAKE_CONFIGURE_DEPENDS ${depsfile})

file(READ ${depsfile} DEPENDENCIES)
STRING(REGEX REPLACE "\n" ";" DEPENDENCIES "${DEPENDENCIES}")
foreach(dep ${DEPENDENCIES})
  STRING(REGEX REPLACE " " ";" dep "${dep}")
  list(GET dep 0 name)
  list(GET dep 1 value)
  if(NOT ${name})
    # _URL variables must NOT be set when USE_EXISTING_SRC_DIR is set,
    # otherwise ExternalProject will try to re-download the sources.
    if(NOT USE_EXISTING_SRC_DIR)
      set(${name} ${value})
    endif()
  endif()
endforeach()

function(get_externalproject_options name DEPS_IGNORE_SHA)
  string(TOUPPER ${name} name_allcaps)
  set(url ${${name_allcaps}_URL})

  set(EXTERNALPROJECT_OPTIONS
    DOWNLOAD_NO_PROGRESS TRUE
    EXTERNALPROJECT_OPTIONS URL ${${name_allcaps}_URL}
    CMAKE_CACHE_ARGS ${DEPS_CMAKE_CACHE_ARGS})

  if(NOT ${DEPS_IGNORE_SHA})
    list(APPEND EXTERNALPROJECT_OPTIONS URL_HASH SHA256=${${name_allcaps}_SHA256})
  endif()

  set(EXTERNALPROJECT_OPTIONS ${EXTERNALPROJECT_OPTIONS} PARENT_SCOPE)
endfunction()