SET(CMAKE_SYSTEM_NAME Linux)
SET(CMAKE_SYSTEM_VERSION 1)

set(ANDROID_HOME "$ENV{ANDROID_HOME}" CACHE PATH "Path to Android SDK" )

#set path for android toolchain -- look

set(ANDROID_ALLEGRO_ROOT "$ENV{ANDROID_ALLEGRO_ROOT}" CACHE PATH "Path to Allegro 5 (>=5.2.2) build directory for Android" )

message( STATUS "Selected Allegro dir: ${ANDROID_ALLEGRO_ROOT}" )
if(NOT EXISTS "${ANDROID_ALLEGRO_ROOT}")
   message( FATAL_ERROR "Invalid ANDROID_ALLEGRO_ROOT! Point it to the build directory of Allegro 5 (>=5.2.2) for Android.")
endif()

set(ANDROID_TOOLCHAIN "$ENV{ANDROID_TOOLCHAIN}" CACHE PATH "Path to the Android NDK Standalone Toolchain" )

message( STATUS "Selected Android toolchain: ${ANDROID_TOOLCHAIN}" )
if(NOT EXISTS ${ANDROID_TOOLCHAIN})
   set(ANDROID_TOOLCHAIN "/opt/android-toolchain" CACHE PATH "Path to the Android NDK Standalone Toolchain" )
   message( STATUS "Using default path for toolchain ${ANDROID_TOOLCHAIN}")
   message( STATUS "If you prefer to use a different location, please set the ANDROID_TOOLCHAIN cmake variable.")
endif()
   
if(NOT EXISTS ${ANDROID_TOOLCHAIN})
  message(FATAL_ERROR
  "${ANDROID_TOOLCHAIN} does not exist!
  You should either set an environment variable:
    export ANDROID_TOOLCHAIN=~/my-toolchain
  or put the toolchain in the default path:
    sudo ln -s ~/android-toolchain /opt/android-toolchain
    ")
endif()

find_program(CMAKE_MAKE_PROGRAM make)

#setup build targets, mutually exclusive
set(PossibleArmTargets
  "x86;x86_64;armeabi;armeabi-v7a;armeabi-v7a with NEON;arm64-v8a;mips;mips64")
set(ARM_TARGETS "armeabi-v7a" CACHE STRING 
    "the arm targets for android, recommend armeabi-v7a 
    for floating point support and NEON.")

if(ARM_TARGETS STREQUAL "x86")
    set(ANDROID_ARCH "i686-linux-android")
elseif(ARM_TARGETS STREQUAL "x86_64")
    set(ANDROID_ARCH "x86_64-linux-android")
elseif(ARM_TARGETS STREQUAL "arm64-v8a")
    set(ANDROID_ARCH "aarch64-linux-android")
elseif(ARM_TARGETS STREQUAL "mips")
    set(ANDROID_ARCH "mipsel-linux-android")
elseif(ARM_TARGETS STREQUAL "mips64")
    set(ANDROID_ARCH "mips64el-linux-android")
elseif(ARM_TARGETS STREQUAL "armeabi")
    set(ANDROID_ARCH "arm-linux-androideabi")
    set(ARMEABI true)
    set(NEON false)
elseif(ARM_TARGETS STREQUAL "armeabi-v7a")
    set(ARMEABI true)
    set(ANDROID_ARCH "arm-linux-androideabi")
    set(NEON false)
elseif(ARM_TARGETS STREQUAL "armeabi-v7a with NEON")
    set(ARMEABI true)
    set(ANDROID_ARCH "arm-linux-androideabi")
    set(NEON true)
else()
    message(FATAL_ERROR "Unknown Android target ${ARM_TARGETS}")
endif()

if(WIN32)
	set(CMAKE_EXECUTABLE_SUFFIX ".exe")
endif()

# specify the cross compiler
SET(CMAKE_C_COMPILER   
  ${ANDROID_TOOLCHAIN}/bin/${ANDROID_ARCH}-clang${CMAKE_EXECUTABLE_SUFFIX} CACHE PATH "C compiler" FORCE)
SET(CMAKE_CXX_COMPILER 
  ${ANDROID_TOOLCHAIN}/bin/${ANDROID_ARCH}-clang++${CMAKE_EXECUTABLE_SUFFIX} CACHE PATH "C++ compiler" FORCE)
#there may be a way to make cmake deduce these TODO deduce the rest of the tools
set(CMAKE_AR
 ${ANDROID_TOOLCHAIN}/bin/${ANDROID_ARCH}-ar${CMAKE_EXECUTABLE_SUFFIX}  CACHE PATH "archive" FORCE)
set(CMAKE_LINKER
 ${ANDROID_TOOLCHAIN}/bin/${ANDROID_ARCH}-ld${CMAKE_EXECUTABLE_SUFFIX}  CACHE PATH "linker" FORCE)
set(CMAKE_NM
 ${ANDROID_TOOLCHAIN}/bin/${ANDROID_ARCH}-nm${CMAKE_EXECUTABLE_SUFFIX}  CACHE PATH "nm" FORCE)
set(CMAKE_OBJCOPY
 ${ANDROID_TOOLCHAIN}/bin/${ANDROID_ARCH}-objcopy${CMAKE_EXECUTABLE_SUFFIX}  CACHE PATH "objcopy" FORCE)
set(CMAKE_OBJDUMP
 ${ANDROID_TOOLCHAIN}/bin/${ANDROID_ARCH}-objdump${CMAKE_EXECUTABLE_SUFFIX}  CACHE PATH "objdump" FORCE)
set(CMAKE_STRIP
 ${ANDROID_TOOLCHAIN}/bin/${ANDROID_ARCH}-strip${CMAKE_EXECUTABLE_SUFFIX}  CACHE PATH "strip" FORCE)
set(CMAKE_RANLIB
 ${ANDROID_TOOLCHAIN}/bin/${ANDROID_ARCH}-ranlib${CMAKE_EXECUTABLE_SUFFIX}  CACHE PATH "ranlib" FORCE)

set_property(CACHE ARM_TARGETS PROPERTY STRINGS ${PossibleArmTargets} )

set(LIBRARY_OUTPUT_PATH_ROOT ${CMAKE_BINARY_DIR}/android/app CACHE PATH
    "root for library output, set this to change where
    android libs are installed to")
    
#set these flags for client use
set(LIBRARY_OUTPUT_PATH ${LIBRARY_OUTPUT_PATH_ROOT}/libs/${ARM_TARGETS}
    CACHE PATH "path for android libs" FORCE)
set(CMAKE_INSTALL_PREFIX ${ANDROID_TOOLCHAIN}/user/${ARM_TARGETS}
    CACHE STRING "path for installing" FORCE)

# where is the target environment 
SET(CMAKE_FIND_ROOT_PATH  ${ANDROID_TOOLCHAIN}/bin ${ANDROID_TOOLCHAIN}/arm-linux-androideabi ${ANDROID_TOOLCHAIN}/sysroot ${CMAKE_INSTALL_PREFIX} ${CMAKE_INSTALL_PREFIX}/share)

SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM ONLY)
# only search for libraries and includes in the ndk toolchain
SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

#set these global flags for cmake client scripts to change behavior
set(ANDROID True)
set(BUILD_ANDROID True)

#make use of ANDROID_CFLAGS, ANDROID_LDFLAGS and ANDROID_CXXFLAGS
set(CMAKE_C_FLAGS "$ENV{ANDROID_CFLAGS} $ENV{CFLAGS}" CACHE STRING "" FORCE)
set(CMAKE_CXX_FLAGS "$ENV{ANDROID_CXXFLAGS} $ENV{CXXFLAGS}" CACHE STRING "" FORCE)
set(CMAKE_SHARED_LINKER_FLAGS "$ENV{ANDROID_LDFLAGS} $ENV{LDFLAGS}" CACHE STRING "" FORCE)
set(CMAKE_MODULE_LINKER_FLAGS "$ENV{ANDROID_LDFLAGS} $ENV{LDFLAGS}" CACHE STRING "" FORCE)
set(CMAKE_EXE_LINKER_FLAGS "-Wl,-pie $ENV{ANDROID_LDFLAGS} $ENV{LDFLAGS}" CACHE STRING "" FORCE)

# Do a no-op access on the CMAKE_TOOLCHAIN_FILE variable so that CMake will not issue a warning on it being unused.
if (CMAKE_TOOLCHAIN_FILE)
endif()