Problems with Cmakelists.txt for OSX/Windows compilation - c++

Question

I'm attempting to alter my CmakeLists.txt file for my currently working MacOSX version of my OpenGL engine, so that it will compile and run on windows. I'm positive that I'm doing something wrong in the way I'm writing my Cmakelists.txt and would like some help correcting it.
Have already tried a multitude of different tutorials and examples found online. The problem most likely lies in how I'm trying to link dll files but I'm unsure of what I'm doing wrong.
cmake_minimum_required(VERSION 3.1)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -w")
project (sake)
add_subdirectory(src/imgui)
add_subdirectory(libs/assimp)
add_subdirectory(src/GLM/glm)
include_directories(${PROJECT_SOURCE_DIR})
file(GLOB SRC_FILES src/*.cpp)
add_executable(sake ${SRC_FILES})
target_link_libraries(sake imgui)
target_link_libraries(sake assimp)
# glfw
if (WIN32)
add_subdirectory(F:/glfw-3.3 F:/glfw-3.3/src)
include_directories(F:/glfw-3.3/include)
link_libraries(${GLFW_LIBRARY_DIRS})
endif (WIN32)
if(APPLE)
find_package(glfw3 REQUIRED)
include_directories(${GLFW_INCLUDE_DIRS})
link_libraries(${GLFW_LIBRARY_DIRS})
endif (APPLE)
# opengl
find_package(OpenGL REQUIRED)
include_directories(${OPENGL_INCLUDE_DIRS})
# glew
if(WIN32)
include_directories(F:/GLEW/glew-2.1.0/include)
endif (WIN32)
if(APPLE)
find_package(GLEW REQUIRED)
include_directories(${GLEW_INCLUDE_DIRS})
endif (APPLE)
if(WIN32)
include_directories(libs/assimp/include)
endif(WIN32)
if(APPLE)
find_package(assimp REQUIRED)
include_directories(${ASSIMP_INCLUDE_DIR})
endif(APPLE)
if (APPLE)
find_library(COCOA_LIBRARY Cocoa)
find_library(OpenGL_LIBRARY OpenGL)
find_library(IOKIT_LIBRARY IOKit)
find_library(COREVIDEO_LIBRARY CoreVideo)
SET(EXTRA_LIBS ${COCOA_LIBRARY} ${OpenGL_LIBRARY} ${IOKIT_LIBRARY} ${COREVIDEO_LIBRARY})
endif (APPLE)
target_link_libraries(
sake
glfw
${OPENGL_LIBRARIES}
${GLEW_LIBRARIES}
${EXTRA_LIBS}
)
add_custom_target(run
COMMAND ./sake
DEPENDS sake
WORKING_DIRECTORY ${CMAKE_PROJECT_DIR}
)
current error message happens when I cmake .
CMake Error at F:/glfw-3.3/src/CMakeLists.txt:95 (add_library):
add_library cannot create target "glfw" because another target with the
same name already exists. The existing target is a shared library created
in source directory "F:/glfw-3.3/src". See documentation for policy
CMP0002 for more details.