[TODO/Planning] Better CMake support

[sacceus]

It would be nice if the library could be downloaded, configured and installed as dependency for user's own projects in more automated way. The current CMakeLists.txt does not export and install package that would be easily consumed by other projects.

I had a few tries at it, but without success so far.

set(PACKAGE_PUBLISHER   "chronoxor")
set(PACKAGE_REPOSITORY  "CppServer")
set(PACKAGE_NAME        "${PACKAGE_PUBLISHER}_${PACKAGE_REPOSITORY}")
set(PACKAGE_PROJECT     "${PACKAGE_NAME}_project")
set(PACKAGE_VERSION     1.0.0)

FetchContent_Declare(${PACKAGE_PROJECT}
    VERSION           ${PACKAGE_VERSION}
    GIT_REPOSITORY    https://github.com/chronoxor/CppServer
    GIT_TAG           50f2deb26342a8a4de819a30a35b450db51af45e # 1.0.0+ (Jan 10, 2021)
    )
FetchContent_GetProperties(${PACKAGE_PROJECT})
if(NOT ${PACKAGE_PROJECT}_POPULATED)
    message(STATUS "Downloading external dependency: ${PACKAGE_NAME}")
    FetchContent_Populate(${PACKAGE_PROJECT})

    set(CPPSERVER_MODULE TRUE)
    add_subdirectory(
        "${${PACKAGE_PROJECT}_SOURCE_DIR}"
        "${${PACKAGE_PROJECT}_BINARY_DIR}"
        )
endif()

The install and export commands are also rather complicated to get right. A library such as PackageProject.cmake could help with this. In theory if CppServer's CMakeLists.txt would be perfect, the other project CPM.cmake by TheLartians should work for configuration step also. A custom approach might suit this project better.
https://github.com/TheLartians/CPM.cmake
https://github.com/TheLartians/PackageProject.cmake

# PackageProject.cmake will be used to make our target installable.
CPMAddPackage(
    NAME PackageProject.cmake
    GITHUB_REPOSITORY TheLartians/PackageProject.cmake
    VERSION 1.4
)
packageProject(                                                                               
    NAME ${REF_LIBRARY}                                                                       
    VERSION ${PACKAGE_VERSION}                                                                
    NAMESPACE ${REF_LIBRARY}                                                                  
    BINARY_DIR ${${PACKAGE_PROJECT}_BINARY_DIR}/build                                         
    INCLUDE_DIR ${${PACKAGE_PROJECT}_SOURCE_DIR}/include                                      
    INCLUDE_DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/${PACKAGE_PUBLISHER}/${PACKAGE_REPOSITORY}                                                 
    ) 

Custom install should have some commands like following

install(
    TARGETS
        ${INSTALL_TARGETS}
    EXPORT
        ${PROJECT_NAME}Targets
    ...
    )
install(
    DIRECTORY
        "${CMAKE_CURRENT_LIST_DIR}/include/"
    DESTINATION
        "${CMAKE_INSTALL_INCLUDEDIR}
    ...
    )

Exporting depends on whether using normal Targets or Component approach for project.

export(
    TARGETS
        ${INSTALL_TARGETS}
    NAMESPACE
        ${PROJECT_NAME}::
    FILE
        ${CMAKE_CURRENT_BINARY_DIR}/${TARGETS_EXPORT_NAME}.cmake
    )
install(
    EXPORT
        ${TARGETS_EXPORT_NAME}
    DESTINATION
        ${CMAKE_INSTALL_CMAKEDIR}
    NAMESPACE
        ${PROJECT_NAME}::
    )

And somehow finally when that works, it is possible to use CppServer in own project in more straightforward way.

find_package(${PACKAGE_NAME}
    1.0.0
    REQUIRED
    CONFIG
    HINTS
        "C:/Codes/chronoxor/CppServer/install"
    )
target_link_libraries(${PROJECT_NAME} PRIVATE chronoxor::CppServer)

CppServer/install/lib/cmake/CppServer
CppServerTargets.cmake
CppServerConfig.cmake
CppServerConfigVersion.cmake
CppServer/install/include
And so on...