# Lines that begin with a # are comments
# set the minimum required version of cmake, usually the first line
cmake_minimum_required(VERSION 3.22)

# project_name sets the name of the project and causes cmake to
# find the c and c++ compilers
project(project_name)

# Find dependencies.
# Many libraries ship with files that allow CMake to find them
# Then general behavior is to call "find_package" but the options
# provided are package specific.  Usually there is then a CMAKE variable
# That is defined to reference the library
# here: we find the eigen library as per the instruction
# https://eigen.tuxfamily.org/dox/TopicCMakeGuide.html
find_package(Eigen3 3.3 REQUIRED NO_MODULE)

# Create a library.  Can specify if it is shared or static but usually
# you don't need or want to.
# name is the name of the library without the extension or lib prefix
# name creates a cmake "target" (in this case the target is called "libname"
add_library(libname src/libfile1.cpp src/libfile2.cpp)

# Use target_include_directories so that #include"mylibrary/header.hpp" works
# The use of the <BUILD_INTERFACE> and <INSTALL_INTERFACE> is because when
# using the library from the build directory or after installation the header
# files are actually in different locations.
# During the build, the headers are read from the source code directory
# When used from the installed location, headers are in the
# system include/ directory
target_include_directories(libname
    PUBLIC
    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include/>
    $<INSTALL_INTERFACE:include/>)

# specify additional compilation flags for the library
# Public causes the flags to propagate to anything
# that links against this library
target_compile_options(libname PUBLIC -Wall -Wextra -pedantic)

# Enable c++23 support.
# PUBLIC causes the features to propagate to anything
# that links against this library
# whereas PRIVATE would make it apply only to the library itself
target_compile_features(libname PUBLIC cxx_std_23)

# Create an executable from the following source code files
# The Name of the executable creates a cmake "target"
add_executable(Name src/Name_main.cpp)

# Use target_link_libraries to add dependencies to a "target"
# (e.g., a library or executable)
# This will automatically add all required library files
# that need to be linked
# and paths to th locations of header files.
# Because libname has PUBLIC cxx_std_23 as a compile feature
# Name will also be compiled with c++23 as the standard.
target_link_libraries(Name Eigen3::Eigen libname)

# install the include files by copying the whole include directory
install(DIRECTORY include/mylibrary DESTINATION include)

# Create a CMake Exported Target containing the lib and exe.
# Also create CMake Export called project_name-targets
# The CMake Export contains files that allow other CMake projects
# to find this project. It must be installed separately.
install(TARGETS Name libname EXPORT project_name-targets)

# The project_name-targets created by install(TARGETS) needs to be installed.
# install(EXPORT ...) will generate a file called project_name-config.cmake
# that contains the exported targets.
# After installation this file will then be found when calling
# find_package(project_name) from another cmake project
# A user can then target_link_libraries(target project_name::library)
# to use the libraries installed here
install(EXPORT project_name-targets
        FILE project_name-config.cmake
        NAMESPACE project_name::
        DESTINATION lib/cmake/${PROJECT_NAME})