cmake_minimum_required(VERSION 3.12 FATAL_ERROR)
include(GNUInstallDirs)

project(mcl LANGUAGES CXX VERSION 0.1.12)

# Determine if we're built as a subproject (using add_subdirectory)
# or if this is the master project.
set(MASTER_PROJECT OFF)
if (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
  set(MASTER_PROJECT ON)
endif()

# Project options
option(MCL_WARNINGS_AS_ERRORS "Warnings as errors" ${MASTER_PROJECT})
option(MCL_INSTALL "Enable installation" ${MASTER_PROJECT})

# Default to a Release build
if (NOT CMAKE_BUILD_TYPE)
    set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Choose the type of build, options are: Debug Release RelWithDebInfo MinSizeRel." FORCE)
    message(STATUS "Defaulting to a Release build")
endif()

# Set hard requirements for C++
set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

# Warn on CMake API deprecations
set(CMAKE_WARN_DEPRECATED ON)

# Disable in-source builds
set(CMAKE_DISABLE_SOURCE_CHANGES ON)
set(CMAKE_DISABLE_IN_SOURCE_BUILD ON)
if ("${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}")
    message(SEND_ERROR "In-source builds are not allowed.")
endif()

# Add the module directory to the list of paths
list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/CMakeModules")

# Compiler flags
if (MSVC)
    set(MCL_CXX_FLAGS
        /std:c++latest
        /experimental:external
        /external:W0
        /external:anglebrackets
        /W4
        /w44263 # Non-virtual member function hides base class virtual function
        /w44265 # Class has virtual functions, but destructor is not virtual
        /w44456 # Declaration of 'var' hides previous local declaration
        /w44457 # Declaration of 'var' hides function parameter
        /w44458 # Declaration of 'var' hides class member
        /w44459 # Declaration of 'var' hides global definition
        /w44946 # Reinterpret-cast between related types
        /wd4592 # Symbol will be dynamically initialized (implementation limitation)
        /permissive- # Stricter C++ standards conformance
        /MP
        /Zi
        /Zo
        /EHsc
        /Zc:externConstexpr # Allows external linkage for variables declared "extern constexpr", as the standard permits.
        /Zc:inline          # Omits inline functions from object-file output.
        /Zc:throwingNew     # Assumes new (without std::nothrow) never returns null.
        /volatile:iso       # Use strict standard-abiding volatile semantics
        /bigobj             # Increase number of sections in .obj files
        /DNOMINMAX)

    if (MCL_WARNINGS_AS_ERRORS)
        list(APPEND MCL_CXX_FLAGS /WX)
    endif()

    if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
        list(APPEND MCL_CXX_FLAGS
             -Qunused-arguments
             -Wno-missing-braces)
    endif()
else()
    set(MCL_CXX_FLAGS
        -Wall
        -Wextra
        -Wcast-qual
        -pedantic
        -pedantic-errors
        -Wfatal-errors
        -Wno-missing-braces)

    if (MCL_WARNINGS_AS_ERRORS)
        list(APPEND MCL_CXX_FLAGS -Werror)
    endif()
endif()

# Dependencies

if (NOT TARGET Catch2::Catch2)
    find_package(Catch2 3 QUIET)
endif()

if (NOT TARGET fmt::fmt)
    find_package(fmt REQUIRED)
endif()

# Project files

add_subdirectory(src)
if (TARGET Catch2::Catch2 AND MASTER_PROJECT)
    add_subdirectory(tests)
endif()

# Install instructions
if (MCL_INSTALL)
    include(GNUInstallDirs)
    include(CMakePackageConfigHelpers)

    install(TARGETS mcl EXPORT mclTargets)
    install(EXPORT mclTargets
        NAMESPACE merry::
        DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/mcl"
    )

    configure_package_config_file(CMakeModules/mclConfig.cmake.in
        mclConfig.cmake
        INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/mcl"
    )
    write_basic_package_version_file(mclConfigVersion.cmake
        COMPATIBILITY SameMajorVersion
    )
    install(FILES
        "${CMAKE_CURRENT_BINARY_DIR}/mclConfig.cmake"
        "${CMAKE_CURRENT_BINARY_DIR}/mclConfigVersion.cmake"
        DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/mcl"
    )

    install(DIRECTORY include/ TYPE INCLUDE FILES_MATCHING PATTERN "*.hpp")
endif()