cmake_minimum_required(VERSION 3.0.0)

##
## PROJECT
## name and version
##
project(nlohmann_json VERSION 3.0.1 LANGUAGES CXX)

##
## INCLUDE
##
##
include(ExternalProject)

##
## OPTIONS
##
option(JSON_BuildTests "Build the unit tests when BUILD_TESTING is enabled." ON)

##
## CONFIGURATION
##
set(NLOHMANN_JSON_TARGET_NAME               ${PROJECT_NAME})
set(NLOHMANN_JSON_SOURCE_DIR                "src")
set(NLOHMANN_JSON_CONFIG_INSTALL_DIR        "lib/cmake/${PROJECT_NAME}")
set(NLOHMANN_JSON_INCLUDE_INSTALL_DIR       "include")
set(NLOHMANN_JSON_HEADER_INSTALL_DIR        "${NLOHMANN_JSON_INCLUDE_INSTALL_DIR}/nlohmann")
set(NLOHMANN_JSON_TARGETS_EXPORT_NAME       "${PROJECT_NAME}Targets")
set(NLOHMANN_JSON_CMAKE_CONFIG_TEMPLATE     "cmake/config.cmake.in")
set(NLOHMANN_JSON_CMAKE_CONFIG_DIR          "${CMAKE_CURRENT_BINARY_DIR}/cmake_config")
set(NLOHMANN_JSON_CMAKE_VERSION_CONFIG_FILE "${NLOHMANN_JSON_CMAKE_CONFIG_DIR}/${PROJECT_NAME}ConfigVersion.cmake")
set(NLOHMANN_JSON_CMAKE_PROJECT_CONFIG_FILE "${NLOHMANN_JSON_CMAKE_CONFIG_DIR}/${PROJECT_NAME}Config.cmake")

##
## TARGET
## create target and add include path
##
add_library(${NLOHMANN_JSON_TARGET_NAME} INTERFACE)

target_include_directories(
    ${NLOHMANN_JSON_TARGET_NAME}
    INTERFACE
    $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/src>
    $<INSTALL_INTERFACE:include>
)

## add debug view defintion file for msvc (natvis) [cmake <= 3.2.2 does not support export of source files]
if (MSVC AND CMAKE_VERSION VERSION_GREATER "3.2.2")
    set(NLOHMANN_ADD_NATVIS TRUE)
    set(NLOHMANN_NATVIS_FILE "nlohmann_json.natvis")
    target_sources(
        ${NLOHMANN_JSON_TARGET_NAME} 
        INTERFACE 
            $<INSTALL_INTERFACE:${NLOHMANN_NATVIS_FILE}>
            $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/${NLOHMANN_NATVIS_FILE}>  
    )
endif()
           
##
## TESTS
## create and configure the unit test target
##
include(CTest) #adds option BUILD_TESTING (default ON)

if(BUILD_TESTING AND JSON_BuildTests)
    enable_testing()
    include_directories(${NLOHMANN_JSON_SOURCE_DIR})
    add_subdirectory(test)
endif()

##
## AMALGAMATION
## create a single header file
##
option(JSON_Amalgamate "Build and use amalgamation" OFF)

if(JSON_Amalgamate)
    ExternalProject_Add(amalgamate
      GIT_REPOSITORY "https://github.com/theodelrieu/Amalgamate"
      CMAKE_ARGS "-DCMAKE_INSTALL_PREFIX=${CMAKE_BINARY_DIR}"
    )

    # There is no way to tell amalgamate to force-write the output file even if it already exists...
    add_custom_target(single_header ALL rm -f "${CMAKE_SOURCE_DIR}/${NLOHMANN_JSON_SOURCE_DIR}/json.hpp"
      COMMENT "Amalgamating json.hpp..."
      WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}/develop
      DEPENDS amalgamate
      COMMAND "${CMAKE_BINARY_DIR}/bin/amalgamate" -w '*.hpp' -i . json.hpp "${CMAKE_SOURCE_DIR}/${NLOHMANN_JSON_SOURCE_DIR}/json.hpp"
    )
endif()

##
## INSTALL
## install header files, generate and install cmake config files for find_package()
##
include(CMakePackageConfigHelpers)
write_basic_package_version_file(
    ${NLOHMANN_JSON_CMAKE_VERSION_CONFIG_FILE} COMPATIBILITY SameMajorVersion
)
configure_package_config_file(
    ${NLOHMANN_JSON_CMAKE_CONFIG_TEMPLATE}
    ${NLOHMANN_JSON_CMAKE_PROJECT_CONFIG_FILE}
    INSTALL_DESTINATION ${NLOHMANN_JSON_CONFIG_INSTALL_DIR}
)
install(
    DIRECTORY ${NLOHMANN_JSON_SOURCE_DIR}
    DESTINATION ${NLOHMANN_JSON_HEADER_INSTALL_DIR}
)
install(
    FILES ${NLOHMANN_JSON_CMAKE_PROJECT_CONFIG_FILE} ${NLOHMANN_JSON_CMAKE_VERSION_CONFIG_FILE}
    DESTINATION ${NLOHMANN_JSON_CONFIG_INSTALL_DIR}
)
if (NLOHMANN_ADD_NATVIS)
    install(
        FILES ${NLOHMANN_NATVIS_FILE}
        DESTINATION .
)
endif()
install(
    TARGETS ${NLOHMANN_JSON_TARGET_NAME}
    EXPORT ${NLOHMANN_JSON_TARGETS_EXPORT_NAME}
    INCLUDES DESTINATION ${NLOHMANN_JSON_INCLUDE_INSTALL_DIR}
)
install(
    EXPORT ${NLOHMANN_JSON_TARGETS_EXPORT_NAME}
    DESTINATION ${NLOHMANN_JSON_CONFIG_INSTALL_DIR}
)