INCLUDE(ExternalProject)

SET(EIGEN_SOURCE_DIR ${THIRD_PARTY_PATH}/eigen3)
SET(EIGEN_INCLUDE_DIR ${EIGEN_SOURCE_DIR}/src/extern_eigen3)
INCLUDE_DIRECTORIES(${EIGEN_INCLUDE_DIR})

ExternalProject_Add(
    extern_eigen3
    ${EXTERNAL_PROJECT_LOG_ARGS}
    GIT_REPOSITORY  "https://github.com/RLovelett/eigen.git"
    GIT_TAG         70661066beef694cadf6c304d0d07e0758825c10
    PREFIX          ${EIGEN_SOURCE_DIR}
    UPDATE_COMMAND  ""
    CONFIGURE_COMMAND ""
    BUILD_COMMAND     ""
    INSTALL_COMMAND   ""
    TEST_COMMAND      ""
)

if (${CMAKE_VERSION} VERSION_LESS "3.3.0")
    set(dummyfile ${CMAKE_CURRENT_BINARY_DIR}/eigen3_dummy.c)
    file(WRITE ${dummyfile} "const char *dummy_eigen3 = \"${dummyfile}\";")
    add_library(eigen3 STATIC ${dummyfile})
else()
    add_library(eigen3 INTERFACE)
endif()

add_dependencies(eigen3 extern_eigen3)

LIST(APPEND external_project_dependencies eigen3)

set(lib_dir "${CMAKE_INSTALL_PREFIX}/third_party/eigen3")
add_custom_target(eigen3_lib
    COMMAND mkdir -p "${lib_dir}/Eigen" "${lib_dir}/unsupported"
    COMMAND cp "${EIGEN_INCLUDE_DIR}/Eigen/Core" "${lib_dir}/Eigen"
    COMMAND cp -r "${EIGEN_INCLUDE_DIR}/Eigen/src" "${lib_dir}/Eigen"
    COMMAND cp -r "${EIGEN_INCLUDE_DIR}/unsupported/Eigen" "${lib_dir}/unsupported"
)