if (STATIC_BUILD OR NOT USE_SYSTEM_OPENSSL)
  SET(OPENSSL_SOURCES_DIR ${CMAKE_BINARY_DIR}/openssl-1.0.2o)
  SET(OPENSSL_URL "http://orthanc.osimis.io/ThirdPartyDownloads/openssl-1.0.2o.tar.gz")
  SET(OPENSSL_MD5 "44279b8557c3247cbe324e2322ecd114")

  if (IS_DIRECTORY "${OPENSSL_SOURCES_DIR}")
    set(FirstRun OFF)
  else()
    set(FirstRun ON)
  endif()

  DownloadPackage(${OPENSSL_MD5} ${OPENSSL_URL} "${OPENSSL_SOURCES_DIR}")

  if (FirstRun)
    file(MAKE_DIRECTORY ${OPENSSL_SOURCES_DIR}/include/openssl)

    foreach(header
      ${OPENSSL_SOURCES_DIR}/crypto/aes/aes.h
      ${OPENSSL_SOURCES_DIR}/crypto/asn1/asn1.h
      ${OPENSSL_SOURCES_DIR}/crypto/asn1/asn1_mac.h
      ${OPENSSL_SOURCES_DIR}/crypto/asn1/asn1t.h
      ${OPENSSL_SOURCES_DIR}/crypto/bf/blowfish.h
      ${OPENSSL_SOURCES_DIR}/crypto/bio/bio.h
      ${OPENSSL_SOURCES_DIR}/crypto/bn/bn.h
      ${OPENSSL_SOURCES_DIR}/crypto/buffer/buffer.h
      ${OPENSSL_SOURCES_DIR}/crypto/camellia/camellia.h
      ${OPENSSL_SOURCES_DIR}/crypto/cast/cast.h
      ${OPENSSL_SOURCES_DIR}/crypto/cmac/cmac.h
      ${OPENSSL_SOURCES_DIR}/crypto/cms/cms.h
      ${OPENSSL_SOURCES_DIR}/crypto/comp/comp.h
      ${OPENSSL_SOURCES_DIR}/crypto/conf/conf.h
      ${OPENSSL_SOURCES_DIR}/crypto/conf/conf_api.h
      ${OPENSSL_SOURCES_DIR}/crypto/crypto.h
      ${OPENSSL_SOURCES_DIR}/crypto/des/des.h
      ${OPENSSL_SOURCES_DIR}/crypto/des/des_old.h
      ${OPENSSL_SOURCES_DIR}/crypto/dh/dh.h
      ${OPENSSL_SOURCES_DIR}/crypto/dsa/dsa.h
      ${OPENSSL_SOURCES_DIR}/crypto/dso/dso.h
      ${OPENSSL_SOURCES_DIR}/crypto/ebcdic.h
      ${OPENSSL_SOURCES_DIR}/crypto/ec/ec.h
      ${OPENSSL_SOURCES_DIR}/crypto/ecdh/ecdh.h
      ${OPENSSL_SOURCES_DIR}/crypto/ecdsa/ecdsa.h
      ${OPENSSL_SOURCES_DIR}/crypto/engine/engine.h
      ${OPENSSL_SOURCES_DIR}/crypto/err/err.h
      ${OPENSSL_SOURCES_DIR}/crypto/evp/evp.h
      ${OPENSSL_SOURCES_DIR}/crypto/hmac/hmac.h
      ${OPENSSL_SOURCES_DIR}/crypto/idea/idea.h
      ${OPENSSL_SOURCES_DIR}/crypto/jpake/jpake.h
      ${OPENSSL_SOURCES_DIR}/crypto/krb5/krb5_asn.h
      ${OPENSSL_SOURCES_DIR}/crypto/lhash/lhash.h
      ${OPENSSL_SOURCES_DIR}/crypto/md2/md2.h
      ${OPENSSL_SOURCES_DIR}/crypto/md4/md4.h
      ${OPENSSL_SOURCES_DIR}/crypto/md5/md5.h
      ${OPENSSL_SOURCES_DIR}/crypto/mdc2/mdc2.h
      ${OPENSSL_SOURCES_DIR}/crypto/modes/modes.h
      ${OPENSSL_SOURCES_DIR}/crypto/objects/obj_mac.h
      ${OPENSSL_SOURCES_DIR}/crypto/objects/objects.h
      ${OPENSSL_SOURCES_DIR}/crypto/ocsp/ocsp.h
      ${OPENSSL_SOURCES_DIR}/crypto/opensslconf.h
      ${OPENSSL_SOURCES_DIR}/crypto/opensslv.h
      ${OPENSSL_SOURCES_DIR}/crypto/ossl_typ.h
      ${OPENSSL_SOURCES_DIR}/crypto/pem/pem.h
      ${OPENSSL_SOURCES_DIR}/crypto/pem/pem2.h
      ${OPENSSL_SOURCES_DIR}/crypto/pkcs12/pkcs12.h
      ${OPENSSL_SOURCES_DIR}/crypto/pkcs7/pkcs7.h
      ${OPENSSL_SOURCES_DIR}/crypto/pqueue/pqueue.h
      ${OPENSSL_SOURCES_DIR}/crypto/rand/rand.h
      ${OPENSSL_SOURCES_DIR}/crypto/rc2/rc2.h
      ${OPENSSL_SOURCES_DIR}/crypto/rc4/rc4.h
      ${OPENSSL_SOURCES_DIR}/crypto/rc5/rc5.h
      ${OPENSSL_SOURCES_DIR}/crypto/ripemd/ripemd.h
      ${OPENSSL_SOURCES_DIR}/crypto/rsa/rsa.h
      ${OPENSSL_SOURCES_DIR}/crypto/seed/seed.h
      ${OPENSSL_SOURCES_DIR}/crypto/sha/sha.h
      ${OPENSSL_SOURCES_DIR}/crypto/srp/srp.h
      ${OPENSSL_SOURCES_DIR}/crypto/stack/safestack.h
      ${OPENSSL_SOURCES_DIR}/crypto/stack/stack.h
      ${OPENSSL_SOURCES_DIR}/crypto/store/store.h
      ${OPENSSL_SOURCES_DIR}/crypto/symhacks.h
      ${OPENSSL_SOURCES_DIR}/crypto/ts/ts.h
      ${OPENSSL_SOURCES_DIR}/crypto/txt_db/txt_db.h
      ${OPENSSL_SOURCES_DIR}/crypto/ui/ui.h
      ${OPENSSL_SOURCES_DIR}/crypto/ui/ui_compat.h
      ${OPENSSL_SOURCES_DIR}/crypto/whrlpool/whrlpool.h
      ${OPENSSL_SOURCES_DIR}/crypto/x509/x509.h
      ${OPENSSL_SOURCES_DIR}/crypto/x509/x509_vfy.h
      ${OPENSSL_SOURCES_DIR}/crypto/x509v3/x509v3.h
      ${OPENSSL_SOURCES_DIR}/e_os2.h
      ${OPENSSL_SOURCES_DIR}/ssl/dtls1.h
      ${OPENSSL_SOURCES_DIR}/ssl/kssl.h
      ${OPENSSL_SOURCES_DIR}/ssl/srtp.h
      ${OPENSSL_SOURCES_DIR}/ssl/ssl.h
      ${OPENSSL_SOURCES_DIR}/ssl/ssl2.h
      ${OPENSSL_SOURCES_DIR}/ssl/ssl23.h
      ${OPENSSL_SOURCES_DIR}/ssl/ssl3.h
      ${OPENSSL_SOURCES_DIR}/ssl/tls1.h
      )
      file(COPY ${header} DESTINATION ${OPENSSL_SOURCES_DIR}/include/openssl)
    endforeach()

    file(RENAME
      ${OPENSSL_SOURCES_DIR}/include/openssl/e_os2.h
      ${OPENSSL_SOURCES_DIR}/include/openssl/e_os2_source.h)

    # The following patch of "e_os2.h" prevents from building OpenSSL
    # as a DLL under Windows. Otherwise, symbols have inconsistent
    # linkage if ${OPENSSL_SOURCES} is used to create a DLL (notably
    # if building an Orthanc plugin such as MySQL).
    file(WRITE ${OPENSSL_SOURCES_DIR}/include/openssl/e_os2.h "
#include \"e_os2_source.h\"
#if defined(_WIN32)
#  undef OPENSSL_EXPORT
#  undef OPENSSL_IMPORT
#  undef OPENSSL_EXTERN
#  undef OPENSSL_GLOBAL
#  define OPENSSL_EXPORT
#  define OPENSSL_IMPORT
#  define OPENSSL_EXTERN extern
#  define OPENSSL_GLOBAL
#endif
")
  endif()
  
  add_definitions(
    -DOPENSSL_THREADS
    -DOPENSSL_IA32_SSE2
    -DOPENSSL_NO_ASM
    -DOPENSSL_NO_DYNAMIC_ENGINE
    -DNO_WINDOWS_BRAINDEATH

    -DOPENSSL_NO_BF 
    -DOPENSSL_NO_CAMELLIA
    -DOPENSSL_NO_CAST 
    -DOPENSSL_NO_EC_NISTP_64_GCC_128
    -DOPENSSL_NO_GMP
    -DOPENSSL_NO_GOST
    -DOPENSSL_NO_HW
    -DOPENSSL_NO_JPAKE
    -DOPENSSL_NO_IDEA
    -DOPENSSL_NO_KRB5 
    -DOPENSSL_NO_MD2 
    -DOPENSSL_NO_MDC2 
    #-DOPENSSL_NO_MD4   # MD4 is necessary for MariaDB/MySQL client
    -DOPENSSL_NO_RC2 
    -DOPENSSL_NO_RC4 
    -DOPENSSL_NO_RC5 
    -DOPENSSL_NO_RFC3779
    -DOPENSSL_NO_SCTP
    -DOPENSSL_NO_STORE
    -DOPENSSL_NO_SEED
    -DOPENSSL_NO_WHIRLPOOL
    -DOPENSSL_NO_RIPEMD
    )

  include_directories(
    ${OPENSSL_SOURCES_DIR}
    ${OPENSSL_SOURCES_DIR}/crypto
    ${OPENSSL_SOURCES_DIR}/crypto/asn1
    ${OPENSSL_SOURCES_DIR}/crypto/modes
    ${OPENSSL_SOURCES_DIR}/crypto/evp
    ${OPENSSL_SOURCES_DIR}/include
    )

  set(OPENSSL_SOURCES_SUBDIRS
    ${OPENSSL_SOURCES_DIR}/crypto
    ${OPENSSL_SOURCES_DIR}/crypto/aes
    ${OPENSSL_SOURCES_DIR}/crypto/asn1
    ${OPENSSL_SOURCES_DIR}/crypto/bio
    ${OPENSSL_SOURCES_DIR}/crypto/bn
    ${OPENSSL_SOURCES_DIR}/crypto/buffer
    ${OPENSSL_SOURCES_DIR}/crypto/cmac
    ${OPENSSL_SOURCES_DIR}/crypto/cms
    ${OPENSSL_SOURCES_DIR}/crypto/comp
    ${OPENSSL_SOURCES_DIR}/crypto/conf
    ${OPENSSL_SOURCES_DIR}/crypto/des
    ${OPENSSL_SOURCES_DIR}/crypto/dh
    ${OPENSSL_SOURCES_DIR}/crypto/dsa
    ${OPENSSL_SOURCES_DIR}/crypto/dso
    ${OPENSSL_SOURCES_DIR}/crypto/engine
    ${OPENSSL_SOURCES_DIR}/crypto/err
    ${OPENSSL_SOURCES_DIR}/crypto/evp
    ${OPENSSL_SOURCES_DIR}/crypto/hmac
    ${OPENSSL_SOURCES_DIR}/crypto/lhash
    ${OPENSSL_SOURCES_DIR}/crypto/md4
    ${OPENSSL_SOURCES_DIR}/crypto/md5
    ${OPENSSL_SOURCES_DIR}/crypto/modes
    ${OPENSSL_SOURCES_DIR}/crypto/objects
    ${OPENSSL_SOURCES_DIR}/crypto/ocsp
    ${OPENSSL_SOURCES_DIR}/crypto/pem
    ${OPENSSL_SOURCES_DIR}/crypto/pkcs12
    ${OPENSSL_SOURCES_DIR}/crypto/pkcs7
    ${OPENSSL_SOURCES_DIR}/crypto/pqueue
    ${OPENSSL_SOURCES_DIR}/crypto/rand
    ${OPENSSL_SOURCES_DIR}/crypto/rsa
    ${OPENSSL_SOURCES_DIR}/crypto/sha
    ${OPENSSL_SOURCES_DIR}/crypto/srp
    ${OPENSSL_SOURCES_DIR}/crypto/stack
    ${OPENSSL_SOURCES_DIR}/crypto/ts
    ${OPENSSL_SOURCES_DIR}/crypto/txt_db
    ${OPENSSL_SOURCES_DIR}/crypto/ui
    ${OPENSSL_SOURCES_DIR}/crypto/x509
    ${OPENSSL_SOURCES_DIR}/crypto/x509v3
    ${OPENSSL_SOURCES_DIR}/ssl
    )

  if (ENABLE_OPENSSL_ENGINES)
    list(APPEND OPENSSL_SOURCES_SUBDIRS
      ${OPENSSL_SOURCES_DIR}/engines
      )
  endif()
  
  list(APPEND OPENSSL_SOURCES_SUBDIRS
    # EC, ECDH and ECDSA are necessary for PKCS11, and for contacting
    # HTTPS servers that use TLS certificate encrypted with ECDSA
    # (check the output of a recent version of the "sslscan"
    # command). Until Orthanc <= 1.4.1, these features were only
    # enabled if ENABLE_PKCS11 support was set to "ON".
    # https://groups.google.com/d/msg/orthanc-users/2l-bhYIMEWg/oMmK33bYBgAJ
    ${OPENSSL_SOURCES_DIR}/crypto/ec
    ${OPENSSL_SOURCES_DIR}/crypto/ecdh
    ${OPENSSL_SOURCES_DIR}/crypto/ecdsa
    )

  foreach(d ${OPENSSL_SOURCES_SUBDIRS})
    AUX_SOURCE_DIRECTORY(${d} OPENSSL_SOURCES)
  endforeach()

  list(REMOVE_ITEM OPENSSL_SOURCES
    ${OPENSSL_SOURCES_DIR}/crypto/LPdir_unix.c
    ${OPENSSL_SOURCES_DIR}/crypto/LPdir_vms.c
    ${OPENSSL_SOURCES_DIR}/crypto/LPdir_win.c
    ${OPENSSL_SOURCES_DIR}/crypto/LPdir_win32.c
    ${OPENSSL_SOURCES_DIR}/crypto/LPdir_wince.c
    ${OPENSSL_SOURCES_DIR}/crypto/armcap.c
    ${OPENSSL_SOURCES_DIR}/crypto/bf/bfs.cpp
    ${OPENSSL_SOURCES_DIR}/crypto/bio/bss_rtcp.c
    ${OPENSSL_SOURCES_DIR}/crypto/bn/exp.c
    ${OPENSSL_SOURCES_DIR}/crypto/conf/cnf_save.c
    ${OPENSSL_SOURCES_DIR}/crypto/conf/test.c
    ${OPENSSL_SOURCES_DIR}/crypto/des/des.c
    ${OPENSSL_SOURCES_DIR}/crypto/des/des3s.cpp
    ${OPENSSL_SOURCES_DIR}/crypto/des/des_opts.c
    ${OPENSSL_SOURCES_DIR}/crypto/des/dess.cpp
    ${OPENSSL_SOURCES_DIR}/crypto/des/read_pwd.c
    ${OPENSSL_SOURCES_DIR}/crypto/des/speed.c
    ${OPENSSL_SOURCES_DIR}/crypto/evp/e_dsa.c
    ${OPENSSL_SOURCES_DIR}/crypto/evp/m_ripemd.c
    ${OPENSSL_SOURCES_DIR}/crypto/lhash/lh_test.c
    ${OPENSSL_SOURCES_DIR}/crypto/md4/md4.c
    ${OPENSSL_SOURCES_DIR}/crypto/md4/md4s.cpp
    ${OPENSSL_SOURCES_DIR}/crypto/md4/md4test.c
    ${OPENSSL_SOURCES_DIR}/crypto/md5/md5s.cpp
    ${OPENSSL_SOURCES_DIR}/crypto/pkcs7/bio_ber.c
    ${OPENSSL_SOURCES_DIR}/crypto/pkcs7/pk7_enc.c
    ${OPENSSL_SOURCES_DIR}/crypto/ppccap.c
    ${OPENSSL_SOURCES_DIR}/crypto/rand/randtest.c
    ${OPENSSL_SOURCES_DIR}/crypto/s390xcap.c
    ${OPENSSL_SOURCES_DIR}/crypto/sparcv9cap.c
    ${OPENSSL_SOURCES_DIR}/crypto/x509v3/tabtest.c
    ${OPENSSL_SOURCES_DIR}/crypto/x509v3/v3conf.c
    ${OPENSSL_SOURCES_DIR}/ssl/ssl_task.c
    ${OPENSSL_SOURCES_DIR}/crypto/LPdir_nyi.c
    ${OPENSSL_SOURCES_DIR}/crypto/aes/aes_x86core.c
    ${OPENSSL_SOURCES_DIR}/crypto/bio/bss_dgram.c
    ${OPENSSL_SOURCES_DIR}/crypto/bn/bntest.c
    ${OPENSSL_SOURCES_DIR}/crypto/bn/expspeed.c
    ${OPENSSL_SOURCES_DIR}/crypto/bn/exptest.c
    ${OPENSSL_SOURCES_DIR}/crypto/engine/enginetest.c
    ${OPENSSL_SOURCES_DIR}/crypto/evp/evp_test.c
    ${OPENSSL_SOURCES_DIR}/crypto/hmac/hmactest.c
    ${OPENSSL_SOURCES_DIR}/crypto/md5/md5.c
    ${OPENSSL_SOURCES_DIR}/crypto/md5/md5test.c
    ${OPENSSL_SOURCES_DIR}/crypto/o_dir_test.c
    ${OPENSSL_SOURCES_DIR}/crypto/pkcs7/dec.c
    ${OPENSSL_SOURCES_DIR}/crypto/pkcs7/enc.c
    ${OPENSSL_SOURCES_DIR}/crypto/pkcs7/sign.c
    ${OPENSSL_SOURCES_DIR}/crypto/pkcs7/verify.c
    ${OPENSSL_SOURCES_DIR}/crypto/rsa/rsa_test.c
    ${OPENSSL_SOURCES_DIR}/crypto/sha/sha.c
    ${OPENSSL_SOURCES_DIR}/crypto/sha/sha1.c
    ${OPENSSL_SOURCES_DIR}/crypto/sha/sha1t.c
    ${OPENSSL_SOURCES_DIR}/crypto/sha/sha1test.c
    ${OPENSSL_SOURCES_DIR}/crypto/sha/sha256t.c
    ${OPENSSL_SOURCES_DIR}/crypto/sha/sha512t.c
    ${OPENSSL_SOURCES_DIR}/crypto/sha/shatest.c
    ${OPENSSL_SOURCES_DIR}/crypto/srp/srptest.c

    ${OPENSSL_SOURCES_DIR}/crypto/bn/divtest.c
    ${OPENSSL_SOURCES_DIR}/crypto/bn/bnspeed.c
    ${OPENSSL_SOURCES_DIR}/crypto/des/destest.c
    ${OPENSSL_SOURCES_DIR}/crypto/dh/p192.c
    ${OPENSSL_SOURCES_DIR}/crypto/dh/p512.c
    ${OPENSSL_SOURCES_DIR}/crypto/dh/p1024.c
    ${OPENSSL_SOURCES_DIR}/crypto/des/rpw.c
    ${OPENSSL_SOURCES_DIR}/ssl/ssltest.c
    ${OPENSSL_SOURCES_DIR}/crypto/dsa/dsagen.c
    ${OPENSSL_SOURCES_DIR}/crypto/dsa/dsatest.c
    ${OPENSSL_SOURCES_DIR}/crypto/dh/dhtest.c
    ${OPENSSL_SOURCES_DIR}/crypto/pqueue/pq_test.c
    ${OPENSSL_SOURCES_DIR}/crypto/des/ncbc_enc.c

    ${OPENSSL_SOURCES_DIR}/crypto/evp/evp_extra_test.c
    ${OPENSSL_SOURCES_DIR}/crypto/evp/verify_extra_test.c
    ${OPENSSL_SOURCES_DIR}/crypto/x509/verify_extra_test.c
    ${OPENSSL_SOURCES_DIR}/crypto/x509v3/v3prin.c
    ${OPENSSL_SOURCES_DIR}/crypto/x509v3/v3nametest.c
    ${OPENSSL_SOURCES_DIR}/crypto/constant_time_test.c

    ${OPENSSL_SOURCES_DIR}/ssl/heartbeat_test.c
    ${OPENSSL_SOURCES_DIR}/ssl/fatalerrtest.c
    ${OPENSSL_SOURCES_DIR}/ssl/dtlstest.c
    ${OPENSSL_SOURCES_DIR}/ssl/bad_dtls_test.c
    ${OPENSSL_SOURCES_DIR}/ssl/clienthellotest.c
    ${OPENSSL_SOURCES_DIR}/ssl/sslv2conftest.c

    ${OPENSSL_SOURCES_DIR}/crypto/ec/ecp_nistz256.c
    ${OPENSSL_SOURCES_DIR}/crypto/ec/ecp_nistz256_table.c
    ${OPENSSL_SOURCES_DIR}/crypto/ec/ectest.c
    ${OPENSSL_SOURCES_DIR}/crypto/ecdh/ecdhtest.c
    ${OPENSSL_SOURCES_DIR}/crypto/ecdsa/ecdsatest.c
    )


  if ("${CMAKE_SYSTEM_NAME}" STREQUAL "Windows")
    set_source_files_properties(
      ${OPENSSL_SOURCES}
      PROPERTIES COMPILE_DEFINITIONS
      "OPENSSL_SYSNAME_WIN32;SO_WIN32;WIN32_LEAN_AND_MEAN;L_ENDIAN")

    if (ENABLE_OPENSSL_ENGINES)
      link_libraries(crypt32)
    endif()
  endif()

  source_group(ThirdParty\\OpenSSL REGULAR_EXPRESSION ${OPENSSL_SOURCES_DIR}/.*)

else()
  include(FindOpenSSL)

  if (NOT ${OPENSSL_FOUND})
    message(FATAL_ERROR "Unable to find OpenSSL")
  endif()

  include_directories(${OPENSSL_INCLUDE_DIR})
  link_libraries(${OPENSSL_LIBRARIES})
endif()