# FindOpenSceneGraph.cmake
#
# Locate an installed OpenSceneGraph and expose the module variables that the
# Legatus BuildingViewer stack links against:
#   OSG_INCLUDE_DIR, OPENSCENEGRAPH_INCLUDE_DIRS
#   OPENSCENEGRAPH_LIBRARIES   (the OSG component libs that were found)
#   OPENTHREADS_LIBRARIES
#   OPENSCENEGRAPH_FOUND, OPENSCENEGRAPH_VERSION
#
# NOTE (Qt6-migration port): OSG 3.4.1 ships no FindOpenSceneGraph.cmake and
# installs no OpenSceneGraphConfig.cmake, so this module is supplied to close
# the bld/OSG floor. It finds the 3.4.1 build installed under CMAKE_PREFIX_PATH
# (the component libs live under <prefix>/lib64) and honours the requested
# components -- including the ported Qt6 osgQt (see the .osg-port notes).
#
# Mirrors the classic OSG Find-module variable names that BuildingViewer/Common
# links: ${OSG_INCLUDE_DIR}, ${OPENSCENEGRAPH_LIBRARIES}, ${OPENTHREADS_LIBRARIES}.

SET(OSG_SEARCH_PREFIXES ${CMAKE_PREFIX_PATH} /usr/local /usr)

# Include dir: locate the osg/Version header.
FIND_PATH(OSG_INCLUDE_DIR
    NAMES osg/Version
    PATHS ${OSG_SEARCH_PREFIXES}
    PATH_SUFFIXES include)

# OpenThreads support library (distinct SONAME: libOpenThreads.so.20 for 3.4.1).
FIND_LIBRARY(OPENTHREADS_LIBRARY
    NAMES OpenThreads
    PATHS ${OSG_SEARCH_PREFIXES}
    PATH_SUFFIXES lib lib64)

# OSG component libraries. Find each that exists and collect them so
# OPENSCENEGRAPH_LIBRARIES covers the transitive dependency set the BgViewer
# SDK and BuildingViewerCommon link (the SDK's NEEDED entries require
# osg/DB/GA/Qt/Shadow/Sim/Text/Util/Viewer/Particle/Manipulator/Animation).
SET(OSG_COMPONENT_LIBS
    osg
    osgDB
    osgUtil
    osgGA
    osgText
    osgViewer
    osgAnimation
    osgManipulator
    osgParticle
    osgShadow
    osgSim
    osgWidget
    osgQt)

SET(OPENSCENEGRAPH_LIBRARIES "")
FOREACH(_osg_lib ${OSG_COMPONENT_LIBS})
    FIND_LIBRARY(OSG_LIBRARY_${_osg_lib}
        NAMES ${_osg_lib}
        PATHS ${OSG_SEARCH_PREFIXES}
        PATH_SUFFIXES lib lib64)
    IF(OSG_LIBRARY_${_osg_lib})
        LIST(APPEND OPENSCENEGRAPH_LIBRARIES ${OSG_LIBRARY_${_osg_lib}})
        SET(OPENSCENEGRAPH_${_osg_lib}_FOUND TRUE)
    ELSE()
        SET(OPENSCENEGRAPH_${_osg_lib}_FOUND FALSE)
    ENDIF()
ENDFOREACH()

# Core libs are mandatory for the package to count as found.
SET(_osg_core_ok TRUE)
IF(NOT OSG_LIBRARY_osg OR NOT OSG_LIBRARY_osgDB OR NOT OSG_LIBRARY_osgUtil
   OR NOT OSG_LIBRARY_osgGA OR NOT OSG_LIBRARY_osgViewer OR NOT OPENTHREADS_LIBRARY)
    SET(_osg_core_ok FALSE)
ENDIF()

# Any requested component that is missing makes the package not found.
FOREACH(_osg_req ${OpenSceneGraph_FIND_COMPONENTS})
    IF(NOT OSG_LIBRARY_${_osg_req})
        SET(_osg_core_ok FALSE)
        MESSAGE(STATUS "OpenSceneGraph: required component '${_osg_req}' not found")
    ENDIF()
ENDFOREACH()

# Version string from the installed header's OPENSCENEGRAPH_*_VERSION macros.
IF(OSG_INCLUDE_DIR)
    FILE(READ "${OSG_INCLUDE_DIR}/osg/Version" _osg_version_header)
    STRING(REGEX MATCH "#define[ \t]+OPENSCENEGRAPH_MAJOR_VERSION[ \t]+[0-9]+"
        _osg_m "${_osg_version_header}")
    STRING(REGEX MATCH "#define[ \t]+OPENSCENEGRAPH_MINOR_VERSION[ \t]+[0-9]+"
        _osg_n "${_osg_version_header}")
    STRING(REGEX MATCH "#define[ \t]+OPENSCENEGRAPH_PATCH_VERSION[ \t]+[0-9]+"
        _osg_p "${_osg_version_header}")
    STRING(REGEX REPLACE "[^0-9]" "" _osg_major "${_osg_m}")
    STRING(REGEX REPLACE "[^0-9]" "" _osg_minor "${_osg_n}")
    STRING(REGEX REPLACE "[^0-9]" "" _osg_patch "${_osg_p}")
    IF(_osg_major AND _osg_minor AND _osg_patch)
        SET(OPENSCENEGRAPH_VERSION "${_osg_major}.${_osg_minor}.${_osg_patch}")
    ENDIF()
ENDIF()

IF(OSG_INCLUDE_DIR AND _osg_core_ok)
    SET(OPENSCENEGRAPH_FOUND TRUE)
    SET(OPENSCENEGRAPH_INCLUDE_DIRS ${OSG_INCLUDE_DIR})
    SET(OPENTHREADS_LIBRARIES ${OPENTHREADS_LIBRARY})
ELSE()
    SET(OPENSCENEGRAPH_FOUND FALSE)
ENDIF()

INCLUDE(FindPackageHandleStandardArgs)
FIND_PACKAGE_HANDLE_STANDARD_ARGS(OpenSceneGraph
    FOUND_VAR OPENSCENEGRAPH_FOUND
    VERSION_VAR OPENSCENEGRAPH_VERSION
    REQUIRED_VARS OPENSCENEGRAPH_INCLUDE_DIRS OPENSCENEGRAPH_LIBRARIES OPENTHREADS_LIBRARIES)

MARK_AS_ADVANCED(
    OSG_INCLUDE_DIR OPENTHREADS_LIBRARY
    OSG_LIBRARY_osg OSG_LIBRARY_osgDB OSG_LIBRARY_osgUtil OSG_LIBRARY_osgGA
    OSG_LIBRARY_osgText OSG_LIBRARY_osgViewer OSG_LIBRARY_osgAnimation
    OSG_LIBRARY_osgManipulator OSG_LIBRARY_osgParticle OSG_LIBRARY_osgShadow
    OSG_LIBRARY_osgSim OSG_LIBRARY_osgWidget OSG_LIBRARY_osgQt)