#  ___________________________________________________________________________
#
#  Pyomo: Python Optimization Modeling Objects
#  Copyright 2017 National Technology and Engineering Solutions of Sandia, LLC
#  Under the terms of Contract DE-NA0003525 with National Technology and
#  Engineering Solutions of Sandia, LLC, the U.S. Government retains certain
#  rights in this software.
#  This software is distributed under the 3-clause BSD License.
#  ___________________________________________________________________________

import sys as _sys
if _sys.version_info[0] >= 3:
    import importlib

    def _do_import(pkg_name):
        importlib.import_module(pkg_name)
else:
    def _do_import(pkg_name):
        __import__(pkg_name, globals(), locals(), [], -1)

#
# These packages contain plugins that need to be loaded
#
_packages = [
    'pyomo.common',
    'pyomo.core',
    'pyomo.opt',
    'pyomo.dataportal',
    'pyomo.duality',
    'pyomo.checker',
    'pyomo.repn',
    'pyomo.pysp',
    'pyomo.neos',
    'pyomo.solvers',
    'pyomo.gdp',
    'pyomo.mpec',
    'pyomo.dae',
    'pyomo.bilevel',
    'pyomo.scripting',
    'pyomo.network',
]
#
#
# These packages also contain plugins that need to be loaded, but
# we silently ignore any import errors because these
# packages are optional and/or under development.
#
_optional_packages = set([
    'pyomo.contrib.example',
    'pyomo.contrib.fme',
    'pyomo.contrib.gdpbb',
    'pyomo.contrib.gdpopt',
    'pyomo.contrib.gdp_bounds',
    'pyomo.contrib.mcpp',
    'pyomo.contrib.mindtpy',
    'pyomo.contrib.multistart',
    'pyomo.contrib.petsc',
    'pyomo.contrib.preprocessing',
    'pyomo.contrib.pynumero',
    'pyomo.contrib.trustregion',
])


def _import_packages():
    #
    # Import required packages
    #
    for name in _packages:
        pname = name+'.plugins'
        try:
            _do_import(pname)
        except ImportError:
            exctype, err, tb = _sys.exc_info()  # BUG?
            import traceback
            msg = "pyomo.environ failed to import %s:\nOriginal %s: %s\n"\
                  "Traceback:\n%s" \
                  % (pname, exctype.__name__, err,
                     ''.join(traceback.format_tb(tb)),)
            # clear local variables to remove circular references
            exctype = err = tb = None
            # TODO: Should this just log an error and re-raise the
            # original exception?
            raise ImportError(msg)

        pkg = _sys.modules[pname]
        pkg.load()
    #
    # Import optional packages
    #
    for name in _optional_packages:
        pname = name+'.plugins'
        try:
            _do_import(pname)
        except ImportError:
            continue
        pkg = _sys.modules[pname]
        pkg.load()

_import_packages()

#
# Expose the symbols from pyomo.core
#
from pyomo.dataportal import DataPortal
from pyomo.core import *
from pyomo.opt import (
    SolverFactory, SolverManagerFactory, UnknownSolver,
    TerminationCondition, SolverStatus, check_optimal_termination,
    assert_optimal_termination
    )
from pyomo.core.base.units_container import units