#  ___________________________________________________________________________
#
#  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 os
import json

from pyomo.common.config import (
    ConfigBase, ConfigBlock, ConfigValue, ADVANCED_OPTION, PYOMO_CONFIG_DIR,
)
from pyomo.common.dependencies import yaml, yaml_available, yaml_load_args
import logging
logger = logging.getLogger('pyomo.core')


class _PyomoOptions(object):

    def __init__(self):
        self._options_stack = [ default_pyomo_config() ]

        # Load the user's configuration
        sources = [(json, 'json', True, 'json', {}),
                   (json, 'jsn', True, 'json', {})]
        sources.append((yaml, 'yml', yaml_available, 'yaml', yaml_load_args))
        sources.append((yaml, 'yaml', yaml_available, 'yaml', yaml_load_args))
        for parser, suffix, available, library, parser_args in sources:
            cfg_file = os.path.join( PYOMO_CONFIG_DIR, 'config.'+suffix)
            if not os.path.exists(cfg_file):
                continue
            if not available:
                logger.warning("Default configuration file (%s) cannot be "
                               "loaded; %s is not available"
                               % (cfg_file, library))
                continue
            fp = open(cfg_file)
            try:
                data = parser.load(fp, **parser_args)
            except:
                logger.error("Error parsing the user's default "
                             "configuration file\n\t%s." % (cfg_file,))
            self._options_stack[0].set_value(data)

    def active_config(self):
        return self._options_stack[-1]

    #
    # BEGIN clone of the ConfigBlock API
    #

    def __getitem__(self, key):
        return self.active_config().__getitem__(key)

    def get(self, key, default=ConfigBase.NoArgument):
        return self.active_config().get(key,default)

    def __setitem__(self, key, val):
        return self.active_config().__setitem__(key, val)

    def __contains__(self, key):
        return self.active_config().__contains__(key)

    def __len__(self):
        return self.active_config().__len__()

    def __iter__(self):
        return self.active_config().__iter__()

    def __getattr__(self, name):
        #if name in self.__dict__:
        #    return self.__dict__[name]
        return self._options_stack[-1].__getattr__(name)

    def __setattr__(self, name, value):
        if name == '_options_stack':
            super(_PyomoOptions,self).__setattr__(name, value)
        else:
            return self.active_config().__setattr__(name, value)

    def iterkeys(self):
        return self.active_config().iterkeys()

    def itervalues(self):
        return self.active_config().itervalues()

    def iteritems(self):
        return self.active_config().iteritems()

    #
    # Note: ConfigBlock correctly maps {keys,values,items} to
    # iter{keys,values,items} when running under Python3 ... so we
    # *don't* need to do that mapping here.
    #
    def keys(self):
        return self.active_config().keys()

    def values(self):
        return self.active_config().values()

    def items(self):
        return self.active_config().items()

    def declare(self, name, config):
        return self.active_config().items(name, config)

    def add(self, name, config):
        return self.active_config().add(name, config)

    def value(self, accessValue=True):
        return self.active_config().value(accessValue)

    def set_value(self, value):
        return self.active_config().set_value(value)

    def reset(self):
        return self.active_config().reset()

    #
    # END clone of the ConfigBlock API
    #


def default_pyomo_config():
    config = ConfigBlock("Pyomo configuration file")

    config.declare('paranoia_level', ConfigValue(
        0, int,
        'Pyomo paranoia and error checking level',
        """Higher levels of paranoia enable additional error checking and
        warning messages that may assist users in identifying likely
        modeling problems.
        Default=0""",
        visibility=ADVANCED_OPTION ) )

    return config


PyomoOptions = _PyomoOptions()