import StringIO
import sys

from python25 import DefaultOrderedDict

import numpy
import opt
from theano.configparser import AddConfigVar, FloatParam
from theano import config
AddConfigVar('optdb.position_cutoff',
        'Where to stop eariler during optimization. It represent the'
             ' position of the optimizer where to stop.',
        FloatParam(numpy.inf),
        in_c_key=False)
AddConfigVar('optdb.max_use_ratio',
        'A ratio that prevent infinite loop in EquilibriumOptimizer.',
        FloatParam(5),
        in_c_key=False)


class DB(object):
    def __hash__(self):
        if not hasattr(self, '_optimizer_idx'):
            self._optimizer_idx = opt._optimizer_idx[0]
            opt._optimizer_idx[0] += 1
        return self._optimizer_idx

    def __init__(self):
        self.__db__ = DefaultOrderedDict(set)
        self._names = set()
        self.name = None  # will be reset by register
        #(via obj.name by the thing doing the registering)

    def register(self, name, obj, *tags):
        # N.B. obj is not an instance of class Optimizer.
        # It is an instance of a DB.In the tests for example,
        # this is not always the case.
        if not isinstance(obj, (DB, opt.Optimizer, opt.LocalOptimizer)):
            raise TypeError('Object cannot be registered in OptDB', obj)
        if name in self.__db__:
            raise ValueError('The name of the object cannot be an existing'
                             ' tag or the name of another existing object.',
                             obj, name)
        # This restriction is there because in many place we suppose that
        # something in the DB is there only once.
        if getattr(obj, 'name', "") in self.__db__:
            raise ValueError('''You can\'t register the same optimization
multiple time in a DB. Tryed to register "%s" again under the new name "%s".
 Use theano.gof.ProxyDB to work around that''' % (obj.name, name))

        if self.name is not None:
            tags = tags + (self.name,)
        obj.name = name
        self.__db__[name] = set([obj])
        self._names.add(name)

        self.add_tags(name, *tags)

    def add_tags(self, name, *tags):
        obj = self.__db__[name]
        assert len(obj) == 1
        obj = obj.copy().pop()
        for tag in tags:
            if tag in self._names:
                raise ValueError('The tag of the object collides with a name.',
                                 obj, tag)
            self.__db__[tag].add(obj)

    def __query__(self, q):
        if not isinstance(q, Query):
            raise TypeError('Expected a Query.', q)
        variables = set()
        for tag in q.include:
            variables.update(self.__db__[tag])
        for tag in q.require:
            variables.intersection_update(self.__db__[tag])
        for tag in q.exclude:
            variables.difference_update(self.__db__[tag])
        remove = set()
        add = set()
        for obj in variables:
            if isinstance(obj, DB):
                sq = q.subquery.get(obj.name, q)
                if sq:
                    replacement = obj.query(sq)
                    replacement.name = obj.name
                    remove.add(obj)
                    add.add(replacement)
        variables.difference_update(remove)
        variables.update(add)
        return variables

    def query(self, *tags, **kwtags):
        if len(tags) >= 1 and isinstance(tags[0], Query):
            if len(tags) > 1 or kwtags:
                raise TypeError('If the first argument to query is a Query,'
                                ' there should be no other arguments.',
                                tags, kwtags)
            return self.__query__(tags[0])
        include = [tag[1:] for tag in tags if tag.startswith('+')]
        require = [tag[1:] for tag in tags if tag.startswith('&')]
        exclude = [tag[1:] for tag in tags if tag.startswith('-')]
        if len(include) + len(require) + len(exclude) < len(tags):
            raise ValueError("All tags must start with one of the following"
                             " characters: '+', '&' or '-'", tags)
        return self.__query__(Query(include=include,
                                    require=require,
                                    exclude=exclude,
                                    subquery=kwtags))

    def __getitem__(self, name):
        variables = self.__db__[name]
        if not variables:
            raise KeyError("Nothing registered for '%s'" % name)
        elif len(variables) > 1:
            raise ValueError('More than one match for %s (please use query)' %
                             name)
        for variable in variables:
            return variable

    def print_summary(self, stream=sys.stdout):
        print >> stream, "%s (id %i)" % (self.__class__.__name__, id(self))
        print >> stream, "  names", self._names
        print >> stream, "  db", self.__db__


class Query(object):

    def __init__(self, include, require=None, exclude=None,
                 subquery=None, position_cutoff=None):
        """
        :type position_cutoff: float
        :param position_cutoff: Used by SequenceDB to keep only optimizer that
                                are positioned before the cut_off point.
        """
        self.include = set(include)
        self.require = require or set()
        self.exclude = exclude or set()
        self.subquery = subquery or {}
        self.position_cutoff = position_cutoff
        if isinstance(self.require, (list, tuple)):
            self.require = set(self.require)
        if isinstance(self.exclude, (list, tuple)):
            self.exclude = set(self.exclude)

    #add all opt with this tag
    def including(self, *tags):
        return Query(self.include.union(tags),
                     self.require,
                     self.exclude,
                     self.subquery,
                     self.position_cutoff)

    #remove all opt with this tag
    def excluding(self, *tags):
        return Query(self.include,
                     self.require,
                     self.exclude.union(tags),
                     self.subquery,
                     self.position_cutoff)

    #keep only opt with this tag.
    def requiring(self, *tags):
        return Query(self.include,
                     self.require.union(tags),
                     self.exclude,
                     self.subquery,
                     self.position_cutoff)


class EquilibriumDB(DB):
    """ A set of potential optimizations which should be applied in an
        arbitrary order until equilibrium is reached.

    Canonicalize, Stabilize, and Specialize are all equilibrium optimizations.

    .. note::

        We can put LocalOptimizer and Optimizer as EquilibriumOptimizer
        suppor both.

    """

    def query(self, *tags, **kwtags):
        opts = super(EquilibriumDB, self).query(*tags, **kwtags)
        return opt.EquilibriumOptimizer(opts,
                max_depth=5,
                max_use_ratio=config.optdb.max_use_ratio,
                failure_callback=opt.NavigatorOptimizer.warn_inplace)


class SequenceDB(DB):
    """A sequence of potential optimizations.

    Retrieve a sequence of optimizations (a SeqOptimizer) by calling query().

    Each potential optimization is registered with a floating-point position.
    No matter which optimizations are selected by a query, they are carried
    out in order of increasing position.

    The optdb itself (`theano.compile.mode.optdb`), from which (among many
    other tags) fast_run and fast_compile optimizers are drawn is a SequenceDB.

    """

    def __init__(self, failure_callback=opt.SeqOptimizer.warn):
        super(SequenceDB, self).__init__()
        self.__position__ = {}
        self.failure_callback = failure_callback

    def register(self, name, obj, position, *tags):
        super(SequenceDB, self).register(name, obj, *tags)
        self.__position__[name] = position

    def query(self, *tags, **kwtags):
        """
        :type position_cutoff: float or int
        :param position_cutoff: only optimizations with position less than
                                the cutoff are returned.
        """
        opts = super(SequenceDB, self).query(*tags, **kwtags)

        position_cutoff = kwtags.pop('position_cutoff',
                                     config.optdb.position_cutoff)
        if len(tags) >= 1 and isinstance(tags[0], Query):
#the call to super should have raise an error with a good message
            assert len(tags) == 1
            if getattr(tags[0], 'position_cutoff', None):
                position_cutoff = tags[0].position_cutoff

        opts = [o for o in opts if self.__position__[o.name] < position_cutoff]
        opts.sort(key=lambda obj: self.__position__[obj.name])
        ret = opt.SeqOptimizer(opts, failure_callback=self.failure_callback)
        if hasattr(tags[0], 'name'):
            ret.name = tags[0].name
        return ret

    def print_summary(self, stream=sys.stdout):
        print >> stream, "SequenceDB (id %i)" % id(self)
        positions = self.__position__.items()

        def c(a, b):
            return cmp(a[1], b[1])
        positions.sort(c)

        print >> stream, "  position", positions
        print >> stream, "  names", self._names
        print >> stream, "  db", self.__db__

    def __str__(self):
        sio = StringIO.StringIO()
        self.print_summary(sio)
        return sio.getvalue()


class ProxyDB(DB):
    """
    Wrap an existing proxy.

    This is needed as we can't register the same DB mutiple time in
    different position in a SequentialDB
    """
    def __init__(self, db):
        assert isinstance(db, DB), ""
        self.db = db

    def query(self, *tags, **kwtags):
        return self.db.query(*tags, **kwtags)
