"""Implementation of the Range type and adaptation

"""

# psycopg/_range.py - Implementation of the Range type and adaptation
#
# Copyright (C) 2012 Daniele Varrazzo  <daniele.varrazzo@gmail.com>
#
# psycopg2 is free software: you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# In addition, as a special exception, the copyright holders give
# permission to link this program with the OpenSSL library (or with
# modified versions of OpenSSL that use the same license as OpenSSL),
# and distribute linked combinations including the two.
#
# You must obey the GNU Lesser General Public License in all respects for
# all of the code used other than OpenSSL.
#
# psycopg2 is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
# License for more details.

import re

from psycopg2._psycopg import ProgrammingError, InterfaceError
from psycopg2.extensions import ISQLQuote, adapt, register_adapter
from psycopg2.extensions import new_type, new_array_type, register_type


class Range(object):
    """Python representation for a PostgreSQL |range|_ type.

    :param lower: lower bound for the range. `!None` means unbound
    :param upper: upper bound for the range. `!None` means unbound
    :param bounds: one of the literal strings ``()``, ``[)``, ``(]``, ``[]``,
        representing whether the lower or upper bounds are included
    :param empty: if `!True`, the range is empty

    """
    __slots__ = ('_lower', '_upper', '_bounds')

    def __init__(self, lower=None, upper=None, bounds='[)', empty=False):
        if not empty:
            if bounds not in ('[)', '(]', '()', '[]'):
                raise ValueError("bound flags not valid: %r" % bounds)

            self._lower = lower
            self._upper = upper
            self._bounds = bounds
        else:
            self._lower = self._upper = self._bounds = None

    def __repr__(self):
        if self._bounds is None:
            return "%s(empty=True)" % self.__class__.__name__
        else:
            return "%s(%r, %r, %r)" % (self.__class__.__name__,
                self._lower, self._upper, self._bounds)

    @property
    def lower(self):
        """The lower bound of the range. `!None` if empty or unbound."""
        return self._lower

    @property
    def upper(self):
        """The upper bound of the range. `!None` if empty or unbound."""
        return self._upper

    @property
    def isempty(self):
        """`!True` if the range is empty."""
        return self._bounds is None

    @property
    def lower_inf(self):
        """`!True` if the range doesn't have a lower bound."""
        if self._bounds is None:
            return False
        return self._lower is None

    @property
    def upper_inf(self):
        """`!True` if the range doesn't have an upper bound."""
        if self._bounds is None:
            return False
        return self._upper is None

    @property
    def lower_inc(self):
        """`!True` if the lower bound is included in the range."""
        if self._bounds is None or self._lower is None:
            return False
        return self._bounds[0] == '['

    @property
    def upper_inc(self):
        """`!True` if the upper bound is included in the range."""
        if self._bounds is None or self._upper is None:
            return False
        return self._bounds[1] == ']'

    def __contains__(self, x):
        if self._bounds is None:
            return False

        if self._lower is not None:
            if self._bounds[0] == '[':
                if x < self._lower:
                    return False
            else:
                if x <= self._lower:
                    return False

        if self._upper is not None:
            if self._bounds[1] == ']':
                if x > self._upper:
                    return False
            else:
                if x >= self._upper:
                    return False

        return True

    def __bool__(self):
        return self._bounds is not None

    def __eq__(self, other):
        if not isinstance(other, Range):
            return False
        return (self._lower == other._lower
            and self._upper == other._upper
            and self._bounds == other._bounds)

    def __ne__(self, other):
        return not self.__eq__(other)

    def __hash__(self):
        return hash((self._lower, self._upper, self._bounds))

    # as the postgres docs describe for the server-side stuff,
    # ordering is rather arbitrary, but will remain stable
    # and consistent.

    def __lt__(self, other):
        if not isinstance(other, Range):
            return NotImplemented
        for attr in ('_lower', '_upper', '_bounds'):
            self_value = getattr(self, attr)
            other_value = getattr(other, attr)
            if self_value == other_value:
                pass
            elif self_value is None:
                return True
            elif other_value is None:
                return False
            else:
                return self_value < other_value
        return False

    def __le__(self, other):
        if self == other:
            return True
        else:
            return self.__lt__(other)

    def __gt__(self, other):
        if isinstance(other, Range):
            return other.__lt__(self)
        else:
            return NotImplemented

    def __ge__(self, other):
        if self == other:
            return True
        else:
            return self.__gt__(other)

    def __getstate__(self):
        return dict(
            (slot, getattr(self, slot))
            for slot in self.__slots__
            if hasattr(self, slot)
        )

    def __setstate__(self, state):
        for slot, value in list(state.items()):
            setattr(self, slot, value)


def register_range(pgrange, pyrange, conn_or_curs, globally=False):
    """Create and register an adapter and the typecasters to convert between
    a PostgreSQL |range|_ type and a PostgreSQL `Range` subclass.

    :param pgrange: the name of the PostgreSQL |range| type. Can be
        schema-qualified
    :param pyrange: a `Range` strict subclass, or just a name to give to a new
        class
    :param conn_or_curs: a connection or cursor used to find the oid of the
        range and its subtype; the typecaster is registered in a scope limited
        to this object, unless *globally* is set to `!True`
    :param globally: if `!False` (default) register the typecaster only on
        *conn_or_curs*, otherwise register it globally
    :return: `RangeCaster` instance responsible for the conversion

    If a string is passed to *pyrange*, a new `Range` subclass is created
    with such name and will be available as the `~RangeCaster.range` attribute
    of the returned `RangeCaster` object.

    The function queries the database on *conn_or_curs* to inspect the
    *pgrange* type and raises `~psycopg2.ProgrammingError` if the type is not
    found.  If querying the database is not advisable, use directly the
    `RangeCaster` class and register the adapter and typecasters using the
    provided functions.

    """
    caster = RangeCaster._from_db(pgrange, pyrange, conn_or_curs)
    caster._register(not globally and conn_or_curs or None)
    return caster


class RangeAdapter(object):
    """`ISQLQuote` adapter for `Range` subclasses.

    This is an abstract class: concrete classes must set a `name` class
    attribute or override `getquoted()`.
    """
    name = None

    def __init__(self, adapted):
        self.adapted = adapted

    def __conform__(self, proto):
        if self._proto is ISQLQuote:
            return self

    def prepare(self, conn):
        self._conn = conn

    def getquoted(self):
        if self.name is None:
            raise NotImplementedError(
                'RangeAdapter must be subclassed overriding its name '
                'or the getquoted() method')

        r = self.adapted
        if r.isempty:
            return b"'empty'::" + self.name.encode('utf8')

        if r.lower is not None:
            a = adapt(r.lower)
            if hasattr(a, 'prepare'):
                a.prepare(self._conn)
            lower = a.getquoted()
        else:
            lower = b'NULL'

        if r.upper is not None:
            a = adapt(r.upper)
            if hasattr(a, 'prepare'):
                a.prepare(self._conn)
            upper = a.getquoted()
        else:
            upper = b'NULL'

        return self.name.encode('utf8') + b'(' + lower + b', ' + upper \
            + b", '" + r._bounds.encode('utf8') + b"')"


class RangeCaster(object):
    """Helper class to convert between `Range` and PostgreSQL range types.

    Objects of this class are usually created by `register_range()`. Manual
    creation could be useful if querying the database is not advisable: in
    this case the oids must be provided.
    """
    def __init__(self, pgrange, pyrange, oid, subtype_oid, array_oid=None):
        self.subtype_oid = subtype_oid
        self._create_ranges(pgrange, pyrange)

        name = self.adapter.name or self.adapter.__class__.__name__

        self.typecaster = new_type((oid,), name, self.parse)

        if array_oid is not None:
            self.array_typecaster = new_array_type(
                (array_oid,), name + "ARRAY", self.typecaster)
        else:
            self.array_typecaster = None

    def _create_ranges(self, pgrange, pyrange):
        """Create Range and RangeAdapter classes if needed."""
        # if got a string create a new RangeAdapter concrete type (with a name)
        # else take it as an adapter. Passing an adapter should be considered
        # an implementation detail and is not documented. It is currently used
        # for the numeric ranges.
        self.adapter = None
        if isinstance(pgrange, str):
            self.adapter = type(pgrange, (RangeAdapter,), {})
            self.adapter.name = pgrange
        else:
            try:
                if issubclass(pgrange, RangeAdapter) \
                        and pgrange is not RangeAdapter:
                    self.adapter = pgrange
            except TypeError:
                pass

        if self.adapter is None:
            raise TypeError(
                'pgrange must be a string or a RangeAdapter strict subclass')

        self.range = None
        try:
            if isinstance(pyrange, str):
                self.range = type(pyrange, (Range,), {})
            if issubclass(pyrange, Range) and pyrange is not Range:
                self.range = pyrange
        except TypeError:
            pass

        if self.range is None:
            raise TypeError(
                'pyrange must be a type or a Range strict subclass')

    @classmethod
    def _from_db(self, name, pyrange, conn_or_curs):
        """Return a `RangeCaster` instance for the type *pgrange*.

        Raise `ProgrammingError` if the type is not found.
        """
        from psycopg2.extensions import STATUS_IN_TRANSACTION
        from psycopg2.extras import _solve_conn_curs
        conn, curs = _solve_conn_curs(conn_or_curs)

        if conn.server_version < 90200:
            raise ProgrammingError("range types not available in version %s"
                % conn.server_version)

        # Store the transaction status of the connection to revert it after use
        conn_status = conn.status