# -*- coding: utf-8 -*-
#
# Copyright 2008, 2009, 2010 Brett Adams
# Copyright 2014-2015 Mario Frasca <mario@anche.no>.
#
# This file is part of bauble.classic.
#
# bauble.classic is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# bauble.classic 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with bauble.classic. If not, see <http://www.gnu.org/licenses/>.


import weakref

import gtk

import logging
logger = logging.getLogger(__name__)
#logger.setLevel(logging.DEBUG)

from sqlalchemy import or_, and_
from sqlalchemy import Unicode
from sqlalchemy import UnicodeText
from sqlalchemy.orm import class_mapper
from sqlalchemy.orm.properties import (
    ColumnProperty, RelationshipProperty)
RelationProperty = RelationshipProperty

import bauble
from bauble.error import check
import bauble.utils as utils
from bauble.i18n import _


def search(text, session=None):
    results = set()
    for strategy in _search_strategies.values():
        logger.debug("applying search strategy %s" % strategy)
        results.update(strategy.search(text, session))
    return list(results)


class NoneToken(object):
    def __init__(self, t):
        pass

    def __repr__(self):
        return '(None<NoneType>)'

    def express(self):
        return None


class EmptyToken(object):
    def __init__(self, t=None):
        pass

    def __repr__(self):
        return '(Empty<Set>)'

    def express(self):
        return set()


class ValueABC(object):
    ## abstract base class.

    def express(self):
        return self.value


class ValueToken(object):

    def __init__(self, t):
        self.value = t[0]

    def __repr__(self):
        return repr(self.value)

    def express(self):
        return self.value.express()


class StringToken(ValueABC):
    def __init__(self, t):
        self.value = t[0]  # no need to parse the string

    def __repr__(self):
        return "'%s'" % (self.value)


class NumericToken(ValueABC):
    def __init__(self, t):
        self.value = float(t[0])  # store the float value

    def __repr__(self):
        return "%s" % (self.value)


class TypedValueToken(ValueABC):
    ## |<name>|<paramlist>|
    from datetime import datetime
    constructor = {'datetime': (datetime, int),
                   'now': (datetime.now, id),
                   }

    def __init__(self, t):
        try:
            constructor, converter = self.constructor[t[1]]
        except KeyError:
            return
        params = tuple(converter(i) for i in t[3].express())
        self.value = constructor(*params)

    def __repr__(self):
        return "%s" % (self.value)


class IdentifierToken(object):
    def __init__(self, t):
        self.value = t[0]

    def __repr__(self):
        return '.'.join(self.value)

    def evaluate(self, env):
        """return pair (query, attribute)

        the value associated to the identifier is an altered query where the
        joinpoint is the one relative to the attribute, and the attribute
        itself.
        """

        query = env.session.query(env.domain)
        if len(self.value) == 1:
            # identifier is an attribute of the table being queried
            cls = env.domain
        elif len(self.value) > 1:
            # identifier is an attribute of a joined table
            query = query.join(*self.value[:-1], aliased=True)
            cls = query._joinpoint['_joinpoint_entity']
        attr = getattr(cls, self.value[-1])
        logger.debug('IdentifierToken for %s, %s evaluates to %s'
                     % (cls, self.value[-1], attr))
        return query, attr

    def needs_join(self, env):
        return self.value[:-1]


class IdentExpressionToken(object):
    def __init__(self, t):
        self.op = t[0][1]
        self.operation = {'>': lambda x, y: x > y,
                          '<': lambda x, y: x < y,
                          '>=': lambda x, y: x >= y,
                          '<=': lambda x, y: x <= y,
                          '=': lambda x, y: x == y,
                          '!=': lambda x, y: x != y,
                          'is': lambda x, y: x is y,
                          'like': lambda x, y: utils.ilike(x, '%s' % y)
                          }[self.op]
        self.operands = t[0][0::2]  # every second object is an operand

    def __repr__(self):
        return "(%s %s %s)" % (self.operands[0], self.op, self.operands[1])

    def evaluate(self, env):
        q, a = self.operands[0].evaluate(env)
        if self.operands[1].express() == set():
            if self.op in ('is', '='):
                return q.filter(~a.any())
            elif self.op in ('!='):
                return q.filter(a.any())
        clause = lambda x: self.operation(a, x)
        return q.filter(clause(self.operands[1].express()))

    def needs_join(self, env):
        return [self.operands[0].needs_join(env)]


class BetweenExpressionAction(object):
    def __init__(self, t):
        self.operands = t[0][0::2]  # every second object is an operand

    def __repr__(self):
        return "(BETWEEN %s %s %s)" % tuple(self.operands)

    def evaluate(self, env):
        q, a = self.operands[0].evaluate(env)
        clause_low = lambda low: low <= a
        clause_high = lambda high: a <= high
        return q.filter(and_(clause_low(self.operands[1].express()),
                             clause_high(self.operands[2].express())))

    def needs_join(self, env):
        return [self.operands[0].needs_join(env)]


class UnaryLogical(object):
    ## abstract base class. `name` is defined in derived classes
    def __init__(self, t):
        self.op, self.operand = t[0]

    def __repr__(self):
        return "%s %s" % (self.name, str(self.operand))

    def needs_join(self, env):
        return self.operand.needs_join(env)


class BinaryLogical(object):
    ## abstract base class. `name` is defined in derived classes
    def __init__(self, t):
        self.op = t[0][1]
        self.operands = t[0][0::2]  # every second object is an operand

    def __repr__(self):
        return "(%s %s %s)" % (self.operands[0], self.name, self.operands[1])

    def needs_join(self, env):
        return self.operands[0].needs_join(env) + \
            self.operands[1].needs_join(env)


class SearchAndAction(BinaryLogical):
    name = 'AND'

    def evaluate(self, env):
        result = self.operands[0].evaluate(env)
        for i in self.operands[1:]:
            result = result.intersect(i.evaluate(env))
        return result


class SearchOrAction(BinaryLogical):
    name = 'OR'

    def evaluate(self, env):
        result = self.operands[0].evaluate(env)
        for i in self.operands[1:]:
            result = result.union(i.evaluate(env))
        return result


class SearchNotAction(UnaryLogical):
    name = 'NOT'

    def evaluate(self, env):
        q = env.session.query(env.domain)
        for i in env.domains:
            q.join(*i)
        return q.except_(self.operand.evaluate(env))


class ParenthesisedQuery(object):
    def __init__(self, t):
        self.query = t[1]

    def __repr__(self):
        return "(%s)" % self.query.__repr__()

    def evaluate(self, env):
        return self.query.evaluate(env)

    def needs_join(self, env):
        return self.query.needs_join(env)


class QueryAction(object):
    def __init__(self, t):
        self.domain = t[0]
        self.filter = t[1][0]

    def __repr__(self):
        return "SELECT * FROM %s WHERE %s" % (self.domain, self.filter)

    def invoke(self, search_strategy):
        """
        update search_strategy object with statement results

        Queries can use more database specific features.  This also
        means that the same query might not work the same on different
        database types. For example, on a PostgreSQL database you can
        use ilike but this would raise an error on SQLite.
        """

        domain = self.domain
        check(domain in search_strategy._domains or
              domain in search_strategy._shorthand,
              'Unknown search domain: %s' % domain)
        self.domain = search_strategy._shorthand.get(domain, domain)
        self.domain = search_strategy._domains[domain][0]
        self.search_strategy = search_strategy

        result = set()
        if search_strategy._session is not None:
            self.domains = self.filter.needs_join(self)
            self.session = search_strategy._session
            records = self.filter.evaluate(self).all()
            result.update(records)

        return result


class StatementAction(object):
    def __init__(self, t):
        self.content = t[0]
        self.invoke = lambda x: self.content.invoke(x)

    def __repr__(self):
        return repr(self.content)


class DomainExpressionAction(object):
    """created when the parser hits a domain_expression token.

    Searching using domain expressions is a little more magical than an
    explicit query. you give a domain, a binary_operator and a value,
    the domain expression will return all object with at least one
    property (as passed to add_meta) matching (according to the binop)
    the value.
    """

    def __init__(self, t):
        self.domain = t[0]
        self.cond = t[1]
        self.values = t[2]

    def __repr__(self):
        return "%s %s %s" % (self.domain, self.cond, self.values)

    def invoke(self, search_strategy):
        try:
            if self.domain in search_strategy._shorthand:
                self.domain = search_strategy._shorthand[self.domain]
            cls, properties = search_strategy._domains[self.domain]
        except KeyError:
            raise KeyError(_('Unknown search domain: %s' % self.domain))

        query = search_strategy._session.query(cls)

        ## here is the place where to optionally filter out unrepresented
        ## domain values. each domain class should define its own 'I have
        ## accessions' filter. see issue #42

        result = set()

        # select all objects from the domain
        if self.values == '*':
            result.update(query.all())
            return result

        mapper = class_mapper(cls)

        if self.cond in ('like', 'ilike', 'contains', 'icontains', 'has',
                         'ihas'):
            condition = lambda col: \
                lambda val: utils.ilike(mapper.c[col], '%%%s%%' % val)
        elif self.cond == '=':
            condition = lambda col: \
                lambda val: utils.ilike(mapper.c[col], utils.utf8(val))
        else:
            condition = lambda col: \
                lambda val: mapper.c[col].op(self.cond)(val)

        for col in properties:
            ors = or_(*map(condition(col), self.values.express()))
            result.update(query.filter(ors).all())

        return result


class ValueListAction(object):

    def __init__(self, t):
        logger.debug("ValueListAction::__init__(%s)" % t)
        self.values = t[0]

    def __repr__(self):
        return str(self.values)

    def express(self):
        return [i.express() for i in self.values]

    def invoke(self, search_strategy):
        """
        Called when the whole search string is a value list.

        Search with a list of values is the broadest search and
        searches all the mapper and the properties configured with
        add_meta()
        """

        # make searches case-insensitive, in postgres use ilike,
        # in other use upper()
        like = lambda table, col, val: \
            utils.ilike(table.c[col], ('%%%s%%' % val))

        result = set()
        for cls, columns in search_strategy._properties.iteritems():
            column_cross_value = [(c, v) for c in columns
                                  for v in self.express()]
            # as of SQLAlchemy>=0.4.2 we convert the value to a unicode
            # object if the col is a Unicode or UnicodeText column in order
            # to avoid the "Unicode type received non-unicode bind param"

            def unicol(col, v):
                table = class_mapper(cls)
                if isinstance(table.c[col].type, (Unicode, UnicodeText)):
                    return unicode(v)
                else:
                    return v

            table = class_mapper(cls)
            q = search_strategy._session.query(cls)  # prepares SELECT
            q = q.filter(or_(*[like(table, c, unicol(c, v))
                               for c, v in column_cross_value]))
            result.update(q.all())

        logger.debug("result is now %s" % result)

        def replace(i):
            try:
                return i.replacement()
            except:
                return i
        result = set([replace(i) for i in result])
        logger.debug("result is now %s" % result)
        return result


from pyparsing import (
    Word, alphas8bit, removeQuotes, delimitedList, Regex,
    OneOrMore, oneOf, alphas, alphanums, Group, Literal,
    CaselessLiteral, WordStart, WordEnd,
    stringEnd, Keyword, quotedString,
    infixNotation, opAssoc, Forward)


class SearchParser(object):
    """The parser for bauble.search.MapperSearch
    """

    numeric_value = Regex(
        r'[-]?\d+(\.\d*)?([eE]\d+)?'
        ).setParseAction(NumericToken)('number')
    unquoted_string = Word(alphanums + alphas8bit + '%.-_*;:')
    string_value = (
        quotedString.setParseAction(removeQuotes) | unquoted_string
        ).setParseAction(StringToken)('string')

    none_token = Literal('None').setParseAction(NoneToken)
    empty_token = Literal('Empty').setParseAction(EmptyToken)

    value_list = Forward()
    typed_value = (
        Literal("|") + unquoted_string + Literal("|") +
        value_list + Literal("|")
        ).setParseAction(TypedValueToken)

    value = (
        typed_value | numeric_value | none_token | empty_token | string_value
        ).setParseAction(ValueToken)('value')
    value_list << Group(
        OneOrMore(value) ^ delimitedList(value)
        ).setParseAction(ValueListAction)('value_list')

    domain = Word(alphas, alphanums)
    binop = oneOf('= == != <> < <= > >= not like contains has ilike '
                  'icontains ihas is')
    equals = Literal('=')
    star_value = Literal('*')
    domain_values = (value_list.copy())('domain_values')
    domain_expression = (
        (domain + equals + star_value + stringEnd)
        | (domain + binop + domain_values + stringEnd)
        ).setParseAction(DomainExpressionAction)('domain_expression')

    AND_ = WordStart() + (CaselessLiteral("AND") | Literal("&&")) + WordEnd()
    OR_ = WordStart() + (CaselessLiteral("OR") | Literal("||")) + WordEnd()
    NOT_ = WordStart() + (CaselessLiteral("NOT") | Literal('!')) + WordEnd()
    BETWEEN_ = WordStart() + CaselessLiteral("BETWEEN") + WordEnd()

    query_expression = Forward()('filter')
    identifier = Group(delimitedList(Word(alphas+'_', alphanums+'_'),
                                     '.')).setParseAction(IdentifierToken)
    ident_expression = (
        Group(identifier + binop + value).setParseAction(IdentExpressionToken)
        | (
            Literal('(') + query_expression + Literal(')')
        ).setParseAction(ParenthesisedQuery))
    between_expression = Group(
        identifier + BETWEEN_ + value + AND_ + value
        ).setParseAction(BetweenExpressionAction)
    query_expression << infixNotation(
        (ident_expression | between_expression),
        [(NOT_, 1, opAssoc.RIGHT, SearchNotAction),
         (AND_, 2, opAssoc.LEFT,  SearchAndAction),
         (OR_,  2, opAssoc.LEFT,  SearchOrAction)])
    query = (domain + Keyword('where', caseless=True).suppress() +
             Group(query_expression) + stringEnd).setParseAction(QueryAction)

    statement = (query('query')
                 | domain_expression('domain')
                 | value_list('value_list')
                 ).setParseAction(StatementAction)('statement')

    def parse_string(self, text):
        '''request pyparsing object to parse text

        `text` can be either a query, or a domain expression, or a list of
        values. the `self.statement` pyparsing object parses the input text
        and return a pyparsing.ParseResults object that represents the input
        '''

        return self.statement.parseString(text)


class SearchStrategy(object):
    """
    Interface for adding search strategies to a view.
    """

    def search(self, text, session=None):
        '''
        :param text: the search string
        :param session: the session to use for the search

        Return an iterator that iterates over mapped classes retrieved
        from the search.
        '''
        logger.debug('SearchStrategy "%s" %s)' % (text, session))
        pass


class MapperSearch(SearchStrategy):

    """
    Mapper Search support three types of search expression:
    1. value searches: search that are just list of values, e.g. value1,
    value2, value3, searches all domains and registered columns for values
    2. expression searches: searched of the form domain=value, resolves the
    domain and searches specific columns from the mapping
    3. query searchs: searches of the form domain where ident.ident = value,
    resolve the domain and identifiers and search for value
    """

    _domains = {}
    _shorthand = {}
    _properties = {}

    def __init__(self):
        super(MapperSearch, self).__init__()
        self._results = set()
        self.parser = SearchParser()

    def add_meta(self, domain, cls, properties):
        """Add a domain to the search space

        an example of domain is a database table, where the properties would
        be the table columns to consider in the search.  continuing this
        example, a record is be selected if any of the fields matches the
        searched value.

        :param domain: a string, list or tuple of domains that will resolve
                       a search string to cls.  domain act as a shorthand to
                       the class name.
        :param cls: the class the domain will resolve to
        :param properties: a list of string names of the properties to
                           search by default
        """

        logger.debug('%s.add_meta(%s, %s, %s)' %
                     (self, domain, cls, properties))

        check(isinstance(properties, list),
              _('MapperSearch.add_meta(): '
                'default_columns argument must be list'))
        check(len(properties) > 0,
              _('MapperSearch.add_meta(): '
                'default_columns argument cannot be empty'))
        if isinstance(domain, (list, tuple)):
            self._domains[domain[0]] = cls, properties
            for d in domain[1:]:
                self._shorthand[d] = domain[0]
        else:
            self._domains[domain] = cls, properties
        self._properties[cls] = properties

    @classmethod
    def get_domain_classes(cls):
        d = {}
        for domain, item in cls._domains.iteritems():
            d.setdefault(domain, item[0])
        return d

    def search(self, text, session=None):
        """
        Returns a set() of database hits for the text search string.

        If session=None then the session should be closed after the results
        have been processed or it is possible that some database backends
        could cause deadlocks.
        """
        self._session = session

        self._results.clear()
        results = self.parser.parse_string(text.decode())
        self._results.update(results.statement.invoke(self))

        # these _results get filled in when the parse actions are called
        return self._results


## list of search strategies to be tried on each search string
_search_strategies = {'MapperSearch': MapperSearch()}


def add_strategy(strategy):
    obj = strategy()
    _search_strategies[obj.__class__.__name__] = obj


def get_strategy(name):
    return _search_strategies.get(name, None)


class SchemaBrowser(gtk.VBox):

    def __init__(self, *args, **kwargs):
        super(SchemaBrowser, self).__init__(*args, **kwargs)
        self.props.spacing = 10
        # WARNING: this is a hack from MapperSearch
        self.domain_map = {}
        self.domain_map = MapperSearch.get_domain_classes().copy()

        frame = gtk.Frame(_("Search Domain"))
        self.pack_start(frame, expand=False, fill=False)
        self.table_combo = gtk.combo_box_new_text()
        frame.add(self.table_combo)
        for key in sorted(self.domain_map.keys()):
            self.table_combo.append_text(key)

        self.table_combo.connect('changed', self.on_table_combo_changed)

        self.prop_tree = gtk.TreeView()
        self.prop_tree.set_headers_visible(False)
        cell = gtk.CellRendererText()
        column = gtk.TreeViewColumn(_("Property"), cell)
        self.prop_tree.append_column(column)
        column.add_attribute(cell, 'text', 0)

        self.prop_tree.connect('test_expand_row', self.on_row_expanded)

        frame = gtk.Frame(_('Domain Properties'))
        sw = gtk.ScrolledWindow()
        sw.add(self.prop_tree)
        frame.add(sw)
        self.pack_start(frame, expand=True, fill=True)

    def _insert_props(self, mapper, model, treeiter):
        """
        Insert the properties from mapper into the model at treeiter
        """
        column_properties = sorted(
            filter(lambda x: isinstance(x, ColumnProperty)
                   and not x.key.startswith('_'),
                   mapper.iterate_properties),
            key=lambda k: k.key)
        for prop in column_properties:
            model.append(treeiter, [prop.key, prop])

        relation_properties = sorted(
            filter(lambda x: isinstance(x, RelationProperty)
                   and not x.key.startswith('_'),
                   mapper.iterate_properties),
            key=lambda k: k.key)
        for prop in relation_properties:
            it = model.append(treeiter, [prop.key, prop])
            model.append(it, ['', None])

    def on_row_expanded(self, treeview, treeiter, path):
        """
        Called before the row is expanded and populates the children of the
        row.
        """
        logger.debug('on_row_expanded')
        model = treeview.props.model
        parent = treeiter
        while model.iter_has_child(treeiter):
            nkids = model.iter_n_children(parent)
            child = model.iter_nth_child(parent, nkids-1)
            model.remove(child)

        # prop should always be a RelationProperty
        prop = treeview.props.model[treeiter][1]
        self._insert_props(prop.mapper, model, treeiter)

    def on_table_combo_changed(self, combo, *args):
        """
        Change the table to use for the query
        """
        utils.clear_model(self.prop_tree)
        it = combo.get_active_iter()
        domain = combo.props.model[it][0]
        mapper = class_mapper(self.domain_map[domain])
        model = gtk.TreeStore(str, object)
        root = model.get_iter_root()
        self._insert_props(mapper, model, root)
        self.prop_tree.props.model = model


class SchemaMenu(gtk.Menu):
    """
    SchemaMenu

    :param mapper:
    :param activate cb:
    :param relation_filter:
    """

    def __init__(self, mapper, activate_cb=None,
                 relation_filter=lambda p: True):
        super(SchemaMenu, self).__init__()
        self.activate_cb = activate_cb
        self.relation_filter = relation_filter
        map(self.append, self._get_prop_menuitems(mapper))
        self.show_all()

    def on_activate(self, menuitem, prop):
        """
        Call when menu items that hold column properties are activated.
        """
        path = []
        path = [menuitem.get_child().props.label]
        menu = menuitem.get_parent()
        while menu is not None:
            menuitem = menu.props.attach_widget
            if not menuitem:
                break
            label = menuitem.get_child().props.label
            path.append(label)
            menu = menuitem.get_parent()
        full_path = '.'.join(reversed(path))
        self.activate_cb(menuitem, full_path, prop)

    def on_select(self, menuitem, prop):
        """
        Called when menu items that have submenus are selected
        """

        submenu = menuitem.get_submenu()
        if len(submenu.get_children()) == 0:
            map(submenu.append, self._get_prop_menuitems(prop.mapper))
        submenu.show_all()

    def _get_prop_menuitems(self, mapper):
        items = []
        column_properties = sorted(
            filter(lambda x: isinstance(x, ColumnProperty)
                   and not x.key.startswith('_'),
                   mapper.iterate_properties),
            key=lambda k: k.key)

        for prop in column_properties:
            if not self.relation_filter(prop):
                continue
            item = gtk.MenuItem(prop.key, use_underline=False)
            item.connect('activate', self.on_activate, prop)
            items.append(item)

        # filter out properties that start with underscore since they
        # are considered private
        relation_properties = sorted(
            filter(lambda x: isinstance(x, RelationProperty)
                   and not x.key.startswith('_'),
                   mapper.iterate_properties),
            key=lambda k: k.key)
        for prop in relation_properties:
            if not self.relation_filter(prop):
                continue
            item = gtk.MenuItem(prop.key, use_underline=False)
            items.append(item)
            submenu = gtk.Menu()
            item.set_submenu(submenu)
            item.connect('select', self.on_select, prop)
        return items


class ExpressionRow(object):
    """
    """

    def __init__(self, query_builder, remove_callback, row_number=None):
        self.mapper = weakref.proxy(query_builder.mapper)
        self.table = weakref.proxy(query_builder.expressions_table)
        self.dialog = weakref.proxy(query_builder)
        self.menu_item_selected = False
        if row_number is None:
            # assume we want the row appended to the end of the table
            row_number = self.table.props.n_rows

        self.and_or_combo = None
        if row_number != 1:
            self.and_or_combo = gtk.combo_box_new_text()
            self.and_or_combo.append_text("and")
            self.and_or_combo.append_text("or")
            self.and_or_combo.set_active(0)
            self.table.attach(self.and_or_combo, 0, 1,
                              row_number, row_number + 1)

        self.prop_button = gtk.Button(_('Choose a property...'))
        self.prop_button.props.use_underline = False

        def on_prop_button_clicked(button, event, menu):
            menu.popup(None, None, None, event.button, event.time)

        self.schema_menu = SchemaMenu(self.mapper,
                                      self.on_schema_menu_activated,
                                      self.relation_filter)
        self.prop_button.connect('button-press-event', on_prop_button_clicked,
                                 self.schema_menu)
        self.table.attach(self.prop_button, 1, 2, row_number, row_number+1)

        self.cond_combo = gtk.combo_box_new_text()
        conditions = ['=', '!=', '<', '<=', '>', '>=', 'is', 'is not', 'like',
                      'ilike']
        map(self.cond_combo.append_text, conditions)
        self.cond_combo.set_active(0)
        self.table.attach(self.cond_combo, 2, 3, row_number, row_number+1)

        # by default we start with an entry but value_widget can
        # change depending on the type of the property chosen in the
        # schema menu, see self.on_schema_menu_activated
        self.value_widget = gtk.Entry()
        self.value_widget.connect('changed', self.on_value_changed)
        self.table.attach(self.value_widget, 3, 4, row_number, row_number+1)

        if row_number != 1:
            image = gtk.image_new_from_stock(gtk.STOCK_REMOVE,
                                             gtk.ICON_SIZE_BUTTON)
            self.remove_button = gtk.Button()
            self.remove_button.props.image = image
            self.remove_button.connect('clicked',
                                       lambda b: remove_callback(self))
            self.table.attach(self.remove_button, 4, 5,
                              row_number, row_number + 1)

    def on_value_changed(self, widget, *args):
        """
        Call the QueryBuilder.validate() for this row.
        Set the sensitivity of the gtk.RESPONSE_OK button on the QueryBuilder.
        """
        self.dialog.validate()

    def on_schema_menu_activated(self, menuitem, path, prop):
        """
        Called when an item in the schema menu is activated
        """
        self.prop_button.props.label = path
        self.menu_item_activated = True
        top = self.table.child_get_property(self.value_widget, 'top-attach')
        bottom = self.table.child_get_property(self.value_widget,
                                               'bottom-attach')
        right = self.table.child_get_property(self.value_widget,
                                              'right-attach')
        left = self.table.child_get_property(self.value_widget, 'left-attach')
        self.table.remove(self.value_widget)

        # change the widget depending on the type of the selected property
        if isinstance(prop.columns[0].type, bauble.btypes.Enum):
            self.value_widget = gtk.ComboBox()
            cell = gtk.CellRendererText()
            self.value_widget.pack_start(cell, True)
            self.value_widget.add_attribute(cell, 'text', 1)
            model = gtk.ListStore(str, str)
            if prop.columns[0].type.translations:
                trans = prop.columns[0].type.translations
                prop_values = [(k, trans[k]) for k in sorted(trans.keys())]
            else:
                values = prop.columns[0].type.values
                prop_values = [(v, v) for v in sorted(values)]
            for value, translation in prop_values:
                model.append([value, translation])
            self.value_widget.props.model = model
            self.value_widget.connect('changed', self.on_value_changed)
        elif not isinstance(self.value_widget, gtk.Entry):
            self.value_widget = gtk.Entry()
            self.value_widget.connect('changed', self.on_value_changed)

        self.table.attach(self.value_widget, left, right, top, bottom)
        self.table.show_all()
        self.dialog.validate()

    def relation_filter(self, prop):
        if isinstance(prop, ColumnProperty) and \
                isinstance(prop.columns[0].type, bauble.btypes.Date):
            return False
        return True

    def get_widgets(self):
        """
        Returns a tuple of the and_or_combo, prop_button, cond_combo,
        value_widget, and remove_button widgets.
        """
        return self.and_or_combo, self.prop_button, self.cond_combo, \
            self.value_widget, self.remove_button

    def get_expression(self):
        """
        Return the expression represented but this ExpressionRow.  If
        the expression is not valid then return None.

        :param self:
        """

        if not self.menu_item_activated:
            return None

        value = ''
        if isinstance(self.value_widget, gtk.ComboBox):
            model = self.value_widget.props.model
            active_iter = self.value_widget.get_active_iter()
            if active_iter:
                value = model[active_iter][0]
        else:
            # assume it's a gtk.Entry or other widget with a text property
            value = self.value_widget.props.text.strip()
        and_or = ''
        if self.and_or_combo:
            and_or = self.and_or_combo.get_active_text()
        return ' '.join([and_or, self.prop_button.props.label,
                         self.cond_combo.get_active_text(),
                         '"%s"' % value]).strip()


class QueryBuilder(gtk.Dialog):

    def __init__(self, parent=None):
        """
        """
        super(QueryBuilder, self).__init__(
            title=_("Query Builder"), parent=parent,
            flags=gtk.DIALOG_MODAL | gtk.DIALOG_DESTROY_WITH_PARENT,
            buttons=(gtk.STOCK_CANCEL, gtk.RESPONSE_CANCEL,
                     gtk.STOCK_OK, gtk.RESPONSE_OK))

        self.vbox.props.spacing = 15
        self.expression_rows = []
        self.mapper = None
        self._first_choice = True
        self.set_response_sensitive(gtk.RESPONSE_OK, False)
        self.domain_map = MapperSearch.get_domain_classes().copy()

        frame = gtk.Frame(_("Search Domain"))
        self.vbox.pack_start(frame, expand=False, fill=False)
        self.domain_combo = gtk.combo_box_new_text()
        frame.add(self.domain_combo)
        for key in sorted(self.domain_map.keys()):
            self.domain_combo.append_text(key)
        self.domain_combo.insert_text(0, _("Choose a search domain..."))
        self.domain_combo.set_active(0)

        self.domain_combo.connect('changed', self.on_domain_combo_changed)

        frame = gtk.Frame(_("Expressions"))
        self.expressions_table = gtk.Table()
        self.expressions_table.props.column_spacing = 10
        frame.add(self.expressions_table)
        self.vbox.pack_start(frame, expand=False, fill=False)

        # add button to add additional expression rows
        self.add_button = gtk.Button()
        self.add_button.props.sensitive = False
        img = gtk.image_new_from_stock(gtk.STOCK_ADD, gtk.ICON_SIZE_BUTTON)
        self.add_button.props.image = img
        self.add_button.connect("clicked", lambda w: self.add_expression_row())
        align = gtk.Alignment(0, 0, 0, 0)
        align.add(self.add_button)
        self.vbox.pack_end(align, fill=False, expand=False)

    def on_domain_combo_changed(self, *args):
        """
        Change the search domain.  Resets the expression table and
        deletes all the expression rows.
        """
        if self._first_choice:
            self.domain_combo.remove_text(0)
            self._first_choice = False

        for kid in self.expressions_table.get_children():
            self.expressions_table.remove(kid)
        self.expressions_table.props.n_rows = 1
        del self.expression_rows[:]
        self.add_button.props.sensitive = True
        self.add_expression_row()
        self.expressions_table.show_all()

    def validate(self):
        """
        Validate the search expression is a valid expression.
        """
        valid = False
        for row in self.expression_rows:
            value = None
            if isinstance(row.value_widget, gtk.Entry):
                value = row.value_widget.props.text
            elif isinstance(row.value_widget, gtk.ComboBox):
                value = row.value_widget.get_active() >= 0

            if value and row.menu_item_activated:
                valid = True
            else:
                valid = False
                break

        self.set_response_sensitive(gtk.RESPONSE_OK, valid)
        return valid

    def remove_expression_row(self, row):
        """
        Remove a row from the expressions table.
        """
        map(self.expressions_table.remove, row.get_widgets())
        self.expressions_table.props.n_rows -= 1
        self.expression_rows.remove(row)
        del row

    def add_expression_row(self):
        """
        Add a row to the expressions table.
        """
        domain = self.domain_map[self.domain_combo.get_active_text()]
        self.mapper = class_mapper(domain)
        row = ExpressionRow(self, self.remove_expression_row)
        self.set_response_sensitive(gtk.RESPONSE_OK, False)
        self.expression_rows.append(row)
        self.expressions_table.show_all()

    def start(self):
        self.vbox.show_all()
        response = self.run()
        self.hide()
        return response

    def get_query(self):
        """
        Return query expression string.
        """

        domain = self.domain_combo.get_active_text()
        query = [domain, 'where']
        for row in self.expression_rows:
            expr = row.get_expression()
            if expr:
                query.append(expr)
        return ' '.join(query)
