from django.db.backends.mysql.base import DatabaseOperations

from django.contrib.gis.db.backends.adapter import WKTAdapter

from django.contrib.gis.db.backends.base import BaseSpatialOperations

class MySQLOperations(DatabaseOperations, BaseSpatialOperations):

    compiler_module = 'django.contrib.gis.db.models.sql.compiler'

    mysql = True

    name = 'mysql'

    select = 'AsText(%s)'

    from_wkb = 'GeomFromWKB'

    from_text = 'GeomFromText'

    Adapter = WKTAdapter

    Adaptor = Adapter # Backwards-compatibility alias.

    geometry_functions = {

        'bbcontains' : 'MBRContains', # For consistency w/PostGIS API

        'bboverlaps' : 'MBROverlaps', # .. ..

        'contained' : 'MBRWithin',    # .. ..

        'contains' : 'MBRContains',

        'disjoint' : 'MBRDisjoint',

        'equals' : 'MBREqual',

        'exact' : 'MBREqual',

        'intersects' : 'MBRIntersects',

        'overlaps' : 'MBROverlaps',

        'same_as' : 'MBREqual',

        'touches' : 'MBRTouches',

        'within' : 'MBRWithin',

        }

    gis_terms = dict([(term, None) for term in geometry_functions.keys() + ['isnull']])

    def geo_db_type(self, f):

        return f.geom_type

    def get_geom_placeholder(self, value, srid):

        """

        The placeholder here has to include MySQL's WKT constructor.  Because

        MySQL does not support spatial transformations, there is no need to

        modify the placeholder based on the contents of the given value.

        """

        if hasattr(value, 'expression'):

            placeholder = '%s.%s' % tuple(map(self.quote_name, value.cols[value.expression]))

        else:

            placeholder = '%s(%%s)' % self.from_text

        return placeholder

    def spatial_lookup_sql(self, lvalue, lookup_type, value, field, qn):

        alias, col, db_type = lvalue

        geo_col = '%s.%s' % (qn(alias), qn(col))

        lookup_info = self.geometry_functions.get(lookup_type, False)

        if lookup_info:

            return "%s(%s, %s)" % (lookup_info, geo_col,

                                   self.get_geom_placeholder(value, field.srid))

        # TODO: Is this really necessary? MySQL can't handle NULL geometries

        #  in its spatial indexes anyways.

        if lookup_type == 'isnull':

            return "%s IS %sNULL" % (geo_col, (not value and 'NOT ' or ''))

        raise TypeError("Got invalid lookup_type: %s" % repr(lookup_type))