from django.contrib.gis.db.models.fields import GeometryField
from django.db.backends.oracle.schema import DatabaseSchemaEditor
from django.db.backends.utils import truncate_name


class OracleGISSchemaEditor(DatabaseSchemaEditor):
    sql_add_geometry_metadata = ("""
        INSERT INTO USER_SDO_GEOM_METADATA
            ("TABLE_NAME", "COLUMN_NAME", "DIMINFO", "SRID")
        VALUES (
            %(table)s,
            %(column)s,
            MDSYS.SDO_DIM_ARRAY(
                MDSYS.SDO_DIM_ELEMENT('LONG', %(dim0)s, %(dim2)s, %(tolerance)s),
                MDSYS.SDO_DIM_ELEMENT('LAT', %(dim1)s, %(dim3)s, %(tolerance)s)
            ),
            %(srid)s
        )""")
    sql_add_spatial_index = 'CREATE INDEX %(index)s ON %(table)s(%(column)s) INDEXTYPE IS MDSYS.SPATIAL_INDEX'
    sql_drop_spatial_index = 'DROP INDEX %(index)s'
    sql_clear_geometry_table_metadata = 'DELETE FROM USER_SDO_GEOM_METADATA WHERE TABLE_NAME = %(table)s'
    sql_clear_geometry_field_metadata = (
        'DELETE FROM USER_SDO_GEOM_METADATA WHERE TABLE_NAME = %(table)s '
        'AND COLUMN_NAME = %(column)s'
    )

    def __init__(self, *args, **kwargs):
        super(OracleGISSchemaEditor, self).__init__(*args, **kwargs)
        self.geometry_sql = []

    def geo_quote_name(self, name):
        return self.connection.ops.geo_quote_name(name)

    def column_sql(self, model, field, include_default=False):
        column_sql = super(OracleGISSchemaEditor, self).column_sql(model, field, include_default)
        if isinstance(field, GeometryField):
            db_table = model._meta.db_table
            self.geometry_sql.append(
                self.sql_add_geometry_metadata % {
                    'table': self.geo_quote_name(db_table),
                    'column': self.geo_quote_name(field.column),
                    'dim0': field._extent[0],
                    'dim1': field._extent[1],
                    'dim2': field._extent[2],
                    'dim3': field._extent[3],
                    'tolerance': field._tolerance,
                    'srid': field.srid,
                }
            )
            if field.spatial_index:
                self.geometry_sql.append(
                    self.sql_add_spatial_index % {
                        'index': self.quote_name(self._create_spatial_index_name(model, field)),
                        'table': self.quote_name(db_table),
                        'column': self.quote_name(field.column),
                    }
                )
        return column_sql

    def create_model(self, model):
        super(OracleGISSchemaEditor, self).create_model(model)
        self.run_geometry_sql()

    def delete_model(self, model):
        super(OracleGISSchemaEditor, self).delete_model(model)
        self.execute(self.sql_clear_geometry_table_metadata % {
            'table': self.geo_quote_name(model._meta.db_table),
        })

    def add_field(self, model, field):
        super(OracleGISSchemaEditor, self).add_field(model, field)
        self.run_geometry_sql()

    def remove_field(self, model, field):
        if isinstance(field, GeometryField):
            self.execute(self.sql_clear_geometry_field_metadata % {
                'table': self.geo_quote_name(model._meta.db_table),
                'column': self.geo_quote_name(field.column),
            })
            if field.spatial_index:
                self.execute(self.sql_drop_spatial_index % {
                    'index': self.quote_name(self._create_spatial_index_name(model, field)),
                })
        super(OracleGISSchemaEditor, self).remove_field(model, field)

    def run_geometry_sql(self):
        for sql in self.geometry_sql:
            self.execute(sql)
        self.geometry_sql = []

    def _create_spatial_index_name(self, model, field):
        # Oracle doesn't allow object names > 30 characters. Use this scheme
        # instead of self._create_index_name() for backwards compatibility.
        return truncate_name('%s_%s_id' % (model._meta.db_table, field.column), 30)
