# mssql/information_schema.py
# Copyright (C) 2005-2016 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php

# TODO: should be using the sys. catalog with SQL Server, not information
# schema

from ... import Table, MetaData, Column
from ...types import String, Unicode, UnicodeText, Integer, TypeDecorator
from ... import cast
from ... import util
from ...sql import expression
from ...ext.compiler import compiles

ischema = MetaData()


class CoerceUnicode(TypeDecorator):
    impl = Unicode

    def process_bind_param(self, value, dialect):
        if util.py2k and isinstance(value, util.binary_type):
            value = value.decode(dialect.encoding)
        return value

    def bind_expression(self, bindvalue):
        return _cast_on_2005(bindvalue)


class _cast_on_2005(expression.ColumnElement):
    def __init__(self, bindvalue):
        self.bindvalue = bindvalue


@compiles(_cast_on_2005)
def _compile(element, compiler, **kw):
    from . import base
    if compiler.dialect.server_version_info < base.MS_2005_VERSION:
        return compiler.process(element.bindvalue, **kw)
    else:
        return compiler.process(cast(element.bindvalue, Unicode), **kw)

schemata = Table("SCHEMATA", ischema,
                 Column("CATALOG_NAME", CoerceUnicode, key="catalog_name"),
                 Column("SCHEMA_NAME", CoerceUnicode, key="schema_name"),
                 Column("SCHEMA_OWNER", CoerceUnicode, key="schema_owner"),
                 schema="INFORMATION_SCHEMA")

tables = Table("TABLES", ischema,
               Column("TABLE_CATALOG", CoerceUnicode, key="table_catalog"),
               Column("TABLE_SCHEMA", CoerceUnicode, key="table_schema"),
               Column("TABLE_NAME", CoerceUnicode, key="table_name"),
               Column(
                   "TABLE_TYPE", String(convert_unicode=True),
                   key="table_type"),
               schema="INFORMATION_SCHEMA")

columns = Table("COLUMNS", ischema,
                Column("TABLE_SCHEMA", CoerceUnicode, key="table_schema"),
                Column("TABLE_NAME", CoerceUnicode, key="table_name"),
                Column("COLUMN_NAME", CoerceUnicode, key="column_name"),
                Column("IS_NULLABLE", Integer, key="is_nullable"),
                Column("DATA_TYPE", String, key="data_type"),
                Column("ORDINAL_POSITION", Integer, key="ordinal_position"),
                Column("CHARACTER_MAXIMUM_LENGTH", Integer,
                       key="character_maximum_length"),
                Column("NUMERIC_PRECISION", Integer, key="numeric_precision"),
                Column("NUMERIC_SCALE", Integer, key="numeric_scale"),
                Column("COLUMN_DEFAULT", Integer, key="column_default"),
                Column("COLLATION_NAME", String, key="collation_name"),
                schema="INFORMATION_SCHEMA")

constraints = Table("TABLE_CONSTRAINTS", ischema,
                    Column("TABLE_SCHEMA", CoerceUnicode, key="table_schema"),
                    Column("TABLE_NAME", CoerceUnicode, key="table_name"),
                    Column("CONSTRAINT_NAME", CoerceUnicode,
                           key="constraint_name"),
                    Column("CONSTRAINT_TYPE", String(
                        convert_unicode=True), key="constraint_type"),
                    schema="INFORMATION_SCHEMA")

column_constraints = Table("CONSTRAINT_COLUMN_USAGE", ischema,
                           Column("TABLE_SCHEMA", CoerceUnicode,
                                  key="table_schema"),
                           Column("TABLE_NAME", CoerceUnicode,
                                  key="table_name"),
                           Column("COLUMN_NAME", CoerceUnicode,
                                  key="column_name"),
                           Column("CONSTRAINT_NAME", CoerceUnicode,
                                  key="constraint_name"),
                           schema="INFORMATION_SCHEMA")

key_constraints = Table("KEY_COLUMN_USAGE", ischema,
                        Column("TABLE_SCHEMA", CoerceUnicode,
                               key="table_schema"),
                        Column("TABLE_NAME", CoerceUnicode,
                               key="table_name"),
                        Column("COLUMN_NAME", CoerceUnicode,
                               key="column_name"),
                        Column("CONSTRAINT_NAME", CoerceUnicode,
                               key="constraint_name"),
                        Column("ORDINAL_POSITION", Integer,
                               key="ordinal_position"),
                        schema="INFORMATION_SCHEMA")

ref_constraints = Table("REFERENTIAL_CONSTRAINTS", ischema,
                        Column("CONSTRAINT_CATALOG", CoerceUnicode,
                               key="constraint_catalog"),
                        Column("CONSTRAINT_SCHEMA", CoerceUnicode,
                               key="constraint_schema"),
                        Column("CONSTRAINT_NAME", CoerceUnicode,
                               key="constraint_name"),
                        # TODO: is CATLOG misspelled ?
                        Column("UNIQUE_CONSTRAINT_CATLOG", CoerceUnicode,
                               key="unique_constraint_catalog"),

                        Column("UNIQUE_CONSTRAINT_SCHEMA", CoerceUnicode,
                               key="unique_constraint_schema"),
                        Column("UNIQUE_CONSTRAINT_NAME", CoerceUnicode,
                               key="unique_constraint_name"),
                        Column("MATCH_OPTION", String, key="match_option"),
                        Column("UPDATE_RULE", String, key="update_rule"),
                        Column("DELETE_RULE", String, key="delete_rule"),
                        schema="INFORMATION_SCHEMA")

views = Table("VIEWS", ischema,
              Column("TABLE_CATALOG", CoerceUnicode, key="table_catalog"),
              Column("TABLE_SCHEMA", CoerceUnicode, key="table_schema"),
              Column("TABLE_NAME", CoerceUnicode, key="table_name"),
              Column("VIEW_DEFINITION", CoerceUnicode, key="view_definition"),
              Column("CHECK_OPTION", String, key="check_option"),
              Column("IS_UPDATABLE", String, key="is_updatable"),
              schema="INFORMATION_SCHEMA")
