# testing/requirements.py
# Copyright (C) 2005-2018 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

"""Global database feature support policy.

Provides decorators to mark tests requiring specific feature support from the
target database.

External dialect test suites should subclass SuiteRequirements
to provide specific inclusion/exclusions.

"""

import sys

from . import exclusions
from .. import util


class Requirements(object):
    pass


class SuiteRequirements(Requirements):

    @property
    def create_table(self):
        """target platform can emit basic CreateTable DDL."""

        return exclusions.open()

    @property
    def drop_table(self):
        """target platform can emit basic DropTable DDL."""

        return exclusions.open()

    @property
    def foreign_keys(self):
        """Target database must support foreign keys."""

        return exclusions.open()

    @property
    def on_update_cascade(self):
        """"target database must support ON UPDATE..CASCADE behavior in
        foreign keys."""

        return exclusions.open()

    @property
    def non_updating_cascade(self):
        """target database must *not* support ON UPDATE..CASCADE behavior in
        foreign keys."""
        return exclusions.closed()

    @property
    def deferrable_fks(self):
        return exclusions.closed()

    @property
    def on_update_or_deferrable_fks(self):
        # TODO: exclusions should be composable,
        # somehow only_if([x, y]) isn't working here, negation/conjunctions
        # getting confused.
        return exclusions.only_if(
            lambda: self.on_update_cascade.enabled or
            self.deferrable_fks.enabled
        )

    @property
    def self_referential_foreign_keys(self):
        """Target database must support self-referential foreign keys."""

        return exclusions.open()

    @property
    def foreign_key_ddl(self):
        """Target database must support the DDL phrases for FOREIGN KEY."""

        return exclusions.open()

    @property
    def named_constraints(self):
        """target database must support names for constraints."""

        return exclusions.open()

    @property
    def subqueries(self):
        """Target database must support subqueries."""

        return exclusions.open()

    @property
    def offset(self):
        """target database can render OFFSET, or an equivalent, in a
        SELECT.
        """

        return exclusions.open()

    @property
    def bound_limit_offset(self):
        """target database can render LIMIT and/or OFFSET using a bound
        parameter
        """

        return exclusions.open()

    @property
    def parens_in_union_contained_select_w_limit_offset(self):
        """Target database must support parenthesized SELECT in UNION
        when LIMIT/OFFSET is specifically present.

        E.g. (SELECT ...) UNION (SELECT ..)

        This is known to fail on SQLite.

        """
        return exclusions.open()

    @property
    def parens_in_union_contained_select_wo_limit_offset(self):
        """Target database must support parenthesized SELECT in UNION
        when OFFSET/LIMIT is specifically not present.

        E.g. (SELECT ... LIMIT ..) UNION (SELECT .. OFFSET ..)

        This is known to fail on SQLite.  It also fails on Oracle
        because without LIMIT/OFFSET, there is currently no step that
        creates an additional subquery.

        """
        return exclusions.open()

    @property
    def boolean_col_expressions(self):
        """Target database must support boolean expressions as columns"""

        return exclusions.closed()

    @property
    def nullsordering(self):
        """Target backends that support nulls ordering."""

        return exclusions.closed()

    @property
    def standalone_binds(self):
        """target database/driver supports bound parameters as column expressions
        without being in the context of a typed column.

        """
        return exclusions.closed()

    @property
    def intersect(self):
        """Target database must support INTERSECT or equivalent."""
        return exclusions.closed()

    @property
    def except_(self):
        """Target database must support EXCEPT or equivalent (i.e. MINUS)."""
        return exclusions.closed()

    @property
    def window_functions(self):
        """Target database must support window functions."""
        return exclusions.closed()

    @property
    def ctes(self):
        """Target database supports CTEs"""

        return exclusions.closed()

    @property
    def ctes_with_update_delete(self):
        """target database supports CTES that ride on top of a normal UPDATE
        or DELETE statement which refers to the CTE in a correlated subquery.

        """

        return exclusions.closed()

    @property
    def ctes_on_dml(self):
        """target database supports CTES which consist of INSERT, UPDATE
        or DELETE *within* the CTE, e.g. WITH x AS (UPDATE....)"""

        return exclusions.closed()

    @property
    def autoincrement_insert(self):
        """target platform generates new surrogate integer primary key values
        when insert() is executed, excluding the pk column."""

        return exclusions.open()

    @property
    def fetch_rows_post_commit(self):
        """target platform will allow cursor.fetchone() to proceed after a
        COMMIT.

        Typically this refers to an INSERT statement with RETURNING which
        is invoked within "autocommit".   If the row can be returned
        after the autocommit, then this rule can be open.

        """

        return exclusions.open()

    @property
    def group_by_complex_expression(self):
        """target platform supports SQL expressions in GROUP BY

        e.g.

        SELECT x + y AS somelabel FROM table GROUP BY x + y

        """

        return exclusions.open()

    @property
    def sane_rowcount(self):
        return exclusions.skip_if(
            lambda config: not config.db.dialect.supports_sane_rowcount,
            "driver doesn't support 'sane' rowcount"
        )

    @property
    def sane_multi_rowcount(self):
        return exclusions.fails_if(
            lambda config: not config.db.dialect.supports_sane_multi_rowcount,
            "driver %(driver)s %(doesnt_support)s 'sane' multi row count"
        )

    @property
    def sane_rowcount_w_returning(self):
        return exclusions.fails_if(
            lambda config:
                not config.db.dialect.supports_sane_rowcount_returning,
            "driver doesn't support 'sane' rowcount when returning is on"
        )

    @property
    def empty_inserts(self):
        """target platform supports INSERT with no values, i.e.
        INSERT DEFAULT VALUES or equivalent."""

        return exclusions.only_if(
            lambda config: config.db.dialect.supports_empty_insert or
            config.db.dialect.supports_default_values,
            "empty inserts not supported"
        )

    @property
    def insert_from_select(self):
        """target platform supports INSERT from a SELECT."""

        return exclusions.open()

    @property
    def returning(self):
        """target platform supports RETURNING."""

        return exclusions.only_if(
            lambda config: config.db.dialect.implicit_returning,
            "%(database)s %(does_support)s 'returning'"
        )

    @property
    def tuple_in(self):
        """Target platform supports the syntax
        "(x, y) IN ((x1, y1), (x2, y2), ...)"
        """

        return exclusions.closed()

    @property
    def duplicate_names_in_cursor_description(self):
        """target platform supports a SELECT statement that has
        the same name repeated more than once in the columns list."""

        return exclusions.open()

    @property
    def denormalized_names(self):
        """Target database must have 'denormalized', i.e.
        UPPERCASE as case insensitive names."""

        return exclusions.skip_if(
            lambda config: not config.db.dialect.requires_name_normalize,
            "Backend does not require denormalized names."
        )

    @property
    def multivalues_inserts(self):
        """target database must support multiple VALUES clauses in an
        INSERT statement."""

        return exclusions.skip_if(
            lambda config: not config.db.dialect.supports_multivalues_insert,
            "Backend does not support multirow inserts."
        )

    @property
    def implements_get_lastrowid(self):
        """"target dialect implements the executioncontext.get_lastrowid()
        method without reliance on RETURNING.

        """
        return exclusions.open()

    @property
    def emulated_lastrowid(self):
        """"target dialect retrieves cursor.lastrowid, or fetches
        from a database-side function after an insert() construct executes,
        within the get_lastrowid() method.

        Only dialects that "pre-execute", or need RETURNING to get last
        inserted id, would return closed/fail/skip for this.

        """
        return exclusions.closed()

    @property
    def dbapi_lastrowid(self):
        """"target platform includes a 'lastrowid' accessor on the DBAPI
        cursor object.

        """
        return exclusions.closed()

    @property
    def views(self):
        """Target database must support VIEWs."""

        return exclusions.closed()