# sql/crud.py
# Copyright (C) 2005-2015 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

"""Functions used by compiler.py to determine the parameters rendered
within INSERT and UPDATE statements.

"""
from .. import util
from .. import exc
from . import elements
import operator

REQUIRED = util.symbol('REQUIRED', """
Placeholder for the value within a :class:`.BindParameter`
which is required to be present when the statement is passed
to :meth:`.Connection.execute`.

This symbol is typically used when a :func:`.expression.insert`
or :func:`.expression.update` statement is compiled without parameter
values present.

""")


def _get_crud_params(compiler, stmt, **kw):
    """create a set of tuples representing column/string pairs for use
    in an INSERT or UPDATE statement.

    Also generates the Compiled object's postfetch, prefetch, and
    returning column collections, used for default handling and ultimately
    populating the ResultProxy's prefetch_cols() and postfetch_cols()
    collections.

    """

    compiler.postfetch = []
    compiler.prefetch = []
    compiler.returning = []

    # no parameters in the statement, no parameters in the
    # compiled params - return binds for all columns
    if compiler.column_keys is None and stmt.parameters is None:
        return [
            (c, _create_bind_param(
                compiler, c, None, required=True))
            for c in stmt.table.columns
        ]

    if stmt._has_multi_parameters:
        stmt_parameters = stmt.parameters[0]
    else:
        stmt_parameters = stmt.parameters

    # getters - these are normally just column.key,
    # but in the case of mysql multi-table update, the rules for
    # .key must conditionally take tablename into account
    _column_as_key, _getattr_col_key, _col_bind_name = \
        _key_getters_for_crud_column(compiler)

    # if we have statement parameters - set defaults in the
    # compiled params
    if compiler.column_keys is None:
        parameters = {}
    else:
        parameters = dict((_column_as_key(key), REQUIRED)
                          for key in compiler.column_keys
                          if not stmt_parameters or
                          key not in stmt_parameters)

    # create a list of column assignment clauses as tuples
    values = []

    if stmt_parameters is not None:
        _get_stmt_parameters_params(
            compiler,
            parameters, stmt_parameters, _column_as_key, values, kw)

    check_columns = {}

    # special logic that only occurs for multi-table UPDATE
    # statements
    if compiler.isupdate and stmt._extra_froms and stmt_parameters:
        _get_multitable_params(
            compiler, stmt, stmt_parameters, check_columns,
            _col_bind_name, _getattr_col_key, values, kw)

    if compiler.isinsert and stmt.select_names:
        _scan_insert_from_select_cols(
            compiler, stmt, parameters,
            _getattr_col_key, _column_as_key,
            _col_bind_name, check_columns, values, kw)
    else:
        _scan_cols(
            compiler, stmt, parameters,
            _getattr_col_key, _column_as_key,
            _col_bind_name, check_columns, values, kw)

    if parameters and stmt_parameters:
        check = set(parameters).intersection(
            _column_as_key(k) for k in stmt.parameters
        ).difference(check_columns)
        if check:
            raise exc.CompileError(
                "Unconsumed column names: %s" %
                (", ".join("%s" % c for c in check))
            )

    if stmt._has_multi_parameters:
        values = _extend_values_for_multiparams(compiler, stmt, values, kw)

    return values


def _create_bind_param(
        compiler, col, value, process=True,
        required=False, name=None):
    if name is None:
        name = col.key
    bindparam = elements.BindParameter(
        name, value, type_=col.type, required=required)
    bindparam._is_crud = True
    if process:
        bindparam = bindparam._compiler_dispatch(compiler)
    return bindparam


def _key_getters_for_crud_column(compiler):
    if compiler.isupdate and compiler.statement._extra_froms:
        # when extra tables are present, refer to the columns
        # in those extra tables as table-qualified, including in
        # dictionaries and when rendering bind param names.
        # the "main" table of the statement remains unqualified,
        # allowing the most compatibility with a non-multi-table
        # statement.
        _et = set(compiler.statement._extra_froms)

        def _column_as_key(key):
            str_key = elements._column_as_key(key)
            if hasattr(key, 'table') and key.table in _et:
                return (key.table.name, str_key)
            else:
                return str_key

        def _getattr_col_key(col):
            if col.table in _et:
                return (col.table.name, col.key)
            else:
                return col.key

        def _col_bind_name(col):
            if col.table in _et:
                return "%s_%s" % (col.table.name, col.key)
            else:
                return col.key

    else:
        _column_as_key = elements._column_as_key
        _getattr_col_key = _col_bind_name = operator.attrgetter("key")

    return _column_as_key, _getattr_col_key, _col_bind_name


def _scan_insert_from_select_cols(
    compiler, stmt, parameters, _getattr_col_key,
        _column_as_key, _col_bind_name, check_columns, values, kw):

    need_pks, implicit_returning, \
        implicit_return_defaults, postfetch_lastrowid = \
        _get_returning_modifiers(compiler, stmt)

    cols = [stmt.table.c[_column_as_key(name)]
            for name in stmt.select_names]

    compiler._insert_from_select = stmt.select

    add_select_cols = []
    if stmt.include_insert_from_select_defaults:
        col_set = set(cols)
        for col in stmt.table.columns:
            if col not in col_set and col.default:
                cols.append(col)

    for c in cols:
        col_key = _getattr_col_key(c)
        if col_key in parameters and col_key not in check_columns:
            parameters.pop(col_key)
            values.append((c, None))
        else:
            _append_param_insert_select_hasdefault(
                compiler, stmt, c, add_select_cols, kw)

    if add_select_cols:
        values.extend(add_select_cols)
        compiler._insert_from_select = compiler._insert_from_select._generate()
        compiler._insert_from_select._raw_columns += tuple(
            expr for col, expr in add_select_cols)


def _scan_cols(
    compiler, stmt, parameters, _getattr_col_key,
        _column_as_key, _col_bind_name, check_columns, values, kw):

    need_pks, implicit_returning, \
        implicit_return_defaults, postfetch_lastrowid = \
        _get_returning_modifiers(compiler, stmt)

    cols = stmt.table.columns

    for c in cols:
        col_key = _getattr_col_key(c)
        if col_key in parameters and col_key not in check_columns:

            _append_param_parameter(
                compiler, stmt, c, col_key, parameters, _col_bind_name,
                implicit_returning, implicit_return_defaults, values, kw)

        elif compiler.isinsert:
            if c.primary_key and \
                    need_pks and \
                    (
                        implicit_returning or
                        not postfetch_lastrowid or
                        c is not stmt.table._autoincrement_column
                    ):

                if implicit_returning:
                    _append_param_insert_pk_returning(
                        compiler, stmt, c, values, kw)
                else:
                    _append_param_insert_pk(compiler, stmt, c, values, kw)

            elif c.default is not None:

                _append_param_insert_hasdefault(
                    compiler, stmt, c, implicit_return_defaults,
                    values, kw)

            elif c.server_default is not None:
                if implicit_return_defaults and \
                        c in implicit_return_defaults:
                    compiler.returning.append(c)
                elif not c.primary_key:
                    compiler.postfetch.append(c)
            elif implicit_return_defaults and \
                    c in implicit_return_defaults:
                compiler.returning.append(c)

        elif compiler.isupdate:
            _append_param_update(
                compiler, stmt, c, implicit_return_defaults, values, kw)


def _append_param_parameter(
        compiler, stmt, c, col_key, parameters, _col_bind_name,
        implicit_returning, implicit_return_defaults, values, kw):
    value = parameters.pop(col_key)
    if elements._is_literal(value):
        value = _create_bind_param(
            compiler, c, value, required=value is REQUIRED,
            name=_col_bind_name(c)
            if not stmt._has_multi_parameters
            else "%s_0" % _col_bind_name(c)
        )
    else:
        if isinstance(value, elements.BindParameter) and \
                value.type._isnull:
            value = value._clone()
            value.type = c.type

        if c.primary_key and implicit_returning:
            compiler.returning.append(c)
            value = compiler.process(value.self_group(), **kw)
        elif implicit_return_defaults and \
                c in implicit_return_defaults:
            compiler.returning.append(c)
            value = compiler.process(value.self_group(), **kw)
        else:
            compiler.postfetch.append(c)
            value = compiler.process(value.self_group(), **kw)
    values.append((c, value))


def _append_param_insert_pk_returning(compiler, stmt, c, values, kw):
    if c.default is not None:
        if c.default.is_sequence:
            if compiler.dialect.supports_sequences and \
                (not c.default.optional or
                 not compiler.dialect.sequences_optional):
                proc = compiler.process(c.default, **kw)
                values.append((c, proc))
            compiler.returning.append(c)
        elif c.default.is_clause_element:
            values.append(
                (c, compiler.process(
                    c.default.arg.self_group(), **kw))
            )
            compiler.returning.append(c)
        else:
            values.append(
                (c, _create_prefetch_bind_param(compiler, c))
            )

    else:
        compiler.returning.append(c)


def _create_prefetch_bind_param(compiler, c, process=True, name=None):
    param = _create_bind_param(compiler, c, None, process=process, name=name)
    compiler.prefetch.append(c)
    return param


class _multiparam_column(elements.ColumnElement):
    def __init__(self, original, index):
        self.key = "%s_%d" % (original.key, index + 1)
        self.original = original
        self.default = original.default

    def __eq__(self, other):
        return isinstance(other, _multiparam_column) and \
            other.key == self.key and \
            other.original == self.original


def _process_multiparam_default_bind(compiler, c, index, kw):

    if not c.default:
        raise exc.CompileError(
            "INSERT value for column %s is explicitly rendered as a bound"
            "parameter in the VALUES clause; "
            "a Python-side value or SQL expression is required" % c)
    elif c.default.is_clause_element:
        return compiler.process(c.default.arg.self_group(), **kw)
    else:
        col = _multiparam_column(c, index)
        return _create_prefetch_bind_param(compiler, col)


def _append_param_insert_pk(compiler, stmt, c, values, kw):
    if (
            (c.default is not None and
             (not c.default.is_sequence or
                 compiler.dialect.supports_sequences)) or
            c is stmt.table._autoincrement_column and
            (compiler.dialect.supports_sequences or
             compiler.dialect.
             preexecute_autoincrement_sequences)
    ):
        values.append(
            (c, _create_prefetch_bind_param(compiler, c))
        )


def _append_param_insert_hasdefault(
        compiler, stmt, c, implicit_return_defaults, values, kw):

    if c.default.is_sequence:
        if compiler.dialect.supports_sequences and \
            (not c.default.optional or
             not compiler.dialect.sequences_optional):
            proc = compiler.process(c.default, **kw)
            values.append((c, proc))
            if implicit_return_defaults and \
                    c in implicit_return_defaults:
                compiler.returning.append(c)
            elif not c.primary_key:
                compiler.postfetch.append(c)
    elif c.default.is_clause_element:
        proc = compiler.process(c.default.arg.self_group(), **kw)
        values.append((c, proc))

        if implicit_return_defaults and \
                c in implicit_return_defaults:
            compiler.returning.append(c)
        elif not c.primary_key:
            # don't add primary key column to postfetch
            compiler.postfetch.append(c)
    else:
        values.append(
            (c, _create_prefetch_bind_param(compiler, c))
        )


def _append_param_insert_select_hasdefault(
        compiler, stmt, c, values, kw):

    if c.default.is_sequence:
        if compiler.dialect.supports_sequences and \
            (not c.default.optional or
             not compiler.dialect.sequences_optional):
            proc = c.default
            values.append((c, proc))
    elif c.default.is_clause_element:
        proc = c.default.arg.self_group()
        values.append((c, proc))
    else:
        values.append(
            (c, _create_prefetch_bind_param(compiler, c, process=False))
        )


def _append_param_update(
        compiler, stmt, c, implicit_return_defaults, values, kw):

    if c.onupdate is not None and not c.onupdate.is_sequence:
        if c.onupdate.is_clause_element:
            values.append(
                (c, compiler.process(
                    c.onupdate.arg.self_group(), **kw))
            )
            if implicit_return_defaults and \
                    c in implicit_return_defaults:
                compiler.returning.append(c)
            else:
                compiler.postfetch.append(c)
        else:
            values.append(
                (c, _create_prefetch_bind_param(compiler, c))
            )
    elif c.server_onupdate is not None:
        if implicit_return_defaults and \
                c in implicit_return_defaults:
            compiler.returning.append(c)
        else:
            compiler.postfetch.append(c)
    elif implicit_return_defaults and \
            c in implicit_return_defaults:
        compiler.returning.append(c)


def _get_multitable_params(
        compiler, stmt, stmt_parameters, check_columns,
        _col_bind_name, _getattr_col_key, values, kw):

    normalized_params = dict(
        (elements._clause_element_as_expr(c), param)
        for c, param in stmt_parameters.items()
    )
    affected_tables = set()
    for t in stmt._extra_froms:
        for c in t.c:
            if c in normalized_params:
                affected_tables.add(t)
                check_columns[_getattr_col_key(c)] = c
                value = normalized_params[c]
                if elements._is_literal(value):
                    value = _create_bind_param(
                        compiler, c, value, required=value is REQUIRED,
                        name=_col_bind_name(c))
                else:
                    compiler.postfetch.append(c)
                    value = compiler.process(value.self_group(), **kw)
                values.append((c, value))
    # determine tables which are actually to be updated - process onupdate
    # and server_onupdate for these
    for t in affected_tables:
        for c in t.c:
            if c in normalized_params:
                continue
            elif (c.onupdate is not None and not
                  c.onupdate.is_sequence):
                if c.onupdate.is_clause_element:
                    values.append(
                        (c, compiler.process(
                            c.onupdate.arg.self_group(),
                            **kw)
                         )
                    )
                    compiler.postfetch.append(c)
                else:
                    values.append(
                        (c, _create_prefetch_bind_param(
                            compiler, c, name=_col_bind_name(c)))
                    )
            elif c.server_onupdate is not None:
                compiler.postfetch.append(c)


def _extend_values_for_multiparams(compiler, stmt, values, kw):
    values_0 = values
    values = [values]

    values.extend(
        [
            (
                c,
                (_create_bind_param(
                    compiler, c, row[c.key],
                    name="%s_%d" % (c.key, i + 1)
                ) if elements._is_literal(row[c.key])
                    else compiler.process(
                        row[c.key].self_group(), **kw))
                if c.key in row else
                _process_multiparam_default_bind(compiler, c, i, kw)
            )
            for (c, param) in values_0
        ]
        for i, row in enumerate(stmt.parameters[1:])
    )
    return values


def _get_stmt_parameters_params(
        compiler, parameters, stmt_parameters, _column_as_key, values, kw):
    for k, v in stmt_parameters.items():
        colkey = _column_as_key(k)
        if colkey is not None:
            parameters.setdefault(colkey, v)
        else:
            # a non-Column expression on the left side;
            # add it to values() in an "as-is" state,
            # coercing right side to bound param
            if elements._is_literal(v):
                v = compiler.process(
                    elements.BindParameter(None, v, type_=k.type),
                    **kw)
            else:
                v = compiler.process(v.self_group(), **kw)

            values.append((k, v))


def _get_returning_modifiers(compiler, stmt):
    need_pks = compiler.isinsert and \
        not compiler.inline and \
        not stmt._returning and \
        not stmt._has_multi_parameters

    implicit_returning = need_pks and \
        compiler.dialect.implicit_returning and \
        stmt.table.implicit_returning

    if compiler.isinsert:
        implicit_return_defaults = (implicit_returning and
                                    stmt._return_defaults)
    elif compiler.isupdate:
        implicit_return_defaults = (compiler.dialect.implicit_returning and
                                    stmt.table.implicit_returning and
                                    stmt._return_defaults)
    else:
        implicit_return_defaults = False

    if implicit_return_defaults:
        if stmt._return_defaults is True:
            implicit_return_defaults = set(stmt.table.c)
        else:
            implicit_return_defaults = set(stmt._return_defaults)

    postfetch_lastrowid = need_pks and compiler.dialect.postfetch_lastrowid

    return need_pks, implicit_returning, \
        implicit_return_defaults, postfetch_lastrowid
