# copyright 2004-2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr

#

# This file is part of cubicweb.

#

# yams is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# yams is distributed in the hope that it will be useful, but WITHOUT ANY

# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR

# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with yams. If not, see <http://www.gnu.org/licenses/>.

"""write a schema as sql"""

from hashlib import md5

from six import string_types, text_type

from six.moves import range

from yams.constraints import (SizeConstraint, UniqueConstraint, Attribute,

                              NOW, TODAY)

from logilab import database

from logilab.common.decorators import monkeypatch

# default are usually not handled at the sql level. If you want them, set

# SET_DEFAULT to True

SET_DEFAULT = False

# backport fix for lgdb #6662663

@monkeypatch(database._GenericAdvFuncHelper)

def sql_create_index(self, table, column, unique=False):

    idx = self._index_name(table, column, unique)

    if unique:

        return 'ALTER TABLE %s ADD CONSTRAINT %s UNIQUE(%s)' % (table, idx, column)

    else:

        return 'CREATE INDEX %s ON %s(%s)' % (idx, table, column)

@monkeypatch(database._GenericAdvFuncHelper)

def _index_name(self, table, column, unique=False):

    if unique:

        return build_index_name(table, [column], prefix='key_')

    else:

        return build_index_name(table, [column], prefix='idx_')

def build_index_name(table, columns, prefix='idx_'):

    """Return a predictable-but-size-constrained name for an index on `table(*columns)`, using an

    md5 hash.

    """

    return '%s%s' % (prefix, md5((table +

                                  ',' +

                                  ','.join(sorted(columns))).encode('ascii')).hexdigest())

def rschema_has_table(rschema, skip_relations):

    """Return True if the given schema should have a table in the database."""

    return not (rschema.final or rschema.inlined or rschema.rule or rschema.type in skip_relations)

def schema2sql(dbhelper, schema, skip_entities=(), skip_relations=(), prefix=''):

    """Yield SQL statements to create a database schema for the given Yams schema.

    `prefix` may be a string that will be prepended to all table / column names (usually, 'cw_').

    """

    for etype in sorted(schema.entities()):

        eschema = schema.eschema(etype)

        if eschema.final or eschema.type in skip_entities:

            continue

        for sql in eschema2sql(dbhelper, eschema, skip_relations, prefix):

            yield sql

    for rtype in sorted(schema.relations()):

        rschema = schema.rschema(rtype)

        if rschema_has_table(rschema, skip_relations):

            for sql in rschema2sql(rschema):

                yield sql

def unique_index_name(eschema, attrs):

    """Return a predictable-but-size-constrained name for a multi-columns unique index on

    given attributes of the entity schema (actually, the later may be a schema or a string).

    """

    # keep giving eschema instead of table name for bw compat

    table = text_type(eschema)

    # unique_index_name is used as name of CWUniqueConstraint, hence it should be unicode

    return text_type(build_index_name(table, attrs, 'unique_'))

def iter_unique_index_names(eschema):

    """Yield (attrs, index name) where attrs is a list of entity type's attribute names that should

    be unique together, and index name the unique index name.

    """

    for attrs in eschema._unique_together or ():

        yield attrs, unique_index_name(eschema, attrs)

def eschema2sql(dbhelper, eschema, skip_relations=(), prefix=''):

    """Yield SQL statements to initialize database from an entity schema."""

    table = prefix + eschema.type

    output = []

    w = output.append

    w('CREATE TABLE %s(' % (table))

    attrs = [attrdef for attrdef in eschema.attribute_definitions()

             if not attrdef[0].type in skip_relations]

    attrs += [(rschema, None)

              for rschema in eschema.subject_relations()

              if not rschema.final and rschema.inlined]

    for i in range(len(attrs)):

        rschema, attrschema = attrs[i]

        if attrschema is not None:

            sqltype = aschema2sql(dbhelper, eschema, rschema, attrschema)

        else:  # inline relation

            sqltype = 'integer REFERENCES entities (eid)'

        if i == len(attrs) - 1:

            w(' %s%s %s' % (prefix, rschema.type, sqltype))

        else:

            w(' %s%s %s,' % (prefix, rschema.type, sqltype))

    for rschema, aschema in attrs:

        if aschema is None:  # inline relation

            continue

        rdef = rschema.rdef(eschema.type, aschema.type)

        for constraint in rdef.constraints:

            cstrname, check = check_constraint(rdef, constraint, dbhelper, prefix=prefix)

            if cstrname is not None:

                w(', CONSTRAINT %s CHECK(%s)' % (cstrname, check))

    w(')')

    yield '\n'.join(output)

    # create indexes

    for i in range(len(attrs)):

        rschema, attrschema = attrs[i]

        if attrschema is None or eschema.rdef(rschema).indexed:

            yield dbhelper.sql_create_index(table, prefix + rschema.type)

        if attrschema and any(isinstance(cstr, UniqueConstraint)

                              for cstr in eschema.rdef(rschema).constraints):

            yield dbhelper.sql_create_index(table, prefix + rschema.type, unique=True)

    for attrs, index_name in iter_unique_index_names(eschema):

        columns = ['%s%s' % (prefix, attr) for attr in attrs]

        sqls = dbhelper.sqls_create_multicol_unique_index(table, columns, index_name)

        for sql in sqls:

            yield sql.rstrip(';')  # remove trailing ';' for consistency

def constraint_value_as_sql(value, dbhelper, prefix):

    """Return the SQL value from a Yams constraint's value, handling special cases where it's a

    `Attribute`, `TODAY` or `NOW` instance instead of a literal value.

    """

    if isinstance(value, Attribute):

        return prefix + value.attr

    elif isinstance(value, TODAY):

        return dbhelper.sql_current_date()

    elif isinstance(value, NOW):

        return dbhelper.sql_current_timestamp()

    else:

        # XXX more quoting for literals?

        return value

def check_constraint(rdef, constraint, dbhelper, prefix=''):

    """Return (constraint name, constraint SQL definition) for the given relation definition's

    constraint. Maybe (None, None) if the constraint is not handled in the backend.

    """

    attr = rdef.rtype.type

    cstrname = constraint.name_for(rdef)

    if constraint.type() == 'BoundaryConstraint':

        value = constraint_value_as_sql(constraint.boundary, dbhelper, prefix)

        return cstrname, '%s%s %s %s' % (prefix, attr, constraint.operator, value)

    elif constraint.type() == 'IntervalBoundConstraint':

        condition = []

        if constraint.minvalue is not None:

            value = constraint_value_as_sql(constraint.minvalue, dbhelper, prefix)

            condition.append('%s%s >= %s' % (prefix, attr, value))

        if constraint.maxvalue is not None:

            value = constraint_value_as_sql(constraint.maxvalue, dbhelper, prefix)

            condition.append('%s%s <= %s' % (prefix, attr, value))

        return cstrname, ' AND '.join(condition)

    elif constraint.type() == 'StaticVocabularyConstraint':

        sample = next(iter(constraint.vocabulary()))

        if not isinstance(sample, string_types):

            values = ', '.join(str(word) for word in constraint.vocabulary())

        else:

            # XXX better quoting?

            values = ', '.join("'%s'" % word.replace("'", "''") for word in constraint.vocabulary())

        return cstrname, '%s%s IN (%s)' % (prefix, attr, values)

    return None, None

def aschema2sql(dbhelper, eschema, rschema, aschema, creating=True):

    """Return string containing a SQL table's column definition from attribute schema."""

    attr = rschema.type

    rdef = rschema.rdef(eschema.type, aschema.type)

    sqltype = type_from_rdef(dbhelper, rdef)

    if SET_DEFAULT:

        default = eschema.default(attr)

        if default is not None:

            if aschema.type == 'Boolean':

                sqltype += ' DEFAULT %s' % dbhelper.boolean_value(default)

            elif aschema.type == 'String':

                sqltype += ' DEFAULT %r' % str(default)

            elif aschema.type in ('Int', 'BigInt', 'Float'):

                sqltype += ' DEFAULT %s' % default

            # XXX ignore default for other type

            # this is expected for NOW / TODAY

    if creating:

        if rdef.uid:

            sqltype += ' PRIMARY KEY REFERENCES entities (eid)'

        elif rdef.cardinality[0] == '1':

            # don't set NOT NULL if backend isn't able to change it later

            if dbhelper.alter_column_support:

                sqltype += ' NOT NULL'

    # else we're getting sql type to alter a column, we don't want key / indexes

    # / null modifiers

    return sqltype

def type_from_rdef(dbhelper, rdef):

    """Return a string containing SQL type name for the given relation definition."""

    constraints = list(rdef.constraints)

    sqltype = None

    if rdef.object.type == 'String':

        for constraint in constraints:

            if isinstance(constraint, SizeConstraint) and constraint.max is not None:

                size_constrained_string = dbhelper.TYPE_MAPPING.get(

                    'SizeConstrainedString', 'varchar(%s)')

                sqltype = size_constrained_string % constraint.max

                break

    if sqltype is None:

        sqltype = sql_type(dbhelper, rdef)

    return sqltype

def sql_type(dbhelper, rdef):

    """Return a string containing SQL type to use to store values of the given relation definition.

    """

    sqltype = dbhelper.TYPE_MAPPING[rdef.object]

    if callable(sqltype):

        sqltype = sqltype(rdef)

    return sqltype

_SQL_SCHEMA = """

CREATE TABLE %(table)s (

  eid_from INTEGER NOT NULL REFERENCES entities (eid),

  eid_to INTEGER NOT NULL REFERENCES entities (eid),

  CONSTRAINT %(pkey_idx)s PRIMARY KEY(eid_from, eid_to)

);

CREATE INDEX %(from_idx)s ON %(table)s(eid_from);

CREATE INDEX %(to_idx)s ON %(table)s(eid_to)"""

def rschema2sql(rschema):

    """Yield SQL statements to create database table and indexes for a Yams relation schema."""

    assert not rschema.rule

    table = '%s_relation' % rschema.type

    sqls = _SQL_SCHEMA % {'table': table,

                          'pkey_idx': build_index_name(table, ['eid_from', 'eid_to'], 'key_'),

                          'from_idx': build_index_name(table, ['eid_from'], 'idx_'),

                          'to_idx': build_index_name(table, ['eid_to'], 'idx_')}

    for sql in sqls.split(';'):

        yield sql.strip()

def grant_schema(schema, user, set_owner=True, skip_entities=(), prefix=''):

    """Yield SQL statements to give all access (and ownership if `set_owner` is True) on the

    database tables for the given Yams schema to `user`.

    `prefix` may be a string that will be prepended to all table / column names (usually, 'cw_').

    """

    for etype in sorted(schema.entities()):

        eschema = schema.eschema(etype)

        if eschema.final or etype in skip_entities:

            continue

        for sql in grant_eschema(eschema, user, set_owner, prefix=prefix):

            yield sql

    for rtype in sorted(schema.relations()):

        rschema = schema.rschema(rtype)

        if rschema_has_table(rschema, skip_relations=()):  # XXX skip_relations should be specified

            for sql in grant_rschema(rschema, user, set_owner):

                yield sql

def grant_eschema(eschema, user, set_owner=True, prefix=''):

    """Yield SQL statements to give all access (and ownership if `set_owner` is True) on the

    database tables for the given Yams entity schema to `user`.

    """

    etype = eschema.type

    if set_owner:

        yield 'ALTER TABLE %s%s OWNER TO %s' % (prefix, etype, user)

    yield 'GRANT ALL ON %s%s TO %s' % (prefix, etype, user)

def grant_rschema(rschema, user, set_owner=True):

    """Yield SQL statements to give all access (and ownership if `set_owner` is True) on the

    database tables for the given Yams relation schema to `user`.

    """

    if set_owner:

        yield 'ALTER TABLE %s_relation OWNER TO %s' % (rschema.type, user)

    yield 'GRANT ALL ON %s_relation TO %s' % (rschema.type, user)