# copyright 2004-2015 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"""

__docformat__ = "restructuredtext en"

from hashlib import md5

from six import string_types

from six.moves import range

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

                              NOW, TODAY)

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

# SET_DEFAULT to True

SET_DEFAULT = False

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=''):

    """write to the output stream a SQL schema to store the objects

    corresponding to the given schema

    """

    output = []

    w = output.append

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

        eschema = schema.eschema(etype)

        if eschema.final or eschema.type in skip_entities:

            continue

        w(eschema2sql(dbhelper, eschema, skip_relations, prefix=prefix))

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

        rschema = schema.rschema(rtype)

        if rschema_has_table(rschema, skip_relations):

            w(rschema2sql(rschema))

    return '\n'.join(output)

def dropschema2sql(dbhelper, schema, skip_entities=(), skip_relations=(), prefix=''):

    """write to the output stream a SQL schema to store the objects

    corresponding to the given schema

    """

    output = []

    w = output.append

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

        eschema = schema.eschema(etype)

        if eschema.final or eschema.type in skip_entities:

            continue

        stmts = dropeschema2sql(dbhelper, eschema, skip_relations, prefix=prefix)

        for stmt in stmts:

            w(stmt)

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

        rschema = schema.rschema(rtype)

        if rschema_has_table(rschema, skip_relations):

            w(droprschema2sql(rschema))

    return '\n'.join(output)

def eschema_attrs(eschema, skip_relations):

    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]

    return attrs

def unique_index_name(eschema, columns):

    return u'unique_%s' % md5((eschema.type +

                              ',' +

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

def iter_unique_index_names(eschema):

    for columns in eschema._unique_together or ():

        yield columns, unique_index_name(eschema, columns)

def dropeschema2sql(dbhelper, eschema, skip_relations=(), prefix=''):

    """return sql to drop an entity type's table"""

    # not necessary to drop indexes, that's implictly done when

    # dropping the table, but we need to drop SQLServer views used to

    # create multicol unique indices

    statements = []

    tablename = prefix + eschema.type

    if eschema._unique_together is not None:

        for columns, index_name in iter_unique_index_names(eschema):

            cols  = ['%s%s' % (prefix, col) for col in columns]

            sqls = dbhelper.sqls_drop_multicol_unique_index(tablename, cols, index_name)

            statements += sqls

    statements += ['DROP TABLE %s;' % (tablename)]

    return statements

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

    """write an entity schema as SQL statements to stdout"""

    output = []

    w = output.append

    table = prefix + eschema.type

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

    attrs = eschema_attrs(eschema, skip_relations)

    # XXX handle objectinline physical mode

    for i in range(len(attrs)):

        rschema, attrschema = attrs[i]

        if attrschema is not None:

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

                                  indent=' ')

        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

        attr = rschema.type

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

        for constraint in rdef.constraints:

            cstrname, check = check_constraint(eschema, aschema, attr, constraint, dbhelper, prefix=prefix)

            if cstrname is not None:

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

    w(');')

    # create indexes

    for i in range(len(attrs)):

        rschema, attrschema = attrs[i]

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

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

    for columns, index_name in iter_unique_index_names(eschema):

        cols  = ['%s%s' % (prefix, col) for col in columns]

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

        for sql in sqls:

            w(sql)

    w('')

    return '\n'.join(output)

def as_sql(value, dbhelper, prefix):

    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(eschema, aschema, attr, constraint, dbhelper, prefix=''):

    # XXX should find a better name

    cstrname = 'cstr' + md5(eschema.type + attr + constraint.type() +

                            (constraint.serialize() or '')).hexdigest()

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

        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 = as_sql(constraint.minvalue, dbhelper, prefix)

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

        if constraint.maxvalue is not None:

            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, indent=''):

    """write an attribute schema as SQL statements to stdout"""

    attr = rschema.type

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

    sqltype = type_from_constraints(dbhelper, aschema.type, rdef.constraints,

                                    creating)

    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_constraints(dbhelper, etype, constraints, creating=True):

    """return a sql type string corresponding to the constraints"""

    constraints = list(constraints)

    unique, sqltype = False, None

    size_constrained_string = dbhelper.TYPE_MAPPING.get('SizeConstrainedString', 'varchar(%s)')

    if etype == 'String':

        for constraint in constraints:

            if isinstance(constraint, SizeConstraint):

                if constraint.max is not None:

                    sqltype = size_constrained_string % constraint.max

            elif isinstance(constraint, UniqueConstraint):

                unique = True

    if sqltype is None:

        sqltype = dbhelper.TYPE_MAPPING[etype]

    if creating and unique:

        sqltype += ' UNIQUE'

    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 %(table)s_p_key PRIMARY KEY(eid_from, eid_to)

);

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

CREATE INDEX %(table)s_to_idx ON %(table)s(eid_to);"""

def rschema2sql(rschema):

    assert not rschema.rule

    return _SQL_SCHEMA % {'table': '%s_relation' % rschema.type}

def droprschema2sql(rschema):

    """return sql to drop a relation type's table"""

    # not necessary to drop indexes, that's implictly done when dropping

    # the table

    return 'DROP TABLE %s_relation;' % rschema.type

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

    """write to the output stream a SQL schema to store the objects

    corresponding to the given schema

    """

    output = []

    w = output.append

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

        eschema = schema.eschema(etype)

        if eschema.final or etype in skip_entities:

            continue

        w(grant_eschema(eschema, user, set_owner, prefix=prefix))

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

        rschema = schema.rschema(rtype)

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

            w(grant_rschema(rschema, user, set_owner))

    return '\n'.join(output)

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

    output = []

    w = output.append

    etype = eschema.type

    if set_owner:

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

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

    return '\n'.join(output)

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

    output = []

    if set_owner:

        output.append('ALTER TABLE %s_relation OWNER TO %s;' % (rschema.type, user))

    output.append('GRANT ALL ON %s_relation TO %s;' % (rschema.type, user))

    return '\n'.join(output)