# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
"""This module contains helpers for DBMS specific (advanced or non standard)
functionalities

Helpers are provided for postgresql, mysql and sqlite.

:author:    Logilab
:copyright: 2003-2008 LOGILAB S.A. (Paris, FRANCE)
:contact:   http://www.logilab.fr/ -- mailto:python-projects@logilab.org
"""
__docformat__ = "restructuredtext en"

from logilab.common.deprecation import obsolete

class BadQuery(Exception): pass
class UnsupportedFunction(BadQuery): pass


class metafunc(type):
    def __new__(mcs, name, bases, dict):
        dict['name'] = name.upper()
        return type.__new__(mcs, name, bases, dict)

    
class FunctionDescr(object):
    __metaclass__ = metafunc

    rtype = None # None <-> returned type should be the same as the first argument
    aggregat = False
    minargs = 1
    maxargs = 1

    def __init__(self, name=None, rtype=rtype, aggregat=aggregat):
        if name is not None:
            name = name.upper()
        self.name = name
        self.rtype = rtype
        self.aggregat = aggregat

    #@classmethod
    def check_nbargs(cls, nbargs):
        if cls.minargs is not None and \
               nbargs < cls.minargs:
            raise BadQuery('not enough argument for function %s' % cls.name)
        if cls.maxargs is not None and \
               nbargs < cls.maxargs:
            raise BadQuery('too many arguments for function %s' % cls.name)
    check_nbargs = classmethod(check_nbargs)

class AggrFunctionDescr(FunctionDescr):
    aggregat = True
    rtype = None 

class MAX(AggrFunctionDescr): pass
class MIN(AggrFunctionDescr): pass
class SUM(AggrFunctionDescr): pass
class COUNT(AggrFunctionDescr): 
    rtype = 'Int'
class AVG(AggrFunctionDescr):
    rtype = 'Float'

class UPPER(FunctionDescr):
    rtype = 'String'
class LOWER(FunctionDescr):
    rtype = 'String'
class IN(FunctionDescr):
    """this is actually a 'keyword' function..."""
    maxargs = None
class LENGTH(FunctionDescr):
    rtype = 'Int'

class _GenericAdvFuncHelper:
    """Generic helper, trying to provide generic way to implement
    specific functionnalities from others DBMS

    An exception is raised when the functionality is not emulatable
    """    
    # DBMS resources descriptors and accessors
    
    needs_from_clause = False
    
    users_support = True
    groups_support = True
    ilike_support = True

    FUNCTIONS = {
        # aggregat functions
        'MIN': MIN, 'MAX': MAX,
        'SUM': SUM,
        'COUNT': COUNT,
        'AVG': AVG,
        # transformation functions
        'UPPER': UPPER, 'LOWER': LOWER,
        'LENGTH': LENGTH,
        # keyword function
        'IN': IN
        }

    TYPE_MAPPING = {
        'String' :   'text',
        'Int' :      'integer',
        'Float' :    'float',
        'Boolean' :  'boolean',
        'Date' :     'date', 
        'Time' :     'time', 
        'Datetime' : 'timestamp',
        'Interval' : 'interval',
        'Password' : 'bytea',
        'Bytes' :    'bytea',
        # FIXME: still there for use from erudi, should be moved out
        # XXX think it can be safely removed now
        'COUNT' : 'integer',
        'MIN' :   'integer',
        'MAX' :   'integer',
        'SUM' :   'integer',
        'LOWER' : 'text',
        'UPPER' : 'text',
        'LENGTH' :'integer',
        }


    #@classmethod
    def register_function(cls, funcdef):
        if isinstance(funcdef, basestring) :
            funcdef = FunctionDescr(funcdef.upper())
        assert not funcdef.name in cls.FUNCTIONS, \
               '%s is already registered' % funcdef.name
        cls.FUNCTIONS[funcdef.name] = funcdef
    register_function = classmethod(register_function)
    
    #@classmethod
    def function_description(cls, funcname):
        """return the description (`FunctionDescription`) for a RQL function"""
        try:
            return cls.FUNCTIONS[funcname.upper()]
        except KeyError:
            raise UnsupportedFunction(funcname)
    function_description = classmethod(function_description)
    
    #@obsolete('use users_support attribute')
    def support_users(self):
        """return True if the DBMS support users (this is usually
        not true for in memory DBMS)
        """
        return self.users_support
    support_user = obsolete('use users_support attribute')(support_users)
    
    #@obsolete('use groups_support attribute')    
    def support_groups(self):
        """return True if the DBMS support groups"""
        return self.groups_support
    support_user = obsolete('use groups_support attribute')(support_groups)

    def system_database(self):
        """return the system database for the given driver"""
        raise NotImplementedError('not supported by this DBMS')
    
    def backup_command(self, dbname, dbhost, dbuser, dbpassword, backupfile,
                       keepownership=True):
        """return a command to backup the given database"""
        raise NotImplementedError('not supported by this DBMS')
    
    def restore_commands(self, dbname, dbhost, dbuser, backupfile,
                         encoding='utf-8', keepownership=True, drop=True):
        """return a list of commands to restore a backup the given database"""
        raise NotImplementedError('not supported by this DBMS')
    
    # helpers to standardize SQL according to the database
    
    def sql_current_date(self):
        return 'CURRENT_DATE'
    
    def sql_current_time(self):
        return 'CURRENT_TIME'
    
    def sql_current_timestamp(self):
        return 'CURRENT_TIMESTAMP'
    
    def sql_create_sequence(self, seq_name):
        return '''CREATE TABLE %s (last INTEGER);
INSERT INTO %s VALUES (0);''' % (seq_name, seq_name)
    
    def sql_create_index(self, table, column, unique=False):
        idx = self._index_name(table, column, unique)
        if unique:
            return 'CREATE UNIQUE INDEX %s ON %s(%s);' % (idx, table, column)
        else:
            return 'CREATE INDEX %s ON %s(%s);' % (idx, table, column)
    
    def sql_drop_sequence(self, seq_name):
        return 'DROP TABLE %s;' % seq_name
    
    def sqls_increment_sequence(self, seq_name):
        return ('UPDATE %s SET last=last+1;' % seq_name,
                'SELECT last FROM %s;' % seq_name)

    def sql_temporary_table(self, table_name, table_schema,
                            drop_on_commit=True):
        return "CREATE TEMPORARY TABLE %s (%s);" % (table_name, table_schema)
    
    def boolean_value(self, value):
        if value:
            return 'TRUE'
        else:
            return 'FALSE'
        
    def increment_sequence(self, cursor, seq_name):
        for sql in self.sqls_increment_sequence(seq_name):
            cursor.execute(sql)
        return cursor.fetchone()[0]

    def create_user(self, cursor, user, password):
        """create a new database user"""
        if not self.users_support:
            raise NotImplementedError('not supported by this DBMS')
        cursor.execute("CREATE USER %(user)s "
                       "WITH PASSWORD '%(password)s'" % locals())

    def _index_name(self, table, column, unique=False):
        if unique:
            # note: this naming is consistent with indices automatically
            # created by postgres when UNIQUE appears in a table schema
            return '%s_%s_key' % (table.lower(), column.lower())
        else:
            return '%s_%s_idx' % (table.lower(), column.lower())
    
    def create_index(self, cursor, table, column, unique=False):
        if not self.index_exists(cursor, table, column, unique):
            cursor.execute(self.sql_create_index(table, column, unique))
            
    def drop_index(self, cursor, table, column, unique=False):
        if self.index_exists(cursor, table, column, unique):
            idx = self._index_name(table, column, unique)
            cursor.execute('DROP INDEX %s' % idx)
        
    def index_exists(self, cursor, table, column, unique=False):
        idx = self._index_name(table, column, unique)
        return idx in self.list_indices(cursor, table)

    def user_exists(self, cursor, username):
        """return True if a user with the given username exists"""
        return username in self.list_users(cursor)
    
    def list_users(self, cursor):
        """return the list of existing database users"""
        raise NotImplementedError('not supported by this DBMS')
    
    def create_database(self, cursor, dbname, owner=None, encoding='utf-8'):
        """create a new database"""
        raise NotImplementedError('not supported by this DBMS')
        
    def list_databases(self):
        """return the list of existing databases"""
        raise NotImplementedError('not supported by this DBMS')
    
    def list_tables(self, cursor):
        """return the list of tables of a database"""
        raise NotImplementedError('not supported by this DBMS')
    
    def list_indices(self, cursor, table=None):
        """return the list of indices of a database, only for the given table if specified"""
        raise NotImplementedError('not supported by this DBMS')
    


def pgdbcmd(cmd, dbhost, dbuser):
    cmd = [cmd]
    if dbhost:
        cmd.append('--host=%s' % dbhost)
    if dbuser:
        cmd.append('--username=%s' % dbuser)
    return cmd


class _PGAdvFuncHelper(_GenericAdvFuncHelper):
    """Postgres helper, taking advantage of postgres SEQUENCE support
    """
    # modifiable but should not be shared
    FUNCTIONS = _GenericAdvFuncHelper.FUNCTIONS.copy()
    
    def system_database(self):
        """return the system database for the given driver"""
        return 'template1'
    
    def backup_command(self, dbname, dbhost, dbuser, backupfile,
                       keepownership=True):
        """return a command to backup the given database"""
        cmd = ['pg_dump -Fc']
        if dbhost:
            cmd.append('--host=%s' % dbhost)
        if dbuser:
            cmd.append('--username=%s' % dbuser)
        if not keepownership:
            cmd.append('--no-owner')
        cmd.append('--file=%s' % backupfile)
        cmd.append(dbname)
        return ' '.join(cmd)
    
    def restore_commands(self, dbname, dbhost, dbuser, backupfile,
                         encoding='utf-8', keepownership=True, drop=True):
        """return a list of commands to restore a backup the given database"""
        cmds = []
        if drop:
            cmd = pgdbcmd('dropdb', dbhost, dbuser)
            cmd.append(dbname)
            cmds.append(' '.join(cmd))
        cmd = pgdbcmd('createdb -T template0 -E %s' % encoding, dbhost, dbuser)
        cmd.append(dbname)
        cmds.append(' '.join(cmd))
        cmd = pgdbcmd('pg_restore -Fc', dbhost, dbuser)
        cmd.append('--dbname %s' % dbname)
        if not keepownership:
            cmd.append('--no-owner')
        cmd.append(backupfile)
        cmds.append(' '.join(cmd))
        return cmds
                
    def sql_create_sequence(self, seq_name):
        return 'CREATE SEQUENCE %s;' % seq_name
    
    def sql_drop_sequence(self, seq_name):
        return 'DROP SEQUENCE %s;' % seq_name
    
    def sqls_increment_sequence(self, seq_name):
        return ("SELECT nextval('%s');" % seq_name,)
    
    def sql_temporary_table(self, table_name, table_schema,
                            drop_on_commit=True):
        if not drop_on_commit:
            return "CREATE TEMPORARY TABLE %s (%s);" % (table_name,
                                                        table_schema)    
        return "CREATE TEMPORARY TABLE %s (%s) ON COMMIT DROP;" % (table_name,
                                                                   table_schema)
    
    def create_database(self, cursor, dbname, owner=None, encoding='utf-8'):
        """create a new database"""
        sql = "CREATE DATABASE %(dbname)s"
        if owner:
            sql += " WITH OWNER=%(owner)s"
        if encoding:
            sql += " ENCODING='%(encoding)s'"
        cursor.execute(sql % locals())

    def create_language(self, cursor, extlang):
        """postgres specific method to install a procedural language on a database"""
        # make sure plpythonu is not directly in template1
        cursor.execute("SELECT * FROM pg_language WHERE lanname='%s';" % extlang)
        if cursor.fetchall():
            print '%s language already installed' % extlang
        else:
            cursor.execute('CREATE LANGUAGE %s' % extlang)
            print '%s language installed' % extlang

    def list_users(self, cursor, username=None):
        """return the list of existing database users"""
        if username:
            warn('username argument is deprecated, use user_exists method',
                 DeprecationWarning, stacklevel=2)
            return self.user_exists(cursor, username)
        cursor.execute("SELECT usename FROM pg_user")
        return [r[0] for r in cursor.fetchall()]

    def list_databases(self, cursor):
        """return the list of existing databases"""
        cursor.execute('SELECT datname FROM pg_database')
        return [r[0] for r in cursor.fetchall()]
    
    def list_tables(self, cursor):
        """return the list of tables of a database"""
        cursor.execute("SELECT tablename FROM pg_tables")
        return [r[0] for r in cursor.fetchall()]

    def list_indices(self, cursor, table=None):
        """return the list of indices of a database, only for the given table if specified"""
        sql = "SELECT indexname FROM pg_indexes"
        if table:
            sql += " WHERE LOWER(tablename)='%s'" % table.lower()
        cursor.execute(sql)
        return [r[0] for r in cursor.fetchall()]

            
class _SqliteAdvFuncHelper(_GenericAdvFuncHelper):
    """Generic helper, trying to provide generic way to implement
    specific functionnalities from others DBMS

    An exception is raised when the functionality is not emulatable
    """
    # modifiable but should not be shared
    FUNCTIONS = _GenericAdvFuncHelper.FUNCTIONS.copy()
    
    users_support = groups_support = False
    ilike_support = False
    
    def list_tables(self, cursor):
        """return the list of tables of a database"""
        # filter type='table' else we get indices as well
        cursor.execute("SELECT name FROM sqlite_master WHERE type='table'")
        return [r[0] for r in cursor.fetchall()]

    def list_indices(self, cursor, table=None):
        """return the list of indices of a database, only for the given table if specified"""
        sql = "SELECT name FROM sqlite_master WHERE type='index'"
        if table:
            sql += " AND LOWER(tbl_name)='%s'" % table.lower()
        cursor.execute(sql)
        return [r[0] for r in cursor.fetchall()]

    
class _MyAdvFuncHelper(_GenericAdvFuncHelper):
    """MySQL helper, taking advantage of postgres SEQUENCE support
    """
    needs_from_clause = True
    ilike_support = False # insensitive search by default

    # modifiable but should not be shared
    FUNCTIONS = _GenericAdvFuncHelper.FUNCTIONS.copy() 
    TYPE_MAPPING = _GenericAdvFuncHelper.TYPE_MAPPING.copy()
    TYPE_MAPPING['Password'] = 'tinyblob'
    TYPE_MAPPING['String'] = 'mediumtext'
    TYPE_MAPPING['Bytes'] = 'longblob'
    
    def system_database(self):
        """return the system database for the given driver"""
        return ''
    
    def backup_command(self, dbname, dbhost, dbuser, backupfile,
                       keepownership=True):
        """return a command to backup the given database"""
        # XXX compress
        return 'mysqldump -h %s -u %s -p -r %s %s' % (dbhost, dbuser, backupfile, dbname)
    
    def restore_commands(self, dbname, dbhost, dbuser, backupfile,
                         encoding='utf-8', keepownership=True, drop=True):
        """return a list of commands to restore a backup the given database"""
        cmds = []
        if drop:
            cmd = 'echo "DROP DATABASE %s;" | mysql -h %s -u %s -p' % (dbname, dbhost, dbuser)
            cmds.append(cmd)
        cmd = 'echo "%s;" | mysql -h %s -u %s -p' % (self.sql_create_database(dbname, encoding),
                                                  dbhost, dbuser)
        cmds.append(cmd)
        cmd = pgdbcmd('mysql -h %s -u %s -p < %s' % (dbname, dbhost, dbuser, backupfile))
        cmds.append(cmd)
        return cmds
                
    def sql_temporary_table(self, table_name, table_schema,
                            drop_on_commit=True):
        if not drop_on_commit:
            return "CREATE TEMPORARY TABLE %s (%s);" % (table_name,
                                                        table_schema)    
        return "CREATE TEMPORARY TABLE %s (%s) ON COMMIT DROP;" % (table_name,
                                                                   table_schema)
    
    def sql_create_database(self, dbname, encoding='utf-8'):
        sql = "CREATE DATABASE %(dbname)s"
        if encoding:
            sql += " CHARACTER SET %(encoding)s"
        return sql % locals()
    
    def create_database(self, cursor, dbname, owner=None, encoding='utf-8'):
        """create a new database"""
        cursor.execute(self.sql_create_database(dbname, encoding))
        if owner:
            cursor.execute('GRANT ALL ON `%s`.* to %s' % (dbname, owner))

    def boolean_value(self, value):
        if value:
            return True
        else:
            return False
        
    def list_users(self, cursor):
        """return the list of existing database users"""
        # Host, Password
        cursor.execute("SELECT User FROM mysql.user")
        return [r[0] for r in cursor.fetchall()]

    def list_databases(self, cursor):
        """return the list of existing databases"""
        cursor.execute('SHOW DATABASES')
        return [r[0] for r in cursor.fetchall()]
    
    def list_tables(self, cursor):
        """return the list of tables of a database"""
        cursor.execute("SHOW TABLES")
        return [r[0] for r in cursor.fetchall()]

    def list_indices(self, cursor, table=None):
        """return the list of indices of a database, only for the given table if specified"""
        if table:
            cursor.execute("SHOW INDEX FROM %s" % table)
            return [r[2] for r in cursor.fetchall()]
        allindices = []
        for table in self.list_tables(cursor):
            allindices += self.list_indices(cursor, table)
        return allindices


    
ADV_FUNC_HELPER_DIRECTORY = {'postgres': _PGAdvFuncHelper(),
                             'sqlite': _SqliteAdvFuncHelper(),
                             'mysql': _MyAdvFuncHelper(),
                             }



def get_adv_func_helper(driver):
    """returns an advanced function helper for the given driver"""
    return ADV_FUNC_HELPER_DIRECTORY[driver]

def register_function(driver, funcdef):
    ADV_FUNC_HELPER_DIRECTORY[driver].register_function(funcdef)