"""
MySQLdb Cursors
---------------

This module implements Cursors of various types for MySQLdb. By
default, MySQLdb uses the Cursor class.

"""

__revision__ = "$Revision$"[11:-2]
__author__ = "$Author$"[9:-2]

import re
import sys
import weakref

INSERT_VALUES = re.compile(r"(?P<start>.+values\s*)"
                           r"(?P<values>\(((?<!\\)'[^\)]*?\)[^\)]*(?<!\\)?'|[^\(\)]|(?:\([^\)]*\)))+\))"
                           r"(?P<end>.*)", re.I)


class Cursor(object):
    
    """A base for Cursor classes. Useful attributes:
    
    description
        A tuple of DB API 7-tuples describing the columns in
        the last executed query; see PEP-249 for details.

    description_flags
        Tuple of column flags for last query, one entry per column
        in the result set. Values correspond to those in
        MySQLdb.constants.FLAG. See MySQL documentation (C API)
        for more information. Non-standard extension.
    
    arraysize
        default number of rows fetchmany() will fetch

    """

    from MySQLdb.exceptions import MySQLError, Warning, Error, InterfaceError, \
         DatabaseError, DataError, OperationalError, IntegrityError, \
         InternalError, ProgrammingError, NotSupportedError

    _defer_warnings = False
    _fetch_type = None

    def __init__(self, connection, encoders):
        from MySQLdb.converters import default_decoders
        self.connection = weakref.proxy(connection)
        self.description = None
        self.description_flags = None
        self.rowcount = -1
        self.arraysize = 1
        self._executed = None
        self.lastrowid = None
        self.messages = []
        self.errorhandler = connection.errorhandler
        self._result = None
        self._warnings = 0
        self._info = None
        self.rownumber = None
        self._encoders = encoders

    def __del__(self):
        self.close()
        self.errorhandler = None
        self._result = None

    def close(self):
        """Close the cursor. No further queries will be possible."""
        if not self.connection:
            return
        try:
            while self.nextset():
                pass
        except:
            pass
        self.connection = None

    def _check_executed(self):
        """Ensure that .execute() has been called."""
        if not self._executed:
            self.errorhandler(self, self.ProgrammingError, "execute() first")

    def _warning_check(self):
        """Check for warnings, and report via the warnings module."""
        from warnings import warn
        if self._warnings:
            warnings = self._get_db()._show_warnings()
            if warnings:
                # This is done in two loops in case
                # Warnings are set to raise exceptions.
                for warning in warnings:
                    self.messages.append((self.Warning, warning))
                for warning in warnings:
                    warn(warning[-1], self.Warning, 3)
            elif self._info:
                self.messages.append((self.Warning, self._info))
                warn(self._info, self.Warning, 3)

    def nextset(self):
        """Advance to the next result set.

        Returns None if there are no more result sets.
        """
        if self._executed:
            self.fetchall()
        del self.messages[:]

        connection = self._get_db()
        num_rows = connection.next_result()
        if num_rows == -1:
            return None
        self._do_get_result()
        self._post_get_result()
        self._warning_check()
        return True

    def _do_get_result(self):
        """Get the result from the last query."""
        connection = self._get_db()
        self._result = self._get_result()
        self.rowcount = connection.affected_rows()
        self.rownumber = 0
        self.description = self._result and self._result.describe() or None
        self.description_flags = self._result and self._result.field_flags() or None
        self.lastrowid = connection.insert_id()
        self._warnings = connection.warning_count()
        self._info = connection.info()
    
    def setinputsizes(self, *args):
        """Does nothing, required by DB API."""
      
    def setoutputsizes(self, *args):
        """Does nothing, required by DB API."""

    def _get_db(self):
        """Get the database connection.
        
        Raises ProgrammingError if the connection has been closed."""
        if not self.connection:
            self.errorhandler(self, self.ProgrammingError, "cursor closed")
        return self.connection._db
    
    def execute(self, query, args=None):
        """Execute a query.
        
        query -- string, query to execute on server
        args -- optional sequence or mapping, parameters to use with query.

        Note: If args is a sequence, then %s must be used as the
        parameter placeholder in the query. If a mapping is used,
        %(key)s must be used as the placeholder.

        Returns long integer rows affected, if any

        """
        del self.messages[:]
        db = self._get_db()
        charset = db.character_set_name()
        if isinstance(query, unicode):
            query = query.encode(charset)
        try:
            if args is not None:
                query = query % tuple(map(self.connection.literal, args))
            result = self._query(query)
        except TypeError, msg:
            if msg.args[0] in ("not enough arguments for format string",
                               "not all arguments converted"):
                self.messages.append((self.ProgrammingError, msg.args[0]))
                self.errorhandler(self, self.ProgrammingError, msg.args[0])
            else:
                self.messages.append((TypeError, msg))
                self.errorhandler(self, TypeError, msg)
        except:
            exc, value, traceback = sys.exc_info()
            del traceback
            self.messages.append((exc, value))
            self.errorhandler(self, exc, value)
            
        self._executed = query
        if not self._defer_warnings:
            self._warning_check()
        return result

    def executemany(self, query, args):
        """Execute a multi-row query.
        
        query
        
            string, query to execute on server

        args

            Sequence of sequences or mappings, parameters to use with
            query.
            
        Returns long integer rows affected, if any.
        
        This method improves performance on multiple-row INSERT and
        REPLACE. Otherwise it is equivalent to looping over args with
        execute().

        """
        del self.messages[:]
        db = self._get_db()
        if not args:
            return
        charset = self.connection.character_set_name()
        if isinstance(query, unicode):
            query = query.encode(charset)
        matched = INSERT_VALUES.match(query)
        if not matched:
            self.rowcount = sum([ self.execute(query, arg) for arg in args ])
            return self.rowcount
        
        start = matched.group('start')
        end = matched.group('end')
        values = matched.group('values')
 
        try:
            sql_params = ( values % tuple(map(self.connection.literal, row)) for row in args )
            multirow_query = '\n'.join([start, ',\n'.join(sql_params), end])
            self._executed = multirow_query
            self.rowcount = int(self._query(multirow_query))

        except TypeError, msg:
            if msg.args[0] in ("not enough arguments for format string",
                               "not all arguments converted"):
                self.messages.append((self.ProgrammingError, msg.args[0]))
                self.errorhandler(self, self.ProgrammingError, msg.args[0])
            else:
                self.messages.append((TypeError, msg))
                self.errorhandler(self, TypeError, msg)
        except:
            exc, value, traceback = sys.exc_info()
            del traceback
            self.errorhandler(self, exc, value)
        
        if not self._defer_warnings:
            self._warning_check()
        return self.rowcount
    
    def callproc(self, procname, args=()):
        """Execute stored procedure procname with args
        
        procname
            string, name of procedure to execute on server

        args
            Sequence of parameters to use with procedure

        Returns the original args.

        Compatibility warning: PEP-249 specifies that any modified
        parameters must be returned. This is currently impossible
        as they are only available by storing them in a server
        variable and then retrieved by a query. Since stored
        procedures return zero or more result sets, there is no
        reliable way to get at OUT or INOUT parameters via callproc.
        The server variables are named @_procname_n, where procname
        is the parameter above and n is the position of the parameter
        (from zero). Once all result sets generated by the procedure
        have been fetched, you can issue a SELECT @_procname_0, ...
        query using .execute() to get any OUT or INOUT values.

        Compatibility warning: The act of calling a stored procedure
        itself creates an empty result set. This appears after any
        result sets generated by the procedure. This is non-standard
        behavior with respect to the DB-API. Be sure to use nextset()
        to advance through all result sets; otherwise you may get
        disconnected.
        """

        db = self._get_db()
        charset = self.connection.character_set_name()
        for index, arg in enumerate(args):
            query = "SET @_%s_%d=%s" % (procname, index,
                                        self.connection.literal(arg))
            if isinstance(query, unicode):
                query = query.encode(charset)
            self._query(query)
            self.nextset()
            
        query = "CALL %s(%s)" % (procname,
                                 ','.join(['@_%s_%d' % (procname, i)
                                           for i in range(len(args))]))
        if isinstance(query, unicode):
            query = query.encode(charset)
        self._query(query)
        self._executed = query
        if not self._defer_warnings:
            self._warning_check()
        return args
    
    def _do_query(self, query):
        """Low-levey query wrapper. Overridden by MixIns."""
        connection = self._get_db()
        self._executed = query
        connection.query(query)
        self._do_get_result()
        return self.rowcount

    def _fetch_row(self, size=1):
        """Low-level fetch_row wrapper."""
        if not self._result:
            return ()
        return self._result.fetch_row(size, self._fetch_type)

    def __iter__(self):
        return iter(self.fetchone, None)

    def _get_result(self):
        """Low-level; uses mysql_store_result()"""
        return self._get_db().store_result()

    def _query(self, query):
        """Low-level; executes query, gets result, and returns rowcount."""
        rowcount = self._do_query(query)
        self._post_get_result()
        return rowcount

    def _post_get_result(self):
        """Low-level"""
        self._rows = self._fetch_row(0)
        self._result = None

    def fetchone(self):
        """Fetches a single row from the cursor. None indicates that
        no more rows are available."""
        self._check_executed()
        if self.rownumber >= len(self._rows):
            return None
        result = self._rows[self.rownumber]
        self.rownumber += 1
        return result

    def fetchmany(self, size=None):
        """Fetch up to size rows from the cursor. Result set may be smaller
        than size. If size is not defined, cursor.arraysize is used."""
        self._check_executed()
        end = self.rownumber + (size or self.arraysize)
        result = self._rows[self.rownumber:end]
        self.rownumber = min(end, len(self._rows))
        return result

    def fetchall(self):
        """Fetchs all available rows from the cursor."""
        self._check_executed()
        if self.rownumber:
            result = self._rows[self.rownumber:]
        else:
            result = self._rows
        self.rownumber = len(self._rows)
        return result
    
    def scroll(self, value, mode='relative'):
        """Scroll the cursor in the result set to a new position according
        to mode.
        
        If mode is 'relative' (default), value is taken as offset to
        the current position in the result set, if set to 'absolute',
        value states an absolute target position."""
        self._check_executed()
        if mode == 'relative':
            row = self.rownumber + value
        elif mode == 'absolute':
            row = value
        else:
            self.errorhandler(self, self.ProgrammingError,
                              "unknown scroll mode %s" % `mode`)
        if row < 0 or row >= len(self._rows):
            self.errorhandler(self, IndexError, "out of range")
        self.rownumber = row

    def __iter__(self):
        self._check_executed()
        result = self.rownumber and self._rows[self.rownumber:] or self._rows
        return iter(result)
    
    _fetch_type = 0