class BatchCopyTool(SrcDstTablesTool):

    """

    Copy data from one table to another, filtering by specified condition.

    """

    def __init__(self):

        SrcDstTablesTool.__init__(self, name='batchcopy', desc='')

    def specify_args(self):

        SrcDstTablesTool.specify_args(self)

        self.parser.add_argument('--table-name', type=str, help='Table to be copied.')

        self.parser.add_argument('--src-filter', type=str, help='WHERE condition for source query.')

        self.parser.add_argument('--file-with-ids', type=str, help='Read source IDs from file (each ID on new line). Use these in --src-filter as {ids}')

        self.parser.add_argument('--dst-exists', choices=['rollback', 'ignore', 'update'], default='rollback', help='What to do when destination record already exists.')

    def main(self):

        # read list of IDs from file

        ids = '<no IDs read>'

        if self.args.file_with_ids:

            with open(self.args.file_with_ids, 'r') as f:

                ids = ','.join(ln.rstrip() for ln in f.readlines())

        # read source data

        with self.pgm.cursor('src') as src_curs:

            condition = self.args.src_filter.format(ids=ids) or 'true'

            src_curs.execute('SELECT * FROM {} WHERE {}'.format(self.args.table_name, condition))

            #TODO:  ORDER BY id OFFSET 0 LIMIT 100

            data = src_curs.fetchall_dict()

            src_curs.connection.commit()

        with self.pgm.cursor('dst') as dst_curs:

            copied = 0

            for row in data:

                keys = ', '.join(row.keys())

                values_mask = ', '.join(['%s'] * len(row))

                query = 'INSERT INTO {} ({}) VALUES ({})'.format(self.args.table_name, keys, values_mask)

                try:

                    dst_curs.execute('SAVEPOINT the_query;')

                    dst_curs.execute(query, list(row.values()))

                    dst_curs.execute('RELEASE SAVEPOINT the_query;')

                    copied += 1

                except IntegrityError:

                    if self.args.dst_exists == 'rollback':

                        dst_curs.connection.rollback()

                        break

                    elif self.args.dst_exists == 'ignore':

                        dst_curs.execute('ROLLBACK TO SAVEPOINT the_query;')

                    elif self.args.dst_exists == 'update':

                        raise NotImplementedError()

            dst_curs.connection.commit()

        self.log.info('Copied %s rows.', copied)

cls = BatchCopyTool