#!/usr/bin/env python3
"""Drop a SylkServer Cassandra table (DROP TABLE): the table and all its rows are gone.
sylk-create-cassandra-tables --apply creates it again, empty.

  sylk-table-delete <table> [--yes] [--config-dir PATH]

The table is one of the configured keyspace. It asks for the table name to be
typed again unless --yes is given.
"""
import argparse
import logging
import os
import sys

sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

from application import log
from application.process import process

logging.getLogger('cassandra').setLevel(logging.WARNING)


def quote(name):
    from cassandra.metadata import maybe_escape_name
    return maybe_escape_name(name)


def known_tables():
    """The tables of the SylkServer models, by name."""
    from cassandra.cqlengine.models import Model
    from sylk.applications.webrtcgateway.configuration import CassandraConfig
    from sylk.applications.webrtcgateway.models.storage import cassandra as models
    if CassandraConfig.push_tokens_table:
        models.PushTokens.__table_name__ = CassandraConfig.push_tokens_table
    return {value.__table_name__ for value in vars(models).values()
            if isinstance(value, type) and issubclass(value, Model) and value is not Model and getattr(value, '__table_name__', None)}


def main(table, assume_yes):
    from cassandra.cluster import EXEC_PROFILE_DEFAULT, Cluster, ExecutionProfile, NoHostAvailable
    from cassandra.policies import DCAwareRoundRobinPolicy
    from sylk.applications.webrtcgateway.configuration import CassandraConfig
    if not CassandraConfig.cluster_contact_points or not CassandraConfig.keyspace:
        log.warning('Cassandra is not configured (webrtcgateway.ini [Cassandra])')
        sys.exit(1)
    keyspace = CassandraConfig.keyspace
    profile = ExecutionProfile(load_balancing_policy=DCAwareRoundRobinPolicy(), request_timeout=120)
    cluster = Cluster(CassandraConfig.cluster_contact_points, protocol_version=4, execution_profiles={EXEC_PROFILE_DEFAULT: profile})
    try:
        session = cluster.connect()
    except NoHostAvailable:
        log.warning("Can't connect to Cassandra cluster")
        sys.exit(1)
    try:
        print(f'Cluster: {", ".join(CassandraConfig.cluster_contact_points)}')
        print(f'Keyspace: {keyspace}\n')
        metadata = cluster.metadata.keyspaces.get(keyspace)
        if metadata is None:
            log.warning(f'Keyspace {keyspace} does not exist')
            sys.exit(1)
        if table not in metadata.tables:
            log.warning(f'Table {table} does not exist in keyspace {keyspace}; tables: {", ".join(sorted(metadata.tables)) or "none"}')
            sys.exit(1)
        if table not in known_tables():
            print(f'Note: {table} is not a table of the SylkServer models')
        statement = f'DROP TABLE {quote(keyspace)}.{quote(table)}'
        print(statement)
        if not assume_yes:
            try:
                answer = input(f'Drop {keyspace}.{table}? Type the table name to confirm: ')
            except (EOFError, KeyboardInterrupt):
                print()
                sys.exit(1)
            if answer.strip() != table:
                print('Not confirmed, nothing done')
                sys.exit(1)
        session.execute(statement, timeout=300)
        print(f'{keyspace}.{table} dropped')
    finally:
        cluster.shutdown()


if __name__ == '__main__':
    process.configuration.subdirectory = 'sylkserver'

    parser = argparse.ArgumentParser(description='''Drop a SylkServer Cassandra table (DROP TABLE): the table and all its rows are gone.''')
    parser.add_argument('--config-dir', '--config-folder', dest='config_directory', default=None, metavar='PATH', help='Set a config directory.')
    parser.add_argument('table', help='the table name')
    parser.add_argument('--yes', action='store_true', help='do not ask for confirmation')
    options = parser.parse_args()

    if options.config_directory is not None:
        process.configuration.local_directory = options.config_directory

    from sylk.server import ServerConfig
    ServerConfig.__cfgtype__(ServerConfig.__cfgfile__)

    try:
        import cassandra.cluster  # noqa: F401
    except ImportError:
        log.warning('The Cassandra driver (python3-cassandra) is not installed')
        sys.exit(1)
    main(options.table.strip(), options.yes)