# Copyright 2020-present ScyllaDB
#
# SPDX-License-Identifier: AGPL-3.0-or-later
##################################################################

# Various utility functions which are useful for multiple tests.
# Note that fixtures aren't here - they are in conftest.py.

import string
import random
import time
import socket
import os
import collections
from contextlib import contextmanager

from cassandra.auth import PlainTextAuthProvider
from cassandra.cluster import Cluster, ConsistencyLevel, ExecutionProfile, EXEC_PROFILE_DEFAULT
from cassandra.policies import RoundRobinPolicy

def random_string(length=10, chars=string.ascii_uppercase + string.digits):
    return ''.join(random.choice(chars) for x in range(length))

def random_bytes(length=10):
    return bytearray(random.getrandbits(8) for _ in range(length))

# A function for picking a unique name for test keyspace or table.
# This name doesn't need to be quoted in CQL - it only contains
# lowercase letters, numbers, and underscores, and starts with a letter.
unique_name_prefix = 'cql_test_'
def unique_name():
    current_ms = int(round(time.time() * 1000))
    # If unique_name() is called twice in the same millisecond...
    if unique_name.last_ms >= current_ms:
        current_ms = unique_name.last_ms + 1
    unique_name.last_ms = current_ms
    return unique_name_prefix + str(current_ms)
unique_name.last_ms = 0

# Functions for picking a unique key to use when multiple tests want to use
# the same shared table and need to pick different keys so as not to collide.
# Because different runs do not share the same table (unique_name() above
# is used to pick the table name), the uniqueness of the keys we generate
# here does not need to be global - we can just use a simple counter to
# guarantee uniqueness.
def unique_key_string():
    unique_key_string.i += 1
    return 's' + str(unique_key_string.i)
unique_key_string.i = 0

def unique_key_int():
    unique_key_int.i += 1
    return unique_key_int.i
unique_key_int.i = 0

# A utility function for creating a new temporary keyspace with given options.
# It can be used in a "with", as:
#   with new_test_keyspace(cql, '...') as keyspace:
# This is not a fixture - see those in conftest.py.
@contextmanager
def new_test_keyspace(cql, opts):
    keyspace = unique_name()
    cql.execute("CREATE KEYSPACE " + keyspace + " " + opts)
    try:
        yield keyspace
    finally:
        cql.execute("DROP KEYSPACE " + keyspace)

# A utility function for creating a new temporary table with a given schema.
# Because Scylla becomes slower when a huge number of uniquely-named tables
# are created and deleted (see https://github.com/scylladb/scylla/issues/7620)
# we keep here a list of previously used but now deleted table names, and
# reuse one of these names when possible.
# This function can be used in a "with", as:
#   with create_table(cql, test_keyspace, '...') as table:
previously_used_table_names = []
@contextmanager
def new_test_table(cql, keyspace, schema, extra=""):
    global previously_used_table_names
    if not previously_used_table_names:
        previously_used_table_names.append(unique_name())
    table_name = previously_used_table_names.pop()
    table = keyspace + "." + table_name
    cql.execute("CREATE TABLE " + table + "(" + schema + ")" + extra)
    try:
        yield table
    finally:
        cql.execute("DROP TABLE " + table)
        previously_used_table_names.append(table_name)

# A utility function for creating a new temporary user-defined type.
@contextmanager
def new_type(cql, keyspace, cmd):
    type_name = keyspace + "." + unique_name()
    cql.execute("CREATE TYPE " + type_name + " " + cmd)
    try:
        yield type_name
    finally:
        cql.execute("DROP TYPE " + type_name)

# A utility function for creating a new temporary user-defined function.
@contextmanager
def new_function(cql, keyspace, body, name=None):
    fun = name if name else unique_name()
    cql.execute(f"CREATE FUNCTION {keyspace}.{fun} {body}")
    try:
        yield fun
    finally:
        cql.execute(f"DROP FUNCTION {keyspace}.{fun}")

# A utility function for creating a new temporary user-defined aggregate.
@contextmanager
def new_aggregate(cql, keyspace, body):
    aggr = unique_name()
    cql.execute(f"CREATE AGGREGATE {keyspace}.{aggr} {body}")
    try:
        yield aggr
    finally:
        cql.execute(f"DROP AGGREGATE {keyspace}.{aggr}")

# A utility function for creating a new temporary materialized view in
# an existing table.
@contextmanager
def new_materialized_view(cql, table, select, pk, where):
    keyspace = table.split('.')[0]
    mv = keyspace + "." + unique_name()
    cql.execute(f"CREATE MATERIALIZED VIEW {mv} AS SELECT {select} FROM {table} WHERE {where} PRIMARY KEY ({pk})")
    try:
        yield mv
    finally:
        cql.execute(f"DROP MATERIALIZED VIEW {mv}")

# A utility function for creating a new temporary secondary index of
# an existing table.
@contextmanager
def new_secondary_index(cql, table, column, name='', extra=''):
    keyspace = table.split('.')[0]
    if not name:
        name = unique_name()
    cql.execute(f"CREATE INDEX {name} ON {table} ({column}) {extra}")
    try:
        yield f"{keyspace}.{name}"
    finally:
        cql.execute(f"DROP INDEX {keyspace}.{name}")

# Helper function for establishing a connection with given username and password
@contextmanager
def cql_session(host, port, ssl, username, password):
    profile = ExecutionProfile(
        load_balancing_policy=RoundRobinPolicy(),
        consistency_level=ConsistencyLevel.LOCAL_QUORUM,
        serial_consistency_level=ConsistencyLevel.LOCAL_SERIAL,
        # The default timeout (in seconds) for execute() commands is 10, which
        # should have been more than enough, but in some extreme cases with a
        # very slow debug build running on a very busy machine and a very slow
        # request (e.g., a DROP KEYSPACE needing to drop multiple tables)
        # 10 seconds may not be enough, so let's increase it. See issue #7838.
        request_timeout = 120)
    if ssl:
        # Scylla does not support any earlier TLS protocol. If you try,
        # you will get mysterious EOF errors (see issue #6971) :-(
        ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLSv1_2)
    else:
        ssl_context = None
    cluster = Cluster(execution_profiles={EXEC_PROFILE_DEFAULT: profile},
        contact_points=[host],
        port=int(port),
        # TODO: make the protocol version an option, to allow testing with
        # different versions. If we drop this setting completely, it will
        # mean pick the latest version supported by the client and the server.
        protocol_version=4,
        auth_provider=PlainTextAuthProvider(username=username, password=password),
        ssl_context=ssl_context,
    )
    yield cluster.connect()
    cluster.shutdown()

@contextmanager
def new_user(cql, username=''):
    if not username:
        username = unique_name()
    cql.execute(f"CREATE ROLE {username} WITH PASSWORD = '{username}' AND LOGIN = true")
    try:
        yield username
    finally:
        cql.execute(f"DROP ROLE {username}")

@contextmanager
def new_session(cql, username):
    endpoint = cql.hosts[0].endpoint
    with cql_session(host=endpoint.address, port=endpoint.port, ssl=False, username=username, password=username) as session:
        yield session
        session.shutdown()

def project(column_name_string, rows):
    """Returns a list of column values from each of the rows."""
    return [getattr(r, column_name_string) for r in rows]

# Utility function for trying to find a local process which is listening to
# the address and port to which our our CQL connection is connected. If such a
# process exists, return its process id (as a string). Otherwise, return None.
# Note that the local process needs to belong to the same user running this
# test, or it cannot be found.
def local_process_id(cql):
    ip = socket.gethostbyname(cql.cluster.contact_points[0])
    port = cql.cluster.port
    # Implement something like the shell "lsof -Pni @{ip}:{port}", just
    # using /proc without any external shell command.
    # First, we look in /proc/net/tcp for a LISTEN socket (state 0x0A) at the
    # desired local address. The address is specially-formatted hex of the ip
    # and port, with 0100007F:2352 for 127.0.0.1:9042. We check for two
    # listening addresses: one is the specific IP address given, and the
    # other is listening on address 0 (INADDR_ANY).
    ip2hex = lambda ip: ''.join([f'{int(x):02X}' for x in reversed(ip.split('.'))])
    port2hex = lambda port: f'{int(port):04X}'
    addr1 = ip2hex(ip) + ':' + port2hex(port)
    addr2 = ip2hex('0.0.0.0') + ':' + port2hex(port)
    LISTEN = '0A'
    with open('/proc/net/tcp', 'r') as f:
        for line in f:
            cols = line.split()
            if cols[3] == LISTEN and (cols[1] == addr1 or cols[1] == addr2):
                inode = cols[9]
                break
        else:
            # Didn't find a process listening on the given address
            return None
    # Now look in /proc/*/fd/* for processes that have this socket "inode"
    # as one of its open files. We can only find a process that belongs to
    # the same user.
    target = f'socket:[{inode}]'
    for proc in os.listdir('/proc'):
        if not proc.isnumeric():
            continue
        dir = f'/proc/{proc}/fd/'
        try:
            for fd in os.listdir(dir):
                if os.readlink(dir + fd) == target:
                    # Found the process!
                    return proc
        except:
            # Ignore errors. We can't check processes we don't own.
            pass
    return None

# user_type("a", 1, "b", 2) creates a named tuple with component names "a", "b"
# and values 1, 2. The return of this function can be used to bind to a UDT.
# The number of arguments is assumed to be even.
def user_type(*args):
    return collections.namedtuple('user_type', args[::2])(*args[1::2])