#!/usr/bin/env python3
#
# This script contains the actual logic for upgrading from an old
# version of Zulip to the new version.  upgrade-zulip-stage-2 is
# always run from the new version of Zulip, so any bug fixes take
# effect on the very next upgrade.
import argparse
import glob
import hashlib
import logging
import os
import re
import shutil
import subprocess
import sys
import time
from typing import Literal, NoReturn, Optional

os.environ["PYTHONUNBUFFERED"] = "y"

# Force a known locale.  Some packages on PyPI fail to install in some locales.
os.environ["LC_ALL"] = "C.UTF-8"
os.environ["LANG"] = "C.UTF-8"
os.environ["LANGUAGE"] = "C.UTF-8"

sys.path.append(os.path.join(os.path.dirname(__file__), "..", ".."))
from scripts.lib.zulip_tools import (
    DEPLOYMENTS_DIR,
    assert_running_as_root,
    get_config,
    get_config_bool,
    get_config_file,
    get_zulip_pwent,
    listening_publicly,
    parse_os_release,
    parse_version_from,
    run_psql_as_postgres,
    start_arg_parser,
    su_to_zulip,
)

assert_running_as_root()

# Set a known, reliable PATH
os.environ["PATH"] = "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

logging.Formatter.converter = time.gmtime
logging.basicConfig(format="%(asctime)s upgrade-zulip-stage-2: %(message)s", level=logging.INFO)


def error_desupported_os(vendor: str, os_version: str) -> NoReturn:
    # Link to documentation for how to correctly upgrade the OS.
    logging.critical("Unsupported platform: %s %s", vendor, os_version)
    logging.info(
        "Sorry! The support for your OS has been discontinued.\n"
        "Please upgrade your OS to a supported release first.\n"
        "See https://zulip.readthedocs.io/en/latest/production/"
        "upgrade.html#upgrading-the-operating-system"
    )
    sys.exit(1)


# Do not upgrade on unsupported OS versions.
UNSUPPORTED_DISTROS = [
    ("ubuntu", "14.04"),
    ("ubuntu", "16.04"),
    ("ubuntu", "18.04"),
    ("debian", "9"),
    ("debian", "10"),
]
distro_info = parse_os_release()
vendor = distro_info["ID"]
os_version = distro_info["VERSION_ID"]

if (vendor, os_version) in UNSUPPORTED_DISTROS:
    error_desupported_os(vendor, os_version)

# make sure we have appropriate file permissions
os.umask(0o22)

restart_parser = start_arg_parser(action="restart", add_help=False)

parser = argparse.ArgumentParser(parents=[restart_parser])
parser.add_argument("deploy_path", metavar="deploy_path", help="Path to deployment directory")
parser.add_argument(
    "--skip-restart",
    action="store_true",
    help="Configure, but do not restart into, the new version; aborts if any system-wide changes would happen.",
)
parser.add_argument("--skip-puppet", action="store_true", help="Skip doing puppet/apt upgrades.")
parser.add_argument("--skip-migrations", action="store_true", help="Skip doing migrations.")
parser.add_argument(
    "--skip-downgrade-check",
    action="store_true",
    help="Skip the safety check to prevent database downgrades.",
)
parser.add_argument(
    "--from-git", action="store_true", help="Upgrading from git, so run update-prod-static."
)
parser.add_argument(
    "--ignore-static-assets",
    action="store_true",
    help="Do not attempt to copy/manage static assets.",
)
parser.add_argument(
    "--skip-purge-old-deployments", action="store_true", help="Skip purging old deployments."
)
parser.add_argument(
    "--audit-fts-indexes", action="store_true", help="Audit and fix full text search indexes."
)
args = parser.parse_args()

# There are two reasons we might want to do a "minimal change" which
# asserts puppet/database are unchanged: if we're setting up for a
# post-upgrade manual restart (--skip-restart), or if we're only
# restarting part of the system (--skip-tornado).
minimal_change = args.skip_restart or args.skip_tornado
if args.skip_restart and args.skip_tornado:
    logging.warning("Ignored --skip-tornado; all upgrades with --skip-restart skip all restarts.")
    args.skip_tornado = False
if minimal_change:
    if args.skip_restart:
        flagname = "--skip-restart"
    else:
        flagname = "--skip-tornado"
    if args.less_graceful:
        logging.warning("Ignored --less-graceful; %s is always graceful.", flagname)
        args.less_graceful = False
    if args.skip_migrations:
        logging.warning(
            "Ignored --skip-migrations; all upgrades with %s assert no migrations.", flagname
        )
        args.skip_migrations = False
    if args.skip_puppet:
        logging.warning(
            "Ignored --skip-puppet; all upgrades with %s assert no puppet changes.", flagname
        )
        args.skip_puppet = False

if not args.skip_puppet and args.less_graceful:
    logging.warning("Ignored --less-graceful; all upgrades without --skip-puppet are ungraceful.")

deploy_path = args.deploy_path
os.chdir(deploy_path)

config_file = get_config_file()

IS_SERVER_UP = True

if args.from_git:
    logging.info("Caching Zulip Git version...")
    subprocess.check_call(["./tools/cache-zulip-git-version"], preexec_fn=su_to_zulip)

from version import ZULIP_MERGE_BASE as NEW_ZULIP_MERGE_BASE
from version import ZULIP_VERSION as NEW_ZULIP_VERSION

old_version = parse_version_from(DEPLOYMENTS_DIR + "/current")
logging.info("Upgrading from %s to %s, in %s", old_version, NEW_ZULIP_VERSION, deploy_path)
old_merge_base = (
    parse_version_from(DEPLOYMENTS_DIR + "/current", merge_base=True) if args.from_git else ""
)

# Check if rabbitmq port 25672 is listening on anything except 127.0.0.1
rabbitmq_dist_listen = listening_publicly(25672)
# Check the erlang magic cookie size
cookie_size: Optional[int] = None
if os.path.exists("/var/lib/rabbitmq/.erlang.cookie"):
    with open("/var/lib/rabbitmq/.erlang.cookie") as cookie_fh:
        cookie_size = len(cookie_fh.readline())
else:
    logging.info("No RabbitMQ erlang cookie found, not auditing RabbitMQ security.")
if (minimal_change or args.skip_puppet) and rabbitmq_dist_listen:
    logging.error(
        "RabbitMQ is publicly-accessible on %s; this is a security vulnerability!",
        ", ".join(rabbitmq_dist_listen),
    )
    issue = "issue"
    if cookie_size is not None and cookie_size == 20:
        # See the below comment -- this is used as a lightweight
        # signal for a cookie made with Erlang's bad randomizer.
        logging.error(
            "RabbitMQ erlang cookie is insecure; this is a critical security vulnerability!"
        )
        issue = "issues"
    logging.error(
        "To fix the above security %s, re-run the upgrade without --skip-puppet "
        "(which may be set in /etc/zulip/zulip.conf), in order to restart the "
        "necessary services.  Running zulip-puppet-apply by itself is not sufficient.",
        issue,
    )
    sys.exit(1)


def shutdown_server() -> None:
    global IS_SERVER_UP

    if minimal_change:
        logging.info("Upgrade would require shutting down Zulip -- aborting!")
        sys.exit(1)

    if IS_SERVER_UP:
        logging.info("Stopping Zulip...")
        subprocess.check_call(["./scripts/stop-server"], preexec_fn=su_to_zulip)
        IS_SERVER_UP = False


if glob.glob("/usr/share/postgresql/*/extension/tsearch_extras.control"):
    # Remove legacy tsearch_extras package references
    run_psql_as_postgres(
        config_file=config_file,
        sql_query="DROP EXTENSION IF EXISTS tsearch_extras;",
    )
    subprocess.check_call(["apt-get", "remove", "-y", "postgresql-*-tsearch-extras"])

if not (minimal_change or args.skip_puppet):
    # We need to temporarily hold pgroonga, if installed -- upgrading
    # it without running the appropriate upgrade SQL can cause
    # PostgreSQL to crash
    if get_config_bool(config_file, "machine", "pgroonga"):
        subprocess.check_call(["apt-mark", "hold", "postgresql-*-pgdg-pgroonga"])
    logging.info("Upgrading system packages...")
    subprocess.check_call(["apt-get", "update"])
    subprocess.check_call(["apt-get", "-y", "--with-new-pkgs", "upgrade"])
    if get_config_bool(config_file, "machine", "pgroonga"):
        subprocess.check_call(["apt-mark", "unhold", "postgresql-*-pgdg-pgroonga"])

# To bootstrap zulip-puppet-apply, we need to install the system yaml
# package; new installs get this, but old installs may not have it.
if not os.path.exists("/usr/share/doc/python3-yaml"):
    logging.info("Installing system YAML package, for puppet...")
    subprocess.check_call(["apt-get", "install", "python3-yaml"])

if not os.path.exists(os.path.join(deploy_path, "zproject/prod_settings.py")):
    # This is normally done in unpack-zulip, but for upgrading from
    # zulip<1.4.0, we need to do it.  See discussion in commit 586b23637.
    os.symlink("/etc/zulip/settings.py", os.path.join(deploy_path, "zproject/prod_settings.py"))

# Now we should have an environment set up where we can run our tools;
# first, creating the production venv.
subprocess.check_call(
    [os.path.join(deploy_path, "scripts", "lib", "create-production-venv"), deploy_path]
)

# Check to make sure that this upgrade is not actually a database
# downgrade.
if not args.skip_downgrade_check:
    subprocess.check_call(
        [os.path.join(deploy_path, "scripts", "lib", "check-database-compatibility")],
        preexec_fn=su_to_zulip,
    )

# Make sure the right version of node is installed
subprocess.check_call([os.path.join(deploy_path, "scripts", "lib", "install-node")])

# Generate any new secrets that were added in the new version required.
# TODO: Do caching to only run this when it has changed.
subprocess.check_call(
    [os.path.join(deploy_path, "scripts", "setup", "generate_secrets.py"), "--production"]
)

# Adjust Puppet class names for the manifest renames in the 4.0 release
class_renames = {
    "zulip::app_frontend": "zulip::profile::app_frontend",
    "zulip::dockervoyager": "zulip::profile::docker",
    "zulip::memcached": "zulip::profile::memcached",
    "zulip::postgres_appdb_tuned": "zulip::profile::postgresql",
    "zulip::postgres_backups": "zulip::postgresql_backups",
    "zulip::rabbit": "zulip::profile::rabbitmq",
    "zulip::voyager": "zulip::profile::standalone",
}
classes = re.split(r"\s*,\s*", get_config(config_file, "machine", "puppet_classes"))
new_classes = [class_renames.get(c, c) for c in classes if c != "zulip::base"]
if classes != new_classes:
    if minimal_change:
        logging.error("Would need to adjust puppet classes -- aborting!")
        sys.exit(1)
    logging.info("Adjusting Puppet classes for renames...")
    subprocess.check_call(
        [
            "crudini",
            "--set",
            "/etc/zulip/zulip.conf",
            "machine",
            "puppet_classes",
            ", ".join(new_classes),
        ]
    )

# Unpleasant migration: Remove any legacy deployed copies of
# images-google-64 from before we renamed that emojiset to
# "googleblob":
emoji_path = "/home/zulip/prod-static/generated/emoji/images-google-64/1f32d.png"
if os.path.exists(emoji_path):
    with open(emoji_path, "rb") as f:
        emoji_data = f.read()
    emoji_sha = hashlib.sha1(emoji_data).hexdigest()
    if emoji_sha == "47033121dc20b376e0f86f4916969872ad22a293":
        if minimal_change:
            logging.error("Would need to delete images-google-64 -- aborting!")
            sys.exit(1)
        shutil.rmtree("/home/zulip/prod-static/generated/emoji/images-google-64")

# And then, building/installing the static assets.
if args.ignore_static_assets:
    # For the OS version upgrade use case, the static assets are
    # already in place, and we don't need to do anything.  Further,
    # neither of the options below will work for all installations,
    # because if we installed from Git, `prod-static/serve` may be
    # empty so we can't do the non-Git thing, whereas if we installed
    # from a tarball, we won't have a `tools/` directory and thus
    # cannot run `tools/update-prod-static`.
    pass
elif args.from_git:
    # Because `upgrade-zulip-from-git` needs to build static assets, it
    # is at risk of being OOM killed on systems with limited free RAM.
    mem_bytes = os.sysconf("SC_PAGE_SIZE") * os.sysconf("SC_PHYS_PAGES")
    mem_gib = mem_bytes / (1024.0**3)  # e.g. 3.74

    # Ideally, we'd have 2 thresholds here, depending on whether the
    # system is running queue workers multithreaded or multiprocess.
    # See puppet/zulip/manifests/app_frontend_base.pp for background.
    if mem_gib < 4.2:
        logging.info("Shutting down server to ensure sufficient free RAM for webpack.")
        shutdown_server()

    # Note: The fact that this is before we apply Puppet changes means
    # that we don't support adding new Puppet dependencies of
    # update-prod-static with the Git upgrade process.  But it'll fail
    # safely; this seems like a worthwhile tradeoff to minimize downtime.
    logging.info("Building static assets...")
    try:
        subprocess.check_call(["./tools/update-prod-static"], preexec_fn=su_to_zulip)
    except subprocess.CalledProcessError:
        logging.error("Failed to build static assets.")
        if IS_SERVER_UP:
            logging.error("Usually the cause is insufficient free RAM to run webpack.")
            logging.error("Try stopping the Zulip server (scripts/stop-server) and trying again.")
        sys.exit(1)

else:
    # Since this doesn't do any actual work, it's likely safe to have
    # this run before we apply Puppet changes (saving a bit of downtime).
    logging.info("Installing static assets...")
    subprocess.check_call(
        ["cp", "-rT", os.path.join(deploy_path, "prod-static/serve"), "/home/zulip/prod-static"],
        preexec_fn=su_to_zulip,
    )

# Perform system checks -- including database checks, so we don't need
# to do them when we do migrations, below.
if not args.skip_checks:
    subprocess.check_call(["./manage.py", "check", "--database", "default"], preexec_fn=su_to_zulip)

# Our next optimization is to check whether any migrations are needed
# before we start the critical section of the restart.  This saves
# about 1s of downtime in a no-op upgrade.  We omit this check if we
# already stopped the server above, due to low memory.
migrations_needed = False
if not IS_SERVER_UP:
    migrations_needed = True
elif not args.skip_migrations:
    logging.info("Checking for needed migrations")
    migrations_output = subprocess.check_output(
        ["./manage.py", "showmigrations", "--skip-checks"], preexec_fn=su_to_zulip, text=True
    )
    for ln in migrations_output.split("\n"):
        line_str = ln.strip()
        if line_str.startswith("[ ]"):
            migrations_needed = True

if minimal_change and migrations_needed:
    logging.error("Would need to apply migrations -- aborting!")
    sys.exit(1)

# If we're skipping tornado restarts, we need to ensure we keep the
# same cache prefix as we currently have.
if args.skip_tornado:
    shutil.copyfile("../current/var/remote_cache_prefix", "./var/remote_cache_prefix")

# If there are no migrations needed, we can fill the caches now,
# instead of after they run.
if not migrations_needed:
    subprocess.check_call(
        ["./manage.py", "fill_memcached_caches", "--skip-checks"], preexec_fn=su_to_zulip
    )

# Install hooks before we check for puppet changes, so we skip an
# unnecessary stop/start cycle if hook changes are the only ones.
logging.info("Installing hooks")
subprocess.check_call(
    ["./scripts/zulip-puppet-apply", "--tags", "hooks", "--force"],
)

# If we are planning on running puppet, we can pre-run it in --noop
# mode and see if it will actually make any changes; if not, we can
# skip it during the upgrade.  We omit this check if the server is
# already stopped, since it's not better than just pressing on.
has_puppet_changes = True
if not args.skip_puppet and IS_SERVER_UP:
    logging.info("Pre-checking for puppet changes...")
    try_puppet = subprocess.run(
        ["./scripts/zulip-puppet-apply", "--noop", "--force"], stdout=subprocess.DEVNULL
    )
    if try_puppet.returncode == 0:
        if minimal_change:
            logging.info("Verified no Puppet changes are necessary.")
        else:
            logging.info("No puppet changes found, skipping!")
        args.skip_puppet = True
        has_puppet_changes = False
    elif try_puppet.returncode == 2:
        logging.error("Puppet error -- aborting!")
        sys.exit(1)
    elif minimal_change:
        logging.error("Would need to apply puppet changes -- aborting!")
        sys.exit(1)


def run_hooks(kind: Literal["pre-deploy", "post-deploy"]) -> None:
    # Updates to the above literal to add a new hook type should
    # adjust puppet's `app_frontend_base.pp` as well.
    path = f"/etc/zulip/hooks/{kind}.d"
    if not os.path.exists(path):
        return
    # Pass in, via environment variables, the old/new "version
    # string" (which is a `git describe` output)
    env = os.environ.copy()
    env["ZULIP_OLD_VERSION"] = old_version
    env["ZULIP_NEW_VERSION"] = NEW_ZULIP_VERSION

    # preexec_fn=su_to_zulip normally handles this, but our explicit
    # env overrides that
    env["HOME"] = get_zulip_pwent().pw_dir

    def resolve_version_string(version: str) -> str:
        matches = re.search(r"-\d+-g([a-f0-9]{7,})$", version)
        to_parse = version
        if matches is not None:
            to_parse = matches.group(1)
        return subprocess.check_output(
            ["git", "rev-parse", to_parse], cwd=deploy_path, preexec_fn=su_to_zulip, text=True
        ).strip()

    if args.from_git:
        # If we have a git repo, we also resolve those `git describe`
        # values to full commit hashes, as well as provide the
        # merge-base of the old/new commits with mainline.
        env["ZULIP_OLD_COMMIT"] = resolve_version_string(old_version)
        env["ZULIP_NEW_COMMIT"] = resolve_version_string(NEW_ZULIP_VERSION)
        env["ZULIP_OLD_MERGE_BASE_COMMIT"] = resolve_version_string(old_merge_base)
        env["ZULIP_NEW_MERGE_BASE_COMMIT"] = resolve_version_string(NEW_ZULIP_MERGE_BASE)
    for script_name in sorted(f for f in os.listdir(path) if f.endswith(".hook")):
        subprocess.check_call(
            [os.path.join(path, script_name)],
            cwd=deploy_path,
            preexec_fn=su_to_zulip,
            env=env,
        )


if args.skip_restart:
    logging.info("Successfully configured in %s!", deploy_path)
else:
    # NOTE: Here begins the most likely critical period, where we may be
    # shutting down the server; we should strive to minimize the number of
    # steps that happen between here and the "Restarting Zulip" line
    # below.

    run_hooks("pre-deploy")

    if rabbitmq_dist_listen:
        shutdown_server()
        logging.info("Shutting down rabbitmq to adjust its ports...")
        subprocess.check_call(["/usr/sbin/service", "rabbitmq-server", "stop"])

    if cookie_size is not None and cookie_size == 20:
        # Checking for a 20-character cookie is used as a signal that it
        # was generated by Erlang's insecure randomizer, which only
        # provides between 20 and 36 bits of entropy; were it 20
        # characters long by a good randomizer, it would be 96 bits and
        # more than sufficient.  We generate, using good randomness, a
        # 255-character cookie, the max allowed length.
        shutdown_server()
        logging.info("Generating a secure erlang cookie...")
        subprocess.check_call(["./scripts/setup/generate-rabbitmq-cookie"])

    if not args.skip_puppet:
        # Puppet may adjust random services; to minimize risk of issues
        # due to inconsistent state, we shut down the server first.
        shutdown_server()
        logging.info("Applying Puppet changes...")
        subprocess.check_call(["./scripts/zulip-puppet-apply", "--force"])
        subprocess.check_call(["apt-get", "-y", "--with-new-pkgs", "upgrade"])
        # Puppet may have reloaded supervisor, and in so doing started
        # services; mark as potentially needing to stop the server.
        IS_SERVER_UP = True

    if migrations_needed:
        # Database migrations assume that they run on a database in
        # quiesced state.
        shutdown_server()
        logging.info("Applying database migrations...")
        subprocess.check_call(
            ["./manage.py", "migrate", "--noinput", "--skip-checks"], preexec_fn=su_to_zulip
        )

    logging.info("Restarting Zulip...")
    start_args = ["--skip-checks"]
    if migrations_needed:
        start_args.append("--fill-cache")
    if IS_SERVER_UP:
        if args.skip_tornado:
            start_args.append("--skip-tornado")
        if args.less_graceful:
            start_args.append("--less-graceful")
        subprocess.check_call(["./scripts/restart-server", *start_args], preexec_fn=su_to_zulip)
    else:
        subprocess.check_call(["./scripts/start-server", *start_args], preexec_fn=su_to_zulip)

    logging.info("Upgrade complete!")

    run_hooks("post-deploy")

if args.audit_fts_indexes:
    logging.info("Correcting full-text search indexes for updated dictionary files")
    logging.info("This may take a while but the server should work while it runs.")
    subprocess.check_call(
        ["./manage.py", "audit_fts_indexes", "--skip-checks"], preexec_fn=su_to_zulip
    )

if not args.skip_purge_old_deployments:
    logging.info("Purging old deployments...")
    subprocess.check_call(["./scripts/purge-old-deployments"])
else:
    logging.info("Skipping purging old deployments.")

if args.skip_puppet and has_puppet_changes:
    logging.info("Showing un-applied Puppet changes:")
    subprocess.check_call(["./scripts/zulip-puppet-apply", "--noop", "--show_diff"])