#!/usr/bin/env python3
import argparse
import datetime
import errno
import hashlib
import logging
import os
import pwd
import re
import shlex
import shutil
import subprocess
import sys
import tempfile
import time
import json
import uuid
import configparser

if False:
    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
    from typing import Sequence, Set, Any, Dict, List, Optional

DEPLOYMENTS_DIR = "/home/zulip/deployments"
LOCK_DIR = os.path.join(DEPLOYMENTS_DIR, "lock")
TIMESTAMP_FORMAT = '%Y-%m-%d-%H-%M-%S'

# Color codes
OKBLUE = '\033[94m'
OKGREEN = '\033[92m'
WARNING = '\033[93m'
FAIL = '\033[91m'
ENDC = '\033[0m'
BLACKONYELLOW = '\x1b[0;30;43m'
WHITEONRED = '\x1b[0;37;41m'
BOLDRED = '\x1B[1;31m'

GREEN = '\x1b[32m'
YELLOW = '\x1b[33m'
BLUE = '\x1b[34m'
MAGENTA = '\x1b[35m'
CYAN = '\x1b[36m'

def overwrite_symlink(src, dst):
    # type: (str, str) -> None
    while True:
        tmp = tempfile.mktemp(
            prefix='.' + os.path.basename(dst) + '.',
            dir=os.path.dirname(dst))
        try:
            os.symlink(src, tmp)
        except FileExistsError:
            continue
        break
    try:
        os.rename(tmp, dst)
    except Exception:
        os.remove(tmp)
        raise

def parse_cache_script_args(description):
    # type: (str) -> argparse.Namespace
    parser = argparse.ArgumentParser(description=description)

    parser.add_argument(
        "--threshold", dest="threshold_days", type=int, default=14,
        nargs="?", metavar="<days>", help="Any cache which is not in "
        "use by a deployment not older than threshold days(current "
        "installation in dev) and older than threshold days will be "
        "deleted. (defaults to 14)")
    parser.add_argument(
        "--dry-run", dest="dry_run", action="store_true",
        help="If specified then script will only print the caches "
        "that it will delete/keep back. It will not delete any cache.")
    parser.add_argument(
        "--verbose", dest="verbose", action="store_true",
        help="If specified then script will print a detailed report "
        "of what is being will deleted/kept back.")

    args = parser.parse_args()
    args.verbose |= args.dry_run    # Always print a detailed report in case of dry run.
    return args

def get_deployment_version(extract_path):
    # type: (str) -> str
    version = '0.0.0'
    for item in os.listdir(extract_path):
        item_path = os.path.join(extract_path, item)
        if item.startswith('zulip-server') and os.path.isdir(item_path):
            with open(os.path.join(item_path, 'version.py')) as f:
                result = re.search('ZULIP_VERSION = "(.*)"', f.read())
                if result:
                    version = result.groups()[0]
            break
    return version

def is_invalid_upgrade(current_version, new_version):
    # type: (str, str) -> bool
    if new_version > '1.4.3' and current_version <= '1.3.10':
        return True
    return False

def subprocess_text_output(args):
    # type: (Sequence[str]) -> str
    return subprocess.check_output(args, universal_newlines=True).strip()

def su_to_zulip():
    # type: () -> None
    pwent = pwd.getpwnam("zulip")
    os.setgid(pwent.pw_gid)
    os.setuid(pwent.pw_uid)
    os.environ['HOME'] = os.path.abspath(os.path.join(DEPLOYMENTS_DIR, '..'))

def make_deploy_path():
    # type: () -> str
    timestamp = datetime.datetime.now().strftime(TIMESTAMP_FORMAT)
    return os.path.join(DEPLOYMENTS_DIR, timestamp)

if __name__ == '__main__':
    cmd = sys.argv[1]
    if cmd == 'make_deploy_path':
        print(make_deploy_path())

def get_dev_uuid_var_path(create_if_missing=False):
    # type: (bool) -> str
    zulip_path = os.path.realpath(os.path.dirname(os.path.dirname(
        os.path.dirname(os.path.realpath(__file__)))))
    uuid_path = os.path.join(os.path.realpath(os.path.dirname(zulip_path)), ".zulip-dev-uuid")
    if os.path.exists(uuid_path):
        with open(uuid_path) as f:
            zulip_uuid = f.read().strip()
    else:
        if create_if_missing:
            zulip_uuid = str(uuid.uuid4())
            # We need sudo here, since the path will be under /srv/ in the
            # development environment.
            subprocess.check_call(["sudo", "/bin/bash", "-c",
                                   "echo %s > %s" % (zulip_uuid, uuid_path)])
        else:
            raise AssertionError("Missing UUID file; please run tools/provision!")

    result_path = os.path.join(zulip_path, "var", zulip_uuid)
    os.makedirs(result_path, exist_ok=True)
    return result_path

def get_deployment_lock(error_rerun_script):
    # type: (str) -> None
    start_time = time.time()
    got_lock = False
    while time.time() - start_time < 300:
        try:
            os.mkdir(LOCK_DIR)
            got_lock = True
            break
        except OSError:
            print(WARNING + "Another deployment in progress; waiting for lock... " +
                  "(If no deployment is running, rmdir %s)" % (LOCK_DIR,) + ENDC)
            sys.stdout.flush()
            time.sleep(3)

    if not got_lock:
        print(FAIL + "Deployment already in progress.  Please run\n" +
              "  %s\n" % (error_rerun_script,) +
              "manually when the previous deployment finishes, or run\n" +
              "  rmdir %s\n"  % (LOCK_DIR,) +
              "if the previous deployment crashed." +
              ENDC)
        sys.exit(1)

def release_deployment_lock():
    # type: () -> None
    shutil.rmtree(LOCK_DIR)

def run(args, **kwargs):
    # type: (Sequence[str], **Any) -> None
    # Output what we're doing in the `set -x` style
    print("+ %s" % (" ".join(map(shlex.quote, args)),))

    try:
        subprocess.check_call(args, **kwargs)
    except subprocess.CalledProcessError:
        print()
        print(WHITEONRED + "Error running a subcommand of %s: %s" %
              (sys.argv[0], " ".join(map(shlex.quote, args))) +
              ENDC)
        print(WHITEONRED + "Actual error output for the subcommand is just above this." +
              ENDC)
        print()
        raise

def log_management_command(cmd, log_path):
    # type: (str, str) -> None
    log_dir = os.path.dirname(log_path)
    if not os.path.exists(log_dir):
        os.makedirs(log_dir)

    formatter = logging.Formatter("%(asctime)s: %(message)s")
    file_handler = logging.FileHandler(log_path)
    file_handler.setFormatter(formatter)
    logger = logging.getLogger("zulip.management")
    logger.addHandler(file_handler)
    logger.setLevel(logging.INFO)

    logger.info("Ran '%s'" % (cmd,))

def get_environment():
    # type: () -> str
    if os.path.exists(DEPLOYMENTS_DIR):
        return "prod"
    if os.environ.get("TRAVIS"):
        return "travis"
    return "dev"

def get_recent_deployments(threshold_days):
    # type: (int) -> Set[str]
    # Returns a list of deployments not older than threshold days
    # including `/root/zulip` directory if it exists.
    recent = set()
    threshold_date = datetime.datetime.now() - datetime.timedelta(days=threshold_days)
    for dir_name in os.listdir(DEPLOYMENTS_DIR):
        target_dir = os.path.join(DEPLOYMENTS_DIR, dir_name)
        if not os.path.isdir(target_dir):
            # Skip things like uwsgi sockets, symlinks, etc.
            continue
        if not os.path.exists(os.path.join(target_dir, "zerver")):
            # Skip things like "lock" that aren't actually a deployment directory
            continue
        try:
            date = datetime.datetime.strptime(dir_name, TIMESTAMP_FORMAT)
            if date >= threshold_date:
                recent.add(target_dir)
        except ValueError:
            # Always include deployments whose name is not in the format of a timestamp.
            recent.add(target_dir)
            # If it is a symlink then include the target as well.
            if os.path.islink(target_dir):
                recent.add(os.path.realpath(target_dir))
    if os.path.exists("/root/zulip"):
        recent.add("/root/zulip")
    return recent

def get_threshold_timestamp(threshold_days):
    # type: (int) -> int
    # Given number of days, this function returns timestamp corresponding
    # to the time prior to given number of days.
    threshold = datetime.datetime.now() - datetime.timedelta(days=threshold_days)
    threshold_timestamp = int(time.mktime(threshold.utctimetuple()))
    return threshold_timestamp

def get_caches_to_be_purged(caches_dir, caches_in_use, threshold_days):
    # type: (str, Set[str], int) -> Set[str]
    # Given a directory containing caches, a list of caches in use
    # and threshold days, this function return a list of caches
    # which can be purged. Remove the cache only if it is:
    # 1: Not in use by the current installation(in dev as well as in prod).
    # 2: Not in use by a deployment not older than `threshold_days`(in prod).
    # 3: Not in use by '/root/zulip'.
    # 4: Not older than `threshold_days`.
    caches_to_purge = set()
    threshold_timestamp = get_threshold_timestamp(threshold_days)
    for cache_dir_base in os.listdir(caches_dir):
        cache_dir = os.path.join(caches_dir, cache_dir_base)
        if cache_dir in caches_in_use:
            # Never purge a cache which is in use.
            continue
        if os.path.getctime(cache_dir) < threshold_timestamp:
            caches_to_purge.add(cache_dir)
    return caches_to_purge

def purge_unused_caches(caches_dir, caches_in_use, cache_type, args):
    # type: (str, Set[str], str, argparse.Namespace) -> None
    all_caches = set([os.path.join(caches_dir, cache) for cache in os.listdir(caches_dir)])
    caches_to_purge = get_caches_to_be_purged(caches_dir, caches_in_use, args.threshold_days)
    caches_to_keep = all_caches - caches_to_purge

    may_be_perform_purging(
        caches_to_purge, caches_to_keep, cache_type, args.dry_run, args.verbose)
    if args.verbose:
        print("Done!")

def generate_sha1sum_emoji(zulip_path):
    # type: (str) -> str
    ZULIP_EMOJI_DIR = os.path.join(zulip_path, 'tools', 'setup', 'emoji')
    sha = hashlib.sha1()

    filenames = ['emoji_map.json', 'build_emoji', 'emoji_setup_utils.py', 'emoji_names.py']

    for filename in filenames:
        file_path = os.path.join(ZULIP_EMOJI_DIR, filename)
        with open(file_path, 'rb') as reader:
            sha.update(reader.read())

    # Take into account the version of `emoji-datasource-google` package
    # while generating success stamp.
    PACKAGE_FILE_PATH = os.path.join(zulip_path, 'package.json')
    with open(PACKAGE_FILE_PATH, 'r') as fp:
        parsed_package_file = json.load(fp)
    dependency_data = parsed_package_file['dependencies']

    if 'emoji-datasource-google' in dependency_data:
        emoji_datasource_version = dependency_data['emoji-datasource-google'].encode('utf-8')
    else:
        emoji_datasource_version = b"0"
    sha.update(emoji_datasource_version)

    return sha.hexdigest()

def may_be_perform_purging(dirs_to_purge, dirs_to_keep, dir_type, dry_run, verbose):
    # type: (Set[str], Set[str], str, bool, bool) -> None
    if dry_run:
        print("Performing a dry run...")
    else:
        print("Cleaning unused %ss..." % (dir_type,))

    for directory in dirs_to_purge:
        if verbose:
            print("Cleaning unused %s: %s" % (dir_type, directory))
        if not dry_run:
            subprocess.check_call(["sudo", "rm", "-rf", directory])

    for directory in dirs_to_keep:
        if verbose:
            print("Keeping used %s: %s" % (dir_type, directory))

def parse_lsb_release():
    # type: () -> Dict[str, str]
    distro_info = {}  # type: Dict[str, str]
    if os.path.exists("/etc/redhat-release"):
        with open('/etc/redhat-release', 'r') as fp:
            info = fp.read().strip().split(' ')
        vendor = info[0]
        if vendor == 'Centos':
            # E.g. "CentOS Linux release 7.5.1804 (Core)"
            codename = vendor.lower() + info[3][0]
        elif vendor == 'Fedora':
            # E.g. "Fedora release 29 (Twenty Nine)"
            codename = vendor.lower() + info[2]
        elif vendor == 'Red':
            # E.g. "Red Hat Enterprise Linux Server release 7.6 (Maipo)"
            vendor = 'RedHat'
            codename = 'rhel' + info[6][0]  # 7
        distro_info = dict(
            DISTRIB_CODENAME=codename,
            DISTRIB_ID=vendor
        )
        return distro_info
    try:
        # For performance reasons, we read /etc/lsb-release directly,
        # rather than using the lsb_release command; this saves ~50ms
        # in several places in provisioning and the installer
        with open('/etc/lsb-release', 'r') as fp:
            data = [line.strip().split('=') for line in fp]
        for k, v in data:
            if k not in ['DISTRIB_CODENAME', 'DISTRIB_ID']:
                # We only return to the caller the values that we get
                # from lsb_release in the exception code path.
                continue
            distro_info[k] = v
    except FileNotFoundError:
        # Unfortunately, Debian stretch doesn't yet have an
        # /etc/lsb-release, so we instead fetch the pieces of data
        # that we use from the `lsb_release` command directly.
        vendor = subprocess_text_output(["lsb_release", "-is"])
        codename = subprocess_text_output(["lsb_release", "-cs"])
        distro_info = dict(
            DISTRIB_CODENAME=codename,
            DISTRIB_ID=vendor
        )
    return distro_info

def file_or_package_hash_updated(paths, hash_name, is_force, package_versions=[]):
    # type: (List[str], str, bool, List[str]) -> bool
    # Check whether the files or package_versions passed as arguments
    # changed compared to the last execution.
    sha1sum = hashlib.sha1()
    for path in paths:
        with open(path, 'rb') as file_to_hash:
            sha1sum.update(file_to_hash.read())

    # The ouput of tools like build_pygments_data depends
    # on the version of some pip packages as well.
    for package_version in package_versions:
        sha1sum.update(package_version.encode("utf-8"))

    hash_path = os.path.join(get_dev_uuid_var_path(), hash_name)
    new_hash = sha1sum.hexdigest()
    with open(hash_path, 'a+') as hash_file:
        hash_file.seek(0)
        last_hash = hash_file.read()

        if is_force or (new_hash != last_hash):
            hash_file.seek(0)
            hash_file.truncate()
            hash_file.write(new_hash)
            return True
    return False

def is_root() -> bool:
    if 'posix' in os.name and os.geteuid() == 0:
        return True
    return False

def assert_not_running_as_root() -> None:
    script_name = os.path.abspath(sys.argv[0])
    if is_root():
        msg = ("{shortname} should not be run as root. Use `su zulip` to switch to the 'zulip'\n"
               "user before rerunning this, or use \n  su zulip -c '{name} ...'\n"
               "to switch users and run this as a single command.").format(
            name=script_name,
            shortname=os.path.basename(script_name))
        print(msg)
        sys.exit(1)

def assert_running_as_root(strip_lib_from_paths: bool=False) -> None:
    script_name = os.path.abspath(sys.argv[0])
    # Since these Python scripts are run inside a thin shell wrapper,
    # we need to replace the paths in order to ensure we instruct
    # users to (re)run the right command.
    if strip_lib_from_paths:
        script_name = script_name.replace("scripts/lib/upgrade", "scripts/upgrade")
    if not is_root():
        print("{} must be run as root.".format(script_name))
        sys.exit(1)

def get_config(config_file, section, key, default_value=""):
    # type: (configparser.RawConfigParser, str, str, str) -> str
    if config_file.has_option(section, key):
        return config_file.get(section, key)
    return default_value

def get_config_file() -> configparser.RawConfigParser:
    config_file = configparser.RawConfigParser()
    config_file.read("/etc/zulip/zulip.conf")
    return config_file

def get_deploy_options(config_file):
    # type: (configparser.RawConfigParser) -> List[str]
    return get_config(config_file, 'deployment', 'deploy_options', "").strip().split()