#!/usr/bin/env python3
import argparse
import datetime
import functools
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

from typing import Sequence, Set, Any, Dict, List

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: str, dst: 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: str) -> argparse.Namespace:
    # Keep this in sync with clean_unused_caches in provision_inner.py
    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.")
    parser.add_argument(
        "--no-print-headings", dest="no_headings", action="store_true",
        help="If specified then script will not print headings for "
        "what will be 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_deploy_root() -> str:
    return os.path.realpath(
        os.path.normpath(os.path.join(os.path.dirname(__file__), "..", ".."))
    )

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

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

def get_zulip_pwent() -> pwd.struct_passwd:
    deploy_root_uid = os.stat(get_deploy_root()).st_uid
    if deploy_root_uid != 0:
        return pwd.getpwuid(deploy_root_uid)

    # In the case that permissions got messed up and the deployment
    # directory is unexpectedly owned by root, we fallback to the
    # `zulip` user as that's the correct value in production.
    return pwd.getpwnam("zulip")

def su_to_zulip(save_suid: bool = False) -> None:
    """Warning: su_to_zulip assumes that the zulip checkout is owned by
    the zulip user (or whatever normal user is running the Zulip
    installation).  It should never be run from the installer or other
    production contexts before /home/zulip/deployments/current is
    created."""
    pwent = get_zulip_pwent()
    os.setgid(pwent.pw_gid)
    if save_suid:
        os.setresuid(pwent.pw_uid, pwent.pw_uid, os.getuid())
    else:
        os.setuid(pwent.pw_uid)
    os.environ['HOME'] = pwent.pw_dir

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

TEMPLATE_DATABASE_DIR = "test-backend/databases"
def get_dev_uuid_var_path(create_if_missing: bool = False) -> str:
    zulip_path = get_deploy_root()
    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 root access here, since the path will be under /srv/ in the
            # development environment.
            run_as_root(["sh", "-c", 'echo "$1" > "$2"', "-",
                         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: 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() -> None:
    shutil.rmtree(LOCK_DIR)

def run(args: Sequence[str], **kwargs: 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: str, log_path: 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() -> str:
    if os.path.exists(DEPLOYMENTS_DIR):
        return "prod"
    return "dev"

def get_recent_deployments(threshold_days: 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: 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: str, caches_in_use: Set[str], threshold_days: 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: str, caches_in_use: Set[str], cache_type: str, args: argparse.Namespace
) -> None:
    all_caches = {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, args.no_headings)
    if args.verbose:
        print("Done!")

def generate_sha1sum_emoji(zulip_path: 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) as fp:
        parsed_package_file = json.load(fp)
    dependency_data = parsed_package_file['dependencies']

    if 'emoji-datasource-google' in dependency_data:
        with open(os.path.join(zulip_path, "yarn.lock")) as fp:
            (emoji_datasource_version,) = re.findall(
                r"^emoji-datasource-google@"
                + re.escape(dependency_data["emoji-datasource-google"])
                + r':\n  version "(.*)"',
                fp.read(),
                re.M,
            )
    else:
        emoji_datasource_version = "0"
    sha.update(emoji_datasource_version.encode())

    return sha.hexdigest()

def may_be_perform_purging(
    dirs_to_purge: Set[str],
    dirs_to_keep: Set[str],
    dir_type: str,
    dry_run: bool,
    verbose: bool,
    no_headings: bool,
) -> None:
    if dry_run:
        print("Performing a dry run...")
    if not no_headings:
        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:
            run_as_root(["rm", "-rf", directory])

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

@functools.lru_cache(None)
def parse_os_release() -> Dict[str, str]:
    """
    Example of the useful subset of the data:
    {
     'ID': 'ubuntu',
     'VERSION_ID': '18.04',
     'NAME': 'Ubuntu',
     'VERSION': '18.04.3 LTS (Bionic Beaver)',
     'PRETTY_NAME': 'Ubuntu 18.04.3 LTS',
    }

    VERSION_CODENAME (e.g. 'bionic') is nice and human-readable, but
    we avoid using it, as it is not available on RHEL-based platforms.
    """
    distro_info = {}  # type: Dict[str, str]
    with open('/etc/os-release') as fp:
        for line in fp:
            line = line.strip()
            if not line or line.startswith('#'):
                # The line may be blank or a comment, see:
                # https://www.freedesktop.org/software/systemd/man/os-release.html
                continue
            k, v = line.split('=', 1)
            [distro_info[k]] = shlex.split(v)
    return distro_info

@functools.lru_cache(None)
def os_families() -> Set[str]:
    """
    Known families:
    debian (includes: debian, ubuntu)
    ubuntu (includes: ubuntu)
    fedora (includes: fedora, rhel, centos)
    rhel (includes: rhel, centos)
    centos (includes: centos)
    """
    distro_info = parse_os_release()
    return {distro_info["ID"], *distro_info.get("ID_LIKE", "").split()}

def files_and_string_digest(filenames: List[str],
                            extra_strings: List[str]) -> str:
    # see is_digest_obsolete for more context
    sha1sum = hashlib.sha1()
    for fn in filenames:
        with open(fn, 'rb') as file_to_hash:
            sha1sum.update(file_to_hash.read())

    for extra_string in extra_strings:
        sha1sum.update(extra_string.encode("utf-8"))

    return sha1sum.hexdigest()

def is_digest_obsolete(hash_name: str,
                       filenames: List[str],
                       extra_strings: List[str]=[]) -> bool:
    '''
    In order to determine if we need to run some
    process, we calculate a digest of the important
    files and strings whose respective contents
    or values may indicate such a need.

        filenames = files we should hash the contents of
        extra_strings = strings we should hash directly

    Grep for callers to see examples of how this is used.

    To elaborate on extra_strings, they will typically
    be things like:

        - package versions (that we import)
        - settings values (that we stringify with
          json, deterministically)
    '''
    last_hash_path = os.path.join(get_dev_uuid_var_path(), hash_name)
    try:
        with open(last_hash_path) as f:
            old_hash = f.read()
    except FileNotFoundError:
        # This is normal for a fresh checkout--a missing
        # digest is an obsolete digest.
        return True

    new_hash = files_and_string_digest(filenames, extra_strings)

    return new_hash != old_hash

def write_new_digest(hash_name: str,
                     filenames: List[str],
                     extra_strings: List[str]=[]) -> None:
    hash_path = os.path.join(get_dev_uuid_var_path(), hash_name)
    new_hash = files_and_string_digest(filenames, extra_strings)
    with open(hash_path, 'w') as f:
        f.write(new_hash)

    # Be a little verbose here--our callers ensure we
    # only write new digests when things have changed, and
    # making this system more transparent to developers
    # can help them troubleshoot provisioning glitches.
    print('New digest written to: ' + hash_path)

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

def run_as_root(args: List[str], **kwargs: Any) -> None:
    sudo_args = kwargs.pop('sudo_args', [])
    if not is_root():
        args = ['sudo'] + sudo_args + ['--'] + args
    run(args, **kwargs)

def assert_not_running_as_root() -> None:
    script_name = os.path.abspath(sys.argv[0])
    if is_root():
        pwent = get_zulip_pwent()
        msg = ("{shortname} should not be run as root. Use `su {user}` to switch to the 'zulip'\n"
               "user before rerunning this, or use \n  su {user} -c '{name} ...'\n"
               "to switch users and run this as a single command.").format(
            name=script_name,
            shortname=os.path.basename(script_name),
            user=pwent.pw_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: configparser.RawConfigParser,
    section: str,
    key: str,
    default_value: 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: configparser.RawConfigParser) -> List[str]:
    return get_config(config_file, 'deployment', 'deploy_options', "").strip().split()

def get_or_create_dev_uuid_var_path(path: str) -> str:
    absolute_path = '{}/{}'.format(get_dev_uuid_var_path(), path)
    os.makedirs(absolute_path, exist_ok=True)
    return absolute_path

def is_vagrant_env_host(path: str) -> bool:
    return '.vagrant' in os.listdir(path)

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