import os
import json
import subprocess

from datetime import datetime
from collections import OrderedDict

from moulinette import m18n
from yunohost.utils.error import YunohostError, YunohostValidationError
from moulinette.utils.log import getActionLogger
from yunohost.regenconf import regen_conf
from yunohost.firewall import firewall_reload

logger = getActionLogger("yunohost.settings")

SETTINGS_PATH = "/etc/yunohost/settings.json"
SETTINGS_PATH_OTHER_LOCATION = "/etc/yunohost/settings-%s.json"


def is_boolean(value):
    TRUE = ["true", "on", "yes", "y", "1"]
    FALSE = ["false", "off", "no", "n", "0"]

    """
    Ensure a string value is intended as a boolean

    Keyword arguments:
        arg -- The string to check

    Returns:
        (is_boolean, boolean_value)

    """
    if isinstance(value, bool):
        return True, value
    if value in [0, 1]:
        return True, bool(value)
    elif isinstance(value, str):
        if str(value).lower() in TRUE + FALSE:
            return True, str(value).lower() in TRUE
        else:
            return False, None
    else:
        return False, None


# a settings entry is in the form of:
# namespace.subnamespace.name: {type, value, default, description, [choices]}
# choices is only for enum
# the keyname can have as many subnamespace as needed but should have at least
# one level of namespace

# description is implied from the translated strings
# the key is "global_settings_setting_%s" % key.replace(".", "_")

# type can be:
# * bool
# * int
# * string
# * enum (in the form of a python list)

DEFAULTS = OrderedDict(
    [
        # Password Validation
        # -1 disabled, 0 alert if listed, 1 8-letter, 2 normal, 3 strong, 4 strongest
        ("security.password.admin.strength", {"type": "int", "default": 1}),
        ("security.password.user.strength", {"type": "int", "default": 1}),
        (
            "service.ssh.allow_deprecated_dsa_hostkey",
            {"type": "bool", "default": False},
        ),
        (
            "security.ssh.compatibility",
            {
                "type": "enum",
                "default": "modern",
                "choices": ["intermediate", "modern"],
            },
        ),
        (
            "security.ssh.port",
            {"type": "int", "default": 22},
        ),
        (
            "security.ssh.password_authentication",
            {"type": "bool", "default": True},
        ),
        (
            "security.nginx.redirect_to_https",
            {
                "type": "bool",
                "default": True,
            },
        ),
        (
            "security.nginx.compatibility",
            {
                "type": "enum",
                "default": "intermediate",
                "choices": ["intermediate", "modern"],
            },
        ),
        (
            "security.postfix.compatibility",
            {
                "type": "enum",
                "default": "intermediate",
                "choices": ["intermediate", "modern"],
            },
        ),
        ("pop3.enabled", {"type": "bool", "default": False}),
        ("smtp.allow_ipv6", {"type": "bool", "default": True}),
        ("smtp.relay.host", {"type": "string", "default": ""}),
        ("smtp.relay.port", {"type": "int", "default": 587}),
        ("smtp.relay.user", {"type": "string", "default": ""}),
        ("smtp.relay.password", {"type": "string", "default": ""}),
        ("backup.compress_tar_archives", {"type": "bool", "default": False}),
        ("ssowat.panel_overlay.enabled", {"type": "bool", "default": True}),
        ("security.webadmin.allowlist.enabled", {"type": "bool", "default": False}),
        ("security.webadmin.allowlist", {"type": "string", "default": ""}),
        ("security.experimental.enabled", {"type": "bool", "default": False}),
    ]
)


def settings_get(key, full=False):
    """
    Get an entry value in the settings

    Keyword argument:
        key -- Settings key

    """
    settings = _get_settings()

    if key not in settings:
        raise YunohostValidationError(
            "global_settings_key_doesnt_exists", settings_key=key
        )

    if full:
        return settings[key]

    return settings[key]["value"]


def settings_list():
    """
    List all entries of the settings

    """
    return _get_settings()


def settings_set(key, value):
    """
    Set an entry value in the settings

    Keyword argument:
        key -- Settings key
        value -- New value

    """
    settings = _get_settings()

    if key not in settings:
        raise YunohostValidationError(
            "global_settings_key_doesnt_exists", settings_key=key
        )

    key_type = settings[key]["type"]

    if key_type == "bool":
        boolean_value = is_boolean(value)
        if boolean_value[0]:
            value = boolean_value[1]
        else:
            raise YunohostValidationError(
                "global_settings_bad_type_for_setting",
                setting=key,
                received_type=type(value).__name__,
                expected_type=key_type,
            )
    elif key_type == "int":
        if not isinstance(value, int) or isinstance(value, bool):
            if isinstance(value, str):
                try:
                    value = int(value)
                except Exception:
                    raise YunohostValidationError(
                        "global_settings_bad_type_for_setting",
                        setting=key,
                        received_type=type(value).__name__,
                        expected_type=key_type,
                    )
            else:
                raise YunohostValidationError(
                    "global_settings_bad_type_for_setting",
                    setting=key,
                    received_type=type(value).__name__,
                    expected_type=key_type,
                )
    elif key_type == "string":
        if not isinstance(value, str):
            raise YunohostValidationError(
                "global_settings_bad_type_for_setting",
                setting=key,
                received_type=type(value).__name__,
                expected_type=key_type,
            )
    elif key_type == "enum":
        if value not in settings[key]["choices"]:
            raise YunohostValidationError(
                "global_settings_bad_choice_for_enum",
                setting=key,
                choice=str(value),
                available_choices=", ".join(settings[key]["choices"]),
            )
    else:
        raise YunohostValidationError(
            "global_settings_unknown_type", setting=key, unknown_type=key_type
        )

    old_value = settings[key].get("value")
    settings[key]["value"] = value
    _save_settings(settings)

    try:
        trigger_post_change_hook(key, old_value, value)
    except Exception as e:
        logger.error(f"Post-change hook for setting {key} failed : {e}")
        raise


def settings_reset(key):
    """
    Set an entry value to its default one

    Keyword argument:
        key -- Settings key

    """
    settings = _get_settings()

    if key not in settings:
        raise YunohostValidationError(
            "global_settings_key_doesnt_exists", settings_key=key
        )

    settings[key]["value"] = settings[key]["default"]
    _save_settings(settings)


def settings_reset_all():
    """
    Reset all settings to their default value

    Keyword argument:
        yes -- Yes I'm sure I want to do that

    """
    settings = _get_settings()

    # For now on, we backup the previous settings in case of but we don't have
    # any mecanism to take advantage of those backups. It could be a nice
    # addition but we'll see if this is a common need.
    # Another solution would be to use etckeeper and integrate those
    # modification inside of it and take advantage of its git history
    old_settings_backup_path = (
        SETTINGS_PATH_OTHER_LOCATION % datetime.utcnow().strftime("%F_%X")
    )
    _save_settings(settings, location=old_settings_backup_path)

    for value in settings.values():
        value["value"] = value["default"]

    _save_settings(settings)

    return {
        "old_settings_backup_path": old_settings_backup_path,
        "message": m18n.n(
            "global_settings_reset_success", path=old_settings_backup_path
        ),
    }


def _get_setting_description(key):
    return m18n.n(f"global_settings_setting_{key}".replace(".", "_"))


def _get_settings():

    settings = {}

    for key, value in DEFAULTS.copy().items():
        settings[key] = value
        settings[key]["value"] = value["default"]
        settings[key]["description"] = _get_setting_description(key)

    if not os.path.exists(SETTINGS_PATH):
        return settings

    # we have a very strict policy on only allowing settings that we know in
    # the OrderedDict DEFAULTS
    # For various reason, while reading the local settings we might encounter
    # settings that aren't in DEFAULTS, those can come from settings key that
    # we have removed, errors or the user trying to modify
    # /etc/yunohost/settings.json
    # To avoid to simply overwrite them, we store them in
    # /etc/yunohost/settings-unknown.json in case of
    unknown_settings = {}
    unknown_settings_path = SETTINGS_PATH_OTHER_LOCATION % "unknown"

    if os.path.exists(unknown_settings_path):
        try:
            unknown_settings = json.load(open(unknown_settings_path, "r"))
        except Exception as e:
            logger.warning(f"Error while loading unknown settings {e}")

    try:
        with open(SETTINGS_PATH) as settings_fd:
            local_settings = json.load(settings_fd)

            for key, value in local_settings.items():
                if key in settings:
                    settings[key] = value
                    settings[key]["description"] = _get_setting_description(key)
                else:
                    logger.warning(
                        m18n.n(
                            "global_settings_unknown_setting_from_settings_file",
                            setting_key=key,
                        )
                    )
                    unknown_settings[key] = value
    except Exception as e:
        raise YunohostValidationError("global_settings_cant_open_settings", reason=e)

    if unknown_settings:
        try:
            _save_settings(unknown_settings, location=unknown_settings_path)
            _save_settings(settings)
        except Exception as e:
            logger.warning(
                f"Failed to save unknown settings (because {e}), aborting."
            )

    return settings


def _save_settings(settings, location=SETTINGS_PATH):
    settings_without_description = {}
    for key, value in settings.items():
        settings_without_description[key] = value
        if "description" in value:
            del settings_without_description[key]["description"]

    try:
        result = json.dumps(settings_without_description, indent=4)
    except Exception as e:
        raise YunohostError("global_settings_cant_serialize_settings", reason=e)

    try:
        with open(location, "w") as settings_fd:
            settings_fd.write(result)
    except Exception as e:
        raise YunohostError("global_settings_cant_write_settings", reason=e)


# Meant to be a dict of setting_name -> function to call
post_change_hooks = {}


def post_change_hook(setting_name):
    def decorator(func):
        assert setting_name in DEFAULTS.keys(), (
            f"The setting {setting_name} does not exists"
        )
        assert setting_name not in post_change_hooks, (
            f"You can only register one post change hook per setting (in particular for {setting_name})"
        )
        post_change_hooks[setting_name] = func
        return func

    return decorator


def trigger_post_change_hook(setting_name, old_value, new_value):
    if setting_name not in post_change_hooks:
        logger.debug(f"Nothing to do after changing setting {setting_name}")
        return

    f = post_change_hooks[setting_name]
    f(setting_name, old_value, new_value)


# ===========================================
#
# Actions to trigger when changing a setting
# You can define such an action with :
#
# @post_change_hook("your.setting.name")
# def some_function_name(setting_name, old_value, new_value):
#     # Do some stuff
#
# ===========================================


@post_change_hook("ssowat.panel_overlay.enabled")
@post_change_hook("security.nginx.redirect_to_https")
@post_change_hook("security.nginx.compatibility")
@post_change_hook("security.webadmin.allowlist.enabled")
@post_change_hook("security.webadmin.allowlist")
def reconfigure_nginx(setting_name, old_value, new_value):
    if old_value != new_value:
        regen_conf(names=["nginx"])


@post_change_hook("security.experimental.enabled")
def reconfigure_nginx_and_yunohost(setting_name, old_value, new_value):
    if old_value != new_value:
        regen_conf(names=["nginx", "yunohost"])


@post_change_hook("security.ssh.compatibility")
@post_change_hook("security.ssh.password_authentication")
def reconfigure_ssh(setting_name, old_value, new_value):
    if old_value != new_value:
        regen_conf(names=["ssh"])


@post_change_hook("security.ssh.port")
def reconfigure_ssh_and_fail2ban(setting_name, old_value, new_value):
    if old_value != new_value:
        regen_conf(names=["ssh", "fail2ban"])
        firewall_reload()


@post_change_hook("smtp.allow_ipv6")
@post_change_hook("smtp.relay.host")
@post_change_hook("smtp.relay.port")
@post_change_hook("smtp.relay.user")
@post_change_hook("smtp.relay.password")
@post_change_hook("security.postfix.compatibility")
def reconfigure_postfix(setting_name, old_value, new_value):
    if old_value != new_value:
        regen_conf(names=["postfix"])


@post_change_hook("pop3.enabled")
def reconfigure_dovecot(setting_name, old_value, new_value):
    dovecot_package = "dovecot-pop3d"

    environment = os.environ.copy()
    environment.update({"DEBIAN_FRONTEND": "noninteractive"})

    if new_value == "True":
        command = [
            "apt-get",
            "-y",
            "--no-remove",
            "-o Dpkg::Options::=--force-confdef",
            "-o Dpkg::Options::=--force-confold",
            "install",
            dovecot_package,
        ]
        subprocess.call(command, env=environment)
        if old_value != new_value:
            regen_conf(names=["dovecot"])
    else:
        if old_value != new_value:
            regen_conf(names=["dovecot"])
        command = ["apt-get", "-y", "remove", dovecot_package]
        subprocess.call(command, env=environment)