import asyncio
import base64
import datetime
import json
import os
import shutil
import subprocess
import tempfile
import time
from contextlib import suppress
from json import JSONDecodeError
from pathlib import Path
from subprocess import TimeoutExpired
from typing import Optional

from defence360agent.application.determine_hosting_panel import (
    is_cpanel_installed,
)
from defence360agent.contracts import sentry
from defence360agent.contracts.config import (
    ANTIVIRUS_MODE,
    Core,
    CustomBilling,
    int_from_envvar,
    logger,
)
from defence360agent.contracts.hook_events import HookEvent
from defence360agent.internals.global_scope import g
from defence360agent.utils import retry_on, timed_cache
from defence360agent.utils.common import HOUR, rate_limit
from peewee import OperationalError

AV_DEFAULT_ID = "IMUNIFYAV"
UNLIMITED_USERS_COUNT = 2147483647
# no need to check the license file more often than
# once every 10 minutes, this should be enough to fix DEF-14677
_CACHE_LICENSE_TOKEN_TIMEOUT = int_from_envvar(
    "IMUNIFY360_CACHE_LICENSE_TOKEN_TIMEOUT", 10 * 60  # in seconds
)
# path to openssl binary used to check license signature
# we need to check several paths because of different OSes
# and different installation paths with fallback to system default
if not (OPENSSL_BIN := Path("/opt/alt/openssl11/bin/openssl")).exists():
    if not (OPENSSL_BIN := Path("/opt/alt/openssl/bin/openssl")).exists():
        OPENSSL_BIN = Path("/usr/bin/openssl")

throttled_log_error = rate_limit(period=HOUR, on_drop=logger.warning)(
    logger.error
)


class LicenseError(Exception):
    """Used to communicate that some function requires a license"""


class LicenseCLN:
    VERIFY_FIELDS_V1 = (
        "id",
        "status",
        "group",
        "limit",
        "token_created_utc",
        "token_expire_utc",
    )

    VERIFY_FIELDS_V2 = (
        "id",
        "status",
        "limit",
        "token_created_utc",
        "token_expire_utc",
        "group_id",
        "permissions",
    )

    VERIFY_FIELDS_MAP = {
        1: VERIFY_FIELDS_V1,
        2: VERIFY_FIELDS_V2,
    }

    _PUBKEY_FILE = "/usr/share/imunify360/cln-pub.key"
    _ALTERNATIVE_PUBKEY_FILES = (
        # keys for self-signed licenses
        "/usr/share/imunify360/alt-license-pub.key",
    )
    _LICENSE_FILE = "/var/imunify360/license.json"
    _FREE_LICENSE_FILE = "/var/imunify360/license-free.json"
    AV_PLUS_BUY_URL = (
        "https://cln.cloudlinux.com/console/purchase/ImunifyAvPlus"
    )
    IM360_BUY_URL_TEMPLATE = (
        "https://www.cloudlinux.com/upgrade-imunify-{user_count}/"
    )
    VERSION_THRESHOLDS = [1, 30, 250]

    _token = {}
    users_count = None

    @staticmethod
    @retry_on(TimeoutExpired, max_tries=2)
    def _verify_signature(
        pubkey_path: str, content: bytes, signature: bytes
    ) -> tuple[bool, Optional[list[str]]]:
        """Verify that `content` is correctly signed with public key from file
        `pubkey_path` with resulting `signature`. Returns a tuple with (success, error_list).
        """
        errors: list[str] = []
        result = False

        with tempfile.NamedTemporaryFile(delete=True) as sig_file:
            sig_file.write(signature)
            sig_file.flush()
            cmd = [
                OPENSSL_BIN,
                "dgst",
                "-sha512",
                "-verify",
                pubkey_path,
                "-signature",
                sig_file.name,
            ]
            try:
                p = subprocess.run(
                    cmd,
                    stdout=subprocess.PIPE,
                    stderr=subprocess.PIPE,
                    input=content,
                    timeout=1,
                )
            except FileNotFoundError as e:
                errors.append(f"openssl command failed: missing {e.filename}")
            else:
                if p.returncode == 0:
                    result = True
                else:
                    errors.append(
                        "Signature verification failed - "
                        f"openssl returned {p.returncode}. "
                        f"stdout: {p.stdout}, stderr: {p.stderr}"
                    )

        return result, errors or None

    @classmethod
    def _get_signature_input(cls, license, version: int = 1) -> bytes:
        parts = []
        for key in cls.VERIFY_FIELDS_MAP[version]:
            value = license[key]
            if isinstance(value, dict):
                parts.append(
                    "".join(
                        f"{subkey}={subvalue}"
                        for subkey, subvalue in value.items()
                    )
                )
            elif value is None:
                parts.append("null")
            else:
                parts.append(str(value))
        return "".join(parts).encode()

    @classmethod
    def _find_signature(
        cls, license_token, signature_list: list[tuple[str, int]]
    ) -> tuple[Optional[str], bool]:
        """
        Verify signatures in license

        :return: signature, is_alternative, version
        """
        sign: str
        all_errors: list[str] = []

        def verify_and_collect_errors(*args, **kwargs):
            success, errors = cls._verify_signature(*args, **kwargs)
            if errors:
                all_errors.extend(errors)
            return success

        for sign, version in signature_list:
            signature = base64.b64decode(sign)

            try:
                content = cls._get_signature_input(
                    license_token, version=version
                )
            except KeyError:
                continue

            if verify_and_collect_errors(cls._PUBKEY_FILE, content, signature):
                return sign, False

            for alt_pubkey in cls._ALTERNATIVE_PUBKEY_FILES:
                if verify_and_collect_errors(alt_pubkey, content, signature):
                    return sign, True

        for error in all_errors:
            logger.warning("%s", error)

        return None, False

    @classmethod
    def _load_token(cls, path):
        """
        Load license token from file and verify signature
        If signature verification successful, put
        first valid signature to 'sign' field of license
        token

        :return: license token
        """
        default = {}  # default value returned on error
        try:
            with open(path) as f:
                license_token = json.load(f)

                if not isinstance(license_token, dict):
                    logger.error(
                        "Failed to load license. Expected JSON object, got %r"
                        % (license_token,)
                    )
                    return default

                signature, is_alternative = cls._find_signature(
                    license_token,
                    [
                        (sign, 1)
                        for sign in license_token.get("signatures", [])
                    ],
                )
                if sign := license_token.get("signature_v2"):
                    _sign, _ = cls._find_signature(license_token, [(sign, 2)])
                    if _sign is None:
                        throttled_log_error(
                            "Failed to verify license signature v2"
                        )
                        license_token.pop("permissions", None)

                if signature is None:
                    throttled_log_error("Failed to verify license signature")
                    return default

                license_token["sign"] = signature
                license_token["is_alternative"] = is_alternative
                return license_token

        except FileNotFoundError:
            # this is a common case
            logger.info("Failed to load license: not registered?")
        except (OSError, JSONDecodeError, KeyError, UnicodeDecodeError) as e:
            # not loading broken license
            logger.error("Failed to load license: %s", e)
        return default

    @classmethod
    @timed_cache(
        datetime.timedelta(seconds=_CACHE_LICENSE_TOKEN_TIMEOUT), maxsize=1
    )
    def get_token(cls) -> dict:
        """
        Get available license.
        In Antivirus mode, if main license is unavailable, return free license

        :return: license token
        """
        lic_token = {}
        license_files = (
            [cls._LICENSE_FILE, cls._FREE_LICENSE_FILE]
            if ANTIVIRUS_MODE
            else [cls._LICENSE_FILE]
        )
        for lf in license_files:
            lic_token = cls._load_token(lf)
            if lic_token:
                return lic_token
        return lic_token

    @classmethod
    def get_server_id(cls) -> Optional[str]:
        """
        :return: server id
        """
        return cls.get_token().get("id")

    @classmethod
    def is_registered(cls):
        """
        :return: bool: if we have token
        """
        return bool(cls.get_token())

    @classmethod
    def is_valid_av_plus(cls):
        """
        :return: Return true only if we have valid ImunifyAV+ or
        Imunify360 license
        """
        return ANTIVIRUS_MODE and cls.is_valid() and (not cls.is_free())

    @classmethod
    def is_free(cls):
        if not ANTIVIRUS_MODE:
            return False
        return cls.get_server_id() == AV_DEFAULT_ID

    @classmethod
    def is_valid(cls, token=None):
        """License check based on license token

        return True - if license token is valid for this server
        return False - if license token is invalid
        """
        token = token or cls.get_token()
        if not token:
            return False

        if ANTIVIRUS_MODE:
            return (
                token.get("status", "").startswith("ok")
                and token["token_expire_utc"] >= time.time()
            )

        return (
            token["status"] in ("ok", "ok-trial")
            and token["token_expire_utc"] >= time.time()
            and (cls.users_count is None or cls.users_count <= token["limit"])
        )

    @classmethod
    def has_permission(cls, permission: str, token=None):
        """License check for a specific permission based on a license token

        return True - if license token has a given permission for this server
        return False - if license token does not have permission
        """
        token = token or cls.get_token()
        if not token:
            return False

        return (
            permission in (perm := token.get("permissions", []))
            and perm[permission] == "ENABLED"
        )

    @classmethod
    def update(cls, token):
        """
        Write new license token to file
        :param token: new token
        :return:
        """

        old_token = cls.get_token()

        temp_file = cls._LICENSE_FILE + ".tmp"
        flags = os.O_WRONLY | os.O_CREAT | os.O_EXCL
        mode = 0o640

        with suppress(FileNotFoundError):
            os.unlink(temp_file)
        with os.fdopen(os.open(temp_file, flags, mode), "w") as f:
            json.dump(token, f)

        shutil.chown(temp_file, user="root", group="_imunify")
        os.rename(temp_file, cls._LICENSE_FILE)
        cls.get_token.cache_clear()
        sentry.set_server_id(cls.get_server_id())
        sentry.set_product_name(cls.get_product_name())
        try:
            cls.renew_hook(old_token, token)
        except OperationalError:
            pass

    @classmethod
    def renew_hook(cls, old_token, token):
        important_keys = ["license_expire_utc", "status", "limit", "id"]
        exp_time = token.get("license_expire_utc")
        license_type = cls.fill_license_type(token)
        condition = any(
            [token.get(elem) != old_token.get(elem) for elem in important_keys]
        )

        if condition:
            license_updated = HookEvent.LicenseRenewed(
                exp_time=exp_time, license=license_type
            )
            from defence360agent.hooks.execute import execute_hooks

            asyncio.gather(
                execute_hooks(license_updated), return_exceptions=True
            )

    @classmethod
    def delete(cls):
        """
        Delete license token along with old-style license data
        :return:
        """
        with suppress(FileNotFoundError):
            os.unlink(cls._LICENSE_FILE)
        cls.get_token.cache_clear()
        sentry.set_server_id(None)
        sentry.set_product_name(cls.get_product_name())

    @classmethod
    def fill_license_type(cls, token):
        license_type = token.get("status")
        license_type_to_product = {
            "ok": "imunify360",
            "ok-trial": "imunify360Trial",
            "ok-av": "imunifyAV",
            "ok-avp": "imunifyAVPlus",
        }
        return license_type_to_product.get(license_type)

    @classmethod
    def license_info(cls):
        token = cls.get_token()
        key_360 = token.get("status") in ("ok", "ok-trial")

        message = token.get("message", None)
        if (
            ANTIVIRUS_MODE
            and CustomBilling.UPGRADE_URL
            and not CustomBilling.NOTIFICATIONS
        ):
            message = None
        if ANTIVIRUS_MODE and key_360 and not message:
            # TODO: remove after auto-upgrade will be implemented
            message = (
                "You've got a license for the advanced security product "
                "Imunify360. Please, uninstall ImunifyAV and replace it with "
                "the Imunify360 providing comprehensive security for your "
                "server. Here are the steps for upgrade: "
                "https://docs.imunify360.com/installation/"
            )

        if token:
            info = {
                "status": cls.is_valid(),
                "expiration": token.get("license_expire_utc", 0),
                "user_limit": token.get("limit"),
                "id": token.get("id"),
                "user_count": cls.users_count,
                "message": message,
                "license_type": cls.fill_license_type(token),
            }
        else:
            info = {"status": False}

        if ANTIVIRUS_MODE:
            ignored_messages = [
                "user limits",
            ]
            if info.get("message"):
                for msg in ignored_messages:
                    if msg in info["message"]:
                        info["message"] = None

            # TODO: detect IP license for registered AV+ without custom billing
            info["ip_license"] = CustomBilling.IP_LICENSE and (
                CustomBilling.UPGRADE_URL is not None
                or CustomBilling.UPGRADE_URL_360 is not None
            )
            info["upgrade_url"] = (
                CustomBilling.UPGRADE_URL
                or token.get("upgrade_url")
                or cls.AV_PLUS_BUY_URL
            )
            info["upgrade_url_360"] = (
                CustomBilling.UPGRADE_URL_360 or upgrade_url_default()
            )
        else:
            info["redirect_url"] = token.get("upgrade_url", None)
        if cls.is_demo():  # pragma: no cover
            info["demo"] = True

        return info

    @classmethod
    def get_product_name(cls) -> str:
        if not ANTIVIRUS_MODE:
            return Core.NAME

        license_status = cls.get_token().get("status", "")

        if license_status == "ok-av":
            return "imunify.av"
        elif license_status in ("ok-avp", "ok", "ok-trial"):
            return "imunify.av+"
        else:
            logger.error("Unknown license %s", license_status)
            return "Unknown license"

    @classmethod
    def is_demo(cls) -> bool:
        return os.path.isfile("/var/imunify360/demo")

    @classmethod
    def is_unlimited(cls):
        token = cls.get_token()
        return token.get("limit", 0) >= UNLIMITED_USERS_COUNT

    @classmethod
    def get_im360_buy_url(cls) -> str:
        if cls.users_count is None:
            return cls.IM360_BUY_URL_TEMPLATE.format(user_count=1)
        for threshold in cls.VERSION_THRESHOLDS:
            if cls.users_count <= threshold:
                return cls.IM360_BUY_URL_TEMPLATE.format(user_count=threshold)
        return cls.IM360_BUY_URL_TEMPLATE.format(user_count="unlimited")


def upgrade_url_default():
    if (
        is_cpanel_installed()
        and CustomBilling.UPGRADE_URL
        == "../../../scripts14/purchase_imunifyavplus_init_IMUNIFY"
    ):
        return "../../../scripts14/purchase_imunify360_init_IMUNIFY"
    else:
        iaid = g.get("iaid", "")
        n = LicenseCLN.users_count
        return (
            LicenseCLN.get_im360_buy_url()
            + f"?iaid={iaid}"
            + f"&users={n}" * bool(n)
        )