#
# Copyright (C) 2015 GNS3 Technologies Inc.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""
Docker server module.
"""

import os
import sys
import json
import asyncio
import logging
import aiohttp
import shutil
import platformdirs

from gns3server.utils import parse_version
from gns3server.config import Config
from gns3server.utils.asyncio import locking
from gns3server.compute.base_manager import BaseManager
from gns3server.compute.docker.docker_vm import DockerVM
from gns3server.compute.docker.vendor_docker_vm import VendorDockerVM
from gns3server.compute.docker.docker_error import DockerError, DockerHttp304Error, DockerHttp404Error, DockerHttp409Error

log = logging.getLogger(__name__)


# Be careful to keep it consistent
DOCKER_MINIMUM_API_VERSION = "1.40"
DOCKER_MINIMUM_VERSION = "19.03.8"
DOCKER_PREFERRED_API_VERSION = "1.44"
CHUNK_SIZE = 1024 * 8  # 8KB


class Docker(BaseManager):

    _NODE_CLASS = DockerVM

    def __init__(self):

        super().__init__()
        self._server_url = "/var/run/docker.sock"
        self._connected = False
        # Allow locking during ubridge operations
        self.ubridge_lock = asyncio.Lock()
        self._connector = None
        self._session = None
        self._api_version = DOCKER_MINIMUM_API_VERSION
        self._host_checked = False

    def _select_node_class(self, **kwargs):
        """Select the node class based on console_type."""
        if kwargs.get("console_type") == "docker_exec":
            return VendorDockerVM
        return DockerVM

    async def create_node(self, name, project_id, node_id, *args, **kwargs):
        self._NODE_CLASS = self._select_node_class(**kwargs)
        return await super().create_node(name, project_id, node_id, *args, **kwargs)

    @staticmethod
    async def install_busybox(dst_dir):

        dst_busybox = os.path.join(dst_dir, "bin", "busybox")
        if os.path.isfile(dst_busybox):
            return
        for busybox_exec in ("busybox-static", "busybox.static", "busybox"):
            busybox_path = shutil.which(busybox_exec)
            if busybox_path:
                try:
                    # check that busybox is statically linked
                    # (dynamically linked busybox will fail to run in a container)
                    proc = await asyncio.create_subprocess_exec(
                        "ldd",
                        busybox_path,
                        stdout=asyncio.subprocess.PIPE,
                        stderr=asyncio.subprocess.DEVNULL
                    )
                    stdout, _ = await proc.communicate()
                    if proc.returncode == 1 or "static" in busybox_exec:
                        # ldd returns 1 if the file is not a dynamic executable
                        # on Alpine/musl, ldd returns 0 even for static binaries,
                        # so also trust binaries named busybox-static or busybox.static
                        log.info(f"Installing busybox from '{busybox_path}' to '{dst_busybox}'")
                        shutil.copy2(busybox_path, dst_busybox, follow_symlinks=True)
                        return
                    else:
                        log.warning(f"Busybox '{busybox_path}' is dynamically linked\n"
                                    f"{stdout.decode('utf-8', errors='ignore').strip()}")
                except OSError as e:
                    raise DockerError(f"Could not install busybox: {e}")
        raise DockerError("No busybox executable could be found, please install busybox (apt install busybox-static on Debian/Ubuntu) and make sure it is in your PATH")

    @staticmethod
    def resources_path():
        """
        Get the Docker resources storage directory
        """

        resources_path = Config.instance().settings.Server.resources_path
        if not resources_path:
            appname = vendor = "GNS3"
            resources_path = platformdirs.user_data_dir(appname, vendor, roaming=True)
        else:
            resources_path = os.path.expanduser(resources_path)
        docker_resources_dir = os.path.join(resources_path, "docker")
        os.makedirs(docker_resources_dir, exist_ok=True)
        return docker_resources_dir

    async def install_resources(self):
        """
        Copy the necessary resources to a writable location and install busybox
        """

        try:
            dst_path = self.resources_path()
            log.info(f"Installing Docker resources in '{dst_path}'")
            from gns3server.controller import Controller
            await Controller.instance().install_resource_files(dst_path, "compute/docker/resources")
            await self.install_busybox(dst_path)
        except OSError as e:
            raise DockerError(f"Could not install Docker resources to {dst_path}: {e}")

    async def _check_connection(self):

        if not self._connected:
            try:
                self._connected = True
                docker_info = await self.query("GET", "version")
            except (aiohttp.ClientError, FileNotFoundError):
                self._connected = False
                raise DockerError("Can't connect to Docker daemon")

            api_version = parse_version(docker_info['ApiVersion'])
            version = docker_info["Version"]

            if api_version < parse_version(DOCKER_MINIMUM_API_VERSION):
                raise DockerError(f"Docker version is {version}. "
                                  f"GNS3 requires a minimum version of {DOCKER_MINIMUM_VERSION}"
                )

            preferred_api_version = parse_version(DOCKER_PREFERRED_API_VERSION)
            if api_version >= preferred_api_version:
                self._api_version = DOCKER_PREFERRED_API_VERSION
            else:
                # use the Min API version supported by the daemon
                self._api_version = docker_info['MinAPIVersion']
                log.warning("Using Docker client with the minimum API version {}".format(self._api_version))

            log.info("Connected to Docker daemon version {} using API version {}".format(version, self._api_version))
            self._check_host_readiness()

    def _check_host_readiness(self):
        """
        Best-effort, read-only check of kernel settings that heavy NOS containers
        (e.g. Cisco XRd) need. The server runs unprivileged (only the setuid
        ubridge helper gets root), so we cannot raise these limits ourselves --
        we only warn, with the exact commands to fix, when they are too low or
        when FUSE support is missing. Runs at most once per process.
        """

        if self._host_checked:
            return
        self._host_checked = True

        # Thresholds recommended for running several heavy containers (sized for
        # ~15 XRd-style nodes). Raising them is harmless; the stock Linux defaults
        # (e.g. max_user_instances=128) are far too low and break such images.
        thresholds = {
            "fs.inotify.max_user_instances": 64000,
            "fs.inotify.max_user_watches": 524288,
            "fs.file-max": 1000000,
        }
        low = []
        for key, minimum in thresholds.items():
            try:
                with open(f"/proc/sys/{key.replace('.', '/')}") as f:
                    current = int(f.read().strip())
            except (OSError, ValueError):
                # One unreadable key must not discard the warnings already
                # collected nor skip the FUSE check — skip just this key.
                continue
            if current < minimum:
                low.append((key, current, minimum))

        fuse_supported = False
        try:
            with open("/proc/filesystems") as f:
                filesystems = {parts[-1] for parts in (line.split() for line in f) if parts}
            fuse_supported = "fuse" in filesystems or "fuseblk" in filesystems
        except OSError:
            pass

        if low:
            details = ", ".join(f"{k}={c} (need >={m})" for k, c, m in low)
            raise_cmd = " ".join(f"{k}={m}" for k, _, m in low)
            log.warning(
                f"Low kernel limits for heavy Docker containers ({details}). "
                f"Some NOS images (e.g. Cisco XRd) may fail to start. Raise once: "
                f"'sudo sysctl -w {raise_cmd}' and persist it under /etc/sysctl.d/."
            )
        if not fuse_supported:
            log.warning(
                "FUSE filesystem support is not available in the kernel. "
                "Containers that need it (e.g. Cisco XRd) will fail. Load it: 'sudo modprobe fuse'."
            )

    def connector(self):

        if self._connector is None or self._connector.closed:
            if not sys.platform.startswith("linux"):
                raise DockerError("Docker is supported only on Linux")
            try:
                self._connector = aiohttp.connector.UnixConnector(self._server_url, limit=None)
            except (aiohttp.ClientError, FileNotFoundError):
                raise DockerError("Can't connect to docker daemon")
        return self._connector

    async def unload(self):

        await super().unload()
        if self._connected:
            if self._connector and not self._connector.closed:
                await self._connector.close()
        if self._session and not self._session.closed:
            await self._session.close()

    async def query(self, method, path, data={}, params={}):
        """
        Makes a query to the Docker daemon and decode the request

        :param method: HTTP method
        :param path: Endpoint in API
        :param data: Dictionary with the body. Will be transformed to a JSON
        :param params: Parameters added as a query arg
        """

        response = await self.http_query(method, path, data=data, params=params)
        body = await response.read()
        response.close()
        if response.headers.get('CONTENT-TYPE') == 'application/json':
            body = json.loads(body.decode("utf-8", errors="ignore"))
        else:
            body = body.decode("utf-8", errors="ignore")
        log.debug("Query Docker %s %s params=%s data=%s Response: %s", method, path, params, data, body)
        return body

    async def http_query(self, method, path, data={}, params={}, timeout=300):
        """
        Makes a query to the docker daemon

        :param method: HTTP method
        :param path: Endpoint in API
        :param data: Dictionary with the body. Will be transformed to a JSON
        :param params: Parameters added as a query arg
        :param timeout: Timeout
        :returns: HTTP response
        """

        data = json.dumps(data)
        if timeout is None:
            timeout = 60 * 60 * 24 * 31  # One month timeout

        if path == 'version':
            url = "http://docker/" + path
        else:
            await self._check_connection()  # version is use by check connection
            url = "http://docker/v" + self._api_version + "/" + path
        try:
            if self._session is None or self._session.closed:
                connector = self.connector()
                self._session = aiohttp.ClientSession(connector=connector)
            response = await self._session.request(
                method,
                url,
                params=params,
                data=data,
                headers={
                    "content-type": "application/json",
                },
                timeout=timeout,
            )
        except aiohttp.ClientError as e:
            raise DockerError(f"Docker has returned an error: {e}")
        except asyncio.TimeoutError:
            raise DockerError("Docker timeout " + method + " " + path)
        if response.status >= 300:
            body = await response.read()
            try:
                body = json.loads(body.decode("utf-8"))["message"]
            except ValueError:
                pass
            log.debug(f"Query Docker {method} {path} params={params} data={data} Response: {body}")
            if response.status == 304:
                raise DockerHttp304Error(f"Docker has returned an error: {response.status} {body}")
            elif response.status == 404:
                raise DockerHttp404Error(f"Docker has returned an error: {response.status} {body}")
            elif response.status == 409:
                raise DockerHttp409Error(f"Docker has returned an error: {response.status} {body}")
            else:
                raise DockerError(f"Docker has returned an error: {response.status} {body}")
        return response

    async def websocket_query(self, path, params={}):
        """
        Opens a websocket connection

        :param path: Endpoint in API
        :param params: Parameters added as a query arg
        :returns: Websocket
        """

        url = "http://docker/v" + self._api_version + "/" + path
        connection = await self._session.ws_connect(url, origin="http://docker", autoping=True)
        return connection

    @locking
    async def pull_image(self, image, progress_callback=None, force=False):
        """
        Pulls an image from the Docker repository

        :params image: Image name
        :params progress_callback: A function that receive a log message about image download progress
        :params force: Pull the image even if it is already available locally
        """

        if not force:
            try:
                await self.query("GET", f"images/{image}/json")
                return  # We already have the image skip the download
            except DockerHttp404Error:
                pass

        if progress_callback:
            progress_callback(f"Pulling '{image}' from Docker repository")
        try:
            response = await self.http_query("POST", "images/create", params={"fromImage": image}, timeout=None)
        except DockerError as e:
            raise DockerError(
                f"Could not pull the '{image}' image from Docker repository, "
                f"please check your Internet connection (original error: {e})"
            )
        # The pull api will stream status via an HTTP JSON stream
        content = ""
        try:
            while True:
                try:
                    chunk = await response.content.read(CHUNK_SIZE)
                except aiohttp.ServerDisconnectedError as e:
                    raise DockerError(
                        f"Disconnected while pulling Docker image '{image}' from Docker repository"
                    ) from e
                except asyncio.TimeoutError as e:
                    raise DockerError(
                        f"Timeout while pulling Docker image '{image}' from Docker repository"
                    ) from e
                if not chunk:
                    break
                content += chunk.decode("utf-8")

                try:
                    while True:
                        content = content.lstrip(" \r\n\t")
                        answer, index = json.JSONDecoder().raw_decode(content)
                        if not isinstance(answer, dict):
                            raise DockerError(f"Invalid response while pulling Docker image '{image}'")
                        error_detail = answer.get("errorDetail")
                        error = answer.get("error")
                        if not error and isinstance(error_detail, dict):
                            error = error_detail.get("message")
                        if error:
                            raise DockerError(error)
                        if "progress" in answer and progress_callback:
                            progress_callback("Pulling image {}:{}: {}".format(image, answer["id"], answer["progress"]))
                        content = content[index:]
                except ValueError:  # Partial JSON
                    pass

            if content.strip():
                raise DockerError(f"Invalid response while pulling Docker image '{image}'")
        finally:
            response.close()

        if progress_callback:
            progress_callback(f"Success pulling image {image}")

    async def list_images(self):
        """
        Gets Docker image list.

        :returns: list of dicts
        :rtype: list
        """

        images = []
        for image in await self.query("GET", "images/json", params={"all": 0}):
            if image["RepoTags"]:
                for tag in image["RepoTags"]:
                    if tag != "<none>:<none>":
                        images.append({"image": tag})
        return sorted(images, key=lambda i: i["image"])