#
# 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.docker_error import DockerError, DockerHttp304Error, DockerHttp404Error

log = logging.getLogger(__name__)


# Be careful to keep it consistent
DOCKER_MINIMUM_API_VERSION = "1.25"
DOCKER_MINIMUM_VERSION = "1.13"
DOCKER_PREFERRED_API_VERSION = "1.30"
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

    @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:
                        # ldd returns 1 if the file is not a dynamic executable
                        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
        """

        server_config = Config.instance().get_section_config("Server")
        appname = vendor = "GNS3"
        resources_path = os.path.expanduser(server_config.get("resources_path", platformdirs.user_data_dir(appname, vendor, roaming=True)))
        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
            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
                version = await self.query("GET", "version")
            except (aiohttp.ClientError, FileNotFoundError):
                self._connected = False
                raise DockerError("Can't connect to docker daemon")

            docker_version = parse_version(version["ApiVersion"])

            if docker_version < parse_version(DOCKER_MINIMUM_API_VERSION):
                raise DockerError(
                    f"Docker version is {version['Version']}. "
                    f"GNS3 requires a minimum version of {DOCKER_MINIMUM_VERSION}"
                )

            preferred_api_version = parse_version(DOCKER_PREFERRED_API_VERSION)
            if docker_version >= preferred_api_version:
                self._api_version = DOCKER_PREFERRED_API_VERSION

    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 body and len(body):
            if response.headers.get('CONTENT-TYPE') == 'application/json':
                body = json.loads(body.decode("utf-8"))
            else:
                body = body.decode("utf-8")
        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: Dictionnary 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/v1.24/" + path
        else:
            url = "http://docker/v" + DOCKER_MINIMUM_API_VERSION + "/" + path
        try:
            if path != "version":  # version is use by check connection
                await self._check_connection()
            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}")
            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):
        """
        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
        """

        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 hub")
        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 Hub, "
                f"please check your Internet connection (original error: {e})"
            )
        # The pull api will stream status via an HTTP JSON stream
        content = ""
        while True:
            try:
                chunk = await response.content.read(CHUNK_SIZE)
            except aiohttp.ServerDisconnectedError:
                log.error(f"Disconnected from server while pulling Docker image '{image}' from docker hub")
                break
            except asyncio.TimeoutError:
                log.error(f"Timeout while pulling Docker image '{image}' from docker hub")
                break
            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 "progress" in answer and progress_callback:
                        progress_callback("Pulling image {}:{}: {}".format(image, answer["id"], answer["progress"]))
                    content = content[index:]
            except ValueError:  # Partial JSON
                pass
        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"])