#!/usr/bin/env python
#
# Copyright (C) 2016 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/>.

import ipaddress
import aiohttp
import asyncio
import async_timeout
import socket
import json
import sys
import io
from fastapi import HTTPException
from aiohttp import web

from ..utils import parse_version
from ..utils.asyncio import locking
from ..controller.controller_error import (
    ControllerError,
    ControllerBadRequestError,
    ControllerNotFoundError,
    ControllerForbiddenError,
    ControllerTimeoutError,
    ControllerUnauthorizedError,
    ComputeError,
    ComputeConflictError
)
from ..version import __version__, __version_info__


import logging

log = logging.getLogger(__name__)


class Compute:
    """
    A GNS3 compute.
    """

    def __init__(
        self,
        compute_id,
        controller=None,
        protocol="http",
        host="localhost",
        port=3080,
        user=None,
        password=None,
        name=None,
        console_host=None,
        ssl_context=None,
    ):
        self._http_session = None
        assert controller is not None
        log.info("Create compute %s", compute_id)

        # if compute_id is None:
        #     self._id = str(uuid.uuid4())
        # else:
        self._id = compute_id

        self.protocol = protocol
        self._console_host = console_host
        self.host = host
        self.port = port
        self._user = None
        self._password = None
        self._connected = False
        self._notifications = None
        self._closed = False  # Close mean we are destroying the compute node
        self._controller = controller
        self._set_auth(user, password)
        self._cpu_usage_percent = 0
        self._memory_usage_percent = 0
        self._disk_usage_percent = 0
        self._last_error = None
        self._ssl_context = ssl_context
        self._capabilities = {"version": "", "platform": "", "cpus": 0, "memory": 0, "disk_size": 0, "node_types": []}
        self.name = name
        # Cache of interfaces on remote host
        self._interfaces_cache = None
        self._connection_failure = 0

    def _session(self):
        if self._http_session is None or self._http_session.closed is True:
            connector = aiohttp.TCPConnector(force_close=True, ssl_context=self._ssl_context)
            self._http_session = aiohttp.ClientSession(connector=connector)
        return self._http_session

    def _set_auth(self, user, password):
        """
        Set authentication parameters
        """

        if user is None or len(user.strip()) == 0:
            self._user = None
            self._password = None
            self._auth = None
        else:
            self._user = user.strip()
            if password:
                self._password = password
                try:
                    self._auth = aiohttp.BasicAuth(self._user, self._password.get_secret_value(), "utf-8")
                except ValueError as e:
                    log.error(str(e))
            else:
                self._password = None
                self._auth = aiohttp.BasicAuth(self._user, "")

    def set_last_error(self, msg):
        """
        Set the last error message for this compute.

        :param msg: message
        """
        self._last_error = msg

    async def interfaces(self):
        """
        Get the list of network on compute
        """
        if not self._interfaces_cache:
            response = await self.get("/network/interfaces")
            self._interfaces_cache = response.json
        return self._interfaces_cache

    async def update(self, **kwargs):

        for kw in kwargs:
            if kw not in ("user", "password"):
                setattr(self, kw, kwargs[kw])
        # It's important to set user and password at the same time
        if "user" in kwargs or "password" in kwargs:
            self._set_auth(kwargs.get("user", self._user), kwargs.get("password", self._password))
        if self._http_session and not self._http_session.closed:
            await self._http_session.close()
        self._connected = False
        self._controller.notification.controller_emit("compute.updated", self.asdict())
        self._controller.save()

    async def close(self):

        self._connected = False
        if self._http_session and not self._http_session.closed:
            await self._http_session.close()
        try:
            if self._notifications:
                await self._notifications
        except asyncio.CancelledError:
            pass
        self._closed = True

    @property
    def name(self):
        """
        :returns: Compute name
        """
        return self._name

    @name.setter
    def name(self, name):

        if name is not None:
            self._name = name
        else:
            if self._user:
                user = self._user
                # Due to random user generated by 1.4 it's common to have a very long user
                if len(user) > 14:
                    user = user[:11] + "..."
                self._name = f"{self._protocol}://{user}@{self._host}:{self._port}"
            else:
                self._name = f"{self._protocol}://{self._host}:{self._port}"

    @property
    def connected(self):
        """
        :returns: True if compute node is connected
        """
        return self._connected

    @property
    def id(self):
        """
        :returns: Compute identifier (string)
        """
        return self._id

    @property
    def host(self):
        """
        :returns: Compute host (string)
        """
        return self._host

    @property
    def host_ip(self):
        """
        Return the IP associated to the host
        """
        try:
            return socket.gethostbyname(self._host)
        except socket.gaierror:
            return "0.0.0.0"

    @host.setter
    def host(self, host):
        self._host = host
        if self._console_host is None:
            self._console_host = host

    @property
    def console_host(self):
        return self._console_host

    @property
    def port(self):
        """
        :returns: Compute port (integer)
        """
        return self._port

    @port.setter
    def port(self, port):
        self._port = port

    @property
    def protocol(self):
        """
        :returns: Compute protocol (string)
        """
        return self._protocol

    @protocol.setter
    def protocol(self, protocol):
        self._protocol = protocol

    @property
    def user(self):
        return self._user

    @user.setter
    def user(self, value):
        self._set_auth(value, self._password)

    @property
    def password(self):
        return self._password

    @password.setter
    def password(self, value):
        self._set_auth(self._user, value)

    @property
    def cpu_usage_percent(self):
        return self._cpu_usage_percent

    @property
    def memory_usage_percent(self):
        return self._memory_usage_percent

    @property
    def disk_usage_percent(self):
        return self._disk_usage_percent

    def asdict(self, topology_dump=False):
        """
        :param topology_dump: Filter to keep only properties require for saving on disk
        """

        if topology_dump:
            return {
                "compute_id": self._id,
                "name": self._name,
                "protocol": self._protocol,
                "host": self._host,
                "port": self._port,
            }
        return {
            "compute_id": self._id,
            "name": self._name,
            "protocol": self._protocol,
            "host": self._host,
            "port": self._port,
            "user": self._user,
            "connected": self._connected,
            "cpu_usage_percent": self._cpu_usage_percent,
            "memory_usage_percent": self._memory_usage_percent,
            "disk_usage_percent": self._disk_usage_percent,
            "capabilities": self._capabilities,
            "last_error": self._last_error,
        }

    async def download_file(self, project, path):
        """
        Read file of a project and download it

        :param project: A project object
        :param path: The path of the file in the project
        :returns: A file stream
        """

        url = self._getUrl(f"/projects/{project.id}/files/{path}")
        response = await self._session().request("GET", url, auth=self._auth)
        if response.status == 404:
            raise ControllerNotFoundError(f"{path} not found on compute")
        return response

    async def download_image(self, image_type, image):
        """
        Read file of a project and download it

        :param image_type: Image type
        :param image: The path of the image
        :returns: A file stream
        """

        url = self._getUrl(f"/{image_type}/images/{image}")
        response = await self._session().request("GET", url, auth=self._auth)
        if response.status == 404:
            raise ControllerNotFoundError(f"{image} not found on compute")
        return response

    async def http_query(self, method, path, data=None, dont_connect=False, **kwargs):
        """
        :param dont_connect: If true do not reconnect if not connected
        """

        if not self._connected and not dont_connect:
            if self._id == "vm" and not self._controller.gns3vm.running:
                await self._controller.gns3vm.start()
            await self.connect()
        if not self._connected and not dont_connect:
            raise ComputeError(f"Cannot connect to compute '{self._name}' with request {method} {path}")
        response = await self._run_http_query(method, path, data=data, **kwargs)
        return response

    async def _try_reconnect(self):
        """
        We catch error during reconnect
        """
        try:
            await self.connect()
        except ControllerError:
            pass

    @locking
    async def connect(self, report_failed_connection=False):
        """
        Check if remote server is accessible
        """

        if not self._connected and not self._closed and self.host:
            try:
                log.info(f"Connecting to compute '{self._id}'")
                response = await self._run_http_query("GET", "/capabilities")
            except ComputeError as e:
                if report_failed_connection:
                    raise
                log.warning(f"Cannot connect to compute '{self._id}': {e}")
                # Try to reconnect after 5 seconds if server unavailable only if not during tests (otherwise we create a ressource usage bomb)
                if not hasattr(sys, "_called_from_test") or not sys._called_from_test:
                    self._connection_failure += 1
                    # After 5 failure we close the project using the compute to avoid sync issues
                    if self._connection_failure == 10:
                        log.error(f"Could not connect to compute '{self._id}' after multiple attempts: {e}")
                        await self._controller.close_compute_projects(self)
                    asyncio.get_event_loop().call_later(5, lambda: asyncio.ensure_future(self._try_reconnect()))
                return
            except web.HTTPNotFound:
                raise ControllerNotFoundError(f"The server {self._id} is not a GNS3 server or it's a 1.X server")
            except web.HTTPUnauthorized:
                raise ControllerUnauthorizedError(f"Invalid auth for server {self._id}")
            except web.HTTPServiceUnavailable:
                raise ControllerNotFoundError(f"The server {self._id} is unavailable")
            except ValueError:
                raise ComputeError(f"Invalid server url for server {self._id}")

            if "version" not in response.json:
                msg = f"The server {self._id} is not a GNS3 server"
                log.error(msg)
                await self._http_session.close()
                raise ControllerNotFoundError(msg)
            self._capabilities = response.json

            if response.json["version"].split("+")[0] != __version__.split("+")[0]:
                if self._name.startswith("GNS3 VM"):
                    msg = (
                        "GNS3 version {} is not the same as the GNS3 VM version {}. Please upgrade the GNS3 VM.".format(
                            __version__, response.json["version"]
                        )
                    )
                else:
                    msg = "GNS3 controller version {} is not the same as compute {} version {}".format(
                        __version__, self._name, response.json["version"]
                    )
                if __version_info__[3] == 0:
                    # Stable release
                    log.error(msg)
                    await self._http_session.close()
                    self._last_error = msg
                    raise ControllerError(msg)
                elif parse_version(__version__)[:2] != parse_version(response.json["version"])[:2]:
                    # We don't allow different major version to interact even with dev build
                    log.error(msg)
                    await self._http_session.close()
                    self._last_error = msg
                    raise ControllerError(msg)
                else:
                    msg = f"{msg}\nUsing different versions may result in unexpected problems. Please use at your own risk."
                    self._controller.notification.controller_emit("log.warning", {"message": msg})

            self._notifications = asyncio.gather(self._connect_notification())
            self._connected = True
            self._connection_failure = 0
            self._last_error = None
            self._controller.notification.controller_emit("compute.updated", self.asdict())

    async def _connect_notification(self):
        """
        Connect to the notification stream
        """

        ws_url = self._getUrl("/notifications/ws")
        try:
            async with self._session().ws_connect(ws_url, auth=self._auth, heartbeat=10) as ws:
                log.info(f"Connected to compute '{self._id}' WebSocket '{ws_url}'")
                async for response in ws:
                    if response.type == aiohttp.WSMsgType.TEXT:
                        msg = json.loads(response.data)
                        action = msg.pop("action")
                        event = msg.pop("event")
                        project_id = msg.pop("project_id", None)
                        if action == "ping":
                            self._cpu_usage_percent = event["cpu_usage_percent"]
                            self._memory_usage_percent = event["memory_usage_percent"]
                            self._disk_usage_percent = event["disk_usage_percent"]
                            # FIXME: slow down number of compute events
                            self._controller.notification.controller_emit("compute.updated", self.asdict())
                        else:
                            if action == "log.error":
                                log.error(event.pop("message"))
                            await self._controller.notification.dispatch(
                                action, event, project_id=project_id, compute_id=self.id
                            )
                    else:
                        if response.type == aiohttp.WSMsgType.CLOSE:
                            await ws.close()
                        elif response.type == aiohttp.WSMsgType.ERROR:
                            log.error(f"Error received on compute '{self._id}' WebSocket '{ws_url}': {ws.exception()}")
                        elif response.type == aiohttp.WSMsgType.CLOSED:
                            pass
                        break
        except aiohttp.ClientError as e:
            log.error(f"Client response error received on compute '{self._id}' WebSocket '{ws_url}': {e}")
        finally:
            self._connected = False
            log.info(f"Connection closed to compute '{self._id}' WebSocket '{ws_url}'")

        # Try to reconnect after 1 second if server unavailable only if not during tests (otherwise we create a ressources usage bomb)
        from gns3server.api.server import app
        if not app.state.exiting and not hasattr(sys, "_called_from_test"):
            log.info(f"Reconnecting to compute '{self._id}' WebSocket '{ws_url}'")
            asyncio.get_event_loop().call_later(1, lambda: asyncio.ensure_future(self.connect()))

        self._cpu_usage_percent = None
        self._memory_usage_percent = None
        self._disk_usage_percent = None
        self._controller.notification.controller_emit("compute.updated", self.asdict())

    def _getUrl(self, path):
        host = self._host
        # IPV6
        if host:
            # IPV6
            if ":" in host:
                # Reduce IPV6 to his simple form
                host = str(ipaddress.IPv6Address(host))
                if host == "::":
                    host = "::1"
                host = f"[{host}]"
            elif host == "0.0.0.0":
                host = "127.0.0.1"
        return f"{self._protocol}://{host}:{self._port}/v3/compute{path}"

    def get_url(self, path):
        """ Returns URL for specific path at Compute"""
        return self._getUrl(path)

    async def _run_http_query(self, method, path, data=None, timeout=20, raw=False):
        with async_timeout.timeout(timeout):
            url = self._getUrl(path)
            headers = {"content-type": "application/json"}
            chunked = None
            if data == {}:
                data = None
            elif data is not None:
                if hasattr(data, "asdict"):
                    data = json.dumps(data.asdict())
                elif isinstance(data, aiohttp.streams.EmptyStreamReader):
                    data = None
                # Stream the request
                elif isinstance(data, aiohttp.streams.StreamReader) or isinstance(data, bytes):
                    chunked = True
                    headers["content-type"] = "application/octet-stream"
                # If the data is an open file we will iterate on it
                elif isinstance(data, io.BufferedIOBase):
                    chunked = True
                    headers["content-type"] = "application/octet-stream"
                else:
                    data = json.dumps(data).encode("utf-8")
        try:
            log.debug(f"Attempting request to compute: {method} {url} {headers}")
            response = await self._session().request(
                method, url, headers=headers, data=data, auth=self._auth, chunked=chunked, timeout=timeout
            )
        except asyncio.TimeoutError:
            raise ComputeError(f"Timeout error for {method} call to {url} after {timeout}s")
        except (
            aiohttp.ClientError,
            aiohttp.ServerDisconnectedError,
            aiohttp.ClientResponseError,
            ValueError,
            KeyError,
            socket.gaierror,
        ) as e:
            #  aiohttp 2.3.1 raises socket.gaierror when cannot find host
            raise ComputeError(str(e))
        body = await response.read()
        if body and not raw:
            body = body.decode()

        if response.status >= 300:
            # Try to decode the GNS3 error
            if body and not raw:
                try:
                    msg = json.loads(body)["message"]
                except (KeyError, ValueError):
                    msg = body
            else:
                msg = ""

            if response.status == 400:
                raise ControllerBadRequestError(msg)
            elif response.status == 401:
                raise ControllerUnauthorizedError(f"Invalid authentication for compute '{self.name}' [{self.id}]")
            elif response.status == 403:
                raise ControllerForbiddenError(msg)
            elif response.status == 404:
                raise ControllerNotFoundError(f"{method} {path} not found")
            elif response.status == 408 or response.status == 504:
                raise ControllerTimeoutError(f"{method} {path} request timeout")
            elif response.status == 409:
                try:
                    raise ComputeConflictError(url, json.loads(body))
                # If the 409 doesn't come from a GNS3 server
                except ValueError:
                    raise ControllerError(msg)
            else:
                raise HTTPException(
                    status_code=response.status,
                    detail=f"HTTP error {response.status} received from compute "
                           f"'{self.name}' for request {method} {path}: {msg}"
                )

        if body and len(body):
            if raw:
                response.body = body
            else:
                try:
                    response.json = json.loads(body)
                except ValueError:
                    raise ControllerError(f"The server {self._id} is not a GNS3 server")
        else:
            response.json = {}
            response.body = b""
        return response

    async def get(self, path, **kwargs):
        return await self.http_query("GET", path, **kwargs)

    async def post(self, path, data={}, **kwargs):
        response = await self.http_query("POST", path, data, **kwargs)
        return response

    async def put(self, path, data={}, **kwargs):
        response = await self.http_query("PUT", path, data, **kwargs)
        return response

    async def delete(self, path, **kwargs):
        return await self.http_query("DELETE", path, **kwargs)

    async def forward(self, method, type, path, data=None):
        """
        Forward a call to the emulator on compute
        """
        try:
            action = f"/{type}/{path}"
            res = await self.http_query(method, action, data=data, timeout=None)
        except aiohttp.ServerDisconnectedError:
            raise ControllerError(f"Connection lost to {self._id} during {method} {action}")
        return res.json

    async def list_files(self, project):
        """
        List files in the project on computes
        """
        path = f"/projects/{project.id}/files"
        res = await self.http_query("GET", path, timeout=None)
        return res.json

    async def get_ip_on_same_subnet(self, other_compute):
        """
        Try to find the best ip for communication from one compute
        to another

        :returns: Tuple (ip_for_this_compute, ip_for_other_compute)
        """
        if other_compute == self:
            return self.host_ip, self.host_ip

        # Perhaps the user has correct network gateway, we trust him
        if self.host_ip not in ("0.0.0.0", "127.0.0.1") and other_compute.host_ip not in ("0.0.0.0", "127.0.0.1"):
            return self.host_ip, other_compute.host_ip

        this_compute_interfaces = await self.interfaces()
        other_compute_interfaces = await other_compute.interfaces()

        # Sort interface to put the compute host in first position
        # we guess that if user specified this host it could have a reason (VMware Nat / Host only interface)
        this_compute_interfaces = sorted(this_compute_interfaces, key=lambda i: i["ip_address"] != self.host_ip)
        other_compute_interfaces = sorted(
            other_compute_interfaces, key=lambda i: i["ip_address"] != other_compute.host_ip
        )

        for this_interface in this_compute_interfaces:
            # Skip if no ip or no netmask (vbox when stopped set a null netmask)
            if len(this_interface["ip_address"]) == 0 or this_interface["netmask"] is None:
                continue
            # Ignore 169.254 network because it's for Windows special purpose
            if this_interface["ip_address"].startswith("169.254."):
                continue

            this_network = ipaddress.ip_network(
                "{}/{}".format(this_interface["ip_address"], this_interface["netmask"]), strict=False
            )

            for other_interface in other_compute_interfaces:
                if len(other_interface["ip_address"]) == 0 or other_interface["netmask"] is None:
                    continue

                # Avoid stuff like 127.0.0.1
                if other_interface["ip_address"] == this_interface["ip_address"]:
                    continue

                other_network = ipaddress.ip_network(
                    "{}/{}".format(other_interface["ip_address"], other_interface["netmask"]), strict=False
                )
                if this_network.overlaps(other_network):
                    return this_interface["ip_address"], other_interface["ip_address"]

        raise ValueError(f"No common subnet for compute {self.name} and {other_compute.name}")