# -*- coding: utf-8 -*-
#
# 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/>.

import sys
import os
import struct
import stat
import asyncio
import aiohttp
import socket
import shutil
import re

import logging
log = logging.getLogger(__name__)

from uuid import UUID, uuid4
from gns3server.utils.interfaces import is_interface_up
from ..config import Config
from ..utils.asyncio import wait_run_in_executor
from ..utils import force_unix_path
from .project_manager import ProjectManager

from .nios.nio_udp import NIOUDP
from .nios.nio_tap import NIOTAP
from .nios.nio_generic_ethernet import NIOGenericEthernet
from ..utils.images import md5sum, remove_checksum
from .node_error import NodeError


class BaseManager:

    """
    Base class for all Manager classes.
    Responsible of management of a node pool of the same type.
    """

    _convert_lock = None

    def __init__(self):

        BaseManager._convert_lock = asyncio.Lock()
        self._nodes = {}
        self._port_manager = None
        self._config = Config.instance()

    @classmethod
    def instance(cls):
        """
        Singleton to return only one instance of BaseManager.

        :returns: instance of BaseManager
        """

        if not hasattr(cls, "_instance") or cls._instance is None:
            cls._instance = cls()
        return cls._instance

    @property
    def module_name(self):
        """
        Returns the module name.

        :returns: module name
        """

        return self.__class__.__name__

    @property
    def port_manager(self):
        """
        Returns the port manager.

        :returns: Port manager
        """

        return self._port_manager

    @port_manager.setter
    def port_manager(self, new_port_manager):

        self._port_manager = new_port_manager

    @property
    def config(self):
        """
        Returns the server config.

        :returns: Config
        """

        return self._config

    @asyncio.coroutine
    def unload(self):

        tasks = []
        for node_id in self._nodes.keys():
            tasks.append(asyncio.async(self.close_node(node_id)))

        if tasks:
            done, _ = yield from asyncio.wait(tasks)
            for future in done:
                try:
                    future.result()
                except (Exception, GeneratorExit) as e:
                    log.error("Could not close node {}".format(e), exc_info=1)
                    continue

        if hasattr(BaseManager, "_instance"):
            BaseManager._instance = None
        log.debug("Module {} unloaded".format(self.module_name))

    def get_node(self, node_id, project_id=None):
        """
        Returns a Node instance.

        :param node_id: Node identifier
        :param project_id: Project identifier

        :returns: Node instance
        """

        if project_id:
            # check the project_id exists
            project = ProjectManager.instance().get_project(project_id)

        try:
            UUID(node_id, version=4)
        except ValueError:
            raise aiohttp.web.HTTPBadRequest(text="Node ID {} is not a valid UUID".format(node_id))

        if node_id not in self._nodes:
            raise aiohttp.web.HTTPNotFound(text="Node ID {} doesn't exist".format(node_id))

        node = self._nodes[node_id]
        if project_id:
            if node.project.id != project.id:
                raise aiohttp.web.HTTPNotFound(text="Project ID {} doesn't belong to node {}".format(project_id, node.name))

        return node

    @asyncio.coroutine
    def convert_old_project(self, project, legacy_id, name):
        """
        Convert projects made before version 1.3

        :param project: Project instance
        :param legacy_id: old identifier
        :param name: node name

        :returns: new identifier
        """

        new_id = str(uuid4())
        legacy_project_files_path = os.path.join(project.path, "{}-files".format(project.name))
        new_project_files_path = os.path.join(project.path, "project-files")
        if os.path.exists(legacy_project_files_path) and not os.path.exists(new_project_files_path):
            # move the project files
            log.info("Converting old project...")
            try:
                log.info('Moving "{}" to "{}"'.format(legacy_project_files_path, new_project_files_path))
                yield from wait_run_in_executor(shutil.move, legacy_project_files_path, new_project_files_path)
            except OSError as e:
                raise aiohttp.web.HTTPInternalServerError(text="Could not move project files directory: {} to {} {}".format(legacy_project_files_path,
                                                                                                                            new_project_files_path, e))

        if project.is_local() is False:
            legacy_remote_project_path = os.path.join(project.location, project.name, self.module_name.lower())
            new_remote_project_path = os.path.join(project.path, "project-files", self.module_name.lower())
            if os.path.exists(legacy_remote_project_path) and not os.path.exists(new_remote_project_path):
                # move the legacy remote project (remote servers only)
                log.info("Converting old remote project...")
                try:
                    log.info('Moving "{}" to "{}"'.format(legacy_remote_project_path, new_remote_project_path))
                    yield from wait_run_in_executor(shutil.move, legacy_remote_project_path, new_remote_project_path)
                except OSError as e:
                    raise aiohttp.web.HTTPInternalServerError(text="Could not move directory: {} to {} {}".format(legacy_remote_project_path,
                                                                                                                  new_remote_project_path, e))

        if hasattr(self, "get_legacy_vm_workdir"):
            # rename old project node working dir
            log.info("Converting old node working directory...")
            legacy_vm_dir = self.get_legacy_vm_workdir(legacy_id, name)
            legacy_vm_working_path = os.path.join(new_project_files_path, legacy_vm_dir)
            new_vm_working_path = os.path.join(new_project_files_path, self.module_name.lower(), new_id)
            if os.path.exists(legacy_vm_working_path) and not os.path.exists(new_vm_working_path):
                try:
                    log.info('Moving "{}" to "{}"'.format(legacy_vm_working_path, new_vm_working_path))
                    yield from wait_run_in_executor(shutil.move, legacy_vm_working_path, new_vm_working_path)
                except OSError as e:
                    raise aiohttp.web.HTTPInternalServerError(text="Could not move vm working directory: {} to {} {}".format(legacy_vm_working_path,
                                                                                                                             new_vm_working_path, e))

        return new_id

    @asyncio.coroutine
    def create_node(self, name, project_id, node_id, *args, **kwargs):
        """
        Create a new node

        :param name: Node name
        :param project_id: Project identifier
        :param node_id: restore a node identifier
        """

        if node_id in self._nodes:
            return self._nodes[node_id]

        project = ProjectManager.instance().get_project(project_id)
        if node_id and isinstance(node_id, int):
            # old project
            with (yield from BaseManager._convert_lock):
                node_id = yield from self.convert_old_project(project, node_id, name)

        if not node_id:
            node_id = str(uuid4())

        node = self._NODE_CLASS(name, node_id, project, self, *args, **kwargs)
        if asyncio.iscoroutinefunction(node.create):
            yield from node.create()
        else:
            node.create()
        self._nodes[node.id] = node
        project.add_node(node)
        return node

    @asyncio.coroutine
    def close_node(self, node_id):
        """
        Close a node

        :param node_id: Node identifier

        :returns: Node instance
        """

        node = self.get_node(node_id)
        if asyncio.iscoroutinefunction(node.close):
            yield from node.close()
        else:
            node.close()
        return node

    @asyncio.coroutine
    def project_closing(self, project):
        """
        Called when a project is about to be closed.

        :param project: Project instance
        """

        pass

    @asyncio.coroutine
    def project_closed(self, project):
        """
        Called when a project is closed.

        :param project: Project instance
        """

        for node in project.nodes:
            if node.id in self._nodes:
                del self._nodes[node.id]

    @asyncio.coroutine
    def project_moved(self, project):
        """
        Called when a project is moved

        :param project: project instance
        """

        pass

    @asyncio.coroutine
    def project_committed(self, project):
        """
        Called when a project is committed.

        :param project: Project instance
        """

        pass

    @asyncio.coroutine
    def delete_node(self, node_id):
        """
        Delete a node. The node working directory will be destroyed when a commit is received.

        :param node_id: Node identifier
        :returns: Node instance
        """

        node = yield from self.close_node(node_id)
        node.project.emit("node.deleted", node)
        node.project.mark_node_for_destruction(node)
        if node.id in self._nodes:
            del self._nodes[node.id]
        return node

    @staticmethod
    def has_privileged_access(executable):
        """
        Check if an executable can access Ethernet and TAP devices in
        RAW mode.

        :param executable: executable path

        :returns: True or False
        """

        if sys.platform.startswith("win"):
            # do not check anything on Windows
            return True

        if os.geteuid() == 0:
            # we are root, so we should have privileged access.
            return True

        if os.stat(executable).st_uid == 0 and (os.stat(executable).st_mode & stat.S_ISUID or os.stat(executable).st_mode & stat.S_ISGID):
            # the executable has set UID bit.
            return True

        # test if the executable has the CAP_NET_RAW capability (Linux only)
        try:
            if sys.platform.startswith("linux") and "security.capability" in os.listxattr(executable):
                caps = os.getxattr(executable, "security.capability")
                # test the 2nd byte and check if the 13th bit (CAP_NET_RAW) is set
                if struct.unpack("<IIIII", caps)[1] & 1 << 13:
                    return True
        except OSError as e:
            log.error("could not determine if CAP_NET_RAW capability is set for {}: {}".format(executable, e))

        return False

    def create_nio(self, executable, nio_settings):
        """
        Creates a new NIO.

        :param nio_settings: information to create the NIO

        :returns: a NIO object
        """

        nio = None
        if nio_settings["type"] == "nio_udp":
            lport = nio_settings["lport"]
            rhost = nio_settings["rhost"]
            rport = nio_settings["rport"]
            try:
                info = socket.getaddrinfo(rhost, rport, socket.AF_UNSPEC, socket.SOCK_DGRAM, 0, socket.AI_PASSIVE)
                if not info:
                    raise aiohttp.web.HTTPInternalServerError(text="getaddrinfo returns an empty list on {}:{}".format(rhost, rport))
                for res in info:
                    af, socktype, proto, _, sa = res
                    with socket.socket(af, socktype, proto) as sock:
                        sock.connect(sa)
            except OSError as e:
                raise aiohttp.web.HTTPInternalServerError(text="Could not create an UDP connection to {}:{}: {}".format(rhost, rport, e))
            nio = NIOUDP(lport, rhost, rport)
        elif nio_settings["type"] == "nio_tap":
            tap_device = nio_settings["tap_device"]
            # if not is_interface_up(tap_device):
            #    raise aiohttp.web.HTTPConflict(text="TAP interface {} does not exist or is down".format(tap_device))
            # FIXME: check for permissions on tap device
            # if not self.has_privileged_access(executable):
            #    raise aiohttp.web.HTTPForbidden(text="{} has no privileged access to {}.".format(executable, tap_device))
            nio = NIOTAP(tap_device)
        elif nio_settings["type"] == "nio_generic_ethernet":
            ethernet_device = nio_settings["ethernet_device"]
            if not is_interface_up(ethernet_device):
                raise aiohttp.web.HTTPConflict(text="Ethernet interface {} does not exist or is down".format(ethernet_device))
            nio = NIOGenericEthernet(ethernet_device)
        assert nio is not None
        return nio

    def get_abs_image_path(self, path):
        """
        Get the absolute path of an image

        :param path: file path
        :return: file path
        """

        if not path:
            return ""

        img_directory = self.get_images_directory()

        # Windows path should not be send to a unix server
        if not sys.platform.startswith("win"):
            if re.match(r"^[A-Z]:", path) is not None:
                raise NodeError("{} is not allowed on this remote server. Please use only a filename in {}.".format(path, img_directory))

        if not os.path.isabs(path):
            s = os.path.split(path)
            path = os.path.normpath(os.path.join(img_directory, *s))

            # Compatibility with old topologies we look in parent directory
            # We look at first in new location
            if not os.path.exists(path):
                old_path = os.path.normpath(os.path.join(img_directory, '..', *s))
                if os.path.exists(old_path):
                    return force_unix_path(old_path)

            return force_unix_path(path)
        else:
            # For non local server we disallow using absolute path outside image directory
            if Config.instance().get_section_config("Server").get("local", False) is False:
                img_directory = self.config.get_section_config("Server").get("images_path", os.path.expanduser("~/GNS3/images"))
                img_directory = force_unix_path(img_directory)
                path = force_unix_path(path)
                if len(os.path.commonprefix([img_directory, path])) < len(img_directory):
                    raise NodeError("{} is not allowed on this remote server. Please use only a filename in {}.".format(path, img_directory))

        return force_unix_path(path)

    def get_relative_image_path(self, path):
        """
        Get a path relative to images directory path
        or an abspath if the path is not located inside
        image directory

        :param path: file path
        :return: file path
        """

        if not path:
            return ""
        img_directory = force_unix_path(self.get_images_directory())
        path = force_unix_path(self.get_abs_image_path(path))
        if os.path.commonprefix([img_directory, path]) == img_directory:
            return os.path.relpath(path, img_directory)
        return path

    @asyncio.coroutine
    def list_images(self):
        """
        Return the list of available images for this node type

        :returns: Array of hash
        """

        images = []
        img_dir = self.get_images_directory()
        for root, dirs, files in os.walk(img_dir):
            for filename in files:
                if filename[0] != "." and not filename.endswith(".md5sum"):
                    path = os.path.relpath(os.path.join(root, filename), img_dir)
                    images.append({
                        "filename": filename,
                        "path": path})
        return images

    def get_images_directory(self):
        """
        Get the image directory on disk
        """

        raise NotImplementedError

    @asyncio.coroutine
    def write_image(self, filename, stream):
        directory = self.get_images_directory()
        path = os.path.abspath(os.path.join(directory, *os.path.split(filename)))
        if os.path.commonprefix([directory, path]) != directory:
            raise aiohttp.web.HTTPForbidden(text="Could not write image: {}, {} is forbiden".format(filename, path))
        log.info("Writting image file %s", path)
        try:
            remove_checksum(path)
            # We store the file under his final name only when the upload is finished
            tmp_path = path + ".tmp"
            os.makedirs(os.path.dirname(path), exist_ok=True)
            with open(tmp_path, 'wb+') as f:
                while True:
                    packet = yield from stream.read(512)
                    if not packet:
                        break
                    f.write(packet)
            os.chmod(tmp_path, stat.S_IWRITE | stat.S_IREAD | stat.S_IEXEC)
            shutil.move(tmp_path, path)
            md5sum(path)
        except OSError as e:
            raise aiohttp.web.HTTPConflict(text="Could not write image: {} because {}".format(filename, e))