#!/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 os
import sys
import stat
import json
import uuid
import shutil
import aiofiles
import itertools
import tempfile
import stat
import gns3server.utils.zipfile_zstd as zipfile_zstd

from .controller_error import ControllerError
from .topology import load_topology
from ..utils.asyncio import wait_run_in_executor
from ..utils.asyncio import aiozipstream

import logging

log = logging.getLogger(__name__)

"""
Handle the import of project from a .gns3project
"""


async def import_project(controller, project_id, stream, location=None, name=None, keep_compute_ids=False,
                         auto_start=False, auto_open=False, auto_close=True):
    """
    Import a project contain in a zip file

    You must handle OSError exceptions

    :param controller: GNS3 Controller
    :param project_id: ID of the project to import
    :param stream: A io.BytesIO of the zipfile
    :param location: Directory for the project if None put in the default directory
    :param name: Wanted project name, generate one from the .gns3 if None
    :param keep_compute_ids: keep compute IDs unchanged

    :returns: Project
    """

    if location and ".gns3" in location:
        raise ControllerError("The destination path should not contain .gns3")

    try:
        with zipfile_zstd.ZipFile(stream) as zip_file:
            project_file = zip_file.read("project.gns3").decode()
    except zipfile_zstd.BadZipFile:
        raise ControllerError("Cannot import project, not a GNS3 project (invalid zip)")
    except KeyError:
        raise ControllerError("Cannot import project, project.gns3 file could not be found")

    try:
        topology = json.loads(project_file)
        # We import the project on top of an existing project (snapshots)
        if topology["project_id"] == project_id:
            project_name = topology["name"]
        else:
            # If the project name is already used we generate a new one
            if name:
                project_name = controller.get_free_project_name(name)
            else:
                project_name = controller.get_free_project_name(topology["name"])
    except (ValueError, KeyError):
        raise ControllerError("Cannot import project, the project.gns3 file is corrupted")

    if location:
        path = location
    else:
        projects_path = controller.projects_directory()
        path = os.path.join(projects_path, project_id)
    try:
        os.makedirs(path, exist_ok=True)
    except UnicodeEncodeError:
        raise ControllerError("The project name contain non supported or invalid characters")

    try:
        with zipfile_zstd.ZipFile(stream) as zip_file:
            await wait_run_in_executor(zip_file.extractall, path)
            _create_symbolic_links(zip_file, path)
    except zipfile_zstd.BadZipFile:
        raise ControllerError("Cannot extract files from GNS3 project (invalid zip)")

    topology = load_topology(os.path.join(path, "project.gns3"))
    topology["name"] = project_name
    # To avoid unexpected behavior (project start without manual operations just after import)
    topology["auto_start"] = auto_start
    topology["auto_open"] = auto_open
    topology["auto_close"] = auto_close

    # Generate a new node id
    node_old_to_new = {}
    for node in topology["topology"]["nodes"]:
        if "node_id" in node:
            node_old_to_new[node["node_id"]] = str(uuid.uuid4())
            _move_node_file(path, node["node_id"], node_old_to_new[node["node_id"]])
            node["node_id"] = node_old_to_new[node["node_id"]]
        else:
            node["node_id"] = str(uuid.uuid4())

    # Update link to use new id
    for link in topology["topology"]["links"]:
        link["link_id"] = str(uuid.uuid4())
        for node in link["nodes"]:
            node["node_id"] = node_old_to_new[node["node_id"]]

    # Generate new drawings id
    for drawing in topology["topology"]["drawings"]:
        drawing["drawing_id"] = str(uuid.uuid4())

    # Modify the compute id of the node depending of compute capacity
    if not keep_compute_ids:
        # For some VM type we move them to the GNS3 VM if possible
        # unless it's a linux host without GNS3 VM
        if not sys.platform.startswith("linux") or controller.has_compute("vm"):
            for node in topology["topology"]["nodes"]:
                if node["node_type"] in ("docker", "qemu", "iou", "nat"):
                    node["compute_id"] = "vm"
        else:
            # Round-robin through available compute resources.
            # computes = []
            # for compute_id in controller.computes:
            #     compute = controller.get_compute(compute_id)
            #     # only use the local compute or any connected compute
            #     if compute_id == "local" or compute.connected:
            #         computes.append(compute_id)
            #     else:
            #         log.warning(compute.name, "is not connected!")
            compute_nodes = itertools.cycle(controller.computes)
            for node in topology["topology"]["nodes"]:
                node["compute_id"] = next(compute_nodes)

    compute_created = set()
    for node in topology["topology"]["nodes"]:
        if node["compute_id"] != "local":
            # Project created on the remote GNS3 VM?
            if node["compute_id"] not in compute_created:
                compute = controller.get_compute(node["compute_id"])
                await compute.post(
                    "/projects",
                    data={
                        "name": project_name,
                        "project_id": project_id,
                    },
                )
                compute_created.add(node["compute_id"])
            await _move_files_to_compute(
                compute, project_id, path, os.path.join("project-files", node["node_type"], node["node_id"])
            )

    # And we dump the updated.gns3
    dot_gns3_path = os.path.join(path, project_name + ".gns3")
    # We change the project_id to avoid erasing the project
    topology["project_id"] = project_id
    with open(dot_gns3_path, "w+") as f:
        json.dump(topology, f, indent=4)
    os.remove(os.path.join(path, "project.gns3"))

    images_path = os.path.join(path, "images")
    if os.path.exists(images_path):
        await _import_images(controller, images_path)

    snapshots_path = os.path.join(path, "snapshots")
    if os.path.exists(snapshots_path):
        await _import_snapshots(snapshots_path, project_name, project_id)

    project = await controller.load_project(dot_gns3_path, load=False)
    return project

def _create_symbolic_links(zip_file, path):
    """
    Manually create symbolic links (if any) because ZipFile does not support it.

    :param zip_file: ZipFile instance
    :param path: project location
    """

    for zip_info in zip_file.infolist():
        if stat.S_ISLNK(zip_info.external_attr >> 16):
            symlink_target = zip_file.read(zip_info.filename).decode()
            symlink_path = os.path.join(path, zip_info.filename)
            try:
                # remove the regular file and replace it by a symbolic link
                os.remove(symlink_path)
                os.symlink(symlink_target, symlink_path)
            except OSError as e:
                raise ControllerError(f"Cannot create symbolic link: {e}")

def _move_node_file(path, old_id, new_id):
    """
    Move a file from a node when changing its id

    :param path: Path of the project
    :param old_id: ID before change
    :param new_id: New node UUID
    """

    root = os.path.join(path, "project-files")
    if os.path.exists(root):
        for dirname in os.listdir(root):
            module_dir = os.path.join(root, dirname)
            if os.path.isdir(module_dir):
                node_dir = os.path.join(module_dir, old_id)
                if os.path.exists(node_dir):
                    shutil.move(node_dir, os.path.join(module_dir, new_id))


async def _move_files_to_compute(compute, project_id, directory, files_path):
    """
    Move files to a remote compute
    """

    location = os.path.join(directory, files_path)
    if os.path.exists(location):
        for (dirpath, dirnames, filenames) in os.walk(location, followlinks=False):
            for filename in filenames:
                path = os.path.join(dirpath, filename)
                if os.path.islink(path):
                    continue
                dst = os.path.relpath(path, directory)
                await _upload_file(compute, project_id, path, dst)
        await wait_run_in_executor(shutil.rmtree, os.path.join(directory, files_path))


async def _upload_file(compute, project_id, file_path, path):
    """
    Upload a file to a remote project

    :param file_path: File path on the controller file system
    :param path: File path on the remote system relative to project directory
    """

    path = "/projects/{}/files/{}".format(project_id, path.replace("\\", "/"))
    with open(file_path, "rb") as f:
        await compute.http_query("POST", path, f, timeout=None)


async def _import_images(controller, images_path):
    """
    Copy images to the images directory or delete them if they already exist.
    """

    image_dir = controller.images_path()
    root = images_path
    for (dirpath, dirnames, filenames) in os.walk(root, followlinks=False):
        for filename in filenames:
            path = os.path.join(dirpath, filename)
            if os.path.islink(path):
                continue
            dst = os.path.join(image_dir, os.path.relpath(path, root))
            os.makedirs(os.path.dirname(dst), exist_ok=True)
            if not os.path.exists(dst):
                await wait_run_in_executor(shutil.move, path, dst)
                os.chmod(dst, stat.S_IWRITE | stat.S_IREAD | stat.S_IEXEC)


async def _import_snapshots(snapshots_path, project_name, project_id):
    """
    Import the snapshots and update their project name and ID to be the same as the main project.
    """

    for snapshot in os.listdir(snapshots_path):
        if not snapshot.endswith(".gns3project"):
            continue
        snapshot_path = os.path.join(snapshots_path, snapshot)
        with tempfile.TemporaryDirectory(dir=snapshots_path) as tmpdir:

            # extract everything to a temporary directory
            try:
                with open(snapshot_path, "rb") as f:
                    with zipfile_zstd.ZipFile(f) as zip_file:
                        await wait_run_in_executor(zip_file.extractall, tmpdir)
                        _create_symbolic_links(zip_file, tmpdir)
            except OSError as e:
                raise ControllerError(f"Cannot open snapshot '{os.path.basename(snapshot)}': {e}")
            except zipfile_zstd.BadZipFile:
                raise ControllerError(
                    f"Cannot extract files from snapshot '{os.path.basename(snapshot)}': not a GNS3 project (invalid zip)"
                )

            # patch the topology with the correct project name and ID
            try:
                topology_file_path = os.path.join(tmpdir, "project.gns3")
                with open(topology_file_path, encoding="utf-8") as f:
                    topology = json.load(f)

                    topology["name"] = project_name
                    topology["project_id"] = project_id
                with open(topology_file_path, "w+", encoding="utf-8") as f:
                    json.dump(topology, f, indent=4, sort_keys=True)
            except OSError as e:
                raise ControllerError(
                    f"Cannot update snapshot '{os.path.basename(snapshot)}': the project.gns3 file cannot be modified: {e}"
                )
            except (ValueError, KeyError):
                raise ControllerError(
                    f"Cannot update snapshot '{os.path.basename(snapshot)}': the project.gns3 file is corrupted"
                )

            # write everything back to the original snapshot file
            try:
                with aiozipstream.ZipFile(compression=zipfile_zstd.ZIP_STORED) as zstream:
                    for root, dirs, files in os.walk(tmpdir, topdown=True, followlinks=False):
                        for file in files:
                            path = os.path.join(root, file)
                            zstream.write(path, os.path.relpath(path, tmpdir))
                    async with aiofiles.open(snapshot_path, "wb+") as f:
                        async for chunk in zstream:
                            await f.write(chunk)
            except OSError as e:
                raise ControllerError(
                    f"Cannot update snapshot '{os.path.basename(snapshot)}': the snapshot cannot be recreated: {e}"
                )