# Copyright 2014 DreamHost, LLC
#
# Author: DreamHost, LLC
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

import functools
import json
import os
import shlex
import subprocess
import tempfile

import flask
import netaddr

from akanda.router import models

DEFAULT_ENABLED_SERVICES = ['router']
VALID_SERVICES = ['router', 'loadbalancer']


def execute(args, root_helper=None):
    if root_helper:
        cmd = shlex.split(root_helper) + args
    else:
        cmd = args
    try:
        return subprocess.check_output(map(str, cmd), stderr=subprocess.STDOUT)
    except subprocess.CalledProcessError as e:
        # The serialization layer doesn't know about the extra output
        # attribute of the CalledProcessError, so we don't get
        # stdout/stderr. Convert to a simpler exception type and
        # include all of the info from the original exception in the
        # message.
        raise RuntimeError('%s: %s' % (e, e.output))


def replace_file(file_name, data):
    """Replaces the contents of file_name with data in a safe manner.

    First write to a temp file and then rename. Since POSIX renames are
    atomic, the file is unlikely to be corrupted by competing writes.

    We create the tempfile on the same device to ensure that it can be renamed.
    """
    base_dir = os.path.dirname(os.path.abspath(file_name))
    tmp_file = tempfile.NamedTemporaryFile('w+', dir=base_dir, delete=False)
    tmp_file.write(data)
    tmp_file.close()
    os.chmod(tmp_file.name, 0644)
    os.rename(tmp_file.name, file_name)


def ensure_directory(dir_path):
    if not os.path.isdir(dir_path):
        os.makedirs(dir_path, 0755)


class ModelSerializer(json.JSONEncoder):
    """
    """
    def default(self, obj):
        if isinstance(obj, set):
            return list(obj)
        elif isinstance(obj, netaddr.IPNetwork):
            return str(obj)
        elif isinstance(obj, netaddr.IPAddress):
            return str(obj)
        elif isinstance(obj, models.ModelBase):
            if hasattr(obj, 'to_dict'):
                return obj.to_dict()
            else:
                return vars(obj)
        return super(ModelSerializer, self).default(obj)


def json_response(f):
    @functools.wraps(f)
    def wrapper(*args, **kwargs):
        retval = f(*args, **kwargs)
        if isinstance(retval, flask.Response):
            return retval
        else:
            return flask.Response(
                json.dumps(retval, cls=ModelSerializer, sort_keys=True),
                status=200
            )
    return wrapper


def blueprint_factory(name):
    name_parts = name.split(".")[-2:]
    blueprint_name = "_".join(name_parts)
    url_prefix = "/" + "/".join(name_parts)
    return flask.Blueprint(blueprint_name, name, url_prefix=url_prefix)