# Copyright 2015, 2016 OpenMarket Ltd
#
# 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.

from ._base import Config, ConfigError

from synapse.appservice import ApplicationService
from synapse.types import UserID

import urllib
import yaml
import logging

logger = logging.getLogger(__name__)


class AppServiceConfig(Config):

    def read_config(self, config):
        self.app_service_config_files = config.get("app_service_config_files", [])
        self.notify_appservices = config.get("notify_appservices", True)

    def default_config(cls, **kwargs):
        return """\
        # A list of application service config file to use
        app_service_config_files: []
        """


def load_appservices(hostname, config_files):
    """Returns a list of Application Services from the config files."""
    if not isinstance(config_files, list):
        logger.warning(
            "Expected %s to be a list of AS config files.", config_files
        )
        return []

    # Dicts of value -> filename
    seen_as_tokens = {}
    seen_ids = {}

    appservices = []

    for config_file in config_files:
        try:
            with open(config_file, 'r') as f:
                appservice = _load_appservice(
                    hostname, yaml.load(f), config_file
                )
                if appservice.id in seen_ids:
                    raise ConfigError(
                        "Cannot reuse ID across application services: "
                        "%s (files: %s, %s)" % (
                            appservice.id, config_file, seen_ids[appservice.id],
                        )
                    )
                seen_ids[appservice.id] = config_file
                if appservice.token in seen_as_tokens:
                    raise ConfigError(
                        "Cannot reuse as_token across application services: "
                        "%s (files: %s, %s)" % (
                            appservice.token,
                            config_file,
                            seen_as_tokens[appservice.token],
                        )
                    )
                seen_as_tokens[appservice.token] = config_file
                logger.info("Loaded application service: %s", appservice)
                appservices.append(appservice)
        except Exception as e:
            logger.error("Failed to load appservice from '%s'", config_file)
            logger.exception(e)
            raise
    return appservices


def _load_appservice(hostname, as_info, config_filename):
    required_string_fields = [
        "id", "as_token", "hs_token", "sender_localpart"
    ]
    for field in required_string_fields:
        if not isinstance(as_info.get(field), basestring):
            raise KeyError("Required string field: '%s' (%s)" % (
                field, config_filename,
            ))

    # 'url' must either be a string or explicitly null, not missing
    # to avoid accidentally turning off push for ASes.
    if (not isinstance(as_info.get("url"), basestring) and
            as_info.get("url", "") is not None):
        raise KeyError(
            "Required string field or explicit null: 'url' (%s)" % (config_filename,)
        )

    localpart = as_info["sender_localpart"]
    if urllib.quote(localpart) != localpart:
        raise ValueError(
            "sender_localpart needs characters which are not URL encoded."
        )
    user = UserID(localpart, hostname)
    user_id = user.to_string()

    # Rate limiting for users of this AS is on by default (excludes sender)
    rate_limited = True
    if isinstance(as_info.get("rate_limited"), bool):
        rate_limited = as_info.get("rate_limited")

    # namespace checks
    if not isinstance(as_info.get("namespaces"), dict):
        raise KeyError("Requires 'namespaces' object.")
    for ns in ApplicationService.NS_LIST:
        # specific namespaces are optional
        if ns in as_info["namespaces"]:
            # expect a list of dicts with exclusive and regex keys
            for regex_obj in as_info["namespaces"][ns]:
                if not isinstance(regex_obj, dict):
                    raise ValueError(
                        "Expected namespace entry in %s to be an object,"
                        " but got %s", ns, regex_obj
                    )
                if not isinstance(regex_obj.get("regex"), basestring):
                    raise ValueError(
                        "Missing/bad type 'regex' key in %s", regex_obj
                    )
                if not isinstance(regex_obj.get("exclusive"), bool):
                    raise ValueError(
                        "Missing/bad type 'exclusive' key in %s", regex_obj
                    )
    # protocols check
    protocols = as_info.get("protocols")
    if protocols:
        # Because strings are lists in python
        if isinstance(protocols, str) or not isinstance(protocols, list):
            raise KeyError("Optional 'protocols' must be a list if present.")
        for p in protocols:
            if not isinstance(p, str):
                raise KeyError("Bad value for 'protocols' item")

    if as_info["url"] is None:
        logger.info(
            "(%s) Explicitly empty 'url' provided. This application service"
            " will not receive events or queries.",
            config_filename,
        )
    return ApplicationService(
        token=as_info["as_token"],
        url=as_info["url"],
        namespaces=as_info["namespaces"],
        hs_token=as_info["hs_token"],
        sender=user_id,
        id=as_info["id"],
        protocols=protocols,
        rate_limited=rate_limited
    )
