# -*- coding: utf-8  -*-
#
# Copyright (C) 2009-2015 Ben Kurtovic <ben.kurtovic@gmail.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

from gzip import GzipFile
from json import loads
from socket import error
from StringIO import StringIO
from urllib import quote
from urllib2 import URLError

from earwigbot import importer
from earwigbot.exceptions import SearchQueryError

oauth = importer.new("oauth2")

__all__ = ["BaseSearchEngine", "YahooBOSSSearchEngine"]

class BaseSearchEngine(object):
    """Base class for a simple search engine interface."""
    name = "Base"

    def __init__(self, cred, opener):
        """Store credentials (*cred*) and *opener* for searching later on."""
        self.cred = cred
        self.opener = opener

    def __repr__(self):
        """Return the canonical string representation of the search engine."""
        return "{0}()".format(self.__class__.__name__)

    def __str__(self):
        """Return a nice string representation of the search engine."""
        return "<{0}>".format(self.__class__.__name__)

    def search(self, query):
        """Use this engine to search for *query*.

        Not implemented in this base class; overridden in subclasses.
        """
        raise NotImplementedError()


class YahooBOSSSearchEngine(BaseSearchEngine):
    """A search engine interface with Yahoo! BOSS."""
    name = "Yahoo! BOSS"

    @staticmethod
    def _build_url(base, params):
        """Works like urllib.urlencode(), but uses %20 for spaces over +."""
        enc = lambda s: quote(s.encode("utf8"), safe="")
        args = ["=".join((enc(k), enc(v))) for k, v in params.iteritems()]
        return base + "?" + "&".join(args)

    def search(self, query):
        """Do a Yahoo! BOSS web search for *query*.

        Returns a list of URLs, no more than five, ranked by relevance
        (as determined by Yahoo).
        Raises :py:exc:`~earwigbot.exceptions.SearchQueryError` on errors.
        """
        key, secret = self.cred["key"], self.cred["secret"]
        consumer = oauth.Consumer(key=key, secret=secret)

        url = "http://yboss.yahooapis.com/ysearch/web"
        params = {
            "oauth_version": oauth.OAUTH_VERSION,
            "oauth_nonce": oauth.generate_nonce(),
            "oauth_timestamp": oauth.Request.make_timestamp(),
            "oauth_consumer_key": consumer.key,
            "q": '"' + query.encode("utf8") + '"', "count": "5",
            "type": "html,text,pdf", "format": "json",
        }

        req = oauth.Request(method="GET", url=url, parameters=params)
        req.sign_request(oauth.SignatureMethod_HMAC_SHA1(), consumer, None)
        try:
            response = self.opener.open(self._build_url(url, req))
            result = response.read()
        except (URLError, error) as exc:
            raise SearchQueryError("Yahoo! BOSS Error: " + str(exc))

        if response.headers.get("Content-Encoding") == "gzip":
            stream = StringIO(result)
            gzipper = GzipFile(fileobj=stream)
            result = gzipper.read()

        if response.getcode() != 200:
            e = "Yahoo! BOSS Error: got response code '{0}':\n{1}'"
            raise SearchQueryError(e.format(response.getcode(), result))
        try:
            res = loads(result)
        except ValueError:
            e = "Yahoo! BOSS Error: JSON could not be decoded"
            raise SearchQueryError(e)

        try:
            results = res["bossresponse"]["web"]["results"]
        except KeyError:
            return []
        return [result["url"] for result in results]