###
# Copyright (c) 2014-2017, James Lu <james@overdrivenetworks.com>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#   * Redistributions of source code must retain the above copyright notice,
#     this list of conditions, and the following disclaimer.
#   * Redistributions in binary form must reproduce the above copyright notice,
#     this list of conditions, and the following disclaimer in the
#     documentation and/or other materials provided with the distribution.
#   * Neither the name of the author of this software nor the name of
#     contributors to this software may be used to endorse or promote products
#     derived from this software without specific prior written consent.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

###

import functools
from html.parser import HTMLParser
from urllib.parse import urlencode, parse_qs

import supybot.utils as utils
from supybot.commands import *
import supybot.plugins as plugins
import supybot.ircutils as ircutils
import supybot.callbacks as callbacks
import supybot.log as log
try:
    from supybot.i18n import PluginInternationalization
    _ = PluginInternationalization('DDG')
except ImportError:
    # Placeholder that allows to run the plugin on a bot
    # without the i18n module
    _ = lambda x: x

from .parser import DDGHTMLParser


class DDG(callbacks.Plugin):
    """Searches for results on DuckDuckGo."""
    threaded = True

    @staticmethod
    def _ddgurl(text):
        # DuckDuckGo has a 'lite' site free of unparseable JavaScript
        # elements, so we'll use that to our advantage!
        url = "https://lite.duckduckgo.com/lite?" + urlencode({"q": text})

        log.debug("DDG: Using URL %s for search %s", url, text)

        real_url, data = utils.web.getUrlTargetAndContent(url)
        data = data.decode("utf-8")
        parser = DDGHTMLParser()
        parser.feed(data)

        # Remove "sponsored link" results
        return (url, real_url, parser.results)

    def search_core(self, text, channel_context=None, max_results=None, show_snippet=None):
        """
        Core results fetcher for the DDG plugin. Other plugins can call this as well via
        irc.getCallback('DDG').search_core(...)
        """
        if show_snippet is None:
            # Note: don't use ternary here, or the registry value will override any False
            # settings given to the function directly.
            show_snippet = self.registryValue("showSnippet", channel_context)
        maxr = max_results or self.registryValue("maxResults", channel_context)
        self.log.debug('DDG: got %s for max results', maxr)

        # In a nutshell, the 'lite' site puts all of its usable content
        # into tables. This does mean that headings, result snippets and
        # everything else are all using the same tag (<td>), so parsing is
        # still somewhat tricky.
        results = []

        url, real_url, raw_results = self._ddgurl(text)

        if real_url != url:
            # We received a redirect, likely from something like a !bang request.
            # Don't bother parsing the target page, as it probably won't work anyways.
            return [('', '', real_url)]

        for t in raw_results:
            if self.registryValue("showsnippet", channel_context):
                snippet = t.snippet.strip()
            else:
                snippet = ''
            title = t.title.strip()
            origlink = link = t.link

            # As of 2017-01-20, some links on DuckDuckGo's site are shown going through
            # a redirect service. The links are in the format "/l/?kh=-1&uddg=https%3A%2F%2Fduckduckgo.com%2F"
            # instead of simply being "https://duckduckgo.com". So, we decode these links here.
            if link.startswith('/l/'):
                linkparse = utils.web.urlparse(link)
                try:
                    link = parse_qs(linkparse.query)['uddg'][0]
                except KeyError:
                    # No link was given here, skip.
                    continue
                except IndexError:
                    self.log.exception("DDG: failed to expand redirected result URL %s", origlink)
                    continue
                else:
                    self.log.debug("DDG: expanded result URL from %s to %s", origlink, link)

            # Return a list of tuples in the form (link title, snippet text, link)
            results.append((title, snippet, link))
        return results[:maxr]

    @wrap(['text'])
    def search(self, irc, msg, args, text):
        """<text>

        Searches for <text> on DuckDuckGo's web search."""
        results = self.search_core(text, msg.args[0])
        if not results:
            irc.error("No results found.")
        else:
            strings = []

            for r in results:
                if not r[0]:
                    # This result has no title, so it's likely a redirect from !bang.
                    strings.append(format("See %u", r[2]))
                else:
                    strings.append(format("%s - %s %u", ircutils.bold(r[0]), r[1], r[2]))

            irc.reply(', '.join(strings))

Class = DDG


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