searxng/searx/webapp.py

#!/usr/bin/env python

'''
searx is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

searx 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 Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with searx. If not, see < http://www.gnu.org/licenses/ >.

(C) 2013- by Adam Tauber, <asciimoo@gmail.com>
'''

import sys
if sys.version_info[0] < 3:
    print('\033[1;31m Python2 is no longer supported\033[0m')
    exit(1)

if __name__ == '__main__':
    from os.path import realpath, dirname
    sys.path.append(realpath(dirname(realpath(__file__)) + '/../'))

import hashlib
import hmac
import json
import os

import requests

from searx import logger
logger = logger.getChild('webapp')

from datetime import datetime, timedelta
from time import time
from html import escape
from io import StringIO
from urllib.parse import urlencode, urlparse, urljoin, urlsplit

from pygments import highlight
from pygments.lexers import get_lexer_by_name
from pygments.formatters import HtmlFormatter

from werkzeug.middleware.proxy_fix import ProxyFix
from flask import (
    Flask, request, render_template, url_for, Response, make_response,
    redirect, send_from_directory
)
from babel.support import Translations
import flask_babel
from flask_babel import Babel, gettext, format_date, format_decimal
from flask.ctx import has_request_context
from flask.json import jsonify
from searx import brand, static_path
from searx import settings, searx_dir, searx_debug
from searx.exceptions import SearxParameterException
from searx.engines import (
    categories, engines, engine_shortcuts, get_engines_stats, initialize_engines
)
from searx.webutils import (
    UnicodeWriter, highlight_content, get_resources_directory,
    get_static_files, get_result_templates, get_themes,
    prettify_url, new_hmac, is_flask_run_cmdline
)
from searx.webadapter import get_search_query_from_webapp, get_selected_categories
from searx.utils import html_to_text, gen_useragent, dict_subset, match_language
from searx.version import VERSION_STRING
from searx.languages import language_codes as languages
from searx.search import SearchWithPlugins
from searx.query import RawTextQuery
from searx.autocomplete import searx_bang, backends as autocomplete_backends
from searx.plugins import plugins
from searx.plugins.oa_doi_rewrite import get_doi_resolver
from searx.preferences import Preferences, ValidationException, LANGUAGE_CODES
from searx.answerers import answerers


# serve pages with HTTP/1.1
from werkzeug.serving import WSGIRequestHandler
WSGIRequestHandler.protocol_version = "HTTP/{}".format(settings['server'].get('http_protocol_version', '1.0'))

# about static
static_path = get_resources_directory(searx_dir, 'static', settings['ui']['static_path'])
logger.debug('static directory is %s', static_path)
static_files = get_static_files(static_path)

# about templates
default_theme = settings['ui']['default_theme']
templates_path = get_resources_directory(searx_dir, 'templates', settings['ui']['templates_path'])
logger.debug('templates directory is %s', templates_path)
themes = get_themes(templates_path)
result_templates = get_result_templates(templates_path)
global_favicons = []
for indice, theme in enumerate(themes):
    global_favicons.append([])
    theme_img_path = os.path.join(static_path, 'themes', theme, 'img', 'icons')
    for (dirpath, dirnames, filenames) in os.walk(theme_img_path):
        global_favicons[indice].extend(filenames)

# Flask app
app = Flask(
    __name__,
    static_folder=static_path,
    template_folder=templates_path
)

app.jinja_env.trim_blocks = True
app.jinja_env.lstrip_blocks = True
app.jinja_env.add_extension('jinja2.ext.loopcontrols')
app.secret_key = settings['server']['secret_key']

# see https://flask.palletsprojects.com/en/1.1.x/cli/
# True if "FLASK_APP=searx/webapp.py FLASK_ENV=development flask run"
flask_run_development = \
    os.environ.get("FLASK_APP") is not None\
    and os.environ.get("FLASK_ENV") == 'development'\
    and is_flask_run_cmdline()

# True if reload feature is activated of werkzeug, False otherwise (including uwsgi, etc..)
#  __name__ != "__main__" if searx.webapp is imported (make test, make docs, uwsgi...)
# see run() at the end of this file : searx_debug activates the reload feature.
werkzeug_reloader = flask_run_development or (searx_debug and __name__ == "__main__")

# initialize the engines except on the first run of the werkzeug server.
if not werkzeug_reloader\
   or (werkzeug_reloader and os.environ.get("WERKZEUG_RUN_MAIN") == "true"):
    initialize_engines(settings['engines'])

babel = Babel(app)

rtl_locales = ['ar', 'arc', 'bcc', 'bqi', 'ckb', 'dv', 'fa', 'fa_IR', 'glk', 'he',
               'ku', 'mzn', 'pnb', 'ps', 'sd', 'ug', 'ur', 'yi']

# used when translating category names
_category_names = (gettext('files'),
                   gettext('general'),
                   gettext('music'),
                   gettext('social media'),
                   gettext('images'),
                   gettext('videos'),
                   gettext('it'),
                   gettext('news'),
                   gettext('map'),
                   gettext('science'))

outgoing_proxies = settings['outgoing'].get('proxies') or None

_flask_babel_get_translations = flask_babel.get_translations


# monkey patch for flask_babel.get_translations
def _get_translations():
    if has_request_context() and request.form.get('use-translation') == 'oc':
        babel_ext = flask_babel.current_app.extensions['babel']
        return Translations.load(next(babel_ext.translation_directories), 'oc')

    return _flask_babel_get_translations()


flask_babel.get_translations = _get_translations


def _get_browser_or_settings_language(request, lang_list):
    for lang in request.headers.get("Accept-Language", "en").split(","):
        if ';' in lang:
            lang = lang.split(';')[0]
        locale = match_language(lang, lang_list, fallback=None)
        if locale is not None:
            return locale
    return settings['search']['default_lang'] or 'en'


@babel.localeselector
def get_locale():
    if 'locale' in request.form\
       and request.form['locale'] in settings['locales']:
        # use locale from the form
        locale = request.form['locale']
        locale_source = 'form'
    elif request.preferences.get_value('locale') != '':
        # use locale from the preferences
        locale = request.preferences.get_value('locale')
        locale_source = 'preferences'
    else:
        # use local from the browser
        locale = _get_browser_or_settings_language(request, settings['locales'].keys())
        locale_source = 'browser'

    #
    if locale == 'zh_TW':
        locale = 'zh_Hant_TW'

    # see _get_translations function
    # and https://github.com/searx/searx/pull/1863
    if locale == 'oc':
        request.form['use-translation'] = 'oc'
        locale = 'fr_FR'

    logger.debug("%s uses locale `%s` from %s", request.url, locale, locale_source)
    return locale


# code-highlighter
@app.template_filter('code_highlighter')
def code_highlighter(codelines, language=None):
    if not language:
        language = 'text'

    try:
        # find lexer by programing language
        lexer = get_lexer_by_name(language, stripall=True)
    except:
        # if lexer is not found, using default one
        logger.debug('highlighter cannot find lexer for {0}'.format(language))
        lexer = get_lexer_by_name('text', stripall=True)

    html_code = ''
    tmp_code = ''
    last_line = None

    # parse lines
    for line, code in codelines:
        if not last_line:
            line_code_start = line

        # new codeblock is detected
        if last_line is not None and\
           last_line + 1 != line:

            # highlight last codepart
            formatter = HtmlFormatter(linenos='inline',
                                      linenostart=line_code_start)
            html_code = html_code + highlight(tmp_code, lexer, formatter)

            # reset conditions for next codepart
            tmp_code = ''
            line_code_start = line

        # add codepart
        tmp_code += code + '\n'

        # update line
        last_line = line

    # highlight last codepart
    formatter = HtmlFormatter(linenos='inline', linenostart=line_code_start)
    html_code = html_code + highlight(tmp_code, lexer, formatter)

    return html_code


# Extract domain from url
@app.template_filter('extract_domain')
def extract_domain(url):
    return urlparse(url)[1]


def get_base_url():
    if settings['server']['base_url']:
        hostname = settings['server']['base_url']
    else:
        scheme = 'http'
        if request.is_secure:
            scheme = 'https'
        hostname = url_for('index', _external=True, _scheme=scheme)
    return hostname


def get_current_theme_name(override=None):
    """Returns theme name.

    Checks in this order:
    1. override
    2. cookies
    3. settings"""

    if override and (override in themes or override == '__common__'):
        return override
    theme_name = request.args.get('theme', request.preferences.get_value('theme'))
    if theme_name not in themes:
        theme_name = default_theme
    return theme_name


def get_result_template(theme, template_name):
    themed_path = theme + '/result_templates/' + template_name
    if themed_path in result_templates:
        return themed_path
    return 'result_templates/' + template_name


def url_for_theme(endpoint, override_theme=None, **values):
    if endpoint == 'static' and values.get('filename'):
        theme_name = get_current_theme_name(override=override_theme)
        filename_with_theme = "themes/{}/{}".format(theme_name, values['filename'])
        if filename_with_theme in static_files:
            values['filename'] = filename_with_theme
    url = url_for(endpoint, **values)
    if settings['server']['base_url']:
        if url.startswith('/'):
            url = url[1:]
        url = urljoin(settings['server']['base_url'], url)
    return url


def proxify(url):
    if url.startswith('//'):
        url = 'https:' + url

    if not settings.get('result_proxy'):
        return url

    url_params = dict(mortyurl=url.encode())

    if settings['result_proxy'].get('key'):
        url_params['mortyhash'] = hmac.new(settings['result_proxy']['key'],
                                           url.encode(),
                                           hashlib.sha256).hexdigest()

    return '{0}?{1}'.format(settings['result_proxy']['url'],
                            urlencode(url_params))


def image_proxify(url):

    if url.startswith('//'):
        url = 'https:' + url

    if not request.preferences.get_value('image_proxy'):
        return url

    if url.startswith('data:image/'):
        # 50 is an arbitrary number to get only the beginning of the image.
        partial_base64 = url[len('data:image/'):50].split(';')
        if len(partial_base64) == 2 \
           and partial_base64[0] in ['gif', 'png', 'jpeg', 'pjpeg', 'webp', 'tiff', 'bmp']\
           and partial_base64[1].startswith('base64,'):
            return url
        else:
            return None

    if settings.get('result_proxy'):
        return proxify(url)

    h = new_hmac(settings['server']['secret_key'], url.encode())

    return '{0}?{1}'.format(url_for('image_proxy'),
                            urlencode(dict(url=url.encode(), h=h)))


def render(template_name, override_theme=None, **kwargs):
    disabled_engines = request.preferences.engines.get_disabled()

    enabled_categories = set(category for engine_name in engines
                             for category in engines[engine_name].categories
                             if (engine_name, category) not in disabled_engines)

    if 'categories' not in kwargs:
        kwargs['categories'] = [x for x in
                                _get_ordered_categories()
                                if x in enabled_categories]

    if 'autocomplete' not in kwargs:
        kwargs['autocomplete'] = request.preferences.get_value('autocomplete')

    locale = request.preferences.get_value('locale')

    if locale in rtl_locales and 'rtl' not in kwargs:
        kwargs['rtl'] = True

    kwargs['searx_version'] = VERSION_STRING

    kwargs['method'] = request.preferences.get_value('method')

    kwargs['safesearch'] = str(request.preferences.get_value('safesearch'))

    kwargs['language_codes'] = languages
    if 'current_language' not in kwargs:
        kwargs['current_language'] = match_language(request.preferences.get_value('language'),
                                                    LANGUAGE_CODES)

    # override url_for function in templates
    kwargs['url_for'] = url_for_theme

    kwargs['image_proxify'] = image_proxify

    kwargs['proxify'] = proxify if settings.get('result_proxy', {}).get('url') else None

    kwargs['opensearch_url'] = url_for('opensearch') + '?' \
        + urlencode({'method': kwargs['method'], 'autocomplete': kwargs['autocomplete']})

    kwargs['get_result_template'] = get_result_template

    kwargs['theme'] = get_current_theme_name(override=override_theme)

    kwargs['template_name'] = template_name

    kwargs['cookies'] = request.cookies

    kwargs['errors'] = request.errors

    kwargs['instance_name'] = settings['general']['instance_name']

    kwargs['results_on_new_tab'] = request.preferences.get_value('results_on_new_tab')

    kwargs['preferences'] = request.preferences

    kwargs['brand'] = brand

    kwargs['scripts'] = set()
    kwargs['endpoint'] = 'results' if 'q' in kwargs else request.endpoint
    for plugin in request.user_plugins:
        for script in plugin.js_dependencies:
            kwargs['scripts'].add(script)

    kwargs['styles'] = set()
    for plugin in request.user_plugins:
        for css in plugin.css_dependencies:
            kwargs['styles'].add(css)

    return render_template(
        '{}/{}'.format(kwargs['theme'], template_name), **kwargs)


def _get_ordered_categories():
    ordered_categories = []
    if 'categories_order' not in settings['ui']:
        ordered_categories = ['general']
        ordered_categories.extend(x for x in sorted(categories.keys()) if x != 'general')
        return ordered_categories
    ordered_categories = settings['ui']['categories_order']
    ordered_categories.extend(x for x in sorted(categories.keys()) if x not in ordered_categories)
    return ordered_categories


@app.before_request
def pre_request():
    request.start_time = time()
    request.timings = []
    request.errors = []

    preferences = Preferences(themes, list(categories.keys()), engines, plugins)
    user_agent = request.headers.get('User-Agent', '').lower()
    if 'webkit' in user_agent and 'android' in user_agent:
        preferences.key_value_settings['method'].value = 'GET'
    request.preferences = preferences
    try:
        preferences.parse_dict(request.cookies)
    except:
        request.errors.append(gettext('Invalid settings, please edit your preferences'))

    # merge GET, POST vars
    # request.form
    request.form = dict(request.form.items())
    for k, v in request.args.items():
        if k not in request.form:
            request.form[k] = v

    if request.form.get('preferences'):
        preferences.parse_encoded_data(request.form['preferences'])
    else:
        try:
            preferences.parse_dict(request.form)
        except Exception as e:
            logger.exception('invalid settings')
            request.errors.append(gettext('Invalid settings'))

    # init search language and locale
    if not preferences.get_value("language"):
        preferences.parse_dict({"language": _get_browser_or_settings_language(request, LANGUAGE_CODES)})
    if not preferences.get_value("locale"):
        preferences.parse_dict({"locale": get_locale()})

    # request.user_plugins
    request.user_plugins = []
    allowed_plugins = preferences.plugins.get_enabled()
    disabled_plugins = preferences.plugins.get_disabled()
    for plugin in plugins:
        if ((plugin.default_on and plugin.id not in disabled_plugins)
                or plugin.id in allowed_plugins):
            request.user_plugins.append(plugin)


@app.after_request
def post_request(response):
    total_time = time() - request.start_time
    timings_all = ['total;dur=' + str(round(total_time * 1000, 3))]
    if len(request.timings) > 0:
        timings = sorted(request.timings, key=lambda v: v['total'])
        timings_total = ['total_' + str(i) + '_' + v['engine'] +
                         ';dur=' + str(round(v['total'] * 1000, 3)) for i, v in enumerate(timings)]
        timings_load = ['load_' + str(i) + '_' + v['engine'] +
                        ';dur=' + str(round(v['load'] * 1000, 3)) for i, v in enumerate(timings)]
        timings_all = timings_all + timings_total + timings_load
    response.headers.add('Server-Timing', ', '.join(timings_all))
    return response


def index_error(output_format, error_message):
    if output_format == 'json':
        return Response(json.dumps({'error': error_message}),
                        mimetype='application/json')
    elif output_format == 'csv':
        response = Response('', mimetype='application/csv')
        cont_disp = 'attachment;Filename=searx.csv'
        response.headers.add('Content-Disposition', cont_disp)
        return response
    elif output_format == 'rss':
        response_rss = render(
            'opensearch_response_rss.xml',
            results=[],
            q=request.form['q'] if 'q' in request.form else '',
            number_of_results=0,
            base_url=get_base_url(),
            error_message=error_message,
            override_theme='__common__',
        )
        return Response(response_rss, mimetype='text/xml')
    else:
        # html
        request.errors.append(gettext('search error'))
        return render(
            'index.html',
            selected_categories=get_selected_categories(request.preferences, request.form),
        )


@app.route('/search', methods=['GET', 'POST'])
@app.route('/', methods=['GET', 'POST'])
def index():
    """Render index page.

    Supported outputs: html, json, csv, rss.
    """

    # output_format
    output_format = request.form.get('format', 'html')
    if output_format not in ['html', 'csv', 'json', 'rss']:
        output_format = 'html'

    # check if there is query
    if request.form.get('q') is None:
        if output_format == 'html':
            return render(
                'index.html',
                selected_categories=get_selected_categories(request.preferences, request.form),
            )
        else:
            return index_error(output_format, 'No query'), 400

    # search
    search_query = None
    raw_text_query = None
    result_container = None
    try:
        search_query, raw_text_query, _, _ = get_search_query_from_webapp(request.preferences, request.form)
        # search = Search(search_query) #  without plugins
        search = SearchWithPlugins(search_query, request.user_plugins, request)

        result_container = search.search()

    except Exception as e:
        # log exception
        logger.exception('search error')

        # is it an invalid input parameter or something else ?
        if (issubclass(e.__class__, SearxParameterException)):
            return index_error(output_format, e.message), 400
        else:
            return index_error(output_format, gettext('search error')), 500

    # results
    results = result_container.get_ordered_results()
    number_of_results = result_container.results_number()
    if number_of_results < result_container.results_length():
        number_of_results = 0

    # checkin for a external bang
    if result_container.redirect_url:
        return redirect(result_container.redirect_url)

    # UI
    advanced_search = request.form.get('advanced_search', None)

    # Server-Timing header
    request.timings = result_container.get_timings()

    # output
    for result in results:
        if output_format == 'html':
            if 'content' in result and result['content']:
                result['content'] = highlight_content(escape(result['content'][:1024]), search_query.query)
            if 'title' in result and result['title']:
                result['title'] = highlight_content(escape(result['title'] or ''), search_query.query)
        else:
            if result.get('content'):
                result['content'] = html_to_text(result['content']).strip()
            # removing html content and whitespace duplications
            result['title'] = ' '.join(html_to_text(result['title']).strip().split())

        if 'url' in result:
            result['pretty_url'] = prettify_url(result['url'])

        # TODO, check if timezone is calculated right
        if 'publishedDate' in result:
            try:  # test if publishedDate >= 1900 (datetime module bug)
                result['pubdate'] = result['publishedDate'].strftime('%Y-%m-%d %H:%M:%S%z')
            except ValueError:
                result['publishedDate'] = None
            else:
                if result['publishedDate'].replace(tzinfo=None) >= datetime.now() - timedelta(days=1):
                    timedifference = datetime.now() - result['publishedDate'].replace(tzinfo=None)
                    minutes = int((timedifference.seconds / 60) % 60)
                    hours = int(timedifference.seconds / 60 / 60)
                    if hours == 0:
                        result['publishedDate'] = gettext('{minutes} minute(s) ago').format(minutes=minutes)
                    else:
                        result['publishedDate'] = gettext('{hours} hour(s), {minutes} minute(s) ago').format(hours=hours, minutes=minutes)  # noqa
                else:
                    result['publishedDate'] = format_date(result['publishedDate'])

    if output_format == 'json':
        return Response(json.dumps({'query': search_query.query,
                                    'number_of_results': number_of_results,
                                    'results': results,
                                    'answers': list(result_container.answers),
                                    'corrections': list(result_container.corrections),
                                    'infoboxes': result_container.infoboxes,
                                    'suggestions': list(result_container.suggestions),
                                    'unresponsive_engines': __get_translated_errors(result_container.unresponsive_engines)},  # noqa
                                   default=lambda item: list(item) if isinstance(item, set) else item),
                        mimetype='application/json')
    elif output_format == 'csv':
        csv = UnicodeWriter(StringIO())
        keys = ('title', 'url', 'content', 'host', 'engine', 'score', 'type')
        csv.writerow(keys)
        for row in results:
            row['host'] = row['parsed_url'].netloc
            row['type'] = 'result'
            csv.writerow([row.get(key, '') for key in keys])
        for a in result_container.answers:
            row = {'title': a, 'type': 'answer'}
            csv.writerow([row.get(key, '') for key in keys])
        for a in result_container.suggestions:
            row = {'title': a, 'type': 'suggestion'}
            csv.writerow([row.get(key, '') for key in keys])
        for a in result_container.corrections:
            row = {'title': a, 'type': 'correction'}
            csv.writerow([row.get(key, '') for key in keys])
        csv.stream.seek(0)
        response = Response(csv.stream.read(), mimetype='application/csv')
        cont_disp = 'attachment;Filename=searx_-_{0}.csv'.format(search_query.query)
        response.headers.add('Content-Disposition', cont_disp)
        return response

    elif output_format == 'rss':
        response_rss = render(
            'opensearch_response_rss.xml',
            results=results,
            answers=result_container.answers,
            corrections=result_container.corrections,
            suggestions=result_container.suggestions,
            q=request.form['q'],
            number_of_results=number_of_results,
            base_url=get_base_url(),
            override_theme='__common__',
        )
        return Response(response_rss, mimetype='text/xml')

    # HTML output format

    # suggestions: use RawTextQuery to get the suggestion URLs with the same bang
    suggestion_urls = list(map(lambda suggestion: {
                               'url': raw_text_query.changeQuery(suggestion).getFullQuery(),
                               'title': suggestion
                               },
                               result_container.suggestions))

    correction_urls = list(map(lambda correction: {
                               'url': raw_text_query.changeQuery(correction).getFullQuery(),
                               'title': correction
                               },
                               result_container.corrections))
    #
    return render(
        'results.html',
        results=results,
        q=request.form['q'],
        selected_categories=search_query.categories,
        pageno=search_query.pageno,
        time_range=search_query.time_range,
        number_of_results=format_decimal(number_of_results),
        advanced_search=advanced_search,
        suggestions=suggestion_urls,
        answers=result_container.answers,
        corrections=correction_urls,
        infoboxes=result_container.infoboxes,
        paging=result_container.paging,
        unresponsive_engines=__get_translated_errors(result_container.unresponsive_engines),
        current_language=match_language(search_query.lang,
                                        LANGUAGE_CODES,
                                        fallback=request.preferences.get_value("language")),
        base_url=get_base_url(),
        theme=get_current_theme_name(),
        favicons=global_favicons[themes.index(get_current_theme_name())],
        timeout_limit=request.form.get('timeout_limit', None)
    )


def __get_translated_errors(unresponsive_engines):
    translated_errors = []
    for unresponsive_engine in unresponsive_engines:
        error_msg = gettext(unresponsive_engine[1])
        if unresponsive_engine[2]:
            error_msg = "{} {}".format(error_msg, unresponsive_engine[2])
        translated_errors.append((unresponsive_engine[0], error_msg))
    return translated_errors


@app.route('/about', methods=['GET'])
def about():
    """Render about page"""
    return render(
        'about.html',
    )


@app.route('/autocompleter', methods=['GET', 'POST'])
def autocompleter():
    """Return autocompleter results"""

    # set blocked engines
    disabled_engines = request.preferences.engines.get_disabled()

    # parse query
    raw_text_query = RawTextQuery(request.form.get('q', ''), disabled_engines)

    # check if search query is set
    if not raw_text_query.getQuery():
        return '', 400

    # run autocompleter
    completer = autocomplete_backends.get(request.preferences.get_value('autocomplete'))

    # parse searx specific autocompleter results like !bang
    raw_results = searx_bang(raw_text_query)

    # normal autocompletion results only appear if no inner results returned
    # and there is a query part besides the engine and language bangs
    if len(raw_results) == 0 and completer and (len(raw_text_query.query_parts) > 1 or
                                                (len(raw_text_query.languages) == 0 and
                                                 not raw_text_query.specific)):
        # get language from cookie
        language = request.preferences.get_value('language')
        if not language or language == 'all':
            language = 'en'
        else:
            language = language.split('-')[0]
        # run autocompletion
        raw_results.extend(completer(raw_text_query.getQuery(), language))

    # parse results (write :language and !engine back to result string)
    results = []
    for result in raw_results:
        raw_text_query.changeQuery(result)

        # add parsed result
        results.append(raw_text_query.getFullQuery())

    # return autocompleter results
    if request.headers.get('X-Requested-With') == 'XMLHttpRequest':
        return Response(json.dumps(results),
                        mimetype='application/json')

    return Response(json.dumps([raw_text_query.query, results]),
                    mimetype='application/x-suggestions+json')


@app.route('/preferences', methods=['GET', 'POST'])
def preferences():
    """Render preferences page && save user preferences"""

    # save preferences
    if request.method == 'POST':
        resp = make_response(redirect(urljoin(settings['server']['base_url'], url_for('index'))))
        try:
            request.preferences.parse_form(request.form)
        except ValidationException:
            request.errors.append(gettext('Invalid settings, please edit your preferences'))
            return resp
        return request.preferences.save(resp)

    # render preferences
    image_proxy = request.preferences.get_value('image_proxy')
    lang = request.preferences.get_value('language')
    disabled_engines = request.preferences.engines.get_disabled()
    allowed_plugins = request.preferences.plugins.get_enabled()

    # stats for preferences page
    stats = {}

    engines_by_category = {}
    for c in categories:
        engines_by_category[c] = []
        for e in categories[c]:
            if not request.preferences.validate_token(e):
                continue

            stats[e.name] = {'time': None,
                             'warn_timeout': False,
                             'warn_time': False}
            if e.timeout > settings['outgoing']['request_timeout']:
                stats[e.name]['warn_timeout'] = True
            stats[e.name]['supports_selected_language'] = _is_selected_language_supported(e, request.preferences)

            engines_by_category[c].append(e)

    # get first element [0], the engine time,
    # and then the second element [1] : the time (the first one is the label)
    for engine_stat in get_engines_stats(request.preferences)[0][1]:
        stats[engine_stat.get('name')]['time'] = round(engine_stat.get('avg'), 3)
        if engine_stat.get('avg') > settings['outgoing']['request_timeout']:
            stats[engine_stat.get('name')]['warn_time'] = True
    # end of stats

    return render('preferences.html',
                  selected_categories=get_selected_categories(request.preferences, request.form),
                  all_categories=_get_ordered_categories(),
                  locales=settings['locales'],
                  current_locale=request.preferences.get_value("locale"),
                  image_proxy=image_proxy,
                  engines_by_category=engines_by_category,
                  stats=stats,
                  answerers=[{'info': a.self_info(), 'keywords': a.keywords} for a in answerers],
                  disabled_engines=disabled_engines,
                  autocomplete_backends=autocomplete_backends,
                  shortcuts={y: x for x, y in engine_shortcuts.items()},
                  themes=themes,
                  plugins=plugins,
                  doi_resolvers=settings['doi_resolvers'],
                  current_doi_resolver=get_doi_resolver(request.args, request.preferences.get_value('doi_resolver')),
                  allowed_plugins=allowed_plugins,
                  theme=get_current_theme_name(),
                  preferences_url_params=request.preferences.get_as_url_params(),
                  base_url=get_base_url(),
                  preferences=True)


def _is_selected_language_supported(engine, preferences):
    language = preferences.get_value('language')
    return (language == 'all'
            or match_language(language,
                              getattr(engine, 'supported_languages', []),
                              getattr(engine, 'language_aliases', {}), None))


@app.route('/image_proxy', methods=['GET'])
def image_proxy():
    url = request.args.get('url').encode()

    if not url:
        return '', 400

    h = new_hmac(settings['server']['secret_key'], url)

    if h != request.args.get('h'):
        return '', 400

    headers = dict_subset(request.headers, {'If-Modified-Since', 'If-None-Match'})
    headers['User-Agent'] = gen_useragent()

    resp = requests.get(url,
                        stream=True,
                        timeout=settings['outgoing']['request_timeout'],
                        headers=headers,
                        proxies=outgoing_proxies)

    if resp.status_code == 304:
        return '', resp.status_code

    if resp.status_code != 200:
        logger.debug('image-proxy: wrong response code: {0}'.format(resp.status_code))
        if resp.status_code >= 400:
            return '', resp.status_code
        return '', 400

    if not resp.headers.get('content-type', '').startswith('image/'):
        logger.debug('image-proxy: wrong content-type: {0}'.format(resp.headers.get('content-type')))
        return '', 400

    img = b''
    chunk_counter = 0

    for chunk in resp.iter_content(1024 * 1024):
        chunk_counter += 1
        if chunk_counter > 5:
            return '', 502  # Bad gateway - file is too big (>5M)
        img += chunk

    headers = dict_subset(resp.headers, {'Content-Length', 'Length', 'Date', 'Last-Modified', 'Expires', 'Etag'})

    return Response(img, mimetype=resp.headers['content-type'], headers=headers)


@app.route('/stats', methods=['GET'])
def stats():
    """Render engine statistics page."""
    stats = get_engines_stats(request.preferences)
    return render(
        'stats.html',
        stats=stats,
    )


@app.route('/robots.txt', methods=['GET'])
def robots():
    return Response("""User-agent: *
Allow: /
Allow: /about
Disallow: /stats
Disallow: /preferences
Disallow: /*?*q=*
""", mimetype='text/plain')


@app.route('/opensearch.xml', methods=['GET'])
def opensearch():
    method = 'post'

    if request.preferences.get_value('method') == 'GET':
        method = 'get'

    # chrome/chromium only supports HTTP GET....
    if request.headers.get('User-Agent', '').lower().find('webkit') >= 0:
        method = 'get'

    ret = render('opensearch.xml',
                 opensearch_method=method,
                 host=get_base_url(),
                 urljoin=urljoin,
                 override_theme='__common__')

    resp = Response(response=ret,
                    status=200,
                    mimetype="application/opensearchdescription+xml")
    return resp


@app.route('/favicon.ico')
def favicon():
    return send_from_directory(os.path.join(app.root_path,
                                            static_path,
                                            'themes',
                                            get_current_theme_name(),
                                            'img'),
                               'favicon.png',
                               mimetype='image/vnd.microsoft.icon')


@app.route('/clear_cookies')
def clear_cookies():
    resp = make_response(redirect(urljoin(settings['server']['base_url'], url_for('index'))))
    for cookie_name in request.cookies:
        resp.delete_cookie(cookie_name)
    return resp


@app.route('/config')
def config():
    """Return configuration in JSON format."""
    _engines = []
    for name, engine in engines.items():
        if not request.preferences.validate_token(engine):
            continue

        supported_languages = engine.supported_languages
        if isinstance(engine.supported_languages, dict):
            supported_languages = list(engine.supported_languages.keys())

        _engines.append({
            'name': name,
            'categories': engine.categories,
            'shortcut': engine.shortcut,
            'enabled': not engine.disabled,
            'paging': engine.paging,
            'language_support': engine.language_support,
            'supported_languages': supported_languages,
            'safesearch': engine.safesearch,
            'time_range_support': engine.time_range_support,
            'timeout': engine.timeout
        })

    _plugins = []
    for _ in plugins:
        _plugins.append({'name': _.name, 'enabled': _.default_on})

    return jsonify({
        'categories': list(categories.keys()),
        'engines': _engines,
        'plugins': _plugins,
        'instance_name': settings['general']['instance_name'],
        'locales': settings['locales'],
        'default_locale': settings['ui']['default_locale'],
        'autocomplete': settings['search']['autocomplete'],
        'safe_search': settings['search']['safe_search'],
        'default_theme': settings['ui']['default_theme'],
        'version': VERSION_STRING,
        'brand': {
            'GIT_URL': brand.GIT_URL,
            'DOCS_URL': brand.DOCS_URL
        },
        'doi_resolvers': [r for r in settings['doi_resolvers']],
        'default_doi_resolver': settings['default_doi_resolver'],
    })


@app.route('/translations.js')
def js_translations():
    return render(
        'translations.js.tpl',
        override_theme='__common__',
    ), {'Content-Type': 'text/javascript; charset=UTF-8'}


@app.errorhandler(404)
def page_not_found(e):
    return render('404.html'), 404


def run():
    logger.debug('starting webserver on %s:%s', settings['server']['bind_address'], settings['server']['port'])
    app.run(
        debug=searx_debug,
        use_debugger=searx_debug,
        port=settings['server']['port'],
        host=settings['server']['bind_address'],
        threaded=True
    )


class ReverseProxyPathFix:
    '''Wrap the application in this middleware and configure the
    front-end server to add these headers, to let you quietly bind
    this to a URL other than / and to an HTTP scheme that is
    different than what is used locally.

    http://flask.pocoo.org/snippets/35/

    In nginx:
    location /myprefix {
        proxy_pass http://127.0.0.1:8000;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Scheme $scheme;
        proxy_set_header X-Script-Name /myprefix;
        }

    :param app: the WSGI application
    '''

    def __init__(self, app):
        self.app = app

    def __call__(self, environ, start_response):
        script_name = environ.get('HTTP_X_SCRIPT_NAME', '')
        if script_name:
            environ['SCRIPT_NAME'] = script_name
            path_info = environ['PATH_INFO']
            if path_info.startswith(script_name):
                environ['PATH_INFO'] = path_info[len(script_name):]

        scheme = environ.get('HTTP_X_SCHEME', '')
        if scheme:
            environ['wsgi.url_scheme'] = scheme
        return self.app(environ, start_response)


application = app
# patch app to handle non root url-s behind proxy & wsgi
app.wsgi_app = ReverseProxyPathFix(ProxyFix(application.wsgi_app))

if __name__ == "__main__":
    run()