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 hashlib
import hmac
import json
import os
import time

import requests

from searx import logger


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

from html import escape
from datetime import datetime, timedelta
from werkzeug.middleware.proxy_fix import ProxyFix
from flask import (
    Flask, request, render_template, url_for, Response, make_response,
    redirect, send_from_directory
)
from flask_babel import Babel, gettext, format_date, format_decimal
from flask.json import jsonify
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.utils import (
    highlight_content, get_resources_directory,
    get_static_files, get_result_templates, get_themes, gen_useragent,
    dict_subset, prettify_url, match_language
)
from searx.version import VERSION_STRING, SEARX_VERSION, METADATA_VERSION
from searx.languages import language_codes as languages
from searx.search import Search
from searx.search_database import RedisCache
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
from searx.url_utils import urlencode, urlparse, urljoin
from searx.utils import new_hmac
import threading

# serve pages with HTTP/1.1
from werkzeug.serving import WSGIRequestHandler

logger = logger.getChild('webapp')

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.secret_key = settings['server']['secret_key']

if not searx_debug \
        or os.environ.get("WERKZEUG_RUN_MAIN") == "true" \
        or os.environ.get('UWSGI_ORIGINAL_PROC_NAME') is not None:
    initialize_engines(settings['engines'])

babel = Babel(app)

search = Search(RedisCache) if settings["redis"]["enable"] else Search()

rtl_locales = ['ar', 'arc', 'bcc', 'bqi', 'ckb', 'dv', 'fa', '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


@babel.localeselector
def get_locale():
    locale = "en-US"

    for lang in request.headers.get("Accept-Language", locale).split(","):
        locale = match_language(lang, settings['locales'].keys(), fallback=None)
        if locale is not None:
            break

    logger.debug("default locale from browser info is `%s`", locale)

    if request.preferences.get_value('locale') != '':
        locale = request.preferences.get_value('locale')

    if 'locale' in request.form and request.form['locale'] in settings['locales']:
        locale = request.form['locale']

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

    logger.debug("selected locale is `%s`", locale)

    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 ClassNotFound:
        # 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
    return url_for(endpoint, **values)


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

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

    url_params = dict(mortyurl=url)

    if settings['result_proxy'].get('key'):
        url_params['mortyhash'] = hmac.new(settings['result_proxy']['key'],
                                           url,
                                           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/jpeg;base64,'):
        return url

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

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

    return '{0}?{1}'.format(url_for('image_proxy'),
                            urlencode(dict(url=url, 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'] = ['general']
        kwargs["categories"].extend(
            x
            for x in sorted(categories.keys())
            if x != "general" and x in enabled_categories
        )

    if 'all_categories' not in kwargs:
        kwargs['all_categories'] = ['general']
        kwargs['all_categories'].extend(x for x in
                                        sorted(categories.keys())
                                        if x != 'general')

    if 'selected_categories' not in kwargs:
        kwargs['selected_categories'] = []
        for arg in request.form:
            if arg.startswith('category_'):
                c = arg.split('_', 1)[1]
                if c in categories:
                    kwargs['selected_categories'].append(c)

    if not kwargs['selected_categories']:
        cookie_categories = request.preferences.get_value('categories')
        for ccateg in cookie_categories:
            kwargs['selected_categories'].append(ccateg)

    if not kwargs['selected_categories']:
        kwargs['selected_categories'] = ['general']

    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'] = SEARX_VERSION
    kwargs['metadata_version'] = METADATA_VERSION

    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,
                                                    fallback=locale)

    # 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['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['unicode'] = str

    kwargs['preferences'] = request.preferences

    kwargs['scripts'] = set()
    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)


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

    preferences = Preferences(themes, list(categories.keys()), engines, plugins)
    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:
            logger.exception('invalid settings')
            request.errors.append(gettext('Invalid settings'))

    # init search language and locale
    locale = get_locale()
    if not preferences.get_value("language"):
        preferences.parse_dict({"language": locale})
    if not preferences.get_value("locale"):
        preferences.parse_dict({"locale": 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)


def config_results(results, query):
    for result in results:
        if 'content' in result and result['content']:
            result['content'] = highlight_content(escape(result['content'][:1024]), query)
        result['title'] = highlight_content(escape(result['title'] or ''), query)
        result['pretty_url'] = prettify_url(result['url'])

        if 'pubdate' in result:
            publishedDate = datetime.strptime(result['pubdate'], '%Y-%m-%d %H:%M:%S')
            if publishedDate >= datetime.now() - timedelta(days=1):
                timedifference = datetime.now() - publishedDate
                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(publishedDate)


def index_error(exn, output):
    user_error = gettext("search error")
    if output == "json":
        return jsonify({"error": f"{user_error}: {exn}"})

    request.errors.append(user_error)
    return render('index.html', error_details=exn)


@app.route('/search', methods=['GET', 'POST'])
@app.route('/', methods=['GET', 'POST'])
def index():
    # check the response format
    output = request.form.get("output", "html")

    # check if there is query
    if not request.form.get('q'):
        if output == 'json':
            return jsonify({}), 204
        return render('index.html')

    if request.form.get('category') is None:
        category = None
        for name, value in request.form.items():
            if name.startswith('category_'):
                category = name[9:]
                if category in categories and value == "on":
                    break
        if category is not None:
            request.form["category"] = category

    selected_category = request.form.get('category') or 'general'
    first_page = request.form.get('pageno')
    is_general_first_page = selected_category == 'general' and (first_page is None or first_page == u'1')

    images = []
    videos = []
    # search
    search_data = None
    try:
        if is_general_first_page:
            request.form['categories'] = ['general', 'videos', 'images']
        else:
            request.form['categories'] = [selected_category]
        search_data = search(request)

    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(e, output), 400
        else:
            return index_error(e, output), 500

    if is_general_first_page:
        images = [r for r in search_data.results if r.get('category') == 'images'][:5]
        videos = [r for r in search_data.results if r.get('category') == 'videos'][:2]
        for res in list(search_data.results):
            if res.get('category') != 'general':
                search_data.results.remove(res)

    # output
    config_results(search_data.results, search_data.query)
    config_results(images, search_data.query)
    config_results(videos, search_data.query)

    response = dict(
        results=search_data.results,
        q=search_data.query,
        selected_category=selected_category,
        selected_categories=[selected_category],
        pageno=search_data.pageno,
        time_range=search_data.time_range,
        number_of_results=format_decimal(search_data.results_number),
        advanced_search=request.form.get('advanced_search', None),
        suggestions=list(search_data.suggestions),
        answers=list(search_data.answers),
        corrections=list(search_data.corrections),
        infoboxes=search_data.infoboxes,
        paging=search_data.paging,
        unresponsive_engines=list(search_data.unresponsive_engines),
        current_language=match_language(search_data.language,
                                        LANGUAGE_CODES,
                                        fallback=request.preferences.get_value("language")),
        image_results=images,
        videos_results=videos,
        base_url=get_base_url(),
        theme=get_current_theme_name(),
        favicons=global_favicons[themes.index(get_current_theme_name())]
    )
    if output == 'json':
        return jsonify(response)
    return render('results.html', **response)


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


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

    # check if search query is set
    if not raw_text_query.getSearchQuery():
        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 max 3 inner results returned
    if len(raw_results) <= 3 and completer:
        # 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.getSearchQuery(), language))

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

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

    # return autocompleter results
    if request.form.get('format') == 'x-suggestions':
        return Response(json.dumps([raw_text_query.query, results]),
                        mimetype='application/json')

    return Response(json.dumps(results),
                    mimetype='application/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')
    disabled_engines = request.preferences.engines.get_disabled()
    allowed_plugins = request.preferences.plugins.get_enabled()

    # stats for preferences page
    stats = {}

    for c in categories:
        for e in categories[c]:
            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)

    # 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()[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',
                  locales=settings['locales'],
                  current_locale=request.preferences.get_value("locale"),
                  image_proxy=image_proxy,
                  engines_by_category=categories,
                  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')

    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('/robots.txt', methods=['GET'])
def robots():
    return Response("""User-agent: *
Allow: /
Allow: /about
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="text/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 jsonify({'categories': categories.keys(),
                    'engines': [{'name': engine_name,
                                 'categories': engine.categories,
                                 'shortcut': engine.shortcut,
                                 'enabled': not engine.disabled,
                                 'paging': engine.paging,
                                 'language_support': engine.language_support,
                                 'supported_languages':
                                     engine.supported_languages.keys()
                                     if isinstance(engine.supported_languages, dict)
                                     else engine.supported_languages,
                                 'safesearch': engine.safesearch,
                                 'time_range_support': engine.time_range_support,
                                 'timeout': engine.timeout}
                                for engine_name, engine in engines.items()],
                    'plugins': [{'name': plugin.name,
                                 'enabled': plugin.default_on}
                                for plugin in 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,
                    'doi_resolvers': [r for r in settings['doi_resolvers']],
                    'default_doi_resolver': settings['default_doi_resolver'],
                    })


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


running = threading.Event()


def wait_updating(start_time):
    wait = settings['redis']['upgrade_history'] - int(time.time() - start_time)
    if wait > 0:
        running.wait(wait)


def update_results():
    start_time = time.time()
    x = 0
    while not running.is_set():
        queries = search.cache.get_twenty_queries(x)
        for query in queries:
            result_container = search.search(query)
            searchData = search.create_search_data(query, result_container)
            search.cache.update(searchData)
            if running.is_set():
                return
        x += len(queries)
        if len(queries) < 20:
            x = 0
            wait_updating(start_time)
            start_time = time.time()


def run():
    logger.debug('starting webserver on %s:%s', settings['server']['port'], settings['server']['bind_address'])
    threading.Thread(target=update_results, name='results_updater').start()
    print("engine server starting")
    app.run(
        debug=searx_debug,
        use_debugger=searx_debug,
        port=settings['server']['port'],
        host=settings['server']['bind_address'],
        threaded=True
    )
    print("wait for shutdown...")
    running.set()


class ReverseProxyPathFix(object):
    '''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()