searxng/searx/engines/google_scholar.py

# SPDX-License-Identifier: AGPL-3.0-or-later
# lint: pylint
"""Google (Scholar)

For detailed description of the *REST-full* API see: `Query Parameter
Definitions`_.

.. _Query Parameter Definitions:
   https://developers.google.com/custom-search/docs/xml_results#WebSearch_Query_Parameter_Definitions
"""

# pylint: disable=invalid-name, missing-function-docstring

from urllib.parse import urlencode
from datetime import datetime
from lxml import html
from searx import logger

from searx.utils import (
    eval_xpath,
    eval_xpath_list,
    extract_text,
)

from searx.engines.google import (
    get_lang_info,
    time_range_dict,
    detect_google_sorry,
)

# pylint: disable=unused-import
from searx.engines.google import (
    supported_languages_url,
    _fetch_supported_languages,
)
# pylint: enable=unused-import

# about
about = {
    "website": 'https://scholar.google.com',
    "wikidata_id": 'Q494817',
    "official_api_documentation": 'https://developers.google.com/custom-search',
    "use_official_api": False,
    "require_api_key": False,
    "results": 'HTML',
}

# engine dependent config
categories = ['science']
paging = True
language_support = True
use_locale_domain = True
time_range_support = True
safesearch = False

logger = logger.getChild('google scholar')

def time_range_url(params):
    """Returns a URL query component for a google-Scholar time range based on
    ``params['time_range']``.  Google-Scholar does only support ranges in years.
    To have any effect, all the Searx ranges (*day*, *week*, *month*, *year*)
    are mapped to *year*.  If no range is set, an empty string is returned.
    Example::

        &as_ylo=2019
    """
    # as_ylo=2016&as_yhi=2019
    ret_val = ''
    if params['time_range'] in time_range_dict:
        ret_val= urlencode({'as_ylo': datetime.now().year -1 })
    return '&' + ret_val


def request(query, params):
    """Google-Scholar search request"""

    offset = (params['pageno'] - 1) * 10
    lang_info = get_lang_info(
        # pylint: disable=undefined-variable
        params, supported_languages, language_aliases, False
    )
    logger.debug(
        "HTTP header Accept-Language --> %s", lang_info['headers']['Accept-Language'])

    # subdomain is: scholar.google.xy
    lang_info['subdomain'] = lang_info['subdomain'].replace("www.", "scholar.")

    query_url = 'https://'+ lang_info['subdomain'] + '/scholar' + "?" + urlencode({
        'q':  query,
        **lang_info['params'],
        'ie': "utf8",
        'oe':  "utf8",
        'start' : offset,
    })

    query_url += time_range_url(params)
    params['url'] = query_url

    params['headers'].update(lang_info['headers'])
    params['headers']['Accept'] = (
        'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8'
    )

    #params['google_subdomain'] = subdomain
    return params

def response(resp):
    """Get response from google's search request"""
    results = []

    detect_google_sorry(resp)

    # which subdomain ?
    # subdomain = resp.search_params.get('google_subdomain')

    # convert the text to dom
    dom = html.fromstring(resp.text)

    # parse results
    for result in eval_xpath_list(dom, '//div[@class="gs_ri"]'):

        title = extract_text(eval_xpath(result, './h3[1]//a'))

        if not title:
            # this is a [ZITATION] block
            continue

        url = eval_xpath(result, './h3[1]//a/@href')[0]
        content = extract_text(eval_xpath(result, './div[@class="gs_rs"]')) or ''

        pub_info = extract_text(eval_xpath(result, './div[@class="gs_a"]'))
        if pub_info:
            content += "[%s]" % pub_info

        pub_type = extract_text(eval_xpath(result, './/span[@class="gs_ct1"]'))
        if pub_type:
            title = title + " " + pub_type

        results.append({
            'url':      url,
            'title':    title,
            'content':  content,
        })

    # parse suggestion
    for suggestion in eval_xpath(dom, '//div[contains(@class, "gs_qsuggest_wrap")]//li//a'):
        # append suggestion
        results.append({'suggestion': extract_text(suggestion)})

    for correction in eval_xpath(dom, '//div[@class="gs_r gs_pda"]/a'):
        results.append({'correction': extract_text(correction)})

    return results