[mod] Semantic Scholar engine: revision of the engine (Paper result)

Revision of the engine / use of the result type Paper as well as other
typifications.

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

3 files changed, 128 insertions, 83 deletions

diff --git a/docs/dev/engines/online/semantic_scholar.rst b/docs/dev/engines/online/semantic_scholar.rst
new file mode 100644
index 000000000..795c8296a
--- /dev/null
+++ b/docs/dev/engines/online/semantic_scholar.rst
@@ -0,0 +1,8 @@
+.. _semantic_scholar engine:
+
+================
+Semantic Scholar
+================
+
+.. automodule:: searx.engines.semantic_scholar
+   :members:
diff --git a/searx/engines/semantic_scholar.py b/searx/engines/semantic_scholar.py
index f5a692792..985ebd8a3 100644
--- a/searx/engines/semantic_scholar.py
+++ b/searx/engines/semantic_scholar.py
@@ -1,125 +1,163 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
-"""Semantic Scholar (Science)"""
+"""`Semantic Scholar`_ provides free, AI-driven search and discovery tools, and
+open resources for the global research community.  `Semantic Scholar`_ index
+over 200 million academic papers sourced from publisher partnerships, data
+providers, and web crawls.
+
+.. _Semantic Scholar: https://www.semanticscholar.org/about
+
+Configuration
+=============
+
+To get in use of this engine add the following entry to your engines list in
+``settings.yml``:
+
+.. code:: yaml
+
+   - name: semantic scholar
+     engine: semantic_scholar
+     shortcut: se
+
+Implementations
+===============
+
+"""
+
+import typing as t
 
-from json import dumps
 from datetime import datetime
 from lxml import html
+from flask_babel import gettext  # pyright: ignore[reportUnknownVariableType]
 
-from flask_babel import gettext
 from searx.network import get
 from searx.utils import eval_xpath_getindex, html_to_text
+from searx.enginelib import EngineCache
+from searx.result_types import EngineResults
 
+if t.TYPE_CHECKING:
+    from searx.extended_types import SXNG_Response
+    from searx.search.processors import OnlineParams
 
 about = {
-    "website": 'https://www.semanticscholar.org/',
-    "wikidata_id": 'Q22908627',
-    "official_api_documentation": 'https://api.semanticscholar.org/',
+    "website": "https://www.semanticscholar.org/",
+    "wikidata_id": "Q22908627",
+    "official_api_documentation": "https://api.semanticscholar.org/",
     "use_official_api": True,
     "require_api_key": False,
-    "results": 'JSON',
+    "results": "JSON",
 }
 
-categories = ['science', 'scientific publications']
+categories = ["science", "scientific publications"]
 paging = True
-search_url = 'https://www.semanticscholar.org/api/1/search'
-base_url = 'https://www.semanticscholar.org'
+search_url = "https://www.semanticscholar.org/api/1/search"
+base_url = "https://www.semanticscholar.org"
 
+CACHE: EngineCache
+"""Persistent (SQLite) key/value cache that deletes its values after ``expire``
+seconds."""
 
-def _get_ui_version():
-    resp = get(base_url)
-    if not resp.ok:
-        raise RuntimeError("Can't determine Semantic Scholar UI version")
 
-    doc = html.fromstring(resp.text)
-    ui_version = eval_xpath_getindex(doc, "//meta[@name='s2-ui-version']/@content", 0)
-    if not ui_version:
-        raise RuntimeError("Can't determine Semantic Scholar UI version")
+def setup(engine_settings: dict[str, t.Any]) -> bool:
+    global CACHE  # pylint: disable=global-statement
+    CACHE = EngineCache(engine_settings["name"])
+    return True
 
-    return ui_version
 
+def get_ui_version() -> str:
+    ret_val: str = CACHE.get("X-S2-UI-Version")
+    if not ret_val:
+        resp = get(base_url)
+        if not resp.ok:
+            raise RuntimeError("Can't determine Semantic Scholar UI version")
 
-def request(query, params):
-    params['url'] = search_url
-    params['method'] = 'POST'
-    params['headers'].update(
-        {
-            'Content-Type': 'application/json',
-            'X-S2-UI-Version': _get_ui_version(),
-            'X-S2-Client': "webapp-browser",
-        }
-    )
-    params['data'] = dumps(
+        doc = html.fromstring(resp.text)
+        ret_val = eval_xpath_getindex(doc, "//meta[@name='s2-ui-version']/@content", 0)
+        if not ret_val:
+            raise RuntimeError("Can't determine Semantic Scholar UI version")
+        # hold the cached value for 5min
+        CACHE.set("X-S2-UI-Version", value=ret_val, expire=300)
+        logger.debug("X-S2-UI-Version: %s", ret_val)
+    return ret_val
+
+
+def request(query: str, params: "OnlineParams") -> None:
+    params["url"] = search_url
+    params["method"] = "POST"
+    params["headers"].update(
         {
-            "queryString": query,
-            "page": params['pageno'],
-            "pageSize": 10,
-            "sort": "relevance",
-            "getQuerySuggestions": False,
-            "authors": [],
-            "coAuthors": [],
-            "venues": [],
-            "performTitleMatch": True,
+            "Content-Type": "application/json",
+            "X-S2-UI-Version": get_ui_version(),
+            "X-S2-Client": "webapp-browser",
         }
     )
-    return params
-
-
-def response(resp):
-    res = resp.json()
-
-    results = []
-    for result in res['results']:
-        url = result.get('primaryPaperLink', {}).get('url')
-        if not url and result.get('links'):
-            url = result.get('links')[0]
+    params["json"] = {
+        "queryString": query,
+        "page": params["pageno"],
+        "pageSize": 10,
+        "sort": "relevance",
+        "getQuerySuggestions": False,
+        "authors": [],
+        "coAuthors": [],
+        "venues": [],
+        "performTitleMatch": True,
+    }
+
+
+def response(resp: "SXNG_Response") -> EngineResults:
+    res = EngineResults()
+    json_data = resp.json()
+
+    for result in json_data["results"]:
+        url: str = result.get("primaryPaperLink", {}).get("url")
+        if not url and result.get("links"):
+            url = result.get("links")[0]
         if not url:
-            alternatePaperLinks = result.get('alternatePaperLinks')
+            alternatePaperLinks = result.get("alternatePaperLinks")
             if alternatePaperLinks:
-                url = alternatePaperLinks[0].get('url')
+                url = alternatePaperLinks[0].get("url")
         if not url:
-            url = base_url + '/paper/%s' % result['id']
+            url = base_url + "/paper/%s" % result["id"]
 
-        # publishedDate
-        if 'pubDate' in result:
-            publishedDate = datetime.strptime(result['pubDate'], "%Y-%m-%d")
+        publishedDate: datetime | None
+        if "pubDate" in result:
+            publishedDate = datetime.strptime(result["pubDate"], "%Y-%m-%d")
         else:
             publishedDate = None
 
         # authors
-        authors = [author[0]['name'] for author in result.get('authors', [])]
+        authors: list[str] = [author[0]["name"] for author in result.get("authors", [])]
 
         # pick for the first alternate link, but not from the crawler
-        pdf_url = None
-        for doc in result.get('alternatePaperLinks', []):
-            if doc['linkType'] not in ('crawler', 'doi'):
-                pdf_url = doc['url']
+        pdf_url: str = ""
+        for doc in result.get("alternatePaperLinks", []):
+            if doc["linkType"] not in ("crawler", "doi"):
+                pdf_url = doc["url"]
                 break
 
         # comments
-        comments = None
-        if 'citationStats' in result:
+        comments: str = ""
+        if "citationStats" in result:
             comments = gettext(
-                '{numCitations} citations from the year {firstCitationVelocityYear} to {lastCitationVelocityYear}'
+                "{numCitations} citations from the year {firstCitationVelocityYear} to {lastCitationVelocityYear}"
             ).format(
-                numCitations=result['citationStats']['numCitations'],
-                firstCitationVelocityYear=result['citationStats']['firstCitationVelocityYear'],
-                lastCitationVelocityYear=result['citationStats']['lastCitationVelocityYear'],
+                numCitations=result["citationStats"]["numCitations"],
+                firstCitationVelocityYear=result["citationStats"]["firstCitationVelocityYear"],
+                lastCitationVelocityYear=result["citationStats"]["lastCitationVelocityYear"],
             )
 
-        results.append(
-            {
-                'template': 'paper.html',
-                'url': url,
-                'title': result['title']['text'],
-                'content': html_to_text(result['paperAbstract']['text']),
-                'journal': result.get('venue', {}).get('text') or result.get('journal', {}).get('name'),
-                'doi': result.get('doiInfo', {}).get('doi'),
-                'tags': result.get('fieldsOfStudy'),
-                'authors': authors,
-                'pdf_url': pdf_url,
-                'publishedDate': publishedDate,
-                'comments': comments,
-            }
+        res.add(
+            res.types.Paper(
+                title=result["title"]["text"],
+                url=url,
+                content=html_to_text(result["paperAbstract"]["text"]),
+                journal=result.get("venue", {}).get("text") or result.get("journal", {}).get("name"),
+                doi=result.get("doiInfo", {}).get("doi"),
+                tags=result.get("fieldsOfStudy"),
+                authors=authors,
+                pdf_url=pdf_url,
+                publishedDate=publishedDate,
+                comments=comments,
+            )
         )
 
-    return results
+    return res
diff --git a/searx/settings.yml b/searx/settings.yml
index 3e51a3c38..d72e84ff7 100644
--- a/searx/settings.yml
+++ b/searx/settings.yml
@@ -1964,7 +1964,6 @@ engines:
 
   - name: semantic scholar
     engine: semantic_scholar
-    disabled: true
     shortcut: se
 
   # Spotify needs API credentials