Extract natural language and locale specific dates in content

Previously we just extracted dates in YYYY-MM-DD format from content
for date filterings during search.

Use dateparser to extract dates across locales and natural language

This should improve notes returned as context when chat searches
knowledge base with date filters

Fallback to regex for date parsing from content if dateparser fails

- Limit natural date extractor capabilities to improve performance
  - Assume language is english
    Language detection otherwise takes a REALLY long time
  - Do not extract unix timestamps, timezone
    - This isn't required, as just using date and approximating dates as UTC

src/khoj/search_filter/date_filter.py

@@ -6,10 +6,12 @@ from math import inf
 from typing import List
 
 import dateparser as dtparse
+from dateparser.search import search_dates
+from dateparser_data.settings import default_parsers
 from dateutil.relativedelta import relativedelta
 
 from khoj.search_filter.base_filter import BaseFilter
-from khoj.utils.helpers import LRU, timer
+from khoj.utils.helpers import LRU, merge_dicts, timer
 
 logger = logging.getLogger(__name__)
 
@@ -21,17 +23,40 @@ class DateFilter(BaseFilter):
     # - dt>="last week"
     # - dt:"2 years ago"
     date_regex = r"dt([:><=]{1,2})[\"'](.*?)[\"']"
-    raw_date_regex = r"\d{4}-\d{2}-\d{2}"
+    raw_date_regex = r"\d{4}[-/]\d{2}[-/]\d{2}"
 
     def __init__(self, entry_key="compiled"):
         self.entry_key = entry_key
         self.date_to_entry_ids = defaultdict(set)
         self.cache = LRU()
+        self.dtparser_settings = {
+            "PREFER_DAY_OF_MONTH": "first",
+            "DATE_ORDER": "YMD",  # Prefer YMD and DMY over MDY when parsing ambiguous dates
+        }
 
     def extract_dates(self, content):
-        pattern_matched_dates = re.findall(self.raw_date_regex, content)
+        "Extract all natural and structured dates across formats and locales from content"
+        excluded_parsers = ["relative-time"]
+        dtparser_settings = merge_dicts(
+            {
+                # Exclude relative dates for date extraction from content as very ambiguous
+                "PARSERS": [parser for parser in default_parsers if parser not in excluded_parsers],
+                "RETURN_AS_TIMEZONE_AWARE": False,
+            },
+            self.dtparser_settings,
+        )
+        try:
+            valid_dates = [
+                dt_item[1] for dt_item in search_dates(content, settings=dtparser_settings, languages=["en"]) or []
+            ]
+            return valid_dates
+        except Exception as e:
+            logger.warning(
+                f"Failed to extract natural dates from content with error: {e}. Fallback to regex based extraction."
+            )
 
-        # Filter down to valid dates
+        # Fallback to extracting YYYY-MM-DD format dates from content
+        pattern_matched_dates = re.findall(self.raw_date_regex, content)
         valid_dates = []
         for date_str in pattern_matched_dates:
             try:
@@ -120,18 +145,13 @@ class DateFilter(BaseFilter):
         # clean date string to handle future date parsing by date parser
         future_strings = ["later", "from now", "from today"]
         prefer_dates_from = {True: "future", False: "past"}[any([True for fstr in future_strings if fstr in date_str])]
-        clean_date_str = re.sub("|".join(future_strings), "", date_str)
+        dtquery_settings = {"RELATIVE_BASE": relative_base or datetime.now(), "PREFER_DATES_FROM": prefer_dates_from}
+        dtparser_settings = merge_dicts(dtquery_settings, self.dtparser_settings)
 
         # parse date passed in query date filter
+        clean_date_str = re.sub("|".join(future_strings), "", date_str)
         try:
-            parsed_date = dtparse.parse(
-                clean_date_str,
-                settings={
-                    "RELATIVE_BASE": relative_base or datetime.now(),
-                    "PREFER_DAY_OF_MONTH": "first",
-                    "PREFER_DATES_FROM": prefer_dates_from,
-                },
-            )
+            parsed_date = dtparse.parse(clean_date_str, settings=dtparser_settings)
         except Exception as e:
             logger.error(f"Failed to parse date string: {date_str} with error: {e}")
             return None

tests/test_date_filter.py

@@ -116,7 +116,7 @@ def test_date_filter_regex():
     assert dtrange_match == []
 
 
-def test_get_file_filter_terms():
+def test_get_date_filter_terms():
     dtrange_match = DateFilter().get_filter_terms('multi word head dt>"today" dt:"1984-01-01"')
     assert dtrange_match == ["dt>'today'", "dt:'1984-01-01'"]
 
@@ -134,3 +134,29 @@ def test_get_file_filter_terms():
 
     dtrange_match = DateFilter().get_filter_terms("head tail")
     assert dtrange_match == []
+
+
+def test_date_extraction():
+    extracted_dates = DateFilter().extract_dates("")
+    assert extracted_dates == [], "Expected to handle empty string"
+
+    extracted_dates = DateFilter().extract_dates("head tail")
+    assert extracted_dates == [], "Expected to handle no dates"
+
+    extracted_dates = DateFilter().extract_dates("head CREATED: today tail")
+    assert extracted_dates == [], "Expected relative date to be ignored"
+
+    extracted_dates = DateFilter().extract_dates("head CREATED: today SCHEDULED: 1984-04-01 tail")
+    assert extracted_dates == [datetime(1984, 4, 1, 0, 0, 0)], "Expected only YMD structured date to be extracted"
+
+    extracted_dates = DateFilter().extract_dates("head CREATED: today SCHEDULED: 01-04-1984 tail")
+    assert extracted_dates == [datetime(1984, 4, 1, 0, 0, 0)], "Expected DMY structured date to be extracted"
+
+    extracted_dates = DateFilter().extract_dates("head Updates from April 1984 tail")
+    assert extracted_dates == [datetime(1984, 4, 1, 0, 0, 0)], "Expected natural date to be extracted"
+
+    extracted_dates = DateFilter().extract_dates("CLOCK: [1984-04-01 mer 09:50]--[1984-04-01 mer 10:10] => 24:20")
+    expected_dates = [datetime(1984, 4, 1, 9, 50, 0), datetime(1984, 4, 1, 10, 10, 0)]
+    assert all(
+        [dt in extracted_dates for dt in expected_dates]
+    ), "Expected multiple non-english dates extracted from logbook entry"