[FEAT] Add a filter to check if a page is redirect

Added a -redirect filter to assert if page is a redirect. Likewise,
the filter can be negated by using -redirect:false.

This is a missing feature present in compat, which implemented -redirectonly,
but this is more useful because it can be negated, and the name is different
to make it clearer.

Bug: T261549
Change-Id: If1a2c9bb420d9b5af69371537c7ca724096d8a23
---
M pywikibot/pagegenerators/__init__.py
M pywikibot/pagegenerators/_factory.py
2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/pywikibot/pagegenerators/__init__.py b/pywikibot/pagegenerators/__init__.py
index d3fe693..a18aeb6 100644
--- a/pywikibot/pagegenerators/__init__.py
+++ b/pywikibot/pagegenerators/__init__.py
@@ -500,6 +500,9 @@
                     Valid values are in range 0-4.
                     Multiple values can be comma-separated.
 
+-redirect           Filter pages based on whether they are redirects. To return
+                    only pages that are not redirects, use -redirect:false
+
 -subpage            -subpage:n filters pages to only those that have depth n
                     i.e. a depth of 0 filters out all pages that are subpages,
                     and a depth of 1 filters out all pages that are subpages of
diff --git a/pywikibot/pagegenerators/_factory.py b/pywikibot/pagegenerators/_factory.py
index 4a6f5c4..4a19361 100644
--- a/pywikibot/pagegenerators/_factory.py
+++ b/pywikibot/pagegenerators/_factory.py
@@ -33,6 +33,7 @@
     ItemClaimFilterPageGenerator,
     NamespaceFilterPageGenerator,
     QualityFilterPageGenerator,
+    RedirectFilterPageGenerator,
     RegexBodyFilterPageGenerator,
     RegexFilterPageGenerator,
     SubpageFilterGenerator,
@@ -54,6 +55,7 @@
     WikibaseSearchItemPageGenerator,
     WikidataSPARQLPageGenerator,
 )
+from pywikibot.tools import strtobool
 from pywikibot.tools.collections import DequeGenerator
 from pywikibot.tools.itertools import (
     filter_unique,
@@ -113,6 +115,7 @@
         self.catfilter_list: List['pywikibot.Category'] = []
         self.intersect = False
         self.subpage_max_depth: Optional[int] = None
+        self.redirectfilter: Optional[bool] = None
         self._site = site
         self._positional_arg_name = positional_arg_name
         self._sparql: Optional[str] = None
@@ -241,7 +244,8 @@
                     self.claimfilter_list,
                     self.catfilter_list,
                     self.qualityfilter_list,
-                    self.subpage_max_depth is not None)):
+                    self.subpage_max_depth is not None,
+                    self.redirectfilter is not None)):
                 pywikibot.warning('filter(s) specified but no generators.')
             return None
 
@@ -264,6 +268,12 @@
             dupfiltergen = SubpageFilterGenerator(
                 dupfiltergen, self.subpage_max_depth)
 
+        if self.redirectfilter is not None:
+            # Generator expects second parameter true to exclude redirects, but
+            # our logic is true to assert it is a redirect, false when it isn't
+            dupfiltergen = RedirectFilterPageGenerator(
+                dupfiltergen, not self.redirectfilter)
+
         if self.claimfilter_list:
             for claim in self.claimfilter_list:
                 dupfiltergen = ItemClaimFilterPageGenerator(dupfiltergen,
@@ -902,6 +912,14 @@
                 f'Invalid -logevents parameter "{params[0]}"')
         return self._parse_log_events(*params)
 
+    def _handle_redirect(self, value: str) -> HANDLER_RETURN_TYPE:
+        """Handle `-redirect` argument."""
+        if not value:
+            # True by default
+            value = 'true'
+        self.redirectfilter = strtobool(value)
+        return True
+
     def handle_args(self, args: Iterable[str]) -> List[str]:
         """Handle command line arguments and return the rest as a list.
 

