--- ValBot/Python/check_interwiki_links.py	2023/04/28 00:54:21	1180
+++ ValBot/Python/check_interwiki_links.py	2025/08/15 20:55:01	1196
@@ -1,26 +1,33 @@
 # Check Interwiki Links
 # by iritscen@yahoo.com
-# Looks at each link on a page (or in all the pages in a category) which uses a registered
+# Looks at each link on a page (or all the pages in a category) which uses a registered
 # interwiki prefix and loads the linked page, verifying that it exists and that any section
 # link, if present, is valid as well. The output will use the word "ERROR" when it cannot
 # validate the interwiki link.
 # Recommended viewing width:
 # |---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---|
 
-import os
-
-from urllib.parse import urljoin
-
+import bs4
 import pywikibot
 import re
-import requests # for listing members with dir()
+import requests # for listing members with dir() when debugging
 
-from pywikibot.bot import QuitKeyboardInterrupt
+from bs4 import BeautifulSoup
 from pywikibot import pagegenerators
-from pywikibot.tools.formatter import color_format
+from pywikibot.bot import QuitKeyboardInterrupt
 from pywikibot.comms.http import fetch
 from pywikibot.specialbots import UploadRobot
-from bs4 import BeautifulSoup
+from pywikibot.tools.formatter import color_format
+from urllib.parse import urljoin
+
+class IWLink:
+   def __init__(self, iw_prefix, prefix_url, full_url, page_name, page_slug, curl_response):
+      self.iw_prefix = iw_prefix # e.g. "wp"
+      self.prefix_url = prefix_url # e.g. "https://en.wikipedia.org/wiki/"
+      self.full_url = full_url # e.g. "https://en.wikipedia.org/wiki/Easter_egg"
+      self.page_name = page_name # "Easter egg"
+      self.page_slug = page_slug # "Easter_egg"
+      self.curl_response = curl_response # a class defined in the Requests library
 
 # Parallel arrays based on https://wiki.oni2.net/Special:Interwiki
 interwiki_prefixes = ('acronym', 'cache', 'commons', 'dictionary', 'google', 'metawikimedia', 'mw', 'wikibooks', 'wikidata', 'wikimedia', 'wikinews', 'wikipedia', 'wikiquote', 'wikisource', 'wikispecies', 'wikiversity', 'wikivoyage', 'wikt', 'wiktionary', 'wp')
@@ -32,123 +39,206 @@ debug = 0
 pages_checked = 0
 iw_found = 0
 errors_issued = 0
+unintended_redirects_found = 0
+name_printed = 0
+
+# Prints the name of a page on which something occurred, if it has not been printed before
+def possibly_print(page_name):
+   global debug
+   global name_printed
+   
+   if not name_printed and not debug:
+      pywikibot.stdout('')
+      pywikibot.stdout('From page "{}":'.format(page_name))
+      name_printed = 1
+
+# Search a page for the section specified in the link
+def find_section(the_link, print_result):
+   global errors_issued
+
+   # Isolate section link
+   target_page_name, anchor_name = the_link.page_slug.split('#')
+   target_page_name_human = target_page_name.replace('_', ' ')
+   
+   # Convert dot-notation hex entities to proper characters
+   replacements = [(r'\.22', '"'), (r'\.27', "'"), (r'\.28', '('), (r'\.29', ')')]
+   for pattern, replacement in replacements:
+      anchor_name = re.sub(pattern, replacement, anchor_name)
+   
+   # Read linked page to see if it really has this anchor link
+   soup = BeautifulSoup(the_link.curl_response.text, 'html.parser')
+   tags_to_search = ['span', 'div', 'h2', 'h3', 'h4']
+   found_section = False
+   for tag_name in tags_to_search:
+       for the_tag in soup.find_all(tag_name):
+           if the_tag.get('id') == anchor_name:
+               found_section = True
+               break
+       if found_section:
+           break
+   
+   # Tell user what we found
+   if found_section == False:
+      possibly_print(the_link.page_name)
+      pywikibot.stdout('   ERROR: Could not find section "{0}" on {1} page "{2}".'.format(anchor_name, the_link.iw_prefix, target_page_name_human))
+      # TODO: Check that page name has been corrected to redirected page if there was a redirect
+      errors_issued = errors_issued + 1
+   elif print_result == True:
+      pywikibot.stdout('   The section "{0}" was found on {1} page "{2}".'.format(anchor_name, the_link.iw_prefix, target_page_name_human))
+
+# For a link that redirected us to another page, extract the name of the target page from
+# the target page's source
+def find_canonical_link(the_link):
+   # Extract link from this markup which contains name of redirected-to page:
+   # <link rel="canonical" href="https://en.wikipedia.org/wiki/Page_name"/>
+   canonical_name = the_link.curl_response.text.split('<link rel="canonical" href="')[-1]
+   prefix_length = len(the_link.prefix_url)
+   canonical_name = canonical_name[prefix_length:]
+   tag_end = canonical_name.find('">')
+   
+   if tag_end == -1:
+      pywikibot.stdout('   ERROR: The {0} link "{1}" is a redirect page, but this script could not isolate the target page name.'.format(the_link.iw_prefix, the_link.page_slug))
+      errors_issued = errors_issued + 1
+   else:
+      canonical_name = canonical_name[:tag_end]
+      if len(canonical_name) > 100:
+         # Certain things can cause the trim to fail; report error and avoid slamming the
+         # output with massive page source from a failed trim
+         pywikibot.stdout('   ERROR: The {0} link "{1}" is a redirect to "{2}…" (string overflow).'.format(the_link.iw_prefix, the_link.page_slug, canonical_name[:100]))
+         errors_issued = errors_issued + 1
+      else:
+         canonical_name = canonical_name.replace('_', ' ')
+         if '#' in the_link.page_slug:
+            _, anchor_name = the_link.page_slug.split('#')
+            pywikibot.stdout('   The {0} link "{1}" is a redirect to "{2}#{3}", which is a valid page. Checking for section on that page….'.format(the_link.iw_prefix, the_link.page_slug, canonical_name, anchor_name))
+            the_link.page_slug = the_link.page_slug.replace(the_link.page_name, canonical_name) # update page slug so that find_section() uses the right page name in its messages
+            find_section(the_link, True)
+         else:
+            pywikibot.stdout('   The {0} link "{1}" is a redirect to "{2}", which is a valid page.'.format(the_link.iw_prefix, the_link.page_slug, canonical_name))
+
+# Test an interwiki link and look for a section link if applicable
+def test_interwiki_link(the_link):
+   global errors_issued
+   global unintended_redirects_found
+   
+   the_link.curl_response = fetch(the_link.full_url)
+
+   # One way we tell that a redirect occurred is by checking fetch's history, as it
+   # automatically follows redirects. This will catch formal redirects which come from pages
+   # such as Special:PermanentLink.
+   if the_link.curl_response.history != []:
+      possibly_print(the_link.page_name)
+      
+      # If linked page is in all caps, e.g. WP:BEANS, it's likely a deliberate use of a redirect
+      if the_link.page_slug.startswith('WP:') and the_link.page_slug == the_link.page_slug.upper():
+         pywikibot.stdout('   Got redirection code "{0}" for {1} link "{2}". This appears to be a deliberate use of a Wikipedia shortcut. Checking the target page….'.format(the_link.curl_response.history[0], the_link.iw_prefix, the_link.page_slug))
+         find_canonical_link(the_link)
+      else:
+         permalink1 = 'Special:PermanentLink/'.lower()
+         permalink2 = 'Special:Permalink/'.lower()
+         page_slug_lower = the_link.page_slug.lower()
+         if page_slug_lower.startswith(permalink1) or page_slug_lower.startswith(permalink2):
+            pywikibot.stdout('   Got redirection code "{0}" for {1} permanent revision link "{2}". Checking the target page….'.format(the_link.curl_response.history[0], the_link.iw_prefix, the_link.page_slug))
+            find_canonical_link(the_link)
+         else:
+            pywikibot.stdout('   ERROR: Unrecognized type of redirection (code "{0}") for {1} link "{2}". You should check the link manually.'.format(the_link.curl_response.history[0], the_link.iw_prefix, the_link.page_slug))
+            errors_issued = errors_issued + 1
+   elif the_link.curl_response.status_code != 200:
+      possibly_print(the_link.page_name)
+      pywikibot.stdout('   ERROR: Got response code {0} for {1} link "{2}". The page may not exist.'.format(the_link.curl_response.status_code, the_link.iw_prefix, the_link.page_slug))
+      errors_issued = errors_issued + 1
+   # However the usual way that a redirect occurs is that MediaWiki redirects us sneakily
+   # using JavaScript, while returning code OK 200 as if the link was correct; this happens
+   # when a redirect page is accessed. We must detect these soft redirects by looking at the
+   # page source to find the redirect note inserted at the top of the page for the reader.
+   elif 'Redirected from <a' in the_link.curl_response.text:
+      unintended_redirects_found = unintended_redirects_found + 1
+      possibly_print(the_link.page_name)
+      pywikibot.stdout('   WARNING: Got silently redirected by {0} link "{1}". Checking the target page….'.format(the_link.iw_prefix, the_link.page_slug))
+      find_canonical_link(the_link)
+   elif '#' in the_link.page_slug:
+      find_section(the_link, False)
 
 # Searches the given page text for interwiki links
 def scan_for_interwiki_links(page_text, page_name):
    global debug
    global pages_checked
    global iw_found
-   global errors_issued
+   global name_printed
    pages_checked = pages_checked + 1
-   cur = 0
+   cur_prefix = 0
    name_printed = 0
 
    for prefix in interwiki_prefixes:
       # Isolate strings that start with "[[prefix:" and end with "|" or "]"
-      iw_link = "\[\[" + prefix + ":[^|\]]*(\||\])"
+      iw_link = r"\[\[" + prefix + r":[^|\]]*(\||\])"
       for match in re.finditer(iw_link, page_text):
+         the_link = IWLink(prefix, interwiki_urls[cur_prefix], "", page_name, "", "")
+      
          # Extract just the page title from this regex match
-         s = match.start() + 2 + len(prefix) + 1
+         s = match.start() + 2 + len(the_link.iw_prefix) + 1
          e = match.end() - 1
 
-         # Sometimes we used a space char. instead of a '_', so fix that before querying
-         page_title = page_text[s:e].replace(' ', '_')
+         # Commonly we use spaces instead of underscores, so fix that before querying
+         the_link.page_slug = page_text[s:e].replace(' ', '_')
 
-         # Use only spaces for title when printing it
-         page_title_human = page_title.replace('_', ' ')
-         if debug: pywikibot.stdout('   Validating {0} link "{1}"'.format(prefix, page_title_human))
+         # But use spaces for title when printing it
+         page_title_human = the_link.page_slug.replace('_', ' ')
+         if debug: pywikibot.stdout('   Validating {0} link "{1}"'.format(the_link.iw_prefix, page_title_human))
          iw_found = iw_found + 1
 
          # Construct full URL for the particular wiki
-         iw_url = interwiki_urls[cur] + page_title
+         the_link.full_url = the_link.prefix_url + the_link.page_slug
 
          # Adjust URL if this is a foreign-language WP link
-         if re.match("^[a-zA-Z]{2}:", page_title):
-            lang_code = page_title[0:2] + "."
+         if re.match("^[a-zA-Z]{2}:", the_link.page_slug):
+            lang_code = the_link.page_slug[0:2] + "."
             # "wp:" is the Wikipedia: namespace, not a language
             if lang_code != "wp." and lang_code != "WP.":
-               iw_url = iw_url.replace('en.', lang_code)
-               iw_url = iw_url.replace(page_title[0:3], '')
+               the_link.full_url = the_link.full_url.replace('en.', lang_code)
+               the_link.full_url = the_link.full_url.replace(the_link.page_slug[0:3], '')
 
          # Test the URL
-         response = fetch(iw_url)
+         test_interwiki_link(the_link)
+      cur_prefix = cur_prefix + 1
 
-         # One way we tell that a redirect occurred is by checking the history
-         if response.history != []:
-            if not name_printed and not debug:
-               pywikibot.stdout('From page "{}":'.format(page_name))
-               name_printed = 1
-            if page_title.startswith('WP:') and page_title == page_title.upper():
-               pywikibot.stdout('   ERROR: Got redirection code ({0}) for {1} link "{2}", but this appears to be a deliberate use of a Wikipedia shortcut. You should check the link manually.'.format(response.history[0], prefix, page_title))
-            else:
-               pywikibot.stdout('   ERROR: Got redirection code ({0}) for {1} link "{2}". You should check the link manually.'.format(response.history[0], prefix, page_title))
-            errors_issued = errors_issued + 1
-         elif response.status_code != 200:
-            if not name_printed and not debug:
-               pywikibot.stdout('From page "{}":'.format(page_name))
-               name_printed = 1
-            pywikibot.stdout('   ERROR: Got response code {0} for {1} link "{2}". The page may not exist.'.format(response.status_code, prefix, page_title))
-            errors_issued = errors_issued + 1
-         # The usual way that a redirect occurs is that MediaWiki redirects us sneakily
-         # using JavaScript, while returning code OK 200 as if the link was correct; we
-         # must detect this from the page source
-         elif 'Redirected from <a' in response.text:
-            if not name_printed and not debug:
-               pywikibot.stdout('From page "{}":'.format(page_name))
-               name_printed = 1
-            # Extract link from this source which contains name of redirected-to page:
-            # <link rel="canonical" href="https://en.wikipedia.org/wiki/Page_name"/>
-            canonical_name = response.text.split('<link rel="canonical" href="')[-1]
-            prefix_length = len(interwiki_urls[cur])
-            canonical_name = canonical_name[prefix_length:]
-            tag_end = canonical_name.find('"/>')
-            if tag_end == -1:
-               pywikibot.stdout('   ERROR: The {0} link "{1}" is a redirect page, but this script could not isolate the target page name.', format(prefix, page_title))
-            else:
-               canonical_name = canonical_name[:tag_end]
-               if len(canonical_name) > 100:
-                 # Certain things can cause the trim to fail; here we avoid slamming
-                 # the output with massive page source from a failed trim
-                 pywikibot.stdout('   ERROR: The {0} link "{1}" is a redirect to "{2}…" (string trimmed to 100 chars).'.format(prefix, page_title, canonical_name[:100]))
-               else:
-                 canonical_name = canonical_name.replace('_', ' ')
-                 pywikibot.stdout('   ERROR: The {0} link "{1}" is a redirect to "{2}".'.format(prefix, page_title, canonical_name))
-            errors_issued = errors_issued + 1
-         elif '#' in page_title:
-            # Isolate section link
-            target_page_name, anchor_name = page_title.split('#')
-            
-            # Convert dot-notation hex entities to proper characters
-            anchor_name = anchor_name.replace('.22', '"')
-            anchor_name = anchor_name.replace('.27', '\'')
-            anchor_name = anchor_name.replace('.28', '(')
-            anchor_name = anchor_name.replace('.29', ')')
-            
-            # Read linked page to see if it really has this anchor link
-            soup = BeautifulSoup(response.text, 'html.parser')
-            found_section = False
-            for span_tag in soup.findAll('span'):
-               span_name = span_tag.get('id', None)
-               if span_name == anchor_name:
-                  found_section = True
-                  break
-            if found_section == False:
-               if not name_printed and not debug:
-                  pywikibot.stdout('From page "{}":'.format(page_name))
-                  name_printed = 1
-               target_page_name_human = target_page_name.replace('_', ' ')
-               pywikibot.stdout('   ERROR: Could not find section "{0}" on {1} page "{2}".'.format(anchor_name, prefix, target_page_name_human))
-               errors_issued = errors_issued + 1
-      cur = cur + 1
+# Print a wrap-up message
+def print_summary():
+   global pages_checked
+   global iw_found
+   global errors_issued
+   global unintended_redirects_found
+
+   page_str = "pages"
+   if pages_checked == 1:
+      page_str = "page"
+
+   link_str = "links"
+   if iw_found == 1:
+      link_str = "link"
+
+   pywikibot.stdout('Checked {0} {1} and found {2} interwiki {3}.'.format(pages_checked, page_str, iw_found, link_str))
+
+   error_str = "errors were"
+   if errors_issued == 1:
+      error_str = "error was"
+
+   pywikibot.stdout('{0} {1} encountered in validating these links.'.format(errors_issued, error_str))
 
+   warning_str = "likely-unintended redirects were"
+   if unintended_redirects_found == 1:
+      warning_str = "likely-unintended redirect was"
+
+   pywikibot.stdout('{0} {1} encountered in validating these links.'.format(unintended_redirects_found, warning_str))
+
+# Main function
 def main(*args):
    global debug
    search_cat = ''
    search_page = ''
 
+   # Process arguments
    local_args = pywikibot.handle_args(args)
-   genFactory = pagegenerators.GeneratorFactory()
-
    for arg in local_args:
       if arg.startswith('-cat:'):
          search_cat = arg[5:]
@@ -157,14 +247,15 @@ def main(*args):
       elif arg == '-dbg':
          debug = 1
       else:
-         pywikibot.stdout('Unknown argument "{}".'.format(arg))
+         pywikibot.stdout('Unknown argument "{}". Exiting.'.format(arg))
          return
 
-   site = pywikibot.Site()
-
    #pywikibot.stdout('The members of the requests.models.Response class are:')
    #pywikibot.stdout(format(dir(requests.models.Response)))
-
+   #return
+   
+   # Check specified page or loop through specified category and check all pages
+   site = pywikibot.Site()
    if search_cat != '':
       cat_obj = pywikibot.Category(site, search_cat)
       generator = pagegenerators.CategorizedPageGenerator(cat_obj, recurse=True)
@@ -176,25 +267,8 @@ def main(*args):
       if debug: pywikibot.stdout('Checking page "{}"'.format(page.title()))
       scan_for_interwiki_links(page.text, page.title())
 
-   global pages_checked
-   global iw_found
-   global errors_issued
-
-   page_str = "pages"
-   if pages_checked == 1:
-      page_str = "page"
-
-   link_str = "links"
-   if iw_found == 1:
-      link_str = "link"
-
-   pywikibot.stdout('Checked {0} {1} and found {2} interwiki {3}.'.format(pages_checked, page_str, iw_found, link_str))
-
-   error_str = "errors were"
-   if errors_issued == 1:
-      error_str = "error was"
-
-   pywikibot.stdout('{0} {1} encountered in validating these links.'.format(errors_issued, error_str))
+   # Print the results
+   print_summary()
 
 if __name__ == '__main__':
    main()