--- ValBot/Python/check_interwiki_links.py	2022/03/21 21:22:33	1170
+++ ValBot/Python/check_interwiki_links.py	2025/09/21 21:50:56	1198
@@ -1,152 +1,265 @@
 # 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
-# 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.
+# 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
+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_name_only, page_slug, hosting_page, 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/Marathon_(series)#Rampancy"
+      self.page_name = page_name # "Marathon (series)#Rampancy"
+      self.page_name_only = page_name # "Marathon (series)"
+      self.page_slug = page_slug # "Marathon_(series)#Rampancy"
+      self.hosting_page = hosting_page # "Easter eggs"; page where the link was found
+      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')
 
 interwiki_urls = ('http://www.acronymfinder.com/~/search/af.aspx?string=exact&Acronym=', 'http://www.google.com/search?q=cache:', 'https://commons.wikimedia.org/wiki/', 'http://www.dict.org/bin/Dict?Database=*&Form=Dict1&Strategy=*&Query=', 'http://www.google.com/search?q=', 'https://meta.wikimedia.org/wiki/', 'https://www.mediawiki.org/wiki/', 'https://en.wikibooks.org/wiki/', 'https://www.wikidata.org/wiki/', 'https://foundation.wikimedia.org/wiki/', 'https://en.wikinews.org/wiki/', 'https://en.wikipedia.org/wiki/', 'https://en.wikiquote.org/wiki/', 'https://wikisource.org/wiki/', 'https://species.wikimedia.org/wiki/', 'https://en.wikiversity.org/wiki/', 'https://en.wikivoyage.org/wiki/', 'https://en.wiktionary.org/wiki/', 'https://en.wiktionary.org/wiki/', 'https://en.wikipedia.org/wiki/')
 
+# Initialize globals
+debug = 0
 pages_checked = 0
 iw_found = 0
 errors_issued = 0
+unintended_redirects_found = 0
+name_printed = 0
 
-# Searches the given page text for interwiki links
-def scan_for_iw_links(page_text):
-    global pages_checked
-    global iw_found
-    global errors_issued
-    pages_checked = pages_checked + 1
-    cur = 0
-
-    for prefix in interwiki_prefixes:
-        # Isolate strings that start with "[[prefix:" and end with "|" or "]"
-        iw_link = "\[\[" + prefix + ":[^|\]]*(\||\])"
-        for match in re.finditer(iw_link, page_text):
-            # Extract just the page title from this regex match
-            s = match.start() + 2 + len(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(' ', '_')
-
-            # Construct full URL for the particular wiki
-            iw_url = interwiki_urls[cur] + page_title
-            pywikibot.stdout('   Validating {0} link "{1}"'.format(prefix, page_title))
-            iw_found = iw_found + 1
-
-            # 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] + "."
-                # "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], '')
-
-            # Test the URL
-            #pywikibot.stdout('   Testing URL "{}"'.format(iw_url))
-            response = fetch(iw_url)
-
-            # Redirects are followed automatically by fetch() and treated as "200"s, so the
-            # way we tell that a redirect occurred is by checking the history
-            if response.history != []:
-                pywikibot.stdout('   ERROR: Got redirection code ({0}) on URL "{1}".'.format(response.history[0], iw_url))
-                errors_issued = errors_issued + 1
-            elif response.status_code != 200:
-                pywikibot.stdout('   ERROR: Got response code {0} on URL "{1}".'.format(response.status_code, iw_url))
-                errors_issued = errors_issued + 1
-            elif '#' in page_title:
-                # Isolate section link
-                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:
-                        #pywikibot.stdout('Found section!')
-                        found_section = True
-                        break
-                if found_section == False:
-                    pywikibot.stdout('   ERROR: Could not find section {0} on page {1}.'.format(anchor_name, page_name))
-                    errors_issued = errors_issued + 1
-        cur = cur + 1
+# Prints the name of a page on which something occurred, if it has not been printed before
+def possibly_print(the_link):
+   global debug
+   global name_printed
+   
+   if not name_printed and not debug:
+      pywikibot.stdout('')
+      pywikibot.stdout('From page "{}":'.format(the_link.hosting_page))
+      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
+   _, anchor_name = the_link.page_slug.split('#')
+   
+   # 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)
+      pywikibot.stdout('   ERROR: Could not find section "{0}" on {1} page "{2}".'.format(anchor_name, the_link.iw_prefix, the_link.page_name))
+      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, the_link.page_name))
+
+# 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:
+         the_link.page_name = canonical_name.replace('_', ' ')
+         if '#' in the_link.page_slug:
+            the_link.page_name_only, _ = the_link.page_slug.split('#')
+            pywikibot.stdout('   The {0} link "{1}" is a redirect to "{2}", which is a valid page. Checking for section on that page….'.format(the_link.iw_prefix, the_link.page_name_only, the_link.page_name))
+            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, the_link.page_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)
+      
+      # 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)
+      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)
+      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) # calls find_section() at end
+   elif '#' in the_link.page_slug:
+      find_section(the_link, False)
 
-def main(*args):
-    cat_name = ''
-    page_name = ''
+# 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 name_printed
+   pages_checked = pages_checked + 1
+   cur_prefix = 0
+   name_printed = 0
+
+   for prefix in interwiki_prefixes:
+      # Isolate strings that start with "[[prefix:" and end with "|" or "]"
+      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(the_link.iw_prefix) + 1
+         e = match.end() - 1
+
+         # Use underscores in slug used to constructed URL, but retain spaces for printable name
+         the_link.page_slug = page_text[s:e].replace(' ', '_')
+         the_link.page_name = page_text[s:e]
+         if debug: pywikibot.stdout('   Validating {0} link "{1}"'.format(the_link.iw_prefix, the_link.page_name))
+         iw_found = iw_found + 1
+
+         # Construct full URL for the particular wiki
+         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}:", 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.":
+               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
+         test_interwiki_link(the_link)
+      cur_prefix = cur_prefix + 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"
 
-    local_args = pywikibot.handle_args(args)
-    genFactory = pagegenerators.GeneratorFactory()
+   pywikibot.stdout('{0} {1} encountered in validating these links.'.format(unintended_redirects_found, warning_str))
 
-    for arg in local_args:
-        if arg.startswith('-cat:'):
-            cat_name = arg[5:]
-        elif arg.startswith('-page:'):
-            page_name = arg[6:]
-
-    site = pywikibot.Site()
-
-    #pywikibot.stdout('The members of the requests.models.Response class are:')
-    #pywikibot.stdout(format(dir(requests.models.Response)))
-
-    if cat_name != '':
-        cat_obj = pywikibot.Category(site, cat_name)
-        generator = pagegenerators.CategorizedPageGenerator(cat_obj, recurse=True)
-        for page in pagegenerators.PreloadingGenerator(generator, 100):
-            pywikibot.stdout('Checking page "{}"'.format(page.title()))
-            scan_for_iw_links(page.text)
-    elif page_name != '':
-        page = pywikibot.Page(site, page_name)
-        pywikibot.stdout('Checking page "{}"'.format(page.title()))
-        scan_for_iw_links(page.text)
-
-    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"
+# Main function
+def main(*args):
+   global debug
+   search_cat = ''
+   search_page = ''
+
+   # Process arguments
+   local_args = pywikibot.handle_args(args)
+   for arg in local_args:
+      if arg.startswith('-cat:'):
+         search_cat = arg[5:]
+      elif arg.startswith('-page:'):
+         search_page = arg[6:]
+      elif arg == '-dbg':
+         debug = 1
+      else:
+         pywikibot.stdout('Unknown argument "{}". Exiting.'.format(arg))
+         return
+
+   #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)
+      for page in pagegenerators.PreloadingGenerator(generator, 100):
+         if debug: pywikibot.stdout('Checking page "{}"'.format(page.title()))
+         scan_for_interwiki_links(page.text, page.title())
+   elif search_page != '':
+      page = pywikibot.Page(site, search_page)
+      if debug: pywikibot.stdout('Checking page "{}"'.format(page.title()))
+      scan_for_interwiki_links(page.text, page.title())
 
-    pywikibot.stdout('{0} {1} encountered in validating these links.'.format(errors_issued, error_str))
+   # Print the results
+   print_summary()
 
 if __name__ == '__main__':
-    main()
+   main()