# Check Intrawiki Section Links
# by iritscen@yahoo.com
# Looks at each wikilink on a page (or in all the pages in a category) for a section link ('#'),
# and loads the linked page and verifies that the named section actually exists. It also
# understands section links generated through a call to Template:SectionLink.
# Recommended viewing width:
# |---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- --|

import os

from urllib.parse import urljoin

import pywikibot
import re

from pywikibot.bot import QuitKeyboardInterrupt
from pywikibot import pagegenerators
from pywikibot.tools.formatter import color_format
from pywikibot.comms.http import fetch
from pywikibot.specialbots import UploadRobot
from bs4 import BeautifulSoup

# Tuple of OniGalore's namespaces
intrawiki_prefixes = ('Image', 'Special', 'Talk', 'User', 'User_talk', 'OniGalore', 'OniGalore_talk', 'File', 'File_talk', 'MediaWiki', 'MediaWiki_talk', 'Template', 'Template_talk', 'Help', 'Help_talk', 'Category', 'Category_talk', 'BSL', 'BSL_talk', 'OBD', 'OBD_talk', 'AE', 'AE_talk', 'Oni2', 'Oni2_talk', 'XML', 'XML_talk')

# URL for main namespace of our wiki
onigalore_url = 'https://wiki.oni2.net/'

# Tuple of interwiki prefixes, for recognizing and passing over such links
interwiki_prefixes = ('acronym', 'cache', 'commons', 'dictionary', 'google', 'metawikimedia', 'mw', 'wikibooks', 'wikidata', 'wikimedia', 'wikinews', 'wikipedia', 'wikiquote', 'wikisource', 'wikispecies', 'wikiversity', 'wikivoyage', 'wikt', 'wiktionary', 'wp')

# List of chapter names, for substitution into links that use "{{Cn}}" transclusion
chapter_names = ['CHAPTER_00_._COMBAT_TRAINING', 'CHAPTER_01_._TRIAL_RUN', 'CHAPTER_02_._ENGINES_OF_EVIL', 'CHAPTER_03_._PUZZLE_PIECES', 'CHAPTER_04_._TIGER_BY_THE_TAIL', 'CHAPTER_05_._HOT_PURSUIT', 'CHAPTER_06_._COUNTERATTACK', 'CHAPTER_07_._A_FRIEND_IN_NEED', 'CHAPTER_08_._AN_INNOCENT_LIFE', 'CHAPTER_09_._TRUTH_AND_CONSEQUENCES', 'CHAPTER_10_._CAT_AND_MOUSE', 'CHAPTER_11_._DREAM_DIVER', 'CHAPTER_12_._SINS_OF_THE_FATHER', 'CHAPTER_13_._PHOENIX_RISING', 'CHAPTER_14_._DAWN_OF_THE_CHRYSALIS']

# Tuple of patterns for recognizing wikilinks
# Pattern 1: Detect "[[anything]]", "[[any:thing]]", "[[any|thing]]", "[[any:thi|ng]]"
# Pattern 2: Detect "{{SectionLink|Page|Section name}}", "{{SectionLink||Section name}}"
link_patterns = ("\[\[[^|\]]*(\||\])", "\{\{SectionLink\|[^|\}]*\|[^|\}]*\}\}")

# Initialize globals
debug = 0
pages_checked = 0
iw_found = 0
advice_issued = 0
errors_issued = 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(page_text, page_name, page_slug, print_result):
   global errors_issued

   # Isolate section link
   target_page_name, anchor_name = page_slug.split('#', 1)
   target_page_name_human = target_page_name.replace('_', ' ')
   if debug: pywikibot.stdout('         Searching for section link {} on page.'.format(anchor_name))

   # Read linked page to see if it really has this anchor link
   soup = BeautifulSoup(page_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:
         if debug and not print_result: pywikibot.stdout('         Found section in a span!')
         found_section = True
         break
   if found_section == False:
      # Search for a div with this ID
      for span_tag in soup.findAll('div'):
         span_name = span_tag.get('id', None)
         if span_name == anchor_name:
            if debug and not print_result: pywikibot.stdout('         Found section in a div!')
            found_section = True
            break
   if found_section == False:
      possibly_print(page_name)
      pywikibot.stdout('   ERROR: Could not find section "{0}" on page {1}!'.format(anchor_name, target_page_name_human))
      errors_issued += 1
   elif debug and print_result:
      pywikibot.stdout('   The section "{0}" was found on page "{1}".'.format(anchor_name, 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(page_text, page_name, page_slug):
   # Extract link from this markup which contains name of redirected-to page:
   # <link rel="canonical" href="https://en.wikipedia.org/wiki/Page_name"/>
   # "wgPageName":"Namespace:Page_name",
   canonical_name = page_text.split('"wgPageName":"')[-1]
   tag_end = canonical_name.find('",')
   
   if tag_end == -1:
      pywikibot.stdout('   ERROR: The link "{}" is a redirect page, but this script could not isolate the target page name.'.format(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 link "{}" is a redirect to "{2}…" (string overflow).'.format(page_slug, canonical_name[:100]))
         errors_issued = errors_issued + 1
      else:
         canonical_name = canonical_name.replace('_', ' ')
         if '#' in page_slug:
            _, anchor_name = page_slug.split('#')
            if debug: pywikibot.stdout('   The link "{0}" is a redirect to "{1}#{2}", which is a valid page. Checking section link….'.format(page_slug, canonical_name, anchor_name))
            find_section(page_text, page_name, page_slug, True)
         else:
            pywikibot.stdout('   The link "{0}" is a redirect to "{1}", which is a valid page.'.format(page_slug, canonical_name))

# Test an intrawiki link and look for a section link if applicable
def test_intrawiki_link(iw_url, page_name, page_slug):
   global advice_issued
   global errors_issued
   
   response = fetch(iw_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 response.history != []:
      
      permalink1 = 'Special:PermanentLink/'.lower()
      permalink2 = 'Special:Permalink/'.lower()
      page_slug_lower = page_slug.lower()
      if page_slug_lower.startswith(permalink1) or page_slug_lower.startswith(permalink2):
         if debug:
            possibly_print(page_name)
            pywikibot.stdout('   Got redirection code "{0}" for permanent revision link "{1}". Checking the target page….'.format(response.history[0], page_slug))
         find_canonical_link(response.text, page_name, page_slug)
      else:
         possibly_print(page_name)
         pywikibot.stdout('   ERROR: Unrecognized type of redirection (code "{0}") for link "{1}". You should check the link manually.'.format(response.history[0], page_slug))
         advice_issued += 1
   elif response.status_code != 200:
      possibly_print(page_name)
      pywikibot.stdout('   ERROR: Got response code {0} on URL {1}. The target page may not exist.'.format(response.status_code, iw_url))
      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 response.text:
      if debug:
         possibly_print(page_name)
         pywikibot.stdout('   Got silently redirected by link "{}". Checking the target page….'.format(page_slug))
      find_canonical_link(response.text, page_name, page_slug)
   else: # URL is OK, so proceed
      find_section(response.text, page_name, page_slug, False)

# Searches the given page text for intrawiki links with section links in them
def scan_for_intrawiki_links(page_text, page_name):
   global debug
   global pages_checked
   global iw_found
   global advice_issued
   global errors_issued
   global name_printed
   pages_checked += 1
   name_printed = 0

   for i, the_pattern in enumerate(link_patterns):
      if debug:
         if i == 0:
            pywikibot.stdout('   Checking page for wikilinks with section names.')
         elif i == 1:
            pywikibot.stdout('   Checking page for {{SectionLink}} calls.')
      
      for match in re.finditer(the_pattern, page_text):
         found_iw_match = False
         iw_url = ""
         page_name2 = page_name
   
         # Cut out the matched text from the page, isolating just the page+section name
         target_start = 2 # "[["
         target_end = 1 # "|" or "]" (we only match the first ending bracket)
         if i == 1:
            target_start = 14 # "{{SectionLink|"
            target_end = 2 # "}}"
         s = match.start() + target_start # remove the link-opening markup
         e = match.end() - target_end # remove the link-ending markup
         page_slug = page_text[s:e]
         
         # The second link type will look like "Page|Section" or "|Section", so fix that pipe
         if i == 1:
            page_slug = page_slug.replace('|', '#')

         # Sometimes we use a space char. instead of a '_', so fix that before querying
         page_slug = page_slug.replace(' ', '_')
         if debug: pywikibot.stdout('      Found link {0}.'.format(page_slug))
      
         # If this link doesn't have a section link in it, then we don't care about it, as
         # MediaWiki takes care of checking basic intrawiki links
         if not '#' in page_slug:
            if debug: pywikibot.stdout('         Link doesn\'t have a section anchor in it. Skipping.')
            continue

         # If this link has an interwiki prefix, it can be ignored; see check_interwiki_links.py
         # for the task of checking interwiki page+section links
         is_interwiki = False
         if found_iw_match == False:
            for prefix in interwiki_prefixes:
               if prefix + ":" in page_slug:
                  if debug: pywikibot.stdout('         Skipping link {} because it is an interwiki link.'.format(page_slug))
                  is_interwiki = True
                  break
         if is_interwiki:
            continue
      
         # If there is a '{' in the link, then probably it's a link built on transcluded text.
         # If it's a chapter template transclusion like "Quotes/Diary#{{C3}}", expand it using
         # our "chapter_names" array. If it's another type of transclusion, punt it to the user.
         if '{' in page_slug:
            ch_link_pattern = re.compile(r"{{C[0-9]*}}")
            ch_link = ch_link_pattern.search(page_slug)
            if debug: pywikibot.stdout('         Found transclusion in link: "{}".'.format(ch_link.group(0)))
            if ch_link:
               ch_link_match = ch_link.group(0)
               ch_num_pattern = re.compile("[0-9]+")
               ch_num = ch_num_pattern.search(ch_link_match)
               if ch_num:
                  ch_num_match = int(ch_num.group(0))
                  if ch_num_match >= 0 and ch_num_match <= 14:
                     ch_name = chapter_names[ch_num_match]
                     replace_pattern = re.compile(r"{{C" + ch_num.group(0) + r"}}")
                     page_slug = replace_pattern.sub(ch_name, page_slug)
                     if debug: pywikibot.stdout('         After performing transclusion, link is now "{}".'.format(page_slug))
                  else:
                     possibly_print(page_name)
                     pywikibot.stdout('   ERROR: Link {0} transcludes a chapter name using an out-of-range number, {1}.'.format(page_slug, ch_num_match))
                     errors_issued += 1
                     continue
               else:
                  possibly_print(page_name)
                  pywikibot.stdout('   ADVICE: Link {} seems to be transcluding a chapter name, but this script couldn\'t read it.'.format(page_slug))
                  advice_issued += 1
                  continue
            else:
               possibly_print(page_name)
               pywikibot.stdout('   ADVICE: Link {0} seems to use transclusion. This script can understand chapter name transclusions such as "{1}" but it doesn\'t recognize this one so it can\'t be verified. You should check the link manually.'.format(page_slug, "{{C7}}"))
               advice_issued += 1
               continue

         # If this is a relative "/" link, use the current page as the basis for the URL. Note
         # that only a leading slash is looked for, so if there's multiple steps down ("/x/y"),
         # we're out of luck.
         if page_slug.startswith('/'):
            page_slug = page_name + page_slug
            if debug: pywikibot.stdout('         Changed page_slug to {} on account of "/".'.format(page_slug))
      
         # If this is a relative "../" link, find the parent page, set ourselves to that page,
         # then remove the relative portion of the link. Note that this is only performed once,
         # so if there's multiple steps back ("../../"), we're out of luck.
         if page_slug.startswith('../'):
            last_slash = page_name.rfind('/')
            page_name2 = page_name[0:last_slash]
            if debug: pywikibot.stdout('         Changed page_name to {} on account of "../".'.format(page_name2))
            page_slug = page_slug[3:len(page_slug)]
            if debug: pywikibot.stdout('         Changed page_slug to {} on account of "../".'.format(page_slug))
            # If this is now going to be a bare section link for the parent page, don't add a
            # slash, otherwise do because we are drilling down to another subpage
            if page_slug.startswith('#'):
               page_slug = page_name2 + page_slug
            else:
               page_slug = page_name2 + '/' + page_slug
         
         # If this is a bare section link, build URL based on this page
         if page_slug.startswith('#'):
            iw_url = onigalore_url + page_name2
            iw_found += 1
            if debug: pywikibot.stdout('         Found link to this very page, {}.'.format(page_slug))
            found_iw_match = True
            page_slug = page_name2 + page_slug
      
         # If there's no ":" in the link (before the section link, where a colon would just be
         # part of the text) then it's a Main namespace article; proceed with building URL
         if found_iw_match == False:
            if not re.search(":.*#", page_slug):
               iw_url = onigalore_url + page_slug
               iw_found += 1
               if debug: pywikibot.stdout('         Link is to a Main namespace page.')
               found_iw_match = True
         
         # If there is a ":", match the prefix against the intrawiki prefixes on OniGalore
         # before building URL
         if found_iw_match == False:
            for prefix in intrawiki_prefixes:
               if prefix + ":" in page_slug:
                  iw_url = onigalore_url + page_slug
                  if debug: pywikibot.stdout('         Identified namespace {}.'.format(prefix))
                  iw_found += 1
                  found_iw_match = True
                  break
      
         # If we still haven't turned this match into a URL, something's gone wrong
         if (found_iw_match == False) or (iw_url == ""):
            possibly_print(page_name)
            pywikibot.stdout('   ERROR: Couldn\'t figure out link {}.'.format(page_slug))
            continue

         # Test the URL
         iw_url = iw_url.replace(' ', '_')
         if debug: pywikibot.stdout('         Reading page at {}….'.format(iw_url))
         test_intrawiki_link(iw_url, page_name, page_slug)

# Print a wrap-up message
def print_summary():
   global pages_checked
   global iw_found
   global advice_issued
   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} intrawiki {3}.'.format(pages_checked, page_str, iw_found, link_str))
   pywikibot.stdout('While attempting to follow section links….')

   if advice_issued == 0:
      pywikibot.stdout('   No advice on potential problems was issued.')
   elif advice_issued == 1:
      pywikibot.stdout('   1 piece of advice on a potential problem was issued.')
   else:
      pywikibot.stdout('   {} pieces of advice on potential problems were issued.'.format(advice_issued))

   error_str = "errors were"
   if errors_issued == 1:
      error_str = "error was"
   pywikibot.stdout('   {0} {1} encountered.'.format(errors_issued, error_str))

# 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 "{}".'.format(arg))
         return

   site = pywikibot.Site()

   # This line of code enumerates the methods in the 'page' class
   #pywikibot.stdout(format(dir(page)))

   # Check specified page or loop through specified category and check all pages
   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 {0}'.format(page.title()))
         scan_for_intrawiki_links(page.text, page.title())
   elif search_page != '':
      page = pywikibot.Page(site, search_page)
      if debug: pywikibot.stdout('Checking page {0}'.format(page.title()))
      scan_for_intrawiki_links(page.text, page.title())

   # Print the results
   print_summary()

if __name__ == '__main__':
   main()