#!/usr/bin/env python
# -*- coding: utf-8  -*-
"""
Provides a count of the number of backlinks to a page.

Parameters:
  db          - The name of the database.
                Examples: frwiki for the French Wikipedia, 
                          jawiktionary for Japanese Wiktionary
                Default: enwiki
  callback    - If specified, wraps the output into a given function call and changes Content-Type to application/json for script use.
  filterredir - How to filter for redirects
                One value: all, redirects, nonredirects
                Default: all
  ns          - The assumed namespace of the page
                Default: 0
  title       - Title to search.

Examples:
  http://toolserver.org/~dispenser/cgi-bin/backlinkscount.py?title=User:Jimbo%20Wales
  http://toolserver.org/~dispenser/cgi-bin/backlinkscount.py?title=Jimbo_Wales&ns=2&callback=bragging_rights&filterredir=nonredirects&db=enwiki

Notes:
* The "What links here" page combines the results of both backlinks and embeddedin (transclusions).
* For transclusions count use embeddedincount.py tool.
* This tool does not support namespace localization, use English namespaces or the ns parameter instead.
* Source code is at http://toolserver.org/~dispenser/sources/backlinkscount.py
"""
# I, Dispenser, hereby release this program into the public domain
# November 2009
import oursql, cgi, os
import cgitb; cgitb.enable(logdir='tracebacks')

namespaces = {                       
	'Media':			-2,
	'Special':			-1,
	'':					0,
	'Talk':				1,
	'User':				2,
	'User_talk':		3,
	'Wikipedia':		4,
	'Wikipedia_talk':	5,
	'Image':			6,
	'Image_talk':		7,
	'Mediawiki':		8, # name fudged
	'Mediawiki_talk':	9, # name fudged
	'Template':			10,
	'Template_talk':	11,
	'Help':				12,
	'Help_talk':		13,
	'Category':			14,
	'Category_talk':	15,
}
def main():
	form = cgi.FieldStorage(keep_blank_values=1)
	dbName   = form.getfirst('db', form.getfirst('dbname','enwiki'))
	ns       = form.getfirst('ns', '0')
	title    = form.getfirst('title', '').replace(' ', '_')
	callback = form.getfirst('callback')

	if title == '':
		print "Content-Type: text/plain"
		print __doc__
		return

	if not os.getenv("HTTP_USER_AGENT"):
		print 'Status: 419 No user agent'
		print 'Content-Type: text/plain; charset=utf-8'
		print
		print 'No user agent'
		print 'https://meta.wikimedia.org/wiki/User-Agent_policy'
		return

	if ':' in title:
		name, t = title.split(':', 1)
		ns = namespaces.get(name.capitalize().strip('_:'), ns)
		if ns != 0: title = t

	# Toolserver views hack
	if not dbName.endswith('_p'):
		dbName += '_p'

	conn = oursql.connect(db=dbName, host=dbName.replace('_', '-') + '.rrdb.toolserver.org', read_default_file="/home/dispenser/.my.cnf", charset=None, use_unicode=False)
	cursor = conn.cursor()
	# The redirect pages themselves aren't included if you combine these queries
	count = 0
	# FIXME reports links from non-existant pages
	if form.getfirst('filterredir') != 'nonredirects':
		cursor.execute("/* backlinkscount LIMIT:60 NM */SELECT COUNT(*) FROM pagelinks WHERE pl_namespace=? AND pl_title=?", (ns, title))
		count += cursor.fetchall()[0][0]
	if form.getfirst('filterredir') != 'redirects':
		cursor.execute("""
/* backlinkscount LIMIT:60 NM */
SELECT COUNT(*)
FROM redirect
JOIN page      ON rd_from=page_id
JOIN pagelinks ON pl_namespace=page_namespace AND pl_title=page_title
WHERE rd_namespace=? AND rd_title=?
""", (ns, title))
		count += cursor.fetchall()[0][0]
	conn.close()

	if callback is not None: # getfirst treats &callback=& as None anyway
		callback = ''.join(c for c in callback if (c.isalnum() or c=='.' or c=='_'))
		print 'Content-Type: text/javascript; charset=utf-8'
		print
		print '%s(%d)'%(callback, count)
	else:
		print 'Content-Type: text/plain; charset=utf-8'
		print
		print count
if __name__ == "__main__":
	try:
		import os, time; StartTime=time.time()
		main()
	except oursql.Error as (errno, strerror, extra):
		# FIXME this should be machine readable
		print 'Status: 500 SQL error'
		print 'Content-Type: text/plain; charset=utf-8'
		print
		print (errno, strerror)
	#else:
	#	with open('./generation_stats/backlinkscount', 'a') as f:
	#		f.write('\t'.join((
	#			time.strftime("%Y-%m-%d %H:%M:%S"),
	#			"%6f"%(time.time()-StartTime),
	#			os.getenv("HTTP_X_FORWARDED_FOR", ''),
	#			os.getenv("HTTP_USER_AGENT", ''),
	#			os.getenv("QUERY_STRING", ''),
	#		))+'\n')