#!/usr/bin/env python
"""
An Encoding Normaliser.
License: GPL 2; share and enjoy!
Author: Sean B. Palmer, inamidst.com

Service: http://inamidst.com/encnorm
Source: http://inamidst.com/inside/encnorm

<sbp> heh, heh. that reminds me that I want to implement a utf-8/general 
charset munging CGI, and I don't know why...
<deltab> sbp: as a temporary fix for sites that have the wrong setting?
<sbp> deltab: yes, and for when people use utf-8 in IRC and you wonder 
wearily whilst wandering what they're saying, or for when a program 
outputs something in a character encoding and you don't want to mess 
about with guessing and iconv

@@ http://swtch.com/usr/local/plan9/src/cmd/dict/oed.c
"""

import cgitb; cgitb.enable()
import sys, os, re, cgi, urllib, codecs

method = os.environ.get('REQUEST_METHOD')

form = cgi.FieldStorage()
form.__call__ = lambda s: form[s].value

# sys.stdout = codecs.getwriter('utf-8')(sys.stdout)

# print "Content-Type: text/plain; charset=utf-8"
# print 

def serve(status, body, mime=None, charset=None): 
   mime = mime or 'text/html'
   charset = charset or 'utf-8'
   sys.stdout.write("Status: %s\r\n" % status)
   sys.stdout.write("Content-Type: %s; charset=%s\r\n\r\n" % (mime, charset))
   sys.stdout.write(body)
   sys.exit()

def convert(text, here, there): 
   if (there == 'pyraw'): 
      if (here != '-'): 
         raise Exception, "Can only convert - to pyraw."
      text = ('%r' % str(text))[1:-1]
      return cgi.escape(text) # @@ escape?

   if (here == 'u-cp1252') and (there == 'utf-8'): 
      text = text.decode('utf-8')
      here, there = 'unicode', 'cp1252'

   if (here == 'unicode') and (there == 'cp1252'): 
   # http://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WINDOWS/CP1252.TXT
      map = {0x20AC: 0x80, 0x201A: 0x82, 0x0192: 0x83, 
             0x201E: 0x84, 0x2026: 0x85, 0x2020: 0x86, 
             0x2021: 0x87, 0x02C6: 0x88, 0x2030: 0x89, 
             0x0160: 0x8A, 0x2039: 0x8B, 0x0152: 0x8C,  
             0x017D: 0x8E, 0x2018: 0x91, 0x2019: 0x92, 
             0x201C: 0x93, 0x201D: 0x94, 0x2022: 0x95, 
             0x2013: 0x96, 0x2014: 0x97, 0x02DC: 0x98, 
             0x2122: 0x99, 0x0161: 0x9A, 0x203A: 0x9B, 
             0x0153: 0x9C, 0x017E: 0x9E, 0x0178: 0x9F}
      error = (0x81, 0x8D, 0x8F, 0x90, 0x9D)
      result = ''
      for char in text: 
         char = ord(char)
         if map.has_key(char): 
            result += chr(map[char])
         elif char in error: 
            result += chr(char)
         #    raise Exception, "Can't convert byte %r to cp1252." % char
         elif char <= 0xFF: 
            result += chr(char)
         else: raise Exception, "Can't encode character %r to cp1252." % char
      return result
   elif (here == 'html-bytes') and (there == 'utf-8'): 
      # <div>utf-8: &#195;&#169;</div>
      # <div>iso-8859-1: &#233;</div>
      # <div>utf-8 and iso-8859-1: &#195;&#169; &#233;</div>

      r_hbyte = re.compile(r'&#(\d+);')
      text = r_hbyte.sub(lambda m: chr(int(m.group(1))), str(text))

      result = []
      for nugget in text.split(' '): 
         try: result.append(unicode(nugget, 'utf-8'))
         except: 
            try: result.append(unicode(nugget, 'iso-8859-1'))
            except: result.append(unicode(nugget))
      return ' '.join([n.encode('utf-8') for n in result])

   elif (here == 'double-utf-8') and (there == 'utf-8'): 
      result = []
      for chunk in text.split(' '): 
         # print `chunk`
         try: 
            chunk = chunk.decode('utf-8').encode('iso-8859-1')
            test = unicode(chunk, 'utf-8')
            # print 'WHOO'
            result.append(chunk)
         except Exception, e: 
            # print 'BOO', e
            result.append(chunk)
      return ' '.join(result)
   elif (here == 'utf-8') and (there == 'punycode'): 
      return unicode(text, 'utf-8').encode('punycode')
   elif (here == 'utf-8') and (there == 'html-entities'): 
      result = []
      for character in unicode(text, 'utf-8'): 
         if ord(character) > 0x80: 
            result.append('&#x%04X;' % ord(character))
         else: result.append(character)
      result = ''.join(result)
      return result + '<br /><br />' + cgi.escape(result)
   else: 
      try: return unicode(text, here).encode(there)
      except: raise Exception, "Can't process from %s to %s." % (here, there)

def post(): 
   # @@ from charset, to charset
   # @@ header munging--remove html:meta if it sets the wrong charset, etc.
   if form.has_key('uri'): 
      uri = form('uri')
      u = urllib.urlopen(uri)
      body = u.read()
      mime = u.info().get('Content-Type', 'text/html').split(';')[0]
      u.close()
      lines = body.splitlines()

      here, there = form('from'), form('to')
      result = []
      for line in lines: 
         result.append(convert(line, here, there))

      serve(200, '\n'.join(result), mime=mime)
   elif form.has_key('text'): 
      text = form('text')
      lines = text.splitlines()

      here, there = form('from'), form('to')
      result = [('<p>Converted <strong>%s</strong> to ' + 
                 '<strong>%s</strong>: </p>') % (here, there)]
      for line in lines: 
         result.append('<div>' + convert(line, here, there) + '</div>')

      serve(200, '\n'.join(result))
   else: serve(500, "<p>Form requires either a uri or text value.</p>\n")

def homepage(): 
   if form.has_key('from'): 
      here = '<input type="hidden" name="from" value="%s" />' % form('from')
   else: here = """From: 
   <select name="from">
      <option>-</option>
      <option>utf-8</option>
      <option>u-cp1252</option>
      <option>html-bytes</option>
      <option>double-utf-8</option>
   </select>
   """

   if form.has_key('to'): 
     there = '<input type="hidden" name="to" value="%s" />' % form('to')
   else: there = """To: 
   <select name="to">
      <option>pyraw</option>
      <option>utf-8</option>
      <option>punycode</option>
      <option>html-entities</option>
   </select>
   """

   serve(200, """
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Fix Encoding - A Character Encodings Normaliser</title>
<link rel="stylesheet" type="text/css" href="/trove/simple.css" />
</head>
<body>
<div class="nav">
<a href="/"><img src="/trove/logo" alt="inamidst.com" /></a>
</div>
<h1>Encoding Normaliser</h1>

<form action="" method="GET">
<div>Text: <textarea name="text" rows="15" cols="79"></textarea></div>
<div>%s %s</div>
<div><input type="submit" /></div>
</form>

<form action="" method="GET">
URI: <input type="text" name="uri" size="25" />
<div>%s %s</div>
<div><input type="submit" /></div>
</form>

<p>The <a href="/inside/encnorm/">source</a> is the best place to get an idea
of this service's features at the moment.</p>

<address>
<a href="http://inamidst.com/sbp/">Sean B. Palmer</a>
</address>
</body>
</html>
""" % (here, there, here, there))

def main(): 
   if form.has_key('uri') or form.has_key('text'): post()
   elif method == 'GET': homepage()
   elif method == 'POST': post()
   else: serve(501, "<p>Method must be either GET or POST</p>\n")

if __name__=="__main__": 
   main()