#!/usr/bin/ruby -w

# This is a Pavatar script written in ruby by Jeena Paradies
# I hereby place this script into the public domain.
#
# This is version 0.2 and it could include some bugs I haven't found yet.
# Because the program is licensed free of charge, there is no warranty
# for the program, but it works for me, try it if you want.
#
# If you have some questions contact me: pavatar@jeenaparadies.net

# To run it you need a server with Ruby support and have to call it
# via HTTP with the attribute url like:
# http://example.org/cgi-bin/pavatar.rb?url=http://jeenaparadies.net
# it will output the the Pavatar as a image or the default Pavatar
# defined here:

default_pavatar = "http://example.org/default-pavatar.png"

# If you want to use it in a HTML page use:
# 

# include some libraries to handle HTTP requests
require 'cgi'
require 'uri'
require 'net/http'

class Pavatar
    # content types defined by the spec http://pavatar.com/spec#technical-definition
    @@content_types = ['image/png', 'image/jpeg', 'image/gif']

    # get pavatar url at initialization
    def initialize url
        unless url =~ /^http:\/\//
            url = 'http://' + url
        end
        @url = url
        @purl = URI.parse(@url)

        # check for the first real pavatar url and save it into a class variable
        if (@pavatar = xHeader).nil? and (@pavatar = link).nil? and (@pavatar = path).nil?
            @pavatar = favicon
        end
    end

    # Autodiscovery methods

    # get url from header if there is one
    def xHeader
        begin
            res = FetchHelper.head(@url)
            res['X-Pavatar'] unless res['X-Pavatar'].nil?
        rescue
        end
    end

    # get url from  if there is one
    def link
        begin
            res = FetchHelper.get(@url)
            pavatar = //.match(res.body)
            pavatar[1] unless pavatar.nil?
        rescue
        end
    end

    # look in users path if there is a pavatar
    def path
        begin

            # to discover the given directory is a little bit tricky in ruby
            path = @purl.path.to_s
            unless path[-1..-1] == '/'
                path = File.dirname(path)
                unless path == '.' or path == '/'
                    path << '/'
                end
            end

            if path == '.'
                path = '/'
            end

            url = 'http://' + @purl.host.to_s + path + 'pavatar.png'

            # if would be ok to look at the header here but Apache has a problem with
            # head requests so we use a get request to workaround it
            res = FetchHelper.get(url)

            # some people redirect to a 404 page and send status 200 so we need to check the content type
            raise "Not supported content-type" if res['content-type'].nil? or not @@content_types.include?(res['content-type'])
            url
        rescue
        end
    end

    # look in users home directory if there is a pavatar
    def favicon
        begin
            url = 'http://' + @purl.host.to_s + '/pavatar.png'
            res = FetchHelper.get(url)
            raise "Not supported content-type" if res['content-type'].nil? or not @@content_types.include?(res['content-type'])
            url
        rescue
        end
    end

    # url getter
    def get_url
        @pavatar
    end

    # get a whole html string to show a pavatar
    def get_html (attr = '')
        attr = ' ' + attr unless attr.length > 0
        ''
    end

end


# helps us handle redirections
module FetchHelper

    def FetchHelper.head(url_str, limit = 10)

      # stop if there is a loop
      raise ArgumentError, 'HTTP redirect too deep' if limit == 0

      url = URI.parse(url_str)
      path = File.dirname(url.path.to_s)

      response = nil

      Net::HTTP.start(url.host, url.port) { |http|
        response = http.head(  path == '.' ? '/' : url.path.to_s )
      }

      case response
      when Net::HTTPSuccess     then response
      when Net::HTTPRedirection then FetchHelper.head(response['location'], limit - 1)
      else
        response.error!
      end
    end

    def FetchHelper.get(url_str, limit = 10)
      raise ArgumentError, 'HTTP redirect too deep' if limit == 0

      response = Net::HTTP.get_response(URI.parse(url_str))
      case response
      when Net::HTTPSuccess     then response
      when Net::HTTPRedirection then FetchHelper.get(response['location'], limit - 1)
      else
        response.error!
      end
    end

end

# cach the GET variable
cgi = CGI.new

begin
  pavatar_url = Pavatar.new(cgi['url'])
  pavatar = FetchHelper.get(pavatar_url.get_url)
rescue
  pavatar = FetchHelper.get(default_pavatar)
  print "Content-type: #{pavatar['content-type']}\r\n\r\n"
  print pavatar.body
  exit  
end

# print our HTML header
print "Content-type: #{pavatar['content-type']}\r\n\r\n"
print pavatar.body

# end of file