dijkstra-twitter.rb

#A little Twitter thing to post random quotes from Edsger Dijkstra

require 'yaml'
require 'open-uri'
require 'twitter'  #twitter4r gem
require 'hpricot'

class DijkstraQuote
    class << self

        #Match the website's naming scheme
        def random_ewd
            (rand(1289) + 30).to_s.rjust(4, "0")
        end

        #Get a random quote
        def get_quote
            quote = nil
            while quote.nil? do
                quote = fetch random_ewd
            end

            quote
        end

        #Get a random quote from the specified set of notes
        def fetch ewd

            #Check if we've already retrieved this set of notes
            if File.exists? "ewd#{ewd}"
                quotes = YAML.load_file "ewd#{ewd}"
                quotes[rand quotes.length]
            else
                $stderr.puts "Fetching EWD#{ewd}..." if $DEBUG

                #Fetch a transcript of Dijkstra's notes
                begin
                    file = open("http://www.cs.utexas.edu/~EWD/transcriptions/EWD#{ewd[0,2]}xx/EWD#{ewd}.html") { |f| Hpricot(f) }
                rescue OpenURI::HTTPError
                    $stderr.puts "Not found" if $DEBUG
                    return nil
                end

                text = file.to_plain_text

                #Pick some sentences that seem good
                lines = text.split(/\.(?:\s+|\n+)/).map do |l|
                    l.gsub(/\t|\n|\r/, " ").squeeze(" ").strip
                end.select do |l|
                    l.length > 40 and l.length < 140 and l[0,1] == l[0,1].upcase and l[-3, 3] != "viz"
                end

                #Cache them for later
                File.open "ewd#{ewd}", "w" do |f|
                    YAML.dump lines, f
                end

                #Return a random sentence
                lines[rand lines.length]
            end
        end

        #(Very crudely) tries to find a quote that is related to the message.
        #Note that this only searches the cache.
        def find_related message

            #Get the longer words
            words = message.gsub(/[^a-zA-Z ]/, "").split.select { |w| w.length > 4 }

            quote = nil
            if words.length > 0
                word = /#{Regexp.union(words)}/i

                #Check local files for the search word
                Dir.glob("ewd[0-9][0-9][0-9][0-9]").find do |f|
                    text = File.read f
                    if text =~ word

                        #Get the list of quotes and grab one
                        quotes = YAML.load_file f
                        matches = quotes.grep word
                        quote = matches[rand(matches.length)]
                    else
                        false
                    end
                end
            else
                quote = get_quote
            end

            quote
        end
    end
end

#Post to Twitter
class DijkstraTwitter

    def initialize
        @twitter = Twitter::Client.new :login => "?", :password => "?"
    end 

    #Post a random quote. If _ask_ is true, asks for approval first
    def post_random ask = false
        quote = DijkstraQuote.get_quote

        if ask and ask_permission("Would you like to post this: \"#{quote}\"") or not ask
            @twitter.status :post, quote
        end
    end

    #Check unanswered @ewd messages and come up with responses
    def post_replies ask = false
        require 'set'

        #Keep track of what has been replied to already
        if File.exist? "ewdreplies"
            replied = YAML.load_file "ewdreplies"
        else
            replied = Set.new
        end

        replies = @twitter.status(:replies)

        replies.each do |status|
            status_id = status.id.to_s
            next if replied.include? status_id
            message = status.text
            user = status.user.screen_name
            if reply_to message, user, ask
                replied << status_id
            end
        end

        File.open "ewdreplies", "w" do |f|
            YAML.dump replied, f
        end
    end

    #Send a reply if we can find one
    def reply_to message, sender, ask = false
        puts "Responding to \"#{message}\""

        quote = DijkstraQuote.find_related message
        if not quote
            puts "Nothing related. Skipping."
            return false
        elsif ask and ask_permission("Would you like to post this: \"#{quote}\"") or not ask
            response = "@#{sender} #{quote}"
            if response.length > 140
                response = response[0,140]
            end

            @twitter.status(:post, "@#{sender} #{quote}")
            true
        else
            ask and ask_permission "Ignore this reply?"          
        end
    end

    #Ask the user a question
    def ask_permission message
        puts message 

        response = nil
        until response =~ /^(y|n)/i
            print "(Y/N): "
            response = gets
        end

        $1.downcase == "y"
    end
end

#Try it out
puts DijkstraQuote.get_quote
#dt = DijkstraTwitter.new
##dt.post_random true
##dt.post_replies true