Add a GenericSearch plugin to search sites like Google and Wikipedia

This mimicks behavior of several of our eggdrop plugins.

plugins/generic_search.rb

@@ -0,0 +1,66 @@
+require 'cgi'
+require 'net/http'
+
+#
+# Search sites like Google and Wikipedia
+#
+# You configure the command name and URL pattern.  Given a search
+# term, it attempts to respond with the URL of the first search
+# result.  It does so by simply inserting the term into the URL at the
+# '%s'.  If the url redirects, it responds with the redirect target
+# instead, so you get a hint about what you'll see.  Otherwise, you
+# get just the expanded url pattern.
+#
+# This is useful for a wide range of sites.  Sample config:
+#
+# generic_search_commands:
+#   wikipedia: "http://en.wikipedia.org/wiki/Special:Search?search=%s&go=Go"
+#   google: "http://www.google.com/search?hl=en&q=%s&btnI=I'm+Feeling+Lucky&aq=f&oq="
+#   php: "http://us3.php.net/manual-lookup.php?pattern=%s&lang=en"
+#   letmegooglethatforyou: "http://letmegooglethatforyou.com/?q=%s"
+#
+# Note that the last site never redirects, which is fine.
+#
+class GenericSearch < CampfireBot::Plugin
+  attr_reader :commands
+
+  def initialize
+    @commands = bot.config["generic_search_commands"] || {}
+    commands.each { |c, s|
+      method = "do_#{c}_command".to_sym
+      self.class.send(:define_method, method) {|msg|
+        msg.speak(http_peek(sprintf(s, CGI.escape(msg[:message]))))
+      }
+      self.class.on_command(c, method)
+    }
+  end
+
+  protected
+
+  # Follow the url just enough to see if it redirects.  If so,
+  # return the redirect.  Otherwise, return the original.
+  def http_peek(url)
+    uri = URI.parse url
+    http = Net::HTTP.new(uri.host, uri.port)
+
+    # Unfortunately the net/http(s) API can't seem to do this for us,
+    # even if we require net/https from the beginning (ruby 1.8)
+    if uri.scheme == "https"
+      require 'net/https'
+      http.use_ssl = true
+      http.verify_mode = OpenSSL::SSL::VERIFY_NONE
+    end
+
+    res = http.start { |http|
+      req = Net::HTTP::Get.new uri.request_uri
+      #req.basic_auth u, p
+      response = http.request req
+    }
+    case res
+    when Net::HTTPRedirection
+      uri.merge res.header['Location']
+    else # Net::HTTPSuccess or error
+      url
+    end
+  end
+end