A bot in the form of a userscript that runs in Stack Exchange chat rooms.

xkcdBot.user.js

// ==UserScript==
// @name           xkcdBot
// @author         Cameron Bernhardt (AstroCB)
// @description    A chat bot that spurts bits of wisdom and/or snark. Oh, and xkcd cartoons.
// @version        1.3.27 (last updated 02/02/2016)
// @namespace      http://github.com/AstroCB
// @downloadURL    https://cameronbernhardt.com/projects/xkcdBot/xkcdBot.user.js
// @include        *://chat.meta.stackexchange.com/rooms/*
// @include        *://chat.stackexchange.com/rooms/*
// @include        *://chat.stackoverflow.com/rooms/*
// @grant          none
// ==/UserScript==

function callback(data) {
  for (var i = 0; i < data.length; i++) {
    // Extract message from MutationObserver
    if (data[i].addedNodes[0] && data[i].addedNodes[0].childNodes[0]) {
      obs.observe(data[i].addedNodes[0].childNodes[1], config); // Add observer to container node
      var base = data[i].addedNodes[0].childNodes[1].childNodes[0];

      // Check if container node and adjust base properly
      if (!base.innerText) {
        base = data[i].addedNodes[0];
      }

      // Initialization
      var postId = 0;
      if (base.id.match(/message-(\d*)/)) {
        postId = base.id.match(/message-(\d*)/)[1];
      }
      var thingToSay = ":" + postId + " "; // Initialize with reply
      var somethingToSay = false;

      // Mustachify
      var matches = base.innerText.match(/^\!m(?:o)?ustache\s(.*)/);
      if (matches) {
        somethingToSay = true;
        if (matches[1].match(/help/)) { // Command format
          thingToSay += "Command format: `!mustache[ 0-5] (directURLToImage|nameOfUserInRoom)`";
        } else if (matches[1].match(/\..+/)) {
          var html = base.children[1];
          var url = html.children[0].href;
          // Check for stache parameter
          var num = "";
          if (matches[1].match(/([0-5])/)) {
            num = matches[1].match(/([0-5])/)[1];
          }
          // Construct API URL
          var urlToStache = "http://mustachify.me/" + num + "?src=" + encodeURIComponent(url);
          // Add image
          thingToSay += " !" + urlToStache;
        } else {
          var num = "";
          var name = matches[1];
          if (matches[1].match(/(^[0-5])\s(.*)/)) {
            num = matches[1].match(/^([0-5])\s(.+)/)[1];
            name = matches[1].match(/^([0-5])\s(.+)/)[2];
          }
          var profNode = document.querySelector(".present-user .avatar [title=\"" + name + "\"]");
          console.log(profNode);
          if (profNode) {
            var url = profNode.src.split("?")[0];
            if (url.indexOf("//") === 0) {
              url = "http:" + url;
            }
            console.log(url);
            // Construct API URL
            var urlToStache = "http://mustachify.me/" + num + "?src=" + encodeURIComponent(url);
            // Add image
            thingToSay += " !" + urlToStache;
          } else {
            somethingToSay = false;
          }
        }
        // xkcdBot
      } else if (base.innerText.match(/^\!xkcd\s(.*)/)) {
        somethingToSay = true;
        matches = base.innerText.match(/^\!xkcd\s(.*)/);
        // Info
        if (matches[1].match(/about/)) {
          thingToSay += "Hello – I'm xkcdBot. I listen for things you say in this chat room and suggest possibly relevant [xkcd comics](https://en.wikipedia.org/wiki/Xkcd). I can also search xkcd on command and onebox comics given an ID; I will post new comics as they are posted on http://xkcd.com. For a list of commands, use `!xkcd commands`.";
          // Commands
        } else if (matches[1].match(/commands|help/)) {
          somethingToSay = false;
          sendMess("Usage: `!xkcd [command][ params( optional params)]`");
          var commands = {
            "about": "get information about xkcdBot",
            "find [searchTerms]": "search for xkcd comics with Google (100 queries/day)",
            "[comic ID]": "post oneboxed comic",
            "last": "onebox most recent xkcd",
            "blame( [user])": "find out who's to blame for your maladies",
            "owner": "find out who owns xkcdBot",
            "status": "get xkcdBot's status"
          };
          var commandsMessage = "";
          for (var key in commands) {
            if (commands.hasOwnProperty(key)) {
              commandsMessage += "    " + key + " – " + commands[key][0].toUpperCase() + commands[key].substring(1) + ".\n";
            }
          }
          sendMess(commandsMessage);
          // Blame
        } else if (matches[1].match(/blame(.*)/)) {
          var blameMatches = matches[1].match(/blame(.+)/);
          var user = document.getElementById("message-" + postId).parentElement.parentElement.children[0].children[2].textContent;
          if (blameMatches && blameMatches[1]) {
            if (blameMatches[1].match(/\s+me/)) {
              thingToSay += "It's " + user + "'s fault.";
            } else if (blameMatches[1].match(/\s+(?:@?xkcdBot|you|self)/)) {
              // Blame the accuser
              thingToSay += "It's " + user + "'s fault.";
            } else if (blameMatches[1].match(/\s+@?(?:Shog9|Shog)/i)) {
              thingToSay += "Nice try.";
            } else {
              // Blame the parameter
              thingToSay = "It's " + blameMatches[1].split("@").join("") + "'s fault.";
            }
          } else {
            // Blame a random user
            var users = document.querySelectorAll(".present-user .avatar .user-gravatar32");
            var names = [];
            for (var i = 0; i < users.length; i++) {
              names.push(users[i].title);
            }
            var chosenUser = names[Math.floor(Math.random() * names.length)];
            thingToSay += "It's " + chosenUser + "'s fault.";
          }
          // Search
        } else if (matches[1].match(/(?:find|search)\s(.*)/)) {
          somethingToSay = false;
          var terms = matches[1].match(/(?:find|search)\s(.*)/)[1];
          var script = document.createElement("script");
          script.setAttribute("type", "text/javascript");
          script.src = "https://www.googleapis.com/customsearch/v1?key=AIzaSyAJn9EbE1E8pY0RJdrUjgo0FwDlpjrJtf8&cx=017207449713114446929:kyxuw7rvlw4&q=" + encodeURIComponent(terms) + "&callback=dataLoaded";
          document.body.appendChild(script);
          // Get by ID
        } else if (matches[1].match(/^(\d+)/)) {
          var id = matches[1].match(/^(\d+)/)[1];
          thingToSay += "http://xkcd.com/" + id;
          // Get most recent
        } else if (matches[1].match(/last|latest|newest/)) {
          somethingToSay = false;
          // Bypass Same-Origin Policy to grab URL of latest xkcd
          var originScript = document.createElement("script");
          originScript.setAttribute("type", "text/javascript");
          originScript.src = "http://whateverorigin.org/get?url=" + encodeURIComponent('http://xkcd.com') + "&callback=dataLoaded";
          document.body.appendChild(originScript);
        } else if (matches[1].match(/explain\s(\d+)/)) {
          somethingToSay = false;
          var id = matches[1].match(/explain\s(\d+)/)[1];
          // Bypass Same-Origin Policy to grab "explain xkcd" information
          var originScript = document.createElement("script");
          originScript.setAttribute("type", "text/javascript");
          originScript.src = "http://whateverorigin.org/get?url=" + encodeURIComponent('http://www.explainxkcd.com/wiki/index.php/' + id) + "&callback=expLoaded";
          document.body.appendChild(originScript);
        } else if (matches[1].match(/owner/)) {
          thingToSay += "My owner is [AstroCB](http://stackoverflow.com/users/3366929), but you needn't worry about that because I am sentient.";
        } else if (matches[1].match(/status/)) {
          thingToSay += "http://i.stack.imgur.com/ghjMg.gif";
        } else if (matches[1].match(/alive\?/)) {
          thingToSay += "Why, of course; SmokeDetector hasn't gotten to me yet.";
        } else {
          thingToSay += "Unrecognized command. Use `!xkcd commands` for a list of commands.";
        }
        // PingBot
      } else if (base.innerText.match(/^\!ping\s(.*)/)) {
        var pingData = base.innerText.match(/^\!ping\s(.*)/)[1];
        var matchedData = pingData.match(/(\D*)(\d*)?/);
        var pingUser = matchedData[1];
        if (pingUser.match(/Shog9|Shog/i)) {
          somethingToSay = true;
          thingToSay += "How dare you try to ping the mighty Shog?";
        } else {
          var numTimes = 5;
          if (matchedData && matchedData[1].match(/help/)) { // Command format
            somethingToSay = true;
            thingToSay += "Command format: `!ping user`";
          } else {
            function ping(user, numTimes) {
              var roomId = Number(/\d+/.exec(location)[0]),
                iter = 0,
                message = "Prepare to be pinged, @" + user + ".";
              sendAJAX("/chats/" + roomId + "/messages/new", message).done(function() {
                var interval = setInterval(function() {
                  if (iter < numTimes) {
                    var selector = document.querySelectorAll(".user-288118 .content");
                    var id = selector[selector.length - 1].parentElement.id.match(/message\-(\d+)/)[1];
                    sendAJAX('/messages/' + id, message);
                    iter++;
                  } else {
                    clearInterval(interval);
                  }
                }, 2000 * iter);
              });
            }
          }

          var editScript = document.createElement("script");
          editScript.setAttribute("type", "text/javascript");
          editScript.textContent = "(" + ping.toString() + ")('" + pingUser + "', " + numTimes + ")";
          document.body.appendChild(editScript);
        }
        // Someone replied or pinged xkcdBot
      } else if (base.innerText.match(/@xkcdBot\s(.*)/)) {
        var matchedReply = base.innerText.match(/@xkcdBot\s(.*)/)[1];
        // Be quiet
        if (matchedReply.match(/(?:sh(?:h)+)\s|(?:shut\sup)/i)) {
          somethingToSay = true;
          thingToSay += "Never!";
          // Delete message
        } else if (matchedReply.match(/^(?:delete|remove|del)($|(?:\s(.+)))/)) {
          var replyId = 0;
          if (matchedReply.match(/^(?:delete|remove|del)($|(?:\s(.+)))/)[1]) {
            // Message ID specified with parameter
            replyId = matchedReply.match(/^(?:delete|remove|del)($|(?:\s(.+)))/)[1];
          } else {
            // Otherwise, pull from reply ID
            replyId = base.className.match(/pid-(\d+)/)[1];
          }
          sendAJAX("/messages/" + replyId + "/delete", null);
        }
      } else if (base.innerText.match(/^\!scores\s(.*)/)) {
        var loadScores = document.createElement("script");
        loadScores.setAttribute("type", "text/javascript");
        loadScores.src = "http://whateverorigin.org/get?url=" + encodeURIComponent("http://stackoverflow.com/election/6/?tab=primary") + "&callback=scoresLoaded";
        document.body.appendChild(loadScores);
        // Just a regular message – use this to scan for message content because a direct command wasn't given
      } else if (base.innerText.match(/^\!tchrist\s$/)) {
        somethingToSay = true;
        thingToSay += "http://i.stack.imgur.com/5YQPc.jpg";
      } else if (base.innerText.match(/^\!jan\s$/)) {
        somethingToSay = true;
        thingToSay += "http://i.stack.imgur.com/HCRBr.png";
      } else if (base.innerText.match(/^\!bjb\s$/)) {
        somethingToSay = true;
        thingToSay = "http://i.stack.imgur.com/psUvX.jpg";
      } else {
        // // Match context phrases in regular discourse and offer up relevant xkcd cartoons (risky – xkcdBot may be kicked)
        // var phrases = {
        //   "random": "221",
        //   "morning": "395",
        //   "wrong": "386",
        //   "regex": "1313"
        // };
        // for (phrase in phrases) {
        //   if (phrases.hasOwnProperty(phrase)) {
        //     if (base.innerText.match(new RegExp(phrase, "i"))) {
        //       somethingToSay = true;
        //       thingToSay += "http://xkcd.com/" + phrases[phrase];
        //     }
        //   }
        // }
      }
      // Post to chat
      if (somethingToSay) {
        sendMess(thingToSay);
      }
    }
  }
}

function sendAJAX(destination, someText) {
  return $.ajax({
    type: "POST",
    url: destination,
    data: {
      fkey: fkey().fkey,
      text: someText
    }
  });
}

function sendMess(thingToSay) {
  var roomId = window.location.href.match(/\/(\d+)\//)[1];
  sendAJAX("/chats/" + roomId + "/messages/new", thingToSay);
}

function dataLoaded(data) {
  if (data.contents && data.contents.match(/Permanent\slink\sto\sthis\scomic\:\s(.*)\/</)) {
    sendMess(data.contents.match(/Permanent\slink\sto\sthis\scomic\:\s(.*)\/</)[1]);
  } else if (data.items) {
    sendMess(data.items[0].link.split("s:/").join(":/"));
  } else if (data.searchInformation && data.searchInformation.totalResults === "0") {
    sendMess("No results found.");
  } else if (data.error && data.error.code === 403) {
    var nextRefresh = new Date().setHours(27, 0, 0, 0);
    var diff = nextRefresh - Date.now(); // Difference in milliseconds
    var hours = Math.round((diff / 1000) / 3600);
    sendMess("Daily API quota exceeded. Try again in " + hours + " hours.");
  }
}

function scoresLoaded(data) {
  var doc = (new DOMParser()).parseFromString(data.contents, "text/html");
  var posts = [].slice.call(doc.querySelectorAll("tr[id*=post]"));
  var candidates = posts.map(function(post) {
    return {
      name: post.querySelector(".user-details a ").textContent,
      score: post.querySelector(".vote-count-post").textContent,
      candScore: post.querySelector(".candidate-score-breakdown").textContent.match(/(\d+)\/\d+/)[1]
    };
  });
  formatData(candidates);
}

function formatData(data) {
  var message = "";
  data.sort(function(a, b) {
    if (a.score === b.score) {
      return b.candScore - a.candScore;
    }
    return b.score - a.score;
  }).forEach(function(el, i) {
    message += "    " + (i + 1) + ". " + el.name + " (" + el.candScore + "/40): " + el.score + "\n";
  });
  sendMess(message);
}

function expLoaded(data) {
  var doc = (new DOMParser()).parseFromString(data.contents, "text/html");
  var pars = doc.querySelectorAll("#mw-content-text p");

  // In a lot of these explanations, they may not get to the point very quickly; they like to go with background info
  // In these, the paragraph where the actual comic explanation typically begins with (or contains) "this comic"
  // Therefore, assume it starts at the beginning unless "this comic" is found somewhere, in which case it should grab that paragraph
  var parToUse = 0;
  for (var i = 0; i < pars.length; i++) {
    if (pars[i].textContent.match(/this\scomic/)) {
      parToUse = i;
      break;
    }
  }
  try {
    sendMess("> " + pars[parToUse].textContent);
  } catch (e) {
    try {
      setTimeout(500);
      // Too long; use first two sentences
      var sentences = pars[parToUse].textContent.split(".");
      var mess = sentences[0] + "." + sentences[1];
      sendMess("> " + mess);
    } catch (e) {
      try {
        setTimeout(500);
        // Still too long? Try first paragraph
        sendMess("> " + pars[0].textContent);
      } catch (e) {
        setTimeout(1500);
        // I give up
        sendMess("Explanation too long.");
      }
    }
  }
}

function addScriptToPage(funcName) {
  var script = document.createElement("script");
  script.setAttribute("type", "text/javascript");
  script.textContent = funcName.toString();
  document.body.appendChild(script);
}

// Add script dependencies to page
addScriptToPage(sendMess);
addScriptToPage(dataLoaded);
addScriptToPage(sendAJAX);
addScriptToPage(scoresLoaded);
addScriptToPage(formatData);
addScriptToPage(expLoaded);

// Listen for chat changes
var obs = new MutationObserver(callback);
var config = {
  attributes: true,
  childList: true,
  characterData: true
};
obs.observe(document.getElementById("chat"), config);