add userscript, WIP

userscript.js

@@ -0,0 +1,114 @@
+// ==UserScript==
+// @name     Twitter Archiver
+// @version  1
+// @grant    none
+// @namespace https://twitter.com
+// @include https://twitter.com/*
+// ==/UserScript==
+
+
+// TODO guard against invalid last tweets (photos?)
+// TODO "2 more replies" issue (maybe not a real issue?) auto-expand them somehow?
+// TODO only run it on pages with actual threads
+
+var intervals = {}
+
+function getLastXPath(xpexp) {
+  let iterator = document.evaluate(xpexp, document, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);
+  
+  var result = iterator.iterateNext();
+  var lastEl = result;
+
+  while(result != null) {
+    result = iterator.iterateNext();
+    
+    if (result == null) {
+      break;
+    }
+    lastEl = result;
+  }
+  return lastEl;
+}
+
+function getLastTweet() {
+  let author = window.location.pathname.split('/')[1];
+  let xp = `//a[contains(@href, '${author}/status')]`;
+  
+  return getLastXPath(xp).href;
+}
+
+function getTopTweet() {
+  let xp = "//span[text()='Thread']";
+  return getLastXPath(xp);
+}
+
+function appendButton() {
+  if (!window.location.pathname.includes("/status")) {
+    clearInterval(intervals["appendButton"])
+    return;
+  }
+  
+  var buttonEl = document.getElementById("twitblog");
+  
+  if (buttonEl) {
+    console.log(buttonEl);
+    clearInterval(intervals["appendButton"])
+    return;
+  }
+  
+  console.log("Trying to append the button");
+  let topTweet = getTopTweet();
+  
+  if (!topTweet) {
+    // TODO needs to work on all pages with "status" in it
+    return;
+  }
+  
+  let button = document.createElement("button");
+  button.textContent = "Save Tweet";
+  button.id = "twitblog";
+
+  button.addEventListener("click", ev => { alert(getLastTweet()); });
+  topTweet.appendChild(button);
+
+  buttonAdded = true;
+  clearInterval(intervals["appendButton"])
+}
+
+window.addEventListener('DOMContentLoaded', (event) => {
+  console.log('DOM fully loaded and parsed');
+  
+    /* https://stackoverflow.com/questions/6390341/how-to-detect-url-change-in-javascript */
+  history.pushState = ( f => function pushState() {
+      var ret = f.apply(this, arguments);
+      window.dispatchEvent(new Event('pushstate'));
+      window.dispatchEvent(new Event('locationchange'));
+      return ret;
+  })(history.pushState);
+
+  history.replaceState = ( f => function replaceState() {
+      var ret = f.apply(this, arguments);
+      window.dispatchEvent(new Event('replacestate'));
+      window.dispatchEvent(new Event('locationchange'));
+      return ret;
+  })(history.replaceState);
+
+  window.addEventListener('popstate',() => {
+      window.dispatchEvent(new Event('locationchange'))
+  });
+  
+  window.addEventListener('locationchange', function() {
+    console.log("Location changed");
+    if (window.location.pathname.includes("/status")) {
+      console.log('location changed!');
+    	buttonAdded = false;
+    	intervals["appendButton"] = window.setInterval(appendButton, 5*1000);
+    }
+    else {
+      console.log("Not going to try and add the button");
+      buttonAdded = true
+      clearInterval(intervals["appendButton"]);
+    }
+	})
+  window.setTimeout(appendButton, 5*1000);
+});