WIP post diffs

install/package.json

@@ -39,6 +39,7 @@
         "cropperjs": "^1.2.2",
         "csurf": "^1.9.0",
         "daemon": "^1.1.0",
+        "diff": "^3.4.0",
         "express": "^4.16.2",
         "express-session": "^1.15.6",
         "express-useragent": "1.0.8",

src/posts.js

@@ -25,6 +25,7 @@ require('./posts/tools')(Posts);
 require('./posts/votes')(Posts);
 require('./posts/bookmarks')(Posts);
 require('./posts/queue')(Posts);
+require('./posts/diffs')(Posts);
 
 Posts.exists = function (pid, callback) {
 	db.isSortedSetMember('posts:pid', pid, callback);

src/posts/diffs.js

@@ -0,0 +1,51 @@
+'use strict';
+
+var async = require('async');
+
+var db = require('../database');
+var diff = require('diff');
+
+module.exports = function (Posts) {
+	Posts.diffs = {};
+
+	Posts.diffs.list = function (pid, callback) {
+		db.getSortedSetRangeWithScores('post:' + pid + ':diffs', 0, -1, function (err, diffs) {
+			callback(err, diffs ? diffs.map(function (diffObj) {
+				return diffObj.score;
+			}) : null);
+		});
+	};
+
+	Posts.diffs.save = function (pid, oldContent, newContent, callback) {
+		db.sortedSetAdd('post:' + pid + ':diffs', Date.now(), diff.createPatch('', newContent, oldContent), callback);
+	};
+
+	Posts.diffs.load = function (pid, since, callback) {
+		// Retrieves all diffs made since `since` and replays them to reconstruct what the post looked like at `since`
+		since = parseInt(since, 10);
+
+		if (isNaN(since) || since > Date.now()) {
+			return callback(new Error('[[error:invalid-data]]'));
+		}
+
+		async.parallel({
+			post: async.apply(Posts.getPostData, pid),
+			diffs: async.apply(db.getSortedSetRangeByScore.bind(db), 'post:' + pid + ':diffs', 0, -1, since, Date.now()),
+		}, function (err, data) {
+			if (err) {
+				return callback(err);
+			}
+
+			// Replace content with re-constructed content from that point in time
+			data.post.content = data.diffs.reverse().reduce(function (content, diffString) {
+				return diff.applyPatch(content, diffString);
+			}, data.post.content);
+
+			// Clear editor data (as it is outdated for this content)
+			delete data.post.edited;
+			data.post.editor = null;
+
+			return callback(null, data.post);
+		});
+	};
+};

src/posts/edit.js

@@ -20,6 +20,7 @@ module.exports = function (Posts) {
 	});
 
 	Posts.edit = function (data, callback) {
+		var oldContent;	// for diffing purposes
 		var postData;
 		var results;
 
@@ -39,6 +40,7 @@ module.exports = function (Posts) {
 				}
 
 				postData = _postData;
+				oldContent = postData.content;
 				postData.content = data.content;
 				postData.edited = Date.now();
 				postData.editor = data.uid;
@@ -63,6 +65,9 @@ module.exports = function (Posts) {
 				results = _results;
 				Posts.setPostFields(data.pid, postData, next);
 			},
+			function (next) {
+				Posts.diffs.save(data.pid, oldContent, data.content, next);
+			},
 			function (next) {
 				postData.cid = results.topic.cid;
 				postData.topic = results.topic;

src/socket.io/posts.js

@@ -20,6 +20,7 @@ require('./posts/move')(SocketPosts);
 require('./posts/votes')(SocketPosts);
 require('./posts/bookmarks')(SocketPosts);
 require('./posts/tools')(SocketPosts);
+require('./posts/diffs')(SocketPosts);
 
 SocketPosts.reply = function (socket, data, callback) {
 	if (!data || !data.tid || (parseInt(meta.config.minimumPostLength, 10) !== 0 && !data.content)) {

src/socket.io/posts/diffs.js

@@ -0,0 +1,13 @@
+'use strict';
+
+var posts = require('../../posts');
+
+module.exports = function (SocketPosts) {
+	SocketPosts.getDiffs = function (socket, data, callback) {
+		posts.diffs.list(data.pid, callback);
+	};
+
+	SocketPosts.showPostAt = function (socket, data, callback) {
+		posts.diffs.load(data.pid, data.since, callback);
+	};
+};