calculate topic post indices instead of querying db

src/controllers/topics.js

@@ -116,15 +116,13 @@ topicsController.get = function(req, res, next) {
 				}
 
 				topicData.pageCount = pageCount;
-
 				topicData.currentPage = page;
+
 				if (page > 1) {
 					topicData.posts.splice(0, 1);
 				}
 
-				plugins.fireHook('filter:controllers.topic.get', topicData, function(err, topicData) {
-					next(null, topicData);
-				});
+				plugins.fireHook('filter:controllers.topic.get', topicData, next);
 			});
 		},
 		function (topicData, next) {

src/topics.js

@@ -215,25 +215,11 @@ var async = require('async'),
 			}
 
 			async.parallel({
+				mainPost: function(next) {
+					Topics.getMainPost(tid, uid, next);
+				},
 				posts: function(next) {
-					posts.getPidsFromSet(set, start, end, reverse, function(err, pids) {
-						if (err) {
-							return next(err);
-						}
-
-						pids = topicData.mainPid ? [topicData.mainPid].concat(pids) : pids;
-
-						if (!pids.length) {
-							return next(null, []);
-						}
-						posts.getPostsByPids(pids, uid, function(err, posts) {
-							if (err) {
-								return next(err);
-							}
-
-							Topics.addPostData(posts, uid, next);
-						});
-					});
+					Topics.getTopicPosts(tid, set, start, end, uid, reverse, next);
 				},
 				category: async.apply(Topics.getCategoryData, tid),
 				threadTools: async.apply(plugins.fireHook, 'filter:topic.thread_tools', []),
@@ -244,7 +230,7 @@ var async = require('async'),
 					return callback(err);
 				}
 
-				topicData.posts = results.posts;
+				topicData.posts = results.mainPost ? [results.mainPost].concat(results.posts) : results.posts;
 				topicData.category = results.category;
 				topicData.thread_tools = results.threadTools;
 				topicData.tags = results.tags;
@@ -280,7 +266,11 @@ var async = require('async'),
 				if (err) {
 					return callback(err);
 				}
-
+				postData.forEach(function(post) {
+					if (post) {
+						post.index = 0;
+					}
+				});
 				Topics.addPostData(postData, uid, callback);
 			});
 		});

src/topics/posts.js

@@ -29,15 +29,28 @@ module.exports = function(Topics) {
 		], callback);
 	};
 
-
 	Topics.getTopicPosts = function(tid, set, start, end, uid, reverse, callback) {
 		callback = callback || function() {};
-		posts.getPostsByTid(tid, set, start, end, uid, reverse, function(err, postData) {
+		async.parallel({
+			posts: function(next) {
+				posts.getPostsByTid(tid, set, start, end, uid, reverse, next);
+			},
+			postCount: function(next) {
+				Topics.getTopicField(tid, 'postcount', next);
+			}
+		}, function(err, results) {
 			if (err) {
 				return callback(err);
 			}
 
-			Topics.addPostData(postData, uid, callback);
+			var indices = Topics.calculatePostIndices(start, end, results.postCount, reverse);
+			results.posts.forEach(function(post, index) {
+				if (post) {
+					post.index = indices[index];
+				}
+			});
+
+			Topics.addPostData(results.posts, uid, callback);
 		});
 	};
 
@@ -103,9 +116,6 @@ module.exports = function(Topics) {
 			},
 			privileges: function(next) {
 				privileges.posts.get(pids, uid, next);
-			},
-			indices: function(next) {
-				posts.getPostIndices(postData, uid, next);
 			}
 		}, function(err, results) {
 			if (err) {
@@ -114,7 +124,6 @@ module.exports = function(Topics) {
 
 			postData.forEach(function(postObj, i) {
 				if (postObj) {
-					postObj.index = results.indices[i];
 					postObj.deleted = parseInt(postObj.deleted, 10) === 1;
 					postObj.user = parseInt(postObj.uid, 10) ? results.userData[postObj.uid] : _.clone(results.userData[postObj.uid]);
 					postObj.editor = postObj.editor ? results.editors[postObj.editor] : null;
@@ -141,6 +150,19 @@ module.exports = function(Topics) {
 		});
 	};
 
+	Topics.calculatePostIndices = function(start, end, postCount, reverse) {
+		var indices = [];
+		var count = end - start + 1;
+		for(var i=0; i<count; ++i) {
+			if (reverse) {
+				indices.push(postCount - (start + i + 1));
+			} else {
+				indices.push(start + i + 1);
+			}
+		}
+		return indices;
+	};
+
 	Topics.getLatestUndeletedPid = function(tid, callback) {
 		Topics.getLatestUndeletedReply(tid, function(err, pid) {
 			if (err) {