added support for deep comment counts

.eslintignore

@@ -25,5 +25,6 @@ plugins/*
 !plugins/talk-plugin-moderation-actions
 !plugins/talk-plugin-toxic-comments
 !plugins/talk-plugin-remember-sort
+!plugins/talk-plugin-deep-reply-count
 
 node_modules

.gitignore

@@ -42,5 +42,6 @@ plugins/*
 !plugins/talk-plugin-moderation-actions
 !plugins/talk-plugin-toxic-comments
 !plugins/talk-plugin-remember-sort
+!plugins/talk-plugin-deep-reply-count
 
 **/node_modules/*

graph/typeDefs.graphql

@@ -369,7 +369,8 @@ type Comment {
   # the replies that were made to the comment.
   replies(query: RepliesQuery = {}): CommentConnection!
 
-  # The count of replies on a comment.
+  # replyCount is the number of replies with a depth of 1. Only direct replies
+  # to this comment are counted.
   replyCount: Int
 
   # Actions completed on the parent. Requires the `ADMIN` role.

plugins/talk-plugin-deep-reply-count/index.js

@@ -0,0 +1,74 @@
+const _ = require('lodash');
+const DataLoader = require('dataloader');
+
+const CommentModel = require('../../models/comment');
+
+console.warn('Enabling the talk-plugin-deep-reply-count plugin introduces a signifigant performance impact on larger sites, use with care.');
+
+// genDeepCommentCount will return the deep comment count for a given parent id.
+const genDeepCommentCount = async (context, parent_ids) => {
+
+  // Get all the replies to the parent comments.
+  const replies = await CommentModel
+    .find({
+      parent_id: {
+        $in: _.uniq(parent_ids),
+      },
+    }, {
+      id: 1,
+      reply_count: 1,
+      parent_id: 1,
+    });
+
+  // Get all the replies that have comments on them.
+  const commentedOnReplies = replies.filter(({reply_count}) => {
+    return reply_count && reply_count > 0;
+  });
+
+  let deepReplyCount = [];
+
+  // And if there were any..
+  if (commentedOnReplies.length > 0) {
+
+    // Load the reply count for each of them.
+    deepReplyCount = await context.loaders.Comments.getDeepCount.loadMany(_.uniq(commentedOnReplies.map(({id}) => {
+      return id;
+    })));
+  }
+
+  // Get all the direct replies to the parent comments.
+  const allDirectReplies = _.groupBy(replies, 'parent_id');
+
+  // Collect all the ancestor replies.
+  const allAncestorReplies = _.groupBy(_.zip(commentedOnReplies, deepReplyCount), ([{parent_id}]) => {
+    return parent_id;
+  });
+
+  // Return the replies in an array matching that of the input parent_ids array.
+  return parent_ids.map((parent_id) => {
+
+    // Get the direct replies to this comment.
+    const directReplies = parent_id in allDirectReplies ? allDirectReplies[parent_id] : [];
+    const ancestorReplies = parent_id in allAncestorReplies ? allAncestorReplies[parent_id] : [];
+
+    // Reduce this array.
+    return ancestorReplies.reduce((acc, [, count]) => {
+      return acc + count;
+    }, directReplies.length);
+  });
+};
+
+module.exports = {
+  loaders: (context) => ({
+    Comments: {
+      getDeepCount: new DataLoader((parent_ids) => genDeepCommentCount(context, parent_ids)),
+    }
+  }),
+  resolvers: {
+    Comment: {
+      replyCount({id}, args, {loaders: {Comments}}) {
+        return Comments.getDeepCount.load(id);
+      }
+    }
+  }
+};