Implement #770

1 files changed, 96 insertions, 0 deletions

diff --git a/src/api/endpoints/users/get_frequently_replied_users.ts b/src/api/endpoints/users/get_frequently_replied_users.ts
new file mode 100644
index 0000000000..2e0e2e40a7
--- /dev/null
+++ b/src/api/endpoints/users/get_frequently_replied_users.ts
@@ -0,0 +1,96 @@
+/**
+ * Module dependencies
+ */
+import $ from 'cafy';
+import Post from '../../models/post';
+import User from '../../models/user';
+import serialize from '../../serializers/user';
+
+module.exports = (params, me) => new Promise(async (res, rej) => {
+	// Get 'user_id' parameter
+	const [userId, userIdErr] = $(params.user_id).id().$;
+	if (userIdErr) return rej('invalid user_id param');
+
+	// Lookup user
+	const user = await User.findOne({
+		_id: userId
+	}, {
+		fields: {
+			_id: true
+		}
+	});
+
+	if (user === null) {
+		return rej('user not found');
+	}
+
+	// Fetch recent posts
+	const recentPosts = await Post.find({
+		user_id: user._id,
+		reply_to_id: {
+			$exists: true,
+			$ne: null
+		}
+	}, {
+		sort: {
+			_id: -1
+		},
+		limit: 1000,
+		fields: {
+			_id: false,
+			reply_to_id: true
+		}
+	});
+
+	// 投稿が少なかったら中断
+	if (recentPosts.length === 0) {
+		return res([]);
+	}
+
+	const replyTargetPosts = await Post.find({
+		_id: {
+			$in: recentPosts.map(p => p.reply_to_id)
+		},
+		user_id: {
+			$ne: user._id
+		}
+	}, {
+		fields: {
+			_id: false,
+			user_id: true
+		}
+	});
+
+	const repliedUsers = {};
+
+	// Extract replies from recent posts
+	replyTargetPosts.forEach(post => {
+		const userId = post.user_id.toString();
+		if (repliedUsers[userId]) {
+			repliedUsers[userId]++;
+		} else {
+			repliedUsers[userId] = 1;
+		}
+	});
+
+	// Calc peak
+	let peak = 0;
+	Object.keys(repliedUsers).forEach(user => {
+		if (repliedUsers[user] > peak) peak = repliedUsers[user];
+	});
+
+	// Sort replies by frequency
+	const repliedUsersSorted = Object.keys(repliedUsers).sort((a, b) => repliedUsers[b] - repliedUsers[a]);
+
+	// Lookup top 10 replies
+	const topRepliedUsers = repliedUsersSorted.slice(0, 10);
+
+	// Make replies object (includes weights)
+	const repliesObj = await Promise.all(topRepliedUsers.map(async (user) => ({
+		user: await serialize(user, me, { detail: true }),
+		weight: repliedUsers[user] / peak
+	})));
+
+	// Response
+	res(repliesObj);
+});