recommendations: open user recommendations to all users.

* Open recommendations to all users (not just gold).
* Show recommendations on all posts (not just posts after 2017).
* Allow users to browse recommendations for other users.
* Increase number of recommended posts returned.
* Change endpoints to /recommended_posts?user_id=1234 and
  /recommended_posts?post_id=1234 and add json/xml support.

app/controllers/recommended_posts_controller.rb

@@ -1,23 +1,18 @@
 class RecommendedPostsController < ApplicationController
-  before_action :member_only
-  respond_to :html
+  respond_to :html, :json, :xml, :js
 
   def show
-    @posts = load_posts()
+    @max_recommendations = params.fetch(:max_recommendations, 100).to_i.clamp(0, 1000)
 
-    if request.xhr?
-      render partial: "show", layout: false
+    if params[:user_id].present?
+      @recs = RecommenderService.recommend_for_user(params[:user_id], @max_recommendations)
+    elsif params[:post_id].present?
+      @recs = RecommenderService.recommend_for_post(params[:post_id], @max_recommendations)
+    else
+      @recs = []
     end
-  end
 
-private
-
-  def load_posts
-    if params[:context] == "post"
-      @posts = RecommenderService.recommend(post_id: params[:post_id].to_i)
-
-    elsif params[:context] == "user"
-      @posts = RecommenderService.recommend(user_id: CurrentUser.id)
-    end
+    @posts = @recs.map { |rec| rec[:post] }
+    respond_with(@recs)
   end
 end

app/javascript/src/javascripts/posts.js.erb

@@ -9,6 +9,7 @@ let Post = {};
 Post.pending_update_count = 0;
 Post.SWIPE_THRESHOLD = 60;
 Post.SWIPE_VELOCITY = 0.6;
+Post.MAX_RECOMMENDATIONS = 27; // 3 rows of 9 posts at 1920x1080.
 
 Post.initialize_all = function() {
 
@@ -433,9 +434,7 @@ Post.initialize_post_sections = function() {
       $("#comments").hide();
       $("#edit").hide();
       $("#recommended").show();
-      $.get("/recommended_posts", {context: "post", post_id: Utility.meta("post-id")}, function(data) {
-        $("#recommended").html(data);
-      });
+      $.get("/recommended_posts.js", { post_id: Utility.meta("post-id"), max_recommendations: Post.MAX_RECOMMENDATIONS });
     } else {
       $("#edit").hide();
       $("#comments").hide();

app/logical/recommender_service.rb

@@ -0,0 +1,40 @@
+module RecommenderService
+  module_function
+
+  MIN_POST_FAVS = 5
+  MIN_USER_FAVS = 50
+  CACHE_LIFETIME = 4.hours
+
+  def enabled?
+    Danbooru.config.recommender_server.present?
+  end
+
+  def available_for_post?(post)
+    enabled? && post.fav_count > MIN_POST_FAVS
+  end
+
+  def available_for_user?(user)
+    enabled? && user.favorite_count > MIN_USER_FAVS
+  end
+
+  def recommend_for_user(user_id, limit = 50)
+    body, status = HttpartyCache.get("#{Danbooru.config.recommender_server}/recommend/#{user_id}", params: { limit: limit }, expiry: CACHE_LIFETIME)
+    return [] if status != 200
+
+    process_recs(body)
+  end
+
+  def recommend_for_post(post_id, limit = 50)
+    body, status = HttpartyCache.get("#{Danbooru.config.recommender_server}/similar/#{post_id}", params: { limit: limit }, expiry: CACHE_LIFETIME)
+    return [] if status != 200
+
+    process_recs(body).reject { |rec| rec[:post].id == post_id }
+  end
+
+  def process_recs(recs)
+    recs = JSON.parse(recs).to_h
+    recs = Post.where(id: recs.keys).map { |post| { score: recs[post.id], post: post } }
+    recs = recs.sort_by { |rec| -rec[:score] }
+    recs
+  end
+end

app/models/recommender_service.rb

@@ -1,62 +0,0 @@
-module RecommenderService
-  extend self
-
-  SCORE_THRESHOLD = 5
-
-  def enabled?
-    Danbooru.config.recommender_server.present?
-  end
-
-  def available_for_post?(post)
-    return true if Rails.env.development?
-
-    enabled? && post.created_at > Date.civil(2017, 1, 1) && post.fav_count >= SCORE_THRESHOLD
-  end
-
-  def available_for_user?
-    enabled? && CurrentUser.is_gold?
-  end
-
-  def recommend_for_user(user_id)
-    ids = Cache.get("rsu:#{user_id}", 1.hour) do
-      resp = HTTParty.get(
-        "#{Danbooru.config.recommender_server}/recommend/#{user_id}", 
-        Danbooru.config.httparty_options.merge(
-          basic_auth: {
-            username: "danbooru", 
-            password: Danbooru.config.recommender_key
-          }
-        )
-      )
-      JSON.parse(resp.body)
-    end
-    Post.find(ids.map(&:first))
-  end
-
-  def recommend_for_post(post_id)
-    ids = Cache.get("rss:#{post_id}", 1.hour) do
-      resp = HTTParty.get(
-        "#{Danbooru.config.recommender_server}/similar/#{post_id}", 
-        Danbooru.config.httparty_options.merge(
-          basic_auth: {
-            username: "danbooru", 
-            password: Danbooru.config.recommender_key
-          }
-        )
-      )
-      JSON.parse(resp.body)
-    end
-    if ids.is_a?(Hash) # error state
-      return []
-    end
-    Post.find(ids.reject {|x| x[0] == post_id}.map(&:first))
-  end
-
-  def recommend(post_id: nil, user_id: nil)
-    if post_id
-      recommend_for_post(post_id)
-    elsif user_id
-      recommend_for_user(user_id)
-    end
-  end
-end

app/views/posts/partials/common/_secondary_links.html.erb

@@ -2,8 +2,8 @@
   <%= subnav_link_to "Listing", posts_path %>
   <%= subnav_link_to "Upload", new_upload_path %>
   <%= subnav_link_to "Hot", posts_path(:tags => "order:rank", :d => "1") %>
-  <% if RecommenderService.available_for_user? %>
-    <%= subnav_link_to "Recommended", recommended_posts_path(context: "user") %>
+  <% if RecommenderService.available_for_user?(CurrentUser.user) %>
+    <%= subnav_link_to "Recommended", recommended_posts_path(user_id: CurrentUser.id) %>
   <% end %>
   <% unless CurrentUser.is_anonymous? %>
     <%= subnav_link_to "Favorites", posts_path(tags: "ordfav:#{CurrentUser.user.name}") %>

app/views/recommended_posts/show.html.erb

@@ -2,7 +2,7 @@
   <div id="a-show">
     <h1>Recommended Posts</h1>
 
-    <p>Based on your favorites, you may enjoy these posts. Favorite more to get more accurate results. These recommendations update every hour.</p>
+    <p>Based on your favorites, you may enjoy these posts. Favorite more posts to get more accurate results. These recommendations update every few hours.</p>
 
     <%= render "posts/partials/common/inline_blacklist" %>
     <%= render partial: "show" %> 

app/views/recommended_posts/show.js.erb

@@ -0,0 +1 @@
+$("#recommended").html("<%= j render "recommended_posts/show" %>");