From c4a97fc0c81b3e659338435c3c712c0b8b11fc9b Mon Sep 17 00:00:00 2001
From: Eugen Rochko <eugen@zeonfederated.com>
Date: Sat, 26 Mar 2022 00:26:50 +0100
Subject: [PATCH] Add offset pagination to trends in REST API (#17872)

---
 .../api/v1/trends/links_controller.rb         | 26 ++++++++++++++++++-
 .../api/v1/trends/statuses_controller.rb      | 24 ++++++++++++++++-
 .../api/v1/trends/tags_controller.rb          | 26 ++++++++++++++++++-
 app/models/trends/query.rb                    |  4 +--
 4 files changed, 75 insertions(+), 5 deletions(-)

diff --git a/app/controllers/api/v1/trends/links_controller.rb b/app/controllers/api/v1/trends/links_controller.rb
index ad20e7f8be..b1cde5a4bb 100644
--- a/app/controllers/api/v1/trends/links_controller.rb
+++ b/app/controllers/api/v1/trends/links_controller.rb
@@ -3,6 +3,10 @@
 class Api::V1::Trends::LinksController < Api::BaseController
   before_action :set_links
 
+  after_action :insert_pagination_headers
+
+  DEFAULT_LINKS_LIMIT = 10
+
   def index
     render json: @links, each_serializer: REST::Trends::LinkSerializer
   end
@@ -20,6 +24,26 @@ class Api::V1::Trends::LinksController < Api::BaseController
   end
 
   def links_from_trends
-    Trends.links.query.allowed.in_locale(content_locale).limit(limit_param(10))
+    Trends.links.query.allowed.in_locale(content_locale).offset(offset_param).limit(limit_param(DEFAULT_LINKS_LIMIT))
+  end
+
+  def insert_pagination_headers
+    set_pagination_headers(next_path, prev_path)
+  end
+
+  def pagination_params(core_params)
+    params.slice(:limit).permit(:limit).merge(core_params)
+  end
+
+  def next_path
+    api_v1_trends_links_url pagination_params(offset: offset_param + limit_param(DEFAULT_LINKS_LIMIT))
+  end
+
+  def prev_path
+    api_v1_trends_links_url pagination_params(offset: offset_param - limit_param(DEFAULT_LINKS_LIMIT)) if offset_param > limit_param(DEFAULT_LINKS_LIMIT)
+  end
+
+  def offset_param
+    params[:offset].to_i
   end
 end
diff --git a/app/controllers/api/v1/trends/statuses_controller.rb b/app/controllers/api/v1/trends/statuses_controller.rb
index d4ec97ae5f..4977803fbd 100644
--- a/app/controllers/api/v1/trends/statuses_controller.rb
+++ b/app/controllers/api/v1/trends/statuses_controller.rb
@@ -3,6 +3,8 @@
 class Api::V1::Trends::StatusesController < Api::BaseController
   before_action :set_statuses
 
+  after_action :insert_pagination_headers
+
   def index
     render json: @statuses, each_serializer: REST::StatusSerializer
   end
@@ -22,6 +24,26 @@ class Api::V1::Trends::StatusesController < Api::BaseController
   def statuses_from_trends
     scope = Trends.statuses.query.allowed.in_locale(content_locale)
     scope = scope.filtered_for(current_account) if user_signed_in?
-    scope.limit(limit_param(DEFAULT_STATUSES_LIMIT))
+    scope.offset(offset_param).limit(limit_param(DEFAULT_STATUSES_LIMIT))
+  end
+
+  def insert_pagination_headers
+    set_pagination_headers(next_path, prev_path)
+  end
+
+  def pagination_params(core_params)
+    params.slice(:limit).permit(:limit).merge(core_params)
+  end
+
+  def next_path
+    api_v1_trends_statuses_url pagination_params(offset: offset_param + limit_param(DEFAULT_STATUSES_LIMIT))
+  end
+
+  def prev_path
+    api_v1_trends_statuses_url pagination_params(offset: offset_param - limit_param(DEFAULT_STATUSES_LIMIT)) if offset_param > limit_param(DEFAULT_STATUSES_LIMIT)
+  end
+
+  def offset_param
+    params[:offset].to_i
   end
 end
diff --git a/app/controllers/api/v1/trends/tags_controller.rb b/app/controllers/api/v1/trends/tags_controller.rb
index 1334b72d25..d77857871a 100644
--- a/app/controllers/api/v1/trends/tags_controller.rb
+++ b/app/controllers/api/v1/trends/tags_controller.rb
@@ -3,6 +3,10 @@
 class Api::V1::Trends::TagsController < Api::BaseController
   before_action :set_tags
 
+  after_action :insert_pagination_headers
+
+  DEFAULT_TAGS_LIMIT = 10
+
   def index
     render json: @tags, each_serializer: REST::TagSerializer
   end
@@ -12,10 +16,30 @@ class Api::V1::Trends::TagsController < Api::BaseController
   def set_tags
     @tags = begin
       if Setting.trends
-        Trends.tags.query.allowed.limit(limit_param(10))
+        Trends.tags.query.allowed.limit(limit_param(DEFAULT_TAGS_LIMIT))
       else
         []
       end
     end
   end
+
+  def insert_pagination_headers
+    set_pagination_headers(next_path, prev_path)
+  end
+
+  def pagination_params(core_params)
+    params.slice(:limit).permit(:limit).merge(core_params)
+  end
+
+  def next_path
+    api_v1_trends_tags_url pagination_params(offset: offset_param + limit_param(DEFAULT_TAGS_LIMIT))
+  end
+
+  def prev_path
+    api_v1_trends_tags_url pagination_params(offset: offset_param - limit_param(DEFAULT_TAGS_LIMIT)) if offset_param > limit_param(DEFAULT_TAGS_LIMIT)
+  end
+
+  def offset_param
+    params[:offset].to_i
+  end
 end
diff --git a/app/models/trends/query.rb b/app/models/trends/query.rb
index 64a4c0c1fb..231b652288 100644
--- a/app/models/trends/query.rb
+++ b/app/models/trends/query.rb
@@ -37,7 +37,7 @@ class Trends::Query
   end
 
   def offset!(value)
-    @offset = value
+    @offset = value.to_i
     self
   end
 
@@ -46,7 +46,7 @@ class Trends::Query
   end
 
   def limit!(value)
-    @limit = value
+    @limit = value.to_i
     self
   end