Implement infinity home timeline (#1610)

* Implement infinity home timeline

* Fix test for infinite home timeline

* Fix infinity home timeline with min_id

* Fix infinite home timeline duplicated statuses

* Codeclimate for infinite home timeline

* Refactor code as reviewed

* Fix redis sufficient check

* Fix typo on variable name

app/models/home_feed.rb

@@ -9,4 +9,41 @@ class HomeFeed < Feed
   def regenerating?
     redis.exists?("account:#{@account.id}:regeneration")
   end
+
+  def get(limit, max_id = nil, since_id = nil, min_id = nil)
+    limit    = limit.to_i
+    max_id   = max_id.to_i if max_id.present?
+    since_id = since_id.to_i if since_id.present?
+    min_id   = min_id.to_i if min_id.present?
+
+    statuses = from_redis(limit, max_id, since_id, min_id)
+
+    return statuses if statuses.size >= limit
+
+    redis_min_id = from_redis(1, nil, nil, 0).first&.id if min_id.present? || since_id.present?
+    redis_sufficient = redis_min_id && (
+      (min_id.present? && min_id >= redis_min_id) ||
+      (since_id.present? && since_id >= redis_min_id)
+    )
+
+    unless redis_sufficient
+      remaining_limit = limit - statuses.size
+      max_id = statuses.last.id unless statuses.empty?
+      statuses += from_database(remaining_limit, max_id, since_id, min_id)
+    end
+
+    statuses
+  end
+
+  protected
+
+  def from_database(limit, max_id, since_id, min_id)
+    # Note that this query will not contains direct messages
+    Status
+      .where(account: [@account] + @account.following)
+      .where(visibility: [:public, :unlisted, :private])
+      .to_a_paginated_by_id(limit, min_id: min_id, max_id: max_id, since_id: since_id)
+      .reject { |status| FeedManager.instance.filter?(:home, status, @account) }
+      .sort_by { |status| -status.id }
+  end
 end