chore+fix(backends): Remove external videoplayback proxy support, fix

automatic backend switching on the last backend, sort working ends, skip
companion cookie setting on images, thumbnails, etc.

external videoplayback proxy support was unused and is not really useful
now due to youtube pinning the IP of where a video is being requested to
that IP adresss, so requesting the video from one companion and then
offloading the video traffic to another server with another IP is not
going to work.

src/invidious/helpers/backend_info.cr

@@ -1,18 +1,17 @@
 module BackendInfo
   extend self
-  @@exvpp_url : Array(String) = Array.new(CONFIG.invidious_companion.size, "")
-  @@status : Array(Int32) = Array.new(CONFIG.invidious_companion.size, 0)
+
+  enum Status
+    Dead    = 0
+    Working = 1
+  end
+
+  @@status : Array(Int32) = Array.new(CONFIG.invidious_companion.size, Status::Dead.to_i)
   @@csp : Array(String) = Array.new(CONFIG.invidious_companion.size, "")
   @@working_ends : Array(Int32) = Array(Int32).new(0)
   @@csp_mutex : Mutex = Mutex.new
   @@check_mutex : Mutex = Mutex.new
 
-  enum BackendStatus
-      Dead
-      Problems
-      Working
-  end
-
   def check_backends
     check_companion()
     LOGGER.debug("Invidious companion: New working_ends \"#{@@working_ends}\"")
@@ -25,6 +24,7 @@ module BackendInfo
     channels = Channel(Nil).new(comp_size)
     updated_ends = Array(Int32).new(0)
     updated_status = Array(Int32).new(CONFIG.invidious_companion.size, 0)
+
     LOGGER.debug("Invidious companion: comp_size \"#{comp_size}\"")
     CONFIG.invidious_companion.each_with_index do |companion, index|
       spawn do
@@ -33,19 +33,22 @@ module BackendInfo
           client.connect_timeout = 10.seconds
           response = client.get("/healthz")
           if response.status_code == 200
-            check_videoplayback_proxy(companion, index, updated_status, updated_ends)
-            generate_csp([companion.public_url.to_s, companion.i2p_public_url.to_s], @@exvpp_url[index], index)
+            @@check_mutex.synchronize do
+              updated_status[index] = Status::Working.to_i
+              updated_ends.push(index)
+            end
+            generate_csp([companion.public_url.to_s, companion.i2p_public_url.to_s], index)
           else
             @@check_mutex.synchronize do
-              updated_status[index] = BackendStatus::Dead.to_i
+              updated_status[index] = Status::Dead.to_i
             end
           end
         rescue
           @@check_mutex.synchronize do
-            updated_status[index] = BackendStatus::Dead.to_i
+            updated_status[index] = Status::Dead.to_i
           end
         ensure
-          LOGGER.debug("Invidious companion: Done Index: \"#{index}\"")
+          LOGGER.trace("Invidious companion: Done Index: \"#{index}\"")
           channels.send(nil)
         end
       end
@@ -53,59 +56,16 @@ module BackendInfo
     # Wait until we receive a signal from them all
     LOGGER.debug("Invidious companion: Updating working_ends")
     comp_size.times { channels.receive }
-    @@working_ends = updated_ends
+    @@working_ends = updated_ends.sort!
     @@status = updated_status
   end
 
-  private def check_videoplayback_proxy(companion : Config::CompanionConfig, index : Int32, updated_status : Array(Int32), updated_ends : Array(Int32))
-    begin
-      info = HTTP::Client.get "#{companion.private_url}/info"
-      exvpp_url = JSON.parse(info.body)["external_videoplayback_proxy"]?.try &.to_s
-    rescue JSON::ParseException
-      @@check_mutex.synchronize do
-        updated_status[index] = BackendStatus::Working.to_i
-        updated_ends.push(index)
-      end
-      return
-    end
-
-    exvpp_url = "" if exvpp_url.nil?
-    @@exvpp_url[index] = exvpp_url
-    if exvpp_url.empty?
-      @@check_mutex.synchronize do
-        updated_status[index] = BackendStatus::Working.to_i
-        updated_ends.push(index)
-      end
-      return
-    else
-      begin
-        exvpp_health = HTTP::Client.get "#{exvpp_url}/health"
-        if exvpp_health.status_code == 200
-            @@check_mutex.synchronize do
-              updated_status[index] = BackendStatus::Working.to_i
-              updated_ends.push(index)
-            end
-          return exvpp_url
-        else
-          @@check_mutex.synchronize do
-            updated_status[index] = BackendStatus::Problems.to_i
-          end
-        end
-      rescue
-        @@check_mutex.synchronize do
-          updated_status[index] = BackendStatus::Problems.to_i
-        end
-      end
-    end
-  end
-
-  private def generate_csp(companion_url : Array(String), exvpp_url : String? = nil, index : Int32? = nil)
+  private def generate_csp(companion_url : Array(String), index : Int32? = nil)
     @@csp_mutex.synchronize do
       @@csp[index] = ""
       companion_url.each do |url|
         @@csp[index] += " #{url}"
       end
-      @@csp[index] += " #{exvpp_url}"
     end
   end
 
@@ -119,10 +79,6 @@ module BackendInfo
     return @@working_ends
   end
 
-  def get_exvpp
-    return @@exvpp_url
-  end
-
   def get_csp(index : Int32)
     # A little mutex to prevent sending a partial CSP header
     # Not sure if this is necessary. But if the @@csp[index] is being assigned

src/invidious/routes/before_all.cr

@@ -32,6 +32,13 @@ module Invidious::Routes::BeforeAll
     extra_connect_csp = ""
 
     if CONFIG.invidious_companion.present?
+      if !{
+           "/sb/",
+           "/vi/",
+           "/s_p/",
+           "/yts/",
+           "/ggpht/",
+         }.any? { |r| env.request.resource.starts_with? r }
         current_companion_d = host.split(":")[0].split(".")[0]
 
         if index = COMPANION_PREFIXES.index(current_companion_d)
@@ -57,8 +64,9 @@ module Invidious::Routes::BeforeAll
 
           companion_status = BackendInfo.get_status
 
-        if companion_status[current_companion] != 2
-          alive_companion = companion_status.index(2, offset: current_companion)
+          if companion_status[current_companion] != BackendInfo::Status::Working.to_i
+            current_companion = 0 if current_companion == companion_status.size - 1
+            alive_companion = companion_status.index(BackendInfo::Status::Working.to_i, offset: current_companion)
             if alive_companion
               env.set "companion_switched", true
               current_companion = alive_companion
@@ -77,6 +85,7 @@ module Invidious::Routes::BeforeAll
 
         extra_media_csp, extra_connect_csp = BackendInfo.get_csp(env.get("current_companion").as(Int32))
       end
+    end
 
     # Only allow the pages at /embed/* to be embedded
     if env.request.resource.starts_with?("/embed")

src/invidious/views/template.ecr

@@ -123,9 +123,8 @@
                             <a href="<%= scheme %>://<%= host_backend %><%= env.request.resource %>" style="<%= is_current_backend_host ? "text-decoration-line: underline;" : "" %> display: inline-block;">
                                 <%= HTML.escape(CONFIG.backend_name_prefix + (index + 1).to_s) %> <%= HTML.escape(companion.note) %>
                                 <span style="color:
-                                    <% if status[index] == 0 %> #fd4848; <% end %>
-                                    <% if status[index] == 1 %> #d06925; <% end %>
-                                    <% if status[index] == 2 %> #42ae3c; <% end %>
+                                    <% if status[index] == BackendInfo::Status::Dead.to_i %> #fd4848; <% end %>
+                                    <% if status[index] == BackendInfo::Status::Working.to_i %> #42ae3c; <% end %>
                                 ">•</span>
                             </a>
                             <% if !(index == CONFIG.invidious_companion.size-1) %>
@@ -138,9 +137,8 @@
                             <a href="/switchbackend?backend_id=<%= index.to_s %>&referer=<%= current_page %>" style="<%= current_backend == index ? "text-decoration-line: underline;" : "" %> display: inline-block;">
                                 <%= HTML.escape(CONFIG.backend_name_prefix + (index + 1).to_s) %> <%= HTML.escape(companion.note) %>
                                 <span style="color:
-                                    <% if status[index] == 0 %> #fd4848; <% end %>
-                                    <% if status[index] == 1 %> #d06925; <% end %>
-                                    <% if status[index] == 2 %> #42ae3c; <% end %>
+                                    <% if status[index] == BackendInfo::Status::Dead.to_i %> #fd4848; <% end %>
+                                    <% if status[index] == BackendInfo::Status::Working.to_i %> #42ae3c; <% end %>
                                 ">•</span>
                             </a>
                             <% if !(index == CONFIG.invidious_companion.size-1) %>