feat: click controller performance improvements

- return tuple directly from the block
- avoid to parse remote_address in the main thread
- avoid to replace headers, add only
- avoid separate variables for one-single use

app/controllers/click.cr

@@ -11,21 +11,19 @@ module App::Controllers
 
     def self.redirect_handler
       ->(env : HTTP::Server::Context) {
-        slug = env.params.url["slug"]
+        link_id, url = Database.raw_query("SELECT id, url FROM links WHERE slug = (?) LIMIT 1", env.params.url["slug"]) do |result|
+          result.move_next ? {result.read(Int64), result.read(String)} : nil
+        end || raise App::NotFoundException.new(env)
 
-        link_data = nil
-        Database.raw_query("SELECT id, url FROM links WHERE slug = (?) LIMIT 1", slug) do |result|
-          if result.move_next
-            link_data = {result.read(Int64), result.read(String)}
-          end
-        end
-        raise App::NotFoundException.new(env) unless link_data
+        remote_address = env.request.headers["Cf-Connecting-Ip"]? || env.request.remote_address.to_s
 
-        link_id, url = link_data
-        client_ip = IpLookup.ip_from_address(env.request.headers["Cf-Connecting-Ip"]? || env.request.remote_address.to_s)
+        env.response.status_code = 301
+        env.response.headers.add("Location", url)
+        env.response.headers.add("X-Forwarded-For", remote_address)
 
         spawn do
           begin
+            client_ip = IpLookup.ip_from_address(remote_address)
             user_agent_str = env.request.headers["User-Agent"]?
             referer = env.request.headers["Referer"]?.try { |r| URI.parse(r).host rescue r } || env.params.query["utm_source"]? || "Direct"
 
@@ -34,7 +32,7 @@ module App::Controllers
             click = App::Models::Click.new
             click.link_id = link_id
             click.country = client_ip ? IpLookup.new(client_ip).try(&.country.try(&.code)) : nil
-            click.user_agent = ua_parser.to_s
+            click.user_agent = user_agent_str
             click.browser = ua_parser.try(&.family)
             click.os = ua_parser.try(&.os.try(&.family))
             click.referer = referer
@@ -44,14 +42,6 @@ module App::Controllers
             Log.error { "Click tracking error: #{ex.message}" }
           end
         end
-
-        env.response.status_code = 301
-        env.response.headers.add("Location", url)
-        env.response.headers.add("X-Forwarded-For", client_ip.to_s)
-        env.response.print ""
-        env.response.close
-
-        return
       }
     end
   end