refactor: replace click tracker with direct spawn

app/controllers/click.cr

@@ -0,0 +1,57 @@
+require "user_agent_parser"
+
+UserAgent.load_regexes(File.read("data/uap_core_regexes.yaml"))
+IpLookup.load_mmdb("data/GeoLite2-Country.mmdb")
+
+module App::Controllers
+  class ClickController
+    include App::Models
+    include App::Lib
+    include App::Services
+
+    def initialize(@env : HTTP::Server::Context); end
+
+    def redirect
+      slug = @env.params.url["slug"]
+
+      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
+
+      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["Location"] = url
+      @env.response.headers["X-Forwarded-For"] = client_ip.to_s
+      @env.response.headers["Connection"] = "close"
+
+      @env.response.flush
+
+      spawn do
+        begin
+          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"
+
+          ua_parser = user_agent_str ? UserAgent.new(user_agent_str) : nil
+
+          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.browser = ua_parser.try(&.family)
+          click.os = ua_parser.try(&.os.try(&.family))
+          click.referer = referer
+
+          Database.insert(click)
+        rescue ex
+          Log.error { "Click tracking error: #{ex.message}" }
+        end
+      end
+    end
+  end
+end

app/controllers/link.cr

@@ -5,7 +5,6 @@ module App::Controllers
     include App::Services
 
     def initialize(@env : HTTP::Server::Context)
-      ClickTracker.init
       super(@env)
     end
 
@@ -34,33 +33,6 @@ module App::Controllers
       render_json({"data" => App::Serializers::Link.new(inserted_link)}, 201)
     end
 
-    def redirect
-      slug = @env.params.url["slug"]
-
-      link_data = nil
-      # LIMIT 1 degrades performance on unique field searches
-      # slug autoindex has better perormance than the covering index
-      Database.raw_query("SELECT id, url FROM links WHERE slug = (?)", 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"]?.try(&.presence) || @env.request.remote_address.try &.to_s
-      user_agent_str = @env.request.headers["User-Agent"]? || "Unknown"
-      client_ip = IpLookup.extract_ip(remote_address) || "Unknown"
-
-      @env.response.status_code = 301
-      @env.response.headers["Connection"] = "close"
-
-      @env.response.headers["Location"] = link_data[1]
-      @env.response.headers["X-Forwarded-For"] = client_ip
-      @env.response.headers["User-Agent"] = user_agent_str
-
-      spawn track_click(link_data[0], client_ip, user_agent_str)
-    end
-
     def list_all
       limit, cursor = pagination_params
 
@@ -158,19 +130,6 @@ module App::Controllers
       current_user.id.as(Int64)
     end
 
-    private def track_click(link_id, client_ip, user_agent_str)
-      source = @env.params.query["utm_source"]? || "Direct"
-      referer = @env.request.headers["Referer"]?.try { |r| begin URI.parse(r).host rescue r end } || source
-
-      ClickTracker.track(
-        link_id: link_id,
-        client_ip: client_ip,
-        user_agent: user_agent_str,
-        source: source,
-        referer: referer
-      )
-    end
-
     private def pagination_params
       limit = (@env.params.query["limit"]? || "100").to_i32
       cursor = @env.params.query["cursor"]?