From a1279d682f56928c0834dc2987c998a06fcd9fe4 Mon Sep 17 00:00:00 2001
From: DualFroz <me@dualfroz.com>
Date: Wed, 26 Aug 2026 11:17:00 +0200
Subject: [PATCH] feat(command): add hyperloglog command handlers

---
 lib/excache/command/hyper_log_log.ex | 37 ++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 lib/excache/command/hyper_log_log.ex

diff --git a/lib/excache/command/hyper_log_log.ex b/lib/excache/command/hyper_log_log.ex
new file mode 100644
index 0000000..9dfaace
--- /dev/null
+++ b/lib/excache/command/hyper_log_log.ex
@@ -0,0 +1,37 @@
+defmodule Excache.Command.HyperLogLog do
+  @moduledoc false
+
+  alias Excache.Store
+  alias Excache.Command.Reply
+
+  def dispatch("PFADD", [key | elements], state) do
+    case Store.pfadd(key, elements) do
+      {:ok, changed} -> reply({:integer, changed}, state)
+      {:error, reason} -> reply(hllError(reason), state)
+    end
+  end
+
+  def dispatch("PFCOUNT", [_ | _] = keys, state) do
+    case Store.pfcount(keys) do
+      {:ok, count} -> reply({:integer, count}, state)
+      {:error, reason} -> reply(hllError(reason), state)
+    end
+  end
+
+  def dispatch("PFMERGE", [dest | sources], state) do
+    case Store.pfmerge(dest, sources) do
+      {:ok, "OK"} -> reply({:simple, "OK"}, state)
+      {:error, reason} -> reply(hllError(reason), state)
+    end
+  end
+
+  def dispatch(_name, _args, _state), do: :unhandled
+
+  defp hllError(:not_hll),
+    do: {:error, "WRONGTYPE Key is not a valid HyperLogLog string value."}
+
+  defp hllError(:wrongtype), do: Reply.wrongtype()
+  defp hllError(other), do: {:error, "ERR #{other}"}
+
+  defp reply(term, state), do: {[term], state}
+end