From f3e7fab4d24fe7d98134bd129effed0ae165f85f Mon Sep 17 00:00:00 2001
From: Carsten <carsten@ravensburg.it>
Date: Tue, 21 Apr 2026 22:49:15 +0200
Subject: [PATCH] feat(server): pure Status.compute/2 for
 ok/warning/critical/offline

---
 server/lib/server/status.ex        | 41 ++++++++++++++++++++
 server/test/server/status_test.exs | 61 ++++++++++++++++++++++++++++++
 2 files changed, 102 insertions(+)
 create mode 100644 server/lib/server/status.ex
 create mode 100644 server/test/server/status_test.exs

diff --git a/server/lib/server/status.ex b/server/lib/server/status.ex
new file mode 100644
index 0000000..4f018b2
--- /dev/null
+++ b/server/lib/server/status.ex
@@ -0,0 +1,41 @@
+defmodule Server.Status do
+  @moduledoc """
+  Derive a status level for a host from its latest fast sample.
+    :offline   host has no active agent connection
+    :critical  pool DEGRADED/FAULTED or capacity > 90
+    :warning   capacity 80..90 or pending OS updates
+    :ok        everything nominal
+  """
+
+  @bad_pool_states ~w(DEGRADED FAULTED SUSPENDED UNAVAIL)
+
+  @spec compute(String.t(), map() | nil) :: :offline | :critical | :warning | :ok
+  def compute(host_status, _payload) when host_status in ~w(offline never_connected),
+    do: :offline
+
+  def compute(_host_status, nil), do: :ok
+
+  def compute(_host_status, %{} = payload) do
+    pools = get_in(payload, ["zfs_pools", "pools"]) || []
+    pending = get_in(payload, ["system_info", "pending_updates"]) || 0
+
+    cond do
+      Enum.any?(pools, &critical_pool?/1) -> :critical
+      Enum.any?(pools, &warning_pool?/1) -> :warning
+      pending > 0 -> :warning
+      true -> :ok
+    end
+  end
+
+  defp critical_pool?(pool) do
+    health = pool["health"]
+    cap = pool["capacity_percent"] || 0
+
+    health in @bad_pool_states or cap > 90
+  end
+
+  defp warning_pool?(pool) do
+    cap = pool["capacity_percent"] || 0
+    cap >= 80 and cap <= 90
+  end
+end
diff --git a/server/test/server/status_test.exs b/server/test/server/status_test.exs
new file mode 100644
index 0000000..4089c8e
--- /dev/null
+++ b/server/test/server/status_test.exs
@@ -0,0 +1,61 @@
+defmodule Server.StatusTest do
+  use ExUnit.Case, async: true
+
+  alias Server.Status
+
+  describe "compute/2" do
+    test "returns :offline when host status is offline, regardless of payload" do
+      assert Status.compute("offline", %{"zfs_pools" => %{"pools" => [healthy_pool()]}}) ==
+               :offline
+    end
+
+    test "returns :ok with all-healthy payload" do
+      payload = %{
+        "zfs_pools" => %{"pools" => [healthy_pool()]},
+        "system_info" => %{"pending_updates" => 0}
+      }
+
+      assert Status.compute("online", payload) == :ok
+    end
+
+    test "returns :critical for degraded pool" do
+      payload = %{"zfs_pools" => %{"pools" => [Map.put(healthy_pool(), "health", "DEGRADED")]}}
+      assert Status.compute("online", payload) == :critical
+    end
+
+    test "returns :critical for pool capacity > 90" do
+      payload = %{"zfs_pools" => %{"pools" => [Map.put(healthy_pool(), "capacity_percent", 95)]}}
+      assert Status.compute("online", payload) == :critical
+    end
+
+    test "returns :warning for pool capacity 80..90" do
+      payload = %{"zfs_pools" => %{"pools" => [Map.put(healthy_pool(), "capacity_percent", 85)]}}
+      assert Status.compute("online", payload) == :warning
+    end
+
+    test "returns :warning for pending OS updates > 0" do
+      payload = %{
+        "zfs_pools" => %{"pools" => [healthy_pool()]},
+        "system_info" => %{"pending_updates" => 3}
+      }
+
+      assert Status.compute("online", payload) == :warning
+    end
+
+    test "returns :ok when payload is nil (never-seen host) but host is online" do
+      assert Status.compute("online", nil) == :ok
+    end
+
+    test "treats never_connected like offline" do
+      assert Status.compute("never_connected", nil) == :offline
+    end
+  end
+
+  defp healthy_pool do
+    %{
+      "name" => "rpool",
+      "health" => "ONLINE",
+      "capacity_percent" => 40
+    }
+  end
+end