feat: support firmware uploads, OTA pushes

lib/localiser/domain/firmware.ex

@@ -0,0 +1,37 @@
+defmodule Localiser.Domain.Firmware do
+  @moduledoc false
+
+  def firmware_dir do
+    dir = Application.app_dir(:localiserd, "priv/firmware")
+    File.mkdir_p!(dir)
+    dir
+  end
+
+  def store(version, %Plug.Upload{path: tmp_path}) do
+    dest = Path.join(firmware_dir(), "#{version}.bin")
+    case File.cp(tmp_path, dest) do
+      :ok -> {:ok, version}
+      {:error, reason} -> {:error, reason}
+    end
+  end
+
+  def list do
+    dir = firmware_dir()
+
+    dir
+    |> File.ls!()
+    |> Enum.filter(&String.ends_with?(&1, ".bin"))
+    |> Enum.map(fn filename ->
+      version = String.replace_suffix(filename, ".bin", "")
+      path = Path.join(dir, filename)
+      stat = File.stat!(path, time: :posix)
+      %{version: version, size: stat.size, uploaded_at: stat.mtime}
+    end)
+    |> Enum.sort_by(& &1.uploaded_at, :desc)
+  end
+
+  def get(version) do
+    path = Path.join(firmware_dir(), "#{version}.bin")
+    if File.exists?(path), do: {:ok, path}, else: :not_found
+  end
+end