defmodule ProxmoxAgent.Diagnostics.WriterTest do
  use ExUnit.Case, async: false

  alias ProxmoxAgent.Diagnostics.Writer

  setup do
    dir = Path.join(System.tmp_dir!(), "writer-#{System.unique_integer([:positive])}")
    File.mkdir_p!(dir)
    {:ok, pid} = Writer.start_link(dir: dir)

    on_exit(fn ->
      if Process.alive?(pid), do: GenServer.stop(pid)
      File.rm_rf(dir)
    end)

    %{dir: dir, pid: pid}
  end

  test "handle_cast :command appends a formatted entry to commands.log", %{dir: dir, pid: pid} do
    GenServer.cast(pid, {:command, "zpool", ["list", "-j"], {:ok, "hello body"}, 1_234})
    :ok = GenServer.call(pid, :flush)

    body = File.read!(Path.join(dir, "commands.log"))

    assert body =~ "$ zpool list -j"
    assert body =~ "exit=0"
    assert body =~ "duration=1ms"
    assert body =~ "size=10"
    assert body =~ "hello body"
    assert body =~ "=====\n"
  end

  test "handle_cast :command records errors in place of exit", %{dir: dir, pid: pid} do
    GenServer.cast(pid, {:command, "zpool", ["list"], {:error, {:enoent, "zpool"}}, 300})
    :ok = GenServer.call(pid, :flush)

    body = File.read!(Path.join(dir, "commands.log"))
    assert body =~ "error={:enoent, \"zpool\"}"
    assert body =~ "duration=0ms"
    refute body =~ "exit="
  end

  test "handle_cast :command formats non-zero exit results", %{dir: dir, pid: pid} do
    GenServer.cast(pid, {:command, "/bin/sh", ["-c", "exit 7"], {:error, {:nonzero_exit, 7, "oops"}}, 500})
    :ok = GenServer.call(pid, :flush)

    body = File.read!(Path.join(dir, "commands.log"))
    assert body =~ "exit=7"
    assert body =~ "size=4"
    assert body =~ "oops"
  end

  test "handle_cast :sample appends pretty-printed JSON to samples.log", %{dir: dir, pid: pid} do
    GenServer.cast(pid, {:sample, "fast", %{"host" => %{"load1" => 0.1}}})
    :ok = GenServer.call(pid, :flush)

    body = File.read!(Path.join(dir, "samples.log"))
    assert body =~ "kind=fast"
    assert body =~ "\"host\""
    assert body =~ "\"load1\""
    assert body =~ "=====\n"
  end

  test "multiple casts serialize and do not interleave", %{dir: dir, pid: pid} do
    for i <- 1..50 do
      GenServer.cast(pid, {:command, "cmd#{i}", [], {:ok, "body#{i}"}, 1})
    end

    :ok = GenServer.call(pid, :flush)
    body = File.read!(Path.join(dir, "commands.log"))

    # Every body1..body50 must appear exactly once, in order.
    for i <- 1..50 do
      assert body =~ "body#{i}"
    end
  end

  test "terminate closes handles cleanly", %{pid: pid} do
    ref = Process.monitor(pid)
    GenServer.stop(pid, :normal)
    assert_receive {:DOWN, ^ref, :process, ^pid, :normal}, 1000
  end
end