defmodule Integrations.Dragonfly.Display do
  @moduledoc """
  Dashboard panel for `Integrations.Dragonfly` (same package).

  Nested under the monitor's own namespace deliberately — the package's
  top-level module name never changes, and this module's name is
  guaranteed distinct from any separately-published standalone display
  package. `Display.BundledDefault` auto-hooks this whenever
  `Integrations.Dragonfly` starts, the same as if they were still one module.
  """

  use CodeNameRaven.Display, category: :infrastructure, size_hint: :medium

  @default_port 6379

  @impl true
  def display_name, do: "Dragonfly"

  @impl true
  def compatible_monitors, do: [Integrations.Dragonfly]

  @impl true
  def render(assigns) do
    result = assigns[:result]
    assigns = Map.merge(assigns, %{result: result})

    ~H"""
    <div class="space-y-3">
      <div class="flex items-start justify-between gap-2">
        <div class="min-w-0">
          <h2 class="text-sm font-semibold text-base-content truncate">
            <%= @config.name || instance_title(@config.params) %>
          </h2>
          <p class="text-xs font-mono text-base-content/40 truncate">
            <%= instance_title(@config.params) %>
            <%= if @result && @result[:version], do: " · v#{@result.version}" %>
          </p>
        </div>
        <CodeNameRaven.MonitorComponents.status_chip status={@status} />
      </div>

      <div :if={@result} class="flex gap-2 flex-wrap">
        <CodeNameRaven.MonitorComponents.stat
          label="Latency"
          value={"#{@result.latency_ms} ms"} />
        <CodeNameRaven.MonitorComponents.stat
          :if={@result[:connected_clients]}
          label="Clients"
          value={"#{@result.connected_clients}"} />
        <CodeNameRaven.MonitorComponents.stat
          :if={@result[:ops_per_sec]}
          label="Ops/sec"
          value={"#{@result.ops_per_sec}"} />
        <CodeNameRaven.MonitorComponents.stat
          :if={@result[:hit_rate_pct]}
          label="Hit Rate"
          value={"#{@result.hit_rate_pct}%"} />
        <CodeNameRaven.MonitorComponents.stat
          :if={@result[:used_memory_bytes]}
          label="Memory"
          value={format_memory(@result)} />
      </div>

      <div :if={@result && (@result[:evicted_keys] || @result[:expired_keys])}
           class="text-xs text-base-content/50 flex gap-4">
        <span :if={@result[:evicted_keys]}>Evicted: <%= @result.evicted_keys %></span>
        <span :if={@result[:expired_keys]}>Expired: <%= @result.expired_keys %></span>
      </div>

      <div :if={@result && @result[:replication_lag]} class="text-xs text-base-content/50">
        Replication lag: <%= @result.replication_lag %> bytes
      </div>

      <CodeNameRaven.MonitorComponents.error_message message={@last_error} />
      <CodeNameRaven.MonitorComponents.check_time checked_at={@last_checked_at} />
    </div>
    """
  end

  # ---------------------------------------------------------------------------
  # Helpers
  # ---------------------------------------------------------------------------

  defp instance_title(params) do
    host = params[:host] || params["host"] || "?"
    port = parse_int(params[:port] || params["port"], @default_port)
    "#{host}:#{port}"
  end

  defp format_memory(%{used_memory_bytes: used, maxmemory_bytes: max})
       when is_integer(max) and max > 0 do
    pct = round(used / max * 100)
    "#{format_bytes(used)} / #{format_bytes(max)} (#{pct}%)"
  end
  defp format_memory(%{used_memory_bytes: used}), do: format_bytes(used)
  defp format_memory(_), do: "?"

  defp format_bytes(bytes) when is_integer(bytes) do
    cond do
      bytes >= 1_073_741_824 -> "#{Float.round(bytes / 1_073_741_824, 1)} GB"
      bytes >= 1_048_576     -> "#{Float.round(bytes / 1_048_576, 1)} MB"
      bytes >= 1024          -> "#{Float.round(bytes / 1024, 1)} KB"
      true                   -> "#{bytes} B"
    end
  end
  defp format_bytes(_), do: "?"

  defp parse_int(nil, default), do: default
  defp parse_int(v, _) when is_integer(v), do: v
  defp parse_int(v, default) when is_binary(v) do
    case Integer.parse(v) do
      {n, _} -> n
      :error -> default
    end
  end
  defp parse_int(_, default), do: default
end