defmodule ToweropsWeb.DeviceLive.Index do
  @moduledoc false
  use ToweropsWeb, :live_view

  alias Towerops.Devices
  alias Towerops.Organizations.SubscriptionLimits
  alias Towerops.Sites
  alias Towerops.Snmp
  alias Towerops.Workers.DiscoveryWorker
  alias ToweropsWeb.Live.Helpers.AccessControl

  @impl true
  def mount(_params, _session, socket) do
    organization = socket.assigns.current_scope.organization
    device = Devices.list_organization_devices(organization.id)
    sites = Sites.list_organization_sites(organization.id)
    grouped_devices = group_devices_by_site(device)

    # Load device quota
    {current, limit} = SubscriptionLimits.device_quota(organization)

    {:ok,
     socket
     |> assign(:page_title, t_equipment("Devices"))
     |> assign(:timezone, socket.assigns.current_scope.timezone)
     |> assign(:device, device)
     |> assign(:grouped_devices, grouped_devices)
     |> assign(:sites_enabled, organization.use_sites)
     |> assign(:has_sites, sites != [])
     |> assign(:reorder_mode, false)
     |> assign(:device_quota, %{current: current, limit: limit})}
  end

  @impl true
  def handle_params(params, _url, socket) do
    tab = Map.get(params, "tab", "existing")
    {:noreply, apply_action(socket, socket.assigns.live_action, params, tab)}
  end

  defp apply_action(socket, :index, params, tab) do
    organization = socket.assigns.current_scope.organization

    case tab do
      "discovered" ->
        page = params |> Map.get("page", "1") |> String.to_integer()
        per_page = 20

        # Load all discovered devices - this is temporarily kept in memory for slicing
        # For very large datasets, consider database-level pagination
        all_discovered = Snmp.list_discovered_devices_for_organization(organization.id)
        total_count = length(all_discovered)
        total_pages = ceil(total_count / per_page)

        # Ensure page is within valid range
        page = max(1, min(page, max(1, total_pages)))

        offset = (page - 1) * per_page
        # Only keep the current page in assigns - don't store all_discovered
        discovered_devices = Enum.slice(all_discovered, offset, per_page)

        socket
        |> assign(:active_tab, "discovered")
        # Use temporary assign - will be cleared after render
        |> assign_new(:discovered_devices, fn -> discovered_devices end)
        |> assign(:pagination, %{
          page: page,
          per_page: per_page,
          total_count: total_count,
          total_pages: total_pages
        })

      _ ->
        socket
        |> assign(:active_tab, "existing")
        |> assign(:discovered_devices, [])
        |> assign(:pagination, nil)
    end
  end

  @impl true
  def handle_event("force_rediscover_all", _params, socket) do
    devices = socket.assigns.device
    snmp_devices = Enum.filter(devices, & &1.snmp_enabled)

    if Enum.empty?(snmp_devices) do
      {:noreply, put_flash(socket, :error, t_equipment("No SNMP-enabled devices found"))}
    else
      Enum.each(snmp_devices, fn device ->
        enqueue_discovery(device.id)
      end)

      count = length(snmp_devices)
      message = t_equipment("Discovery started for %{count} device", count: count) <> if count == 1, do: "", else: "s"

      {:noreply, put_flash(socket, :info, message)}
    end
  end

  @impl true
  def handle_event("reorder_site", %{"site_id" => site_id, "new_position" => new_position}, socket) do
    organization = socket.assigns.current_scope.organization

    # Verify site belongs to current organization
    case AccessControl.verify_site_access(site_id, organization.id) do
      {:ok, _site} ->
        perform_site_reorder(socket, site_id, new_position, organization.id)

      {:error, :not_found} ->
        {:noreply, put_flash(socket, :error, t_equipment("Site not found"))}

      {:error, :unauthorized} ->
        {:noreply, put_flash(socket, :error, t_equipment("You don't have access to this site"))}
    end
  end

  @impl true
  def handle_event("reorder_device", %{"device_id" => device_id, "new_position" => new_position}, socket) do
    organization = socket.assigns.current_scope.organization

    # Verify device belongs to current organization
    case AccessControl.verify_device_access(device_id, organization.id) do
      {:ok, _device} ->
        perform_device_reorder(socket, device_id, new_position, organization.id)

      {:error, :not_found} ->
        {:noreply, put_flash(socket, :error, t_equipment("Device not found"))}

      {:error, :unauthorized} ->
        {:noreply, put_flash(socket, :error, t_equipment("You don't have access to this device"))}
    end
  end

  @impl true
  def handle_event("toggle_reorder_mode", _params, socket) do
    {:noreply, assign(socket, :reorder_mode, !socket.assigns.reorder_mode)}
  end

  @impl true
  def handle_event("reset_order", _params, socket) do
    organization_id = socket.assigns.current_scope.organization.id

    Sites.reset_site_order(organization_id)
    Devices.reset_organization_device_order(organization_id)

    # Reload devices with alphabetical order
    devices = Devices.list_organization_devices(organization_id)
    grouped_devices = group_devices_by_site(devices)

    {:noreply,
     socket
     |> assign(:device, devices)
     |> assign(:grouped_devices, grouped_devices)
     |> put_flash(:info, t_equipment("Order reset to alphabetical"))}
  end

  def handle_event("add_discovered_device", params, socket) do
    identifier = Jason.decode!(params["identifier"])
    discovered = Enum.find(socket.assigns.discovered_devices, &(&1.identifier == identifier))

    prefill_params = %{
      "name" => discovered.hostname || "",
      "ip_address" => List.first(discovered.ip_addresses) || "",
      "snmp_enabled" => "true"
    }

    {:noreply, push_navigate(socket, to: ~p"/devices/new?#{prefill_params}")}
  end

  defp perform_site_reorder(socket, site_id, new_position, organization_id) do
    position = if is_integer(new_position), do: new_position, else: String.to_integer(new_position)
    result = Sites.reorder_site(site_id, position)
    perform_reorder(socket, result, "site", organization_id)
  end

  defp perform_device_reorder(socket, device_id, new_position, organization_id) do
    position = if is_integer(new_position), do: new_position, else: String.to_integer(new_position)
    result = Devices.reorder_device(device_id, position)
    perform_reorder(socket, result, "device", organization_id)
  end

  defp perform_reorder(socket, reorder_result, resource_name, organization_id) do
    case reorder_result do
      {:ok, _} ->
        # Reload devices with updated order
        devices = Devices.list_organization_devices(organization_id)
        grouped_devices = group_devices_by_site(devices)

        success_message =
          case resource_name do
            "site" -> t_equipment("Site order updated")
            "device" -> t_equipment("Device order updated")
          end

        {:noreply,
         socket
         |> assign(:device, devices)
         |> assign(:grouped_devices, grouped_devices)
         |> put_flash(:info, success_message)}

      {:error, _changeset} ->
        error_message =
          case resource_name do
            "site" -> t_equipment("Failed to reorder site")
            "device" -> t_equipment("Failed to reorder device")
          end

        {:noreply, put_flash(socket, :error, error_message)}
    end
  end

  defp enqueue_discovery(device_id) do
    if Application.get_env(:towerops, :env) == :test do
      _ = Task.start(fn -> Snmp.discover_device(Devices.get_device!(device_id)) end)
    else
      DiscoveryWorker.enqueue(device_id)
    end
  end

  # Group devices by site with statistics
  # Sites and devices are sorted by display_order (with alphabetical fallback)
  defp group_devices_by_site(devices) do
    devices
    |> Enum.group_by(& &1.site)
    |> Enum.map(fn {site, site_devices} ->
      {site, site_devices, calculate_site_stats(site_devices)}
    end)
    |> Enum.sort_by(
      fn {site, _devices, _stats} ->
        if site do
          {site.display_order || 999_999, site.name}
        else
          # Put devices without sites first (display_order 0)
          {0, ""}
        end
      end,
      :asc
    )
  end

  defp calculate_site_stats(devices) do
    status_counts = Enum.frequencies_by(devices, & &1.status)

    %{
      total: length(devices),
      up: Map.get(status_counts, :up, 0),
      down: Map.get(status_counts, :down, 0),
      unknown: Map.get(status_counts, :unknown, 0)
    }
  end

  defp device_type_icon(:router), do: "hero-signal"
  defp device_type_icon(:switch), do: "hero-squares-2x2"
  defp device_type_icon(:wireless), do: "hero-wifi"
  defp device_type_icon(:server), do: "hero-server"
  defp device_type_icon(:workstation), do: "hero-computer-desktop"
  defp device_type_icon(_), do: "hero-question-mark-circle"

  defp device_type_label(type) do
    type |> to_string() |> String.capitalize()
  end

  # Generate pagination range with ellipsis for large page counts
  # Shows: [1] ... [4] [5] [6] ... [20] when on page 5 of 20
  defp pagination_range(current_page, total_pages) do
    cond do
      total_pages <= 7 ->
        # Show all pages if 7 or fewer
        Enum.to_list(1..total_pages)

      current_page <= 4 ->
        # Near the start
        [1, 2, 3, 4, 5, :ellipsis, total_pages]

      current_page >= total_pages - 3 ->
        # Near the end
        [1, :ellipsis, total_pages - 4, total_pages - 3, total_pages - 2, total_pages - 1, total_pages]

      true ->
        # In the middle
        [1, :ellipsis, current_page - 1, current_page, current_page + 1, :ellipsis, total_pages]
    end
  end
end