defmodule ToweropsWeb.Api.V1.MibController do
  @moduledoc """
  API controller for managing SNMP MIB files.

  Allows uploading MIB files to the persistent storage for use with MIB name translation.

  All endpoints require superuser API token authentication.
  """

  use ToweropsWeb, :controller

  require Logger

  @mib_dir Application.compile_env(:towerops, :mib_dir, "/app/mibs")

  @doc """
  Upload a MIB file or archive (.tar.gz, .zip) containing MIB files.

  Requires superuser API token.

  ## Request

      POST /api/v1/mibs
      Content-Type: multipart/form-data

      file: <mib_file>
      vendor: <vendor_name> (optional)

  ## Response

      201 Created
      {
        "status": "ok",
        "message": "Successfully uploaded MIB file",
        "vendor": "mikrotik",
        "files_count": 15
      }
  """
  def upload(conn, params) do
    with :ok <- require_superuser(conn) do
      case params["file"] do
        %Plug.Upload{} = upload ->
          vendor = params["vendor"] || "custom"
          handle_upload(conn, upload, vendor)

        _ ->
          conn
          |> put_status(:bad_request)
          |> json(%{error: "Missing file parameter"})
      end
    end
  end

  @doc """
  List all available MIB vendors.

  Requires superuser API token.

  ## Response

      200 OK
      {
        "vendors": ["mikrotik", "cisco", "ubiquiti", ...],
        "total_files": 1234
      }
  """
  def index(conn, _params) do
    with :ok <- require_superuser(conn) do
      case list_mib_vendors() do
        {:ok, vendors, total_files} ->
          json(conn, %{
            vendors: vendors,
            total_files: total_files
          })

        {:error, reason} ->
          conn
          |> put_status(:internal_server_error)
          |> json(%{error: inspect(reason)})
      end
    end
  end

  @doc """
  Delete MIB files for a specific vendor.

  Requires superuser API token.

  ## Request

      DELETE /api/v1/mibs/:vendor

  ## Response

      200 OK
      {
        "status": "ok",
        "message": "Deleted MIB files for vendor: mikrotik"
      }
  """
  def delete(conn, %{"vendor" => vendor}) do
    with :ok <- require_superuser(conn) do
      vendor_dir = Path.join(@mib_dir, vendor)

      if File.exists?(vendor_dir) do
        case File.rm_rf(vendor_dir) do
          {:ok, _files} ->
            Logger.info("Deleted MIB files for vendor: #{vendor}")

            json(conn, %{
              status: "ok",
              message: "Deleted MIB files for vendor: #{vendor}"
            })

          {:error, reason, file} ->
            Logger.error("Failed to delete MIB files for #{vendor}: #{file} - #{inspect(reason)}")

            conn
            |> put_status(:internal_server_error)
            |> json(%{error: "Failed to delete MIB files"})
        end
      else
        conn
        |> put_status(:not_found)
        |> json(%{error: "Vendor not found: #{vendor}"})
      end
    end
  end

  # Private functions

  defp require_superuser(conn) do
    user = conn.assigns[:current_user]

    if !user || !user.is_superuser do
      Logger.warning("MIB management attempted by non-superuser: #{inspect(user && user.email)}")

      conn
      |> put_status(:forbidden)
      |> json(%{error: "Superuser access required. Only API tokens created by superusers can manage MIB files."})
      |> halt()
    else
      :ok
    end
  end

  defp handle_upload(conn, upload, vendor) do
    vendor_dir = Path.join(@mib_dir, vendor)
    File.mkdir_p!(vendor_dir)

    cond do
      String.ends_with?(upload.filename, ".tar.gz") or String.ends_with?(upload.filename, ".tgz") ->
        extract_tarball(conn, upload, vendor_dir, vendor)

      String.ends_with?(upload.filename, ".zip") ->
        extract_zip(conn, upload, vendor_dir, vendor)

      true ->
        copy_single_file(conn, upload, vendor_dir, vendor)
    end
  end

  defp extract_tarball(conn, upload, vendor_dir, vendor) do
    case System.cmd("tar", ["-xzf", upload.path, "-C", vendor_dir]) do
      {_output, 0} ->
        files_count = count_files(vendor_dir)
        Logger.info("Extracted #{files_count} MIB files for vendor: #{vendor}")

        conn
        |> put_status(:created)
        |> json(%{
          status: "ok",
          message: "Successfully extracted MIB archive",
          vendor: vendor,
          files_count: files_count
        })

      {error, exit_code} ->
        Logger.error("Failed to extract tarball: #{error}")

        conn
        |> put_status(:bad_request)
        |> json(%{error: "Failed to extract archive (exit code: #{exit_code})"})
    end
  end

  defp extract_zip(conn, upload, vendor_dir, vendor) do
    case System.cmd("unzip", ["-o", upload.path, "-d", vendor_dir]) do
      {_output, 0} ->
        files_count = count_files(vendor_dir)
        Logger.info("Extracted #{files_count} MIB files for vendor: #{vendor}")

        conn
        |> put_status(:created)
        |> json(%{
          status: "ok",
          message: "Successfully extracted MIB archive",
          vendor: vendor,
          files_count: files_count
        })

      {error, exit_code} ->
        Logger.error("Failed to extract zip: #{error}")

        conn
        |> put_status(:bad_request)
        |> json(%{error: "Failed to extract archive (exit code: #{exit_code})"})
    end
  end

  defp copy_single_file(conn, upload, vendor_dir, vendor) do
    target_path = Path.join(vendor_dir, upload.filename)

    # Check if target already exists as a directory
    if File.dir?(target_path) do
      Logger.warning("Cannot upload MIB file: target path is a directory: #{upload.filename} for vendor: #{vendor}")

      conn
      |> put_status(:bad_request)
      |> json(%{error: "Cannot upload: filename conflicts with existing directory"})
    else
      case File.cp(upload.path, target_path) do
        :ok ->
          Logger.info("Uploaded MIB file: #{upload.filename} for vendor: #{vendor}")

          conn
          |> put_status(:created)
          |> json(%{
            status: "ok",
            message: "Successfully uploaded MIB file",
            vendor: vendor,
            filename: upload.filename
          })

        {:error, :eisdir} ->
          Logger.error("Failed to copy MIB file - target is a directory: #{upload.filename} for vendor: #{vendor}")

          conn
          |> put_status(:bad_request)
          |> json(%{error: "Cannot upload: filename conflicts with existing directory"})

        {:error, reason} ->
          Logger.error("Failed to copy MIB file: #{inspect(reason)}")

          conn
          |> put_status(:internal_server_error)
          |> json(%{error: "Failed to upload file: #{inspect(reason)}"})
      end
    end
  end

  defp list_mib_vendors do
    if File.exists?(@mib_dir) do
      vendors =
        @mib_dir
        |> File.ls!()
        |> Enum.filter(fn name ->
          path = Path.join(@mib_dir, name)
          File.dir?(path) and name != "lost+found"
        end)
        |> Enum.sort()

      total_files = count_files(@mib_dir)

      {:ok, vendors, total_files}
    else
      {:ok, [], 0}
    end
  rescue
    e ->
      Logger.error("Failed to list MIB vendors: #{inspect(e)}")
      {:error, e}
  end

  defp count_files(dir) do
    dir
    |> Path.join("**/*")
    |> Path.wildcard()
    |> Enum.count(&File.regular?/1)
  end
end