defmodule Aerospike.Runtime.TxnMonitor do
  @moduledoc false

  import Bitwise

  alias Aerospike.Command.UnaryCommand
  alias Aerospike.Command.UnarySupport
  alias Aerospike.Error
  alias Aerospike.Key
  alias Aerospike.Op.List, as: ListOp
  alias Aerospike.Protocol.AsmMsg
  alias Aerospike.Protocol.AsmMsg.Field
  alias Aerospike.Protocol.AsmMsg.Operation
  alias Aerospike.Protocol.AsmMsg.Value
  alias Aerospike.Protocol.Message
  alias Aerospike.Protocol.Response
  alias Aerospike.Protocol.ResultCode
  alias Aerospike.Runtime.TxnOps
  alias Aerospike.Txn

  @monitor_set "<ERO~MRT"
  @keyds_list_policy [order: :ordered, flags: [:add_unique, :no_fail, :partial]]

  @doc false
  @spec monitor_key(Txn.t(), String.t()) :: Key.t()
  def monitor_key(%Txn{} = txn, namespace) when is_binary(namespace) do
    Key.new(namespace, @monitor_set, txn.id)
  end

  @doc false
  @spec register_key(atom(), Txn.t(), Key.t(), keyword()) :: :ok | {:error, Error.t()}
  def register_key(conn_name, %Txn{} = txn, %Key{} = cmd_key, opts \\ []) do
    with :ok <- TxnOps.verify_command(conn_name, txn),
         false <- TxnOps.write_exists?(conn_name, txn, cmd_key),
         :ok <- TxnOps.set_namespace(conn_name, txn, cmd_key.namespace) do
      do_register_key(conn_name, txn, cmd_key, opts)
    else
      true -> :ok
      {:error, _} = err -> err
    end
  end

  defp do_register_key(conn_name, txn, cmd_key, opts) do
    ns = cmd_key.namespace
    mkey = monitor_key(txn, ns)
    input = monitor_input(:register, conn_name, txn, ns, cmd_key, mkey, opts)

    case run_monitor_command(conn_name, mkey, opts, input) do
      {:ok, _} -> :ok
      {:error, _} = err -> err
    end
  end

  defp register_ops(conn_name, txn, cmd_key) do
    append_op = ListOp.append("keyds", cmd_key.digest, policy: @keyds_list_policy)

    if TxnOps.monitor_exists?(conn_name, txn) do
      [append_op]
    else
      put_id_ops = Value.encode_bin_operations(%{"id" => txn.id})
      put_id_ops ++ [append_op]
    end
  end

  @doc false
  @spec mark_roll_forward(atom(), Txn.t(), keyword()) :: :ok | {:error, Error.t()}
  def mark_roll_forward(conn_name, %Txn{} = txn, opts \\ []) do
    with {:ok, ns} <- fetch_namespace(conn_name, txn) do
      mkey = monitor_key(txn, ns)
      input = monitor_input(:roll_forward, conn_name, txn, ns, nil, mkey, opts)

      case run_monitor_command(conn_name, mkey, opts, input) do
        {:ok, _} -> :ok
        {:error, _} = err -> err
      end
    end
  end

  @doc false
  @spec close(atom(), Txn.t(), keyword()) :: :ok | {:error, Error.t()}
  def close(conn_name, %Txn{} = txn, opts \\ []) do
    with {:ok, ns} <- fetch_namespace(conn_name, txn) do
      mkey = monitor_key(txn, ns)
      input = monitor_input(:close, conn_name, txn, ns, nil, mkey, opts)

      case run_monitor_command(conn_name, mkey, opts, input) do
        {:ok, _} -> :ok
        {:error, _} = err -> err
      end
    end
  end

  defp run_monitor_command(conn_name, route_key, opts, input) do
    with {:ok, policy} <- UnarySupport.write_policy(conn_name, opts) do
      UnarySupport.run_command(conn_name, route_key, policy, monitor_command(), input)
    end
  end

  defp monitor_command do
    UnaryCommand.new!(
      name: __MODULE__,
      dispatch: :write,
      build_request: &encode_monitor_request/1,
      parse_response: &parse_monitor_response/2
    )
  end

  defp monitor_input(kind, conn_name, txn, namespace, cmd_key, mkey, opts) do
    %{
      kind: kind,
      conn_name: conn_name,
      txn: txn,
      namespace: namespace,
      digest: mkey.digest,
      opts: opts,
      operations: monitor_operations(kind, conn_name, txn, cmd_key),
      info2: monitor_info2(kind),
      expiration: monitor_expiration(kind, txn)
    }
  end

  defp monitor_operations(:register, conn_name, txn, cmd_key) do
    register_ops(conn_name, txn, cmd_key)
  end

  defp monitor_operations(:roll_forward, _conn_name, _txn, _cmd_key) do
    Value.encode_bin_operations(%{"fwd" => true})
  end

  defp monitor_operations(:close, _conn_name, _txn, _cmd_key), do: []

  defp monitor_info2(:register) do
    AsmMsg.info2_write() ||| AsmMsg.info2_respond_all_ops()
  end

  defp monitor_info2(:roll_forward), do: AsmMsg.info2_write()

  defp monitor_info2(:close) do
    AsmMsg.info2_write() ||| AsmMsg.info2_delete() ||| AsmMsg.info2_durable_delete()
  end

  defp monitor_expiration(:register, %Txn{} = txn), do: div(txn.timeout, 1000)
  defp monitor_expiration(_kind, _txn), do: 0

  defp encode_monitor_request(%{
         namespace: namespace,
         digest: digest,
         info2: info2,
         expiration: expiration,
         operations: operations
       }) do
    encode_monitor_msg(namespace, digest, info2, expiration, operations)
  end

  defp parse_monitor_response(body, %{kind: :register, conn_name: conn_name, txn: txn}) do
    UnarySupport.parse_as_msg(body, fn msg ->
      with :ok <- check_result_code(msg) do
        set_monitor_deadline(msg, conn_name, txn)
      end
    end)
  end

  defp parse_monitor_response(body, _input) do
    UnarySupport.parse_as_msg(body, fn msg ->
      case check_result_code(msg) do
        :ok -> {:ok, :ok}
        {:error, _} = err -> err
      end
    end)
  end

  defp fetch_namespace(conn_name, txn) do
    case TxnOps.get_tracking(conn_name, txn) do
      {:ok, %{namespace: ns}} when is_binary(ns) ->
        {:ok, ns}

      {:ok, %{namespace: nil}} ->
        {:error, %Error{code: :parameter_error, message: "transaction has no namespace set"}}

      {:error, :not_found} ->
        {:error, %Error{code: :parameter_error, message: "transaction not initialized"}}
    end
  end

  @doc false
  @spec encode_monitor_msg(String.t(), binary(), non_neg_integer(), non_neg_integer(), [
          Operation.t()
        ]) :: iodata()
  def encode_monitor_msg(namespace, digest, info2, expiration, operations) do
    %AsmMsg{
      info2: info2,
      expiration: expiration,
      fields: [
        Field.namespace(namespace),
        Field.set(@monitor_set),
        Field.digest(digest)
      ],
      operations: operations
    }
    |> AsmMsg.encode()
    |> Message.encode_as_msg_iodata()
  end

  @doc false
  def check_result_code(%AsmMsg{result_code: 0}), do: :ok

  @doc false
  def check_result_code(%AsmMsg{result_code: code}) do
    case ResultCode.from_integer(code) do
      {:ok, atom} ->
        {:error, Error.from_result_code(atom)}

      {:error, _} ->
        {:error, Error.from_result_code(:server_error, message: "result code #{code}")}
    end
  end

  defp set_monitor_deadline(msg, conn_name, txn) do
    case Response.extract_mrt_deadline(msg) do
      {:ok, deadline} ->
        TxnOps.set_deadline(conn_name, txn, deadline)
        {:ok, :ok}

      :none ->
        {:ok, :ok}
    end
  end
end