defmodule Membrane.TCP.Socket do
  @moduledoc false

  @enforce_keys [:connection_side, :port_no, :ip_address]
  defstruct [
    :port_no,
    :ip_address,
    :socket_handle,
    :connection_side,
    state: :uninitialized,
    sock_opts: []
  ]

  @type t :: %__MODULE__{
          ip_address: :inet.socket_address(),
          port_no: :inet.port_number(),
          socket_handle: :gen_tcp.socket() | nil,
          state: :listening | :connected | :uninitialized,
          connection_side: :server | :client,
          sock_opts: [:gen_tcp.option()]
        }

  @spec listen(socket :: t()) :: {:ok, listen_socket :: t()} | {:error, :inet.posix()}
  def listen(%__MODULE__{port_no: port_no, ip_address: ip, sock_opts: sock_opts} = local_socket) do
    listen_result =
      :gen_tcp.listen(port_no, [:binary, ip: ip, active: false, reuseaddr: true] ++ sock_opts)

    with {:ok, listen_socket_handle} <- listen_result,
         # Port may change if 0 is used, ip - when either `:any` or `:loopback` is passed
         {:ok, {real_ip_addr, real_port_no}} <- :inet.sockname(listen_socket_handle) do
      updated_socket = %__MODULE__{
        local_socket
        | socket_handle: listen_socket_handle,
          port_no: real_port_no,
          ip_address: real_ip_addr,
          state: :listening
      }

      {:ok, updated_socket}
    end
  end

  @spec accept(listening_socket :: t()) ::
          {:ok, connected_socket :: t()} | {:error, :inet.posix()}
  def accept(%__MODULE__{socket_handle: socket_handle, state: :listening} = socket) do
    accept_result = :gen_tcp.accept(socket_handle)

    with {:ok, connected_socket_handle} <- accept_result do
      :gen_tcp.close(socket_handle)

      updated_socket = %__MODULE__{
        socket
        | socket_handle: connected_socket_handle,
          state: :connected
      }

      {:ok, updated_socket}
    end
  end

  @spec connect(local :: t(), target :: t()) :: {:ok, t()} | {:error, :inet.posix()}
  def connect(
        %__MODULE__{port_no: local_port_no, ip_address: local_ip, sock_opts: sock_opts} =
          local_socket,
        %__MODULE__{port_no: target_port_no, ip_address: target_ip}
      ) do
    connect_result =
      :gen_tcp.connect(
        target_ip,
        target_port_no,
        [:binary, ip: local_ip, port: local_port_no, active: false, reuseaddr: true] ++ sock_opts
      )

    with {:ok, socket_handle} <- connect_result,
         # Port may change if 0 is used, ip - when either `:any` or `:loopback` is passed
         {:ok, {real_ip_addr, real_port_no}} <- :inet.sockname(socket_handle) do
      updated_socket = %__MODULE__{
        local_socket
        | socket_handle: socket_handle,
          port_no: real_port_no,
          ip_address: real_ip_addr,
          state: :connected
      }

      {:ok, updated_socket}
    end
  end

  @spec close(socket :: t()) :: t()
  def close(%__MODULE__{socket_handle: handle} = socket) when is_port(handle) do
    :ok = :gen_tcp.close(handle)
    %__MODULE__{socket | socket_handle: nil, state: :uninitialized}
  end

  @spec send(local_socket :: t(), payload :: Membrane.Payload.t()) ::
          :ok | {:error, :closed | :inet.posix()}
  def send(%__MODULE__{socket_handle: socket_handle}, payload) when is_port(socket_handle) do
    :gen_tcp.send(socket_handle, payload)
  end

  @spec recv(socket :: t(), timeout :: non_neg_integer()) ::
          {:ok, Membrane.Payload.t()} | {:error, :closed | :timeout | :inet.posix()}
  def recv(%__MODULE__{socket_handle: socket_handle}, timeout \\ 0) do
    :gen_tcp.recv(socket_handle, 0, timeout)
  end
end