faux_mq

defmodule FauxMQ do
  @moduledoc """
  FauxMQ - a controllable dummy AMQP 0-9-1 broker for integration testing.

  FauxMQ runs a real TCP server that speaks the AMQP 0-9-1 protocol and allows
  you to control broker behaviour from Elixir tests. It is designed for testing
  ejabberd/XMPP and other systems that use AMQP for backend integration.

  Typical usage:

    * start a FauxMQ server on a random port
    * inject its `endpoint/1` into your system-under-test configuration
    * define expectations and stubs using `stub/3` and `expect/4`
    * run assertions against collected call history via `calls/1`

  This module exposes the main public API. All functions are dialyzer-friendly
  and documented with types.
  """

  alias FauxMQ.{MockServer, Server, Types}

  @type server :: pid()

  @doc """
  Starts a FauxMQ server process linked to the caller.

  Options:

    * `:host` - IP tuple (default: application `:default_host`)
    * `:port` - TCP port; `0` means use application `:default_port` (see `FauxMQ.Server` / README for binding behaviour)
  """
  @spec start_link(keyword()) :: GenServer.on_start()
  def start_link(opts \\ []) do
    Server.start_link(opts)
  end

  @doc """
  Returns a child spec for use in supervision trees.
  """
  @spec child_spec(keyword()) :: Supervisor.child_spec()
  def child_spec(opts) do
    %{
      id: Keyword.get(opts, :id, __MODULE__),
      start: {__MODULE__, :start_link, [opts]},
      type: :worker,
      restart: :temporary,
      shutdown: 5_000
    }
  end

  @doc """
  Gracefully stops a FauxMQ server.
  """
  @spec stop(server()) :: :ok
  def stop(server) do
    Server.stop(server)
  end

  @doc """
  Returns the TCP port that the server is listening on.
  """
  @spec port(server()) :: :inet.port_number()
  def port(server) do
    Server.port(server)
  end

  @doc """
  Returns the host IP tuple that the server is bound to.
  """
  @spec host(server()) :: :inet.ip_address()
  def host(server) do
    Server.host(server)
  end

  @doc """
  Returns a convenient endpoint map `%{host: host, port: port}`.
  """
  @spec endpoint(server()) :: %{host: :inet.ip_address(), port: :inet.port_number()}
  def endpoint(server) do
    %{host: host(server), port: port(server)}
  end

  @doc """
  Registers a stub rule on the given server.

  The simple form `stub(server, match, action)` creates a rule that will be
  applied whenever an incoming AMQP method matches the given `match` pattern.
  The `action` controls how the server responds.

  See `FauxMQ.Types.match_spec/0` and `FauxMQ.Types.action_spec/0` for details.
  """
  @spec stub(server(), Types.match_spec(), Types.action_spec()) :: :ok
  def stub(server, match, action) do
    MockServer.stub(server, match, action)
  end

  @doc """
  Registers an expectation on the given server.

  Expectations are like stubs but are intended for asserting that certain calls
  happened a given number of times. The `times` argument controls how many
  times the rule may fire before it is removed.
  """
  @spec expect(server(), Types.match_spec(), non_neg_integer(), Types.action_spec()) :: :ok
  def expect(server, match, times, action) when times >= 0 do
    MockServer.expect(server, match, times, action)
  end

  @doc """
  Injects a delivery into the server for the specified logical queue/consumer.

  This is useful for tests that want to drive messages to consumers without
  going through `basic.publish` semantics.
  """
  @spec push_delivery(server(), Types.push_delivery_spec()) :: :ok
  def push_delivery(server, delivery) do
    MockServer.push_delivery(server, delivery)
  end

  @doc """
  Injects a raw AMQP frame-level action initiated by the server.
  """
  @spec push_frame(server(), Types.push_frame_spec()) :: :ok
  def push_frame(server, frame_spec) do
    MockServer.push_frame(server, frame_spec)
  end

  @doc """
  Returns the history of handled AMQP calls for the given server.
  """
  @spec calls(server()) :: [Types.call_record()]
  def calls(server) do
    MockServer.calls(server)
  end

  @doc """
  Resets mock rules and call history on the embedded `MockServer` only.

  In-memory AMQP queues/bindings/consumers on `FauxMQ.Server` are **not** cleared;
  use `reset_test_broker_state/1` between tests when published messages must not linger.
  """
  @spec reset!(server()) :: :ok
  def reset!(server) do
    MockServer.reset!(server)
  end

  @doc """
  Clears mock rules/history **and** in-memory queues, bindings, and consumers.

  TCP connections stay open. Prefer this between ExUnit cases so long `mix test`
  runs do not need a Docker/BEAM restart to match a clean broker.
  """
  @spec reset_test_broker_state(server()) :: :ok
  def reset_test_broker_state(server) do
    Server.reset_test_broker_state(server)
  end
end