defmodule EventStore do
  @moduledoc """
  EventStore client API to read and write events to a logical event stream

  Each of the following client functions expects to receive an already started & initialised `EventStore.Storage` pid.

      {:ok, store} = EventStore.Storage.start_link
      EventStore.Storage.initialize_store!(store)
  """

  alias EventStore.Storage

  @doc """
  Append one or more events to a stream atomically.
  
  `stream_uuid` is used to uniquely identify a stream. It should be a UUID string of exactly 36 characters.

  `expected_version` is used for optimistic concurrency.
  Specify 0 for the creation of a new stream. An `{:error, wrong_expected_version}` response will be returned if the stream already exists.
  Any positive number will be used to ensure you can only append to the stream if it is at exactly that version.

  `events` is a list of `%EventStore.EventData{}` structs
  """
  def append_to_stream(storage, stream_uuid, expected_version, events) do
    Storage.append_to_stream(storage, stream_uuid, expected_version, events)
  end

  @doc """
  Reads the requested number of events from the given stream, in the order in which they were originally written.

  `stream_uuid` is used to uniquely identify a stream. It should be a UUID string of exactly 36 characters.

  `start_version` the version number of the first event to read

  `count` optionally, the maximum number of events to read. If not set it will return all events from the stream.
  """
  def read_stream_forward(storage, stream_uuid, start_version, count \\ nil) do
    Storage.read_stream_forward(storage, stream_uuid, start_version, count)
  end
end