defmodule JSONRPC2.Spec.Batch do
  @moduledoc """
  `JSONRPC2.Spec.Batch` allows you to pack operations (function calls and notification sending) that can later be executed into a single request.

  Examples:

      iex> alias JSONRPC2.Spec.Batch
      iex> Batch.notify("event_name", ["arg1", "arg2"]) |> Batch.call("func_name", ["arg1", "arg2"], 1)
      %JSONRPC2.Spec.Batch{
        calls: %{
          1 => %JSONRPC2.Spec.Request{
            id: 1,
            method: "func_name",
            params: ["arg1", "arg2"],
            jsonrpc: "2.0"
          }
        },
        notifies: [
          %JSONRPC2.Spec.Request{
            id: nil,
            method: "event_name",
            params: ["arg1", "arg2"],
            jsonrpc: "2.0"
          }
        ]
      }
  """

  @type t :: %__MODULE__{
    calls: map(),
    notifies: [map()]
  }

  alias JSONRPC2.Spec.Request
  alias JSONRPC2.Spec

  defstruct [calls: %{}, notifies: []]

  @doc """
  Prepare data to send notification.

  The `params` could be either map or list.

  Examples:

      iex> alias JSONRPC2.Spec.Batch
      iex> Batch.notify("name", ["arg1", "arg2"])
      %JSONRPC2.Spec.Batch{
        calls: %{},
        notifies: [
          %JSONRPC2.Spec.Request{
            id: nil,
            method: "name",
            params: ["arg1", "arg2"],
            jsonrpc: "2.0"
          }
        ]
      }

  Functions can be piped:

      iex> Batch.notify("event_name", ["arg1", "arg2"]) |> Batch.call("func_name", ["arg1", "arg2"], 1)
      %JSONRPC2.Spec.Batch{
        calls: %{
          1 => %JSONRPC2.Spec.Request{
            id: 1,
            method: "func_name",
            params: ["arg1", "arg2"],
            jsonrpc: "2.0"
          }
        },
        notifies: [
          %JSONRPC2.Spec.Request{
            id: nil,
            method: "event_name",
            params: ["arg1", "arg2"],
            jsonrpc: "2.0"
          }
        ]
      }
  """
  @spec notify(Spec.method(), Spec.params()) :: t()
  def notify(method, params) do
    notify(%__MODULE__{}, method, params)
  end

  @spec notify(t(), Spec.method(), Spec.params()) :: t()
  def notify(%__MODULE__{notifies: notifies} = req, method, params) when is_binary(method) do
    %__MODULE__{req | notifies: notifies ++ [Request.new(method, params, nil)]}
  end

  @doc """
  Prepare data to call function.

  The `params` could be either map or list.

  The `id` must be unique within `Batch`.

  Examples:

      iex> alias JSONRPC2.Spec.Batch
      iex> Batch.call("name", ["arg1", "arg2"], 1)
      %JSONRPC2.Spec.Batch{
        calls: %{
          1 => %JSONRPC2.Spec.Request{
            id: 1,
            method: "name",
            params: ["arg1", "arg2"],
            jsonrpc: "2.0"
          }
        },
        notifies: []
      }

  Functions can be piped:

      iex> Batch.notify("event_name", ["arg1", "arg2"]) |> Batch.call("func_name", ["arg1", "arg2"], 1)
      %JSONRPC2.Spec.Batch{
        calls: %{
          1 => %JSONRPC2.Spec.Request{
            id: 1,
            method: "func_name",
            params: ["arg1", "arg2"],
            jsonrpc: "2.0"
          }
        },
        notifies: [
          %JSONRPC2.Spec.Request{
            id: nil,
            method: "event_name",
            params: ["arg1", "arg2"],
            jsonrpc: "2.0"
          }
        ]
      }
  """
  @spec call(Spec.method(), Spec.params(), Spec.id()) :: t()
  def call(method, params, id) do
    call(%__MODULE__{}, method, params, id)
  end

  @spec call(t(), Spec.method(), Spec.params(), Spec.id()) :: t()
  def call(%__MODULE__{calls: calls} = req, method, params, id) when is_binary(method) do
    %__MODULE__{req | calls: Map.put(calls, id, Request.new(method, params, id))}
  end
end