defmodule RNS.IdentityStore do
  @moduledoc """
  Manages an ets table that stores all identities and their ratchets.
  """

  @spec child_spec(any()) :: map()
  def child_spec(_args) do
    %{
      id: __MODULE__,
      start: {__MODULE__, :start_link, []}
    }
  end

  @spec start_link() :: {:ok, pid()}
  def start_link() do
    pid = spawn_link(__MODULE__, :init, [])
    {:ok, pid}
  end

  # Client
  @doc "Find an identity in the store using its hash."
  @spec fetch(RNS.Identity.hash()) :: {:ok, RNS.Identity.t()} | {:error, :not_found}
  def fetch(identity_hash) do
    case :ets.lookup(:identities, identity_hash) do
      [identity] ->
        # Check if the identity has expired, if it has, remove it.
        if RNS.Identity.expired?(identity) do
          delete(RNS.Identity.hash(identity))
          {:error, :not_found}
        else
          {:ok, identity}
        end

      [] ->
        {:error, :not_found}
    end
  end

  @doc """
  Put an identity into the store.
  TODO: If the identity is already in the store, verify it IS the same and update it(ratchets).
  """
  @spec put(RNS.Identity.t()) :: boolean()
  def put(identity) do
    :ets.insert(:identities, identity)
  end

  @doc "Delete an identity from the store using its hash."
  @spec delete(RNS.Identity.hash()) :: boolean()
  def delete(identity_hash) do
    :ets.delete(:identities, identity_hash)
  end

  # Callbacks
  @spec init() :: :ok
  def init() do
    :ets.new(:identities, [
      {:read_concurrency, true},
      {:write_concurrency, true},
      {:keypos, RNS.Identity.hash_position() + 1},
      :public,
      :named_table
    ])

    Process.sleep(:infinity)
  end
end