defmodule SpacetimeDB.Types do
  @moduledoc "Structs representing SpacetimeDB WebSocket protocol types."

  # ---------------------------------------------------------------------------
  # Identifiers
  # ---------------------------------------------------------------------------

  defmodule Identity do
    @moduledoc "A 256-bit public key identifying a SpacetimeDB user or module."
    @enforce_keys [:hex]
    defstruct [:hex]
    @type t :: %__MODULE__{hex: String.t()}
  end

  defmodule ConnectionId do
    @moduledoc "An opaque identifier for a single client WebSocket connection."
    @enforce_keys [:hex]
    defstruct [:hex]
    @type t :: %__MODULE__{hex: String.t()}
  end

  defmodule Timestamp do
    @moduledoc "A point in time, in microseconds since the Unix epoch."
    @enforce_keys [:microseconds_since_epoch]
    defstruct [:microseconds_since_epoch]
    @type t :: %__MODULE__{microseconds_since_epoch: integer()}

    @doc "Convert to an Elixir `DateTime`."
    @spec to_datetime(t()) :: DateTime.t()
    def to_datetime(%__MODULE__{microseconds_since_epoch: us}),
      do: DateTime.from_unix!(us, :microsecond)
  end

  # ---------------------------------------------------------------------------
  # Table / row data
  # ---------------------------------------------------------------------------

  defmodule TableUpdate do
    @moduledoc """
    Incremental row changes for a single table, as reported in a transaction or
    initial-subscription response.

    In the JSON protocol rows are plain JSON values (maps, lists, etc.) decoded
    directly from the server's response.
    """
    defstruct table_id: nil, table_name: nil, inserts: [], deletes: []

    @type t :: %__MODULE__{
            table_id: non_neg_integer() | nil,
            table_name: String.t() | nil,
            inserts: [term()],
            deletes: [term()]
          }
  end

  # ---------------------------------------------------------------------------
  # Server → Client messages
  # ---------------------------------------------------------------------------

  defmodule IdentityToken do
    @moduledoc "First message after connecting — contains the client's identity and session token."
    @enforce_keys [:identity, :token, :connection_id]
    defstruct [:identity, :token, :connection_id]

    @type t :: %__MODULE__{
            identity: String.t(),
            token: String.t(),
            connection_id: String.t()
          }
  end

  defmodule InitialSubscription do
    @moduledoc "Initial rows for a legacy multi-query `Subscribe` request."
    defstruct request_id: nil, tables: [], execution_time_micros: 0

    @type t :: %__MODULE__{
            request_id: non_neg_integer() | nil,
            tables: [TableUpdate.t()],
            execution_time_micros: non_neg_integer()
          }
  end

  defmodule SubscribeApplied do
    @moduledoc "Confirmation + initial rows for a `SubscribeSingle` or `SubscribeMulti` request."
    defstruct request_id: nil, query_id: nil, tables: []

    @type t :: %__MODULE__{
            request_id: non_neg_integer() | nil,
            query_id: non_neg_integer() | nil,
            tables: [TableUpdate.t()]
          }
  end

  defmodule UnsubscribeApplied do
    @moduledoc "Confirmation that a `Unsubscribe` was processed."
    defstruct request_id: nil, query_id: nil, tables: []

    @type t :: %__MODULE__{
            request_id: non_neg_integer() | nil,
            query_id: non_neg_integer() | nil,
            tables: [TableUpdate.t()]
          }
  end

  defmodule SubscriptionError do
    @moduledoc "The server rejected or invalidated a subscription."
    defstruct request_id: nil, query_id: nil, error: nil

    @type t :: %__MODULE__{
            request_id: non_neg_integer() | nil,
            query_id: non_neg_integer() | nil,
            error: String.t()
          }
  end

  defmodule ReducerCallInfo do
    @moduledoc "Metadata about the reducer that produced a `TransactionUpdate`."
    defstruct reducer_name: nil, request_id: nil, status: nil

    @type t :: %__MODULE__{
            reducer_name: String.t() | nil,
            request_id: non_neg_integer() | nil,
            status: :committed | {:failed, String.t()} | :out_of_energy | nil
          }
  end

  defmodule TransactionUpdate do
    @moduledoc """
    Pushed to all subscribers whose queries match rows touched by a committed
    reducer call.  Also sent back to the caller of the reducer (even without a
    matching subscription).
    """
    defstruct [
      :caller_identity,
      :caller_connection_id,
      :reducer_call,
      :timestamp,
      tables: [],
      status: :committed,
      energy_consumed: 0
    ]

    @type status :: :committed | {:failed, String.t()} | :out_of_energy

    @type t :: %__MODULE__{
            caller_identity: String.t() | nil,
            caller_connection_id: String.t() | nil,
            reducer_call: ReducerCallInfo.t() | nil,
            timestamp: Timestamp.t() | nil,
            tables: [TableUpdate.t()],
            status: status(),
            energy_consumed: non_neg_integer()
          }
  end

  defmodule OneOffQueryResponse do
    @moduledoc "Response to a `OneOffQuery` request."
    defstruct message_id: nil, error: nil, tables: [], execution_time_micros: 0

    @type t :: %__MODULE__{
            message_id: binary(),
            error: String.t() | nil,
            tables: [TableUpdate.t()],
            execution_time_micros: non_neg_integer()
          }
  end
end