defmodule Xandra.SchemaChange do
  @moduledoc """
  A struct that represents the result of a query that modifies the schema.

  See [`%Xandra.SchemaChange{}`](`__struct__/0`) for information on the fields of this struct.
  """

  @doc """
  The struct for the "schema change" result.

  This struct has the following fields:

    * `:effect` - the type of change involved. It's one of `"CREATED"`,
      `"UPDATED"`, or `"DROPPED"`.

    * `:target` - what has been modified. It's one of `"KEYSPACE"`, `"TABLE"`,
      or `"TYPE"`.

    * `:options` - a map of options that depends on the value of `:target`:
      * if target is `"KEYSPACE"`, the map will have the form
        `%{keyspace: keyspace}`
      * if the target is `"TABLE"` or `"TYPE"`, the map will have the form
        `%{keyspace: keyspace, subject: subject}` where `keyspace` is the
        keyspace where the change happened and `subject` is the name of what
        changed (so the name of the changed table or type)

    * `:tracing_id` - the tracing ID (as a UUID binary) if tracing was enabled,
      or `nil` if no tracing was enabled. See the "Tracing" section in `Xandra.execute/4`.

    * `:custom_payload` - the *custom payload* sent by the server, if present.
      If the server doesn't send a custom payload, this field is `nil`. Otherwise,
      it's of type `t:Xandra.custom_payload/0`. See the "Custom payloads" section
      in the documentation for the `Xandra` module.
  """
  defstruct [:effect, :target, :options, :tracing_id, :custom_payload]

  @typedoc """
  The type for a schema change result.

  See [`%Xandra.SchemaChange{}`](`__struct__/0`) for information.
  """
  @type t :: %__MODULE__{
          effect: String.t(),
          target: String.t(),
          options: map,
          tracing_id: binary | nil,
          custom_payload: Xandra.custom_payload() | nil
        }
end