defmodule Localize.Mf2.TreeSitter.Edit do
  @moduledoc """
  Description of a single text change, for incremental reparsing.

  An edit names the byte range in the *old* source that was replaced
  and the byte range in the *new* source that took its place, plus
  the equivalent `{row, column}` points. Tree-sitter uses this to
  adjust the old parse tree so that unchanged subtrees can be reused
  when parsing the new source.

  ### Fields

  * `start_byte` — byte offset (in both old and new source) at which
    the change begins.

  * `old_end_byte` — end of the replaced range in the *old* source.

  * `new_end_byte` — end of the inserted range in the *new* source.

  * `start_point`, `old_end_point`, `new_end_point` — `{row, column}`
    counterparts of the three byte offsets.

  For a pure insertion `old_end_byte == start_byte`. For a pure
  deletion `new_end_byte == start_byte`. Both rows and byte offsets
  must be consistent — if you change rows, update points; if you
  only change one line, rows are equal.

  See [`TSInputEdit` in the tree-sitter docs](https://tree-sitter.github.io/tree-sitter/using-parsers#editing)
  for the full semantics.
  """

  @enforce_keys [
    :start_byte,
    :old_end_byte,
    :new_end_byte,
    :start_point,
    :old_end_point,
    :new_end_point
  ]
  defstruct [
    :start_byte,
    :old_end_byte,
    :new_end_byte,
    :start_point,
    :old_end_point,
    :new_end_point
  ]

  @type point :: {non_neg_integer(), non_neg_integer()}
  @type t :: %__MODULE__{
          start_byte: non_neg_integer(),
          old_end_byte: non_neg_integer(),
          new_end_byte: non_neg_integer(),
          start_point: point(),
          old_end_point: point(),
          new_end_point: point()
        }

  @doc false
  @spec to_tuple(t()) ::
          {non_neg_integer(), non_neg_integer(), non_neg_integer(), point(), point(), point()}
  def to_tuple(%__MODULE__{} = e) do
    {e.start_byte, e.old_end_byte, e.new_end_byte, e.start_point, e.old_end_point,
     e.new_end_point}
  end
end