export type Tree<Node> = Node | TreeRecord<Node> | ReadonlyArray<Tree<Node>>

/**
 * A record node in a {@link Tree}: an object mapping string keys to child
 * `Tree` nodes.
 *
 * @category Tree
 * @since 4.0.0
 */
export interface TreeRecord<A> {
  readonly [x: string]: Tree<A>
}

/**
 * Creates a recursive schema for a {@link Tree} of values described by `node`.
 * The resulting schema accepts a single node value, an array of trees, or an
 * object whose values are trees.
 *
 * @category Tree
 * @since 4.0.0
 */
export function Tree<S extends Constraint>(node: S) {
  const Tree$ref = suspend((): Codec<
    Tree<S["Type"]>,
    Tree<S["Encoded"]>,
    S["DecodingServices"],
    S["EncodingServices"]
  > => Tree)
  const Tree = Union([
    node,
    ArraySchema(Tree$ref),
    Record(String, Tree$ref)
  ])
  return Tree
}