import type { VectorPoint } from '../model/Asset';
import type { PropertyBag } from '../model/Properties';
import type { Graph } from './Graph';

/** What running another behavior's graph in place needs: its nodes, its variable defaults, its name. */
export interface BehaviorProgram {
  name: string;
  graph: Graph;
  defaults: PropertyBag;
  /** The variables a call hands on to the next call from the same site (#229); absent is none. */
  kept?: readonly string[];
}

/** One state of a machine: the node id is what a port and the runtime hold, the name is the label. */
export interface MachineState {
  id: string;
  name: string;
}

/**
 * An allowed move between two states, both named by state node id, under the name `State
 * transition` asks for. The name is empty until someone gives the transition one.
 */
export interface MachineTransition {
  from: string;
  to: string;
  name: string;
}

export interface StateMachine {
  name: string;
  states: MachineState[];
  transitions: MachineTransition[];
  /** Id of the state every instance begins in, empty when the machine has no start (see #55). */
  start: string;
}

/**
 * What a node may look up in the project around its graph: the behaviors it can run, the state
 * machines it can read, the curves a `Lerp` eases along (#247) and the struct types `Add item`
 * checks (#254). One handle, so no caller can resolve a node with half of it.
 */
export interface GraphLookup {
  behavior(assetId: string): BehaviorProgram | null;
  machine(assetId: string): StateMachine | null;
  curve(assetId: string): readonly VectorPoint[] | null;
  /** A Struct asset as a run knows it: a name and field names, nothing else travels (#254). */
  structType(assetId: string): StructShape | null;
  /** A texture's, frame's or pixel-art frame's own size in pixels; null for no picture. */
  textureSize(pictureId: string): { w: number; h: number } | null;
}

export interface StructShape {
  name: string;
  fields: readonly string[];
}

export const NO_LOOKUP: GraphLookup = {
  behavior: () => null,
  machine: () => null,
  curve: () => null,
  structType: () => null,
  textureSize: () => null,
};