import type { AddNodeCommand } from '../../core/commands/graphCommands';
import type { GraphAsset } from '../../core/model/Asset';
import type { Box } from '../framing';
import type { EditorState } from '../state';
import type { NodeView } from './NodeView';
import type { PaletteEntry } from './paletteEntries';
import type { Point } from './transitions';

/** What the graph canvas lends the gestures that work inside it. */
export interface GraphCanvasHost {
  readonly state: EditorState;
  /** The asset on the canvas; empty when there is none. */
  assetId(): string;
  asset(): GraphAsset | null;
  views(): ReadonlyMap<string, NodeView>;
  /** Views in stacking order, topmost first – a node drawn over another one wins the pointer. */
  topDownViews(): Iterable<NodeView>;
  nodeUnder(global: Point): string | null;
  /** Each node as the rectangle it is actually drawn as. */
  nodeBoxes(): Box[];
  /** The graph point under a global pointer position. */
  toGraph(global: Point): Point;
  /** Screen pixels per graph unit. */
  zoom(): number;
  snapping(): boolean;
  /** What the palette offers for this graph. */
  entries(): PaletteEntry[];
  /** The command that adds a node from the palette at a graph point. */
  newNode(entry: PaletteEntry, at: Point): AddNodeCommand;
  redraw(): void;
}