import type { Asset, BehaviorAsset } from '../../core/model/Asset';
import { findAsset, findAssetOf } from '../../core/model/Project';
import { AssetTabEditor } from '../AssetTabEditor';
import type { EditorState } from '../state';
import { Breadcrumb } from './Breadcrumb';
import { GraphCanvas } from './GraphCanvas';
import { SnapToggle } from './SnapToggle';
import { backTo, descend, follow, type Trail } from './trail';

/** Room kept for the "N nodes · M links" readout, wide enough for a three-digit graph. */
const INFO_WIDTH = 150;

export class GraphEditor extends AssetTabEditor<BehaviorAsset, GraphCanvas> {
  private readonly snap = new SnapToggle(() => this.canvas);
  readonly breadcrumb = new Breadcrumb();
  private trail: Trail = [];

  constructor(state: EditorState) {
    super(state, { noun: 'Behavior', infoWidth: INFO_WIDTH });
    this.breadcrumb.onPick = (index) => this.open(this.trail[index]!, backTo(this.trail, index));
    this.mount(new GraphCanvas(state), this.snap.widgets, this.breadcrumb);
    this.canvas.onOpenBehavior = (id) => this.open(id, descend(this.trail, this.currentAssetId, id));
    // Play swaps in the runtime copy of the project, and back.
    state.on('mode', () => this.refresh());
  }

  /**
   * The bar goes up before the graph switches: switching fits the view to the canvas, and a bar
   * appearing afterwards would cut the bottom of the fitted graph off.
   */
  private open(assetId: string, trail: Trail): void {
    this.trail = trail;
    this.showTrail();
    this.state.select({ kind: 'asset', assetId });
    this.refresh();
  }

  protected override refresh(): void {
    super.refresh();
    const project = this.state.project;
    this.trail = follow(this.trail, this.currentAssetId, (id) =>
      Boolean(findAssetOf(project, id, 'behavior')),
    );
    this.showTrail();
  }

  private showTrail(): void {
    const names = this.trail.map((id) => findAsset(this.state.project, id)?.name ?? '');
    if (this.breadcrumb.show(names)) this.relayout();
  }

  protected override selectedId(): string {
    return this.state.selectedBehaviorId ?? '';
  }

  protected override isMine(asset: Asset): asset is BehaviorAsset {
    return asset.type === 'behavior';
  }

  protected override infoText(asset: BehaviorAsset): string {
    const nodes = asset.graph.nodes.length;
    const links = asset.graph.edges.length;
    return `${nodes} ${nodes === 1 ? 'node' : 'nodes'} · ${links} ${links === 1 ? 'link' : 'links'}`;
  }

  protected override syncExtras(asset: BehaviorAsset | null): void {
    this.snap.setEnabled(Boolean(asset));
  }
}