import { describe, expect, it } from 'vitest';
import { backTo, descend, follow } from '../../src/editor/graph/trail';

const alive = () => true;

describe('breadcrumb trail', () => {
  it('starts at the graph the call was opened from', () => {
    expect(descend([], 'game', 'move')).toEqual(['game', 'move']);
  });

  it('grows by one per call opened further down', () => {
    expect(descend(['game', 'move'], 'move', 'other')).toEqual(['game', 'move', 'other']);
  });

  it('starts over when the call sits in a graph the trail does not end at', () => {
    expect(descend(['game', 'move'], 'jump', 'other')).toEqual(['jump', 'other']);
  });

  it('steps back instead of repeating a behavior already on the trail', () => {
    expect(descend(['game', 'move', 'other'], 'other', 'move')).toEqual(['game', 'move']);
    expect(descend(['game', 'move'], 'move', 'game')).toEqual([]);
  });

  it('leaves the trail alone when a behavior calls itself', () => {
    expect(descend(['game', 'move'], 'move', 'move')).toEqual(['game', 'move']);
  });

  it('cuts back to the crumb clicked, and disappears at the root', () => {
    const trail = ['game', 'move', 'other'];
    expect(backTo(trail, 1)).toEqual(['game', 'move']);
    expect(backTo(trail, 0)).toEqual([]);
  });

  it('survives only while it still leads to the graph shown', () => {
    const trail = ['game', 'move'];
    expect(follow(trail, 'move', alive)).toEqual(trail);
    expect(follow(trail, 'game', alive)).toEqual([]);
    expect(follow(trail, '', alive)).toEqual([]);
  });

  it('is dropped when a behavior along it was deleted', () => {
    expect(follow(['game', 'move', 'other'], 'other', (id) => id !== 'move')).toEqual([]);
  });
});