import { feasibleTree } from './feasible-tree.js';
import { networkSimplex } from './network-simplex.js';
import { longestPath } from './util.js';

export { rank };

/*
 * Assigns a rank to each node in the input graph that respects the "minlen"
 * constraint specified on edges between nodes.
 *
 * This basic structure is derived from Gansner, et al., "A Technique for
 * Drawing Directed Graphs."
 *
 * Pre-conditions:
 *
 *    1. Graph must be a connected DAG
 *    2. Graph nodes must be objects
 *    3. Graph edges must have "weight" and "minlen" attributes
 *
 * Post-conditions:
 *
 *    1. Graph nodes will have a "rank" attribute based on the results of the
 *       algorithm. Ranks can start at any index (including negative), we'll
 *       fix them up later.
 */
function rank(g) {
  switch (g.graph().ranker) {
    case 'network-simplex':
      networkSimplexRanker(g);
      break;
    case 'tight-tree':
      tightTreeRanker(g);
      break;
    case 'longest-path':
      longestPathRanker(g);
      break;
    default:
      networkSimplexRanker(g);
  }
}

// A fast and simple ranker, but results are far from optimal.
var longestPathRanker = longestPath;

function tightTreeRanker(g) {
  longestPath(g);
  feasibleTree(g);
}

function networkSimplexRanker(g) {
  networkSimplex(g);
}