import * as util from "./util";
import { Edge, Graph } from "graphlib";

/*
 * Breaks any long edges in the graph into short segments that span 1 layer
 * each. This operation is undoable with the denormalize function.
 *
 * Pre-conditions:
 *
 *    1. The input graph is a DAG.
 *    2. Each node in the graph has a "rank" property.
 *
 * Post-condition:
 *
 *    1. All edges in the graph have a length of 1.
 *    2. Dummy nodes are added where edges have been split into segments.
 *    3. The graph is augmented with a "dummyChains" attribute which contains
 *       the first dummy in each chain of dummy nodes produced.
 */
export function run(g: Graph) {
  (g.graph() as any).dummyChains = [];
  g.edges().forEach((edge) => {
    normalizeEdge(g, edge);
  });
}

function normalizeEdge(g: Graph, e: Edge) {
  let v = e.v;
  let vRank = g.node(v).rank;
  const w = e.w;
  const wRank = g.node(w).rank;
  const name = e.name;
  const edgeLabel = g.edge(e);
  const labelRank = edgeLabel.labelRank;

  if (wRank === vRank + 1) return;

  g.removeEdge(e);

  let dummy, attrs: any, i;
  for (i = 0, ++vRank; vRank < wRank; ++i, ++vRank) {
    edgeLabel.points = [];
    attrs = {
      width: 0,
      height: 0,
      edgeLabel: edgeLabel,
      edgeObj: e,
      rank: vRank,
    };
    dummy = util.addDummyNode(g, "edge", attrs, "_d");
    if (vRank === labelRank) {
      attrs.width = edgeLabel.width;
      attrs.height = edgeLabel.height;
      attrs.dummy = "edge-label";
      attrs.labelpos = edgeLabel.labelpos;
    }
    g.setEdge(v, dummy, { weight: edgeLabel.weight }, name);
    if (i === 0) {
      (g.graph() as any).dummyChains.push(dummy);
    }
    v = dummy;
  }

  g.setEdge(v, w, { weight: edgeLabel.weight }, name);
}

export function undo(g: Graph) {
  (g.graph() as any).dummyChains.forEach((v: any) => {
    let node = g.node(v);
    const origLabel = node.edgeLabel;
    let w;
    g.setEdge(node.edgeObj, origLabel);
    while (node.dummy) {
      w = (g.successors(v) as string[])[0];
      g.removeNode(v);
      origLabel.points.push({ x: node.x, y: node.y });
      if (node.dummy === "edge-label") {
        origLabel.x = node.x;
        origLabel.y = node.y;
        origLabel.width = node.width;
        origLabel.height = node.height;
      }
      v = w;
      node = g.node(v);
    }
  });
}