guidepost to hiking relation adder

index.js

// overpass query:
/*
[out:xml][timeout:250];
(
  relation[route="hiking"][colour="yellow"]["operator"="KST"];
);
(._;>;);
out meta;
*/

'use strict';

const xmldom = require('xmldom');
const DOMParser = xmldom.DOMParser;
const XMLSerializer = xmldom.XMLSerializer;
const fs = require('fs');

const doc = new DOMParser().parseFromString(fs.readFileSync('./yellow.osm', 'utf8'));

// wayID => way
// nodeID => node

const wayMap = {};
const nodeMap = {};

const nodes = doc.getElementsByTagName('node');
for (let i = 0; i < nodes.length; i++) {
  const node = nodes.item(i);
  node.isKst = isKst(node);
  nodeMap[node.getAttribute('id')] = node;
}

const ways = doc.getElementsByTagName('way');
for (let i = 0; i < ways.length; i++) {
  const way = ways.item(i);
  const nds = way.getElementsByTagName('nd');
  const nodes = [];
  for (let j = 0; j < nds.length; j++) {
    const nd = nds.item(j);
    nodes.push(nodeMap[nd.getAttribute('ref')]);
  }
  wayMap[way.getAttribute('id')] = { way: way, nodes: nodes };
}


const relations = doc.getElementsByTagName('relation');
for (let i = 0; i < relations.length; i++) {
  const relation = relations.item(i);
  if (!isKst(relation)) {
    continue;
  }

  const members = relation.getElementsByTagName('member');

  const nnn = {};

  for (let j = 0; j < members.length; j++) {
    const member = members.item(j);
    if (member.getAttribute('type') === 'node') {
      nnn[member.getAttribute('ref')] = true;
    }
  }

  const nodeIds = {};

  for (let j = 0; j < members.length; j++) {
    const member = members.item(j);
    if (member.getAttribute('type') === 'way') {
      wayMap[member.getAttribute('ref')].nodes.filter(node => node.isKst).map(node => node.getAttribute('id')).filter(id => !(id in nnn)).forEach(id => {
        nodeIds[id] = true;
      })
    }
  }

  Object.keys(nodeIds).forEach(nodeId => {
    const newMember = doc.createElement('member');
    newMember.setAttribute('type', 'node');
    newMember.setAttribute('role', '');
    newMember.setAttribute('ref', nodeId);
    relation.appendChild(newMember);
    relation.setAttribute('action', 'modify');
  });

}

function isKst(node) {
  const tags = node.getElementsByTagName('tag');
  let kst = false;
  let hiking = false;
  let guidepost = false;

  for (let i = 0; i < tags.length; i++) {
    const tag = tags.item(i);
    const key = tag.getAttribute('k');
    const value = tag.getAttribute('v');
    if (key === 'hiking' && value === 'yes') {
      hiking = true;
    } else if (key === 'operator' && value === 'KST') {
      kst = true;
    } else if (key === 'information' && value === 'guidepost') {
      guidepost = true;
    }
    if (node.nodeName === 'node' && hiking && kst && guidepost || node.nodeName === 'relation' && kst) {
      return true;
    }
  }

  return false;
}

console.log(new XMLSerializer().serializeToString(doc));