expand.js

/*
 * partial implementation of overpass turbo extended query syntax
 * (http://wiki.openstreetmap.org/wiki/Overpass_turbo/Extended_Overpass_Queries)
 */

var Promise = require('promise'),
    request = require('request-promise');

// converts relative time to ISO time string
function relativeTime(instr, callback) {
  var now = Date.now();
  // very basic differential date
  instr = instr.toLowerCase().match(/(-?[0-9]+) ?(seconds?|minutes?|hours?|days?|weeks?|months?|years?)?/);
  if (instr === null) {
    return Promise.reject(new Error('unable to expand date shortcut.'));
  }
  var count = parseInt(instr[1]);
  var interval;
  switch (instr[2]) {
    case "second":
    case "seconds":
    interval=1; break;
    case "minute":
    case "minutes":
    interval=60; break;
    case "hour":
    case "hours":
    interval=3600; break;
    case "day":
    case "days":
    default:
    interval=86400; break;
    case "week":
    case "weeks":
    interval=604800; break;
    case "month":
    case "months":
    interval=2628000; break;
    case "year":
    case "years":
    interval=31536000; break;
  }
  var date = now - count*interval*1000;
  return Promise.resolve((new Date(date)).toISOString());
}

// Promise wrapper for browser XMLHttpRequest
// from http://www.html5rocks.com/en/tutorials/es6/promises/
function get(url) {
  return new Promise(function(resolve, reject) {
    var req = new XMLHttpRequest();
    req.open('GET', url);

    req.onload = function() {
      if (req.status == 200) {
        resolve(req.response);
      }
      else {
        reject(Error("XMLHttpRequest Error: "+req.statusText));
      }
    };
    req.onerror = function() {
      reject(Error("Network Error"));
    };
    req.send();
  });
}
// helper function to query nominatim for best fitting result
function nominatimRequest(search,filter) {
  var requestUrl = "https://nominatim.openstreetmap.org/search?format=json&q="+encodeURIComponent(search);
  var _request;
  if (typeof XMLHttpRequest !== "undefined") {
    // browser
    _request = get(requestUrl).then(JSON.parse);
  } else {
    // node
    _request = request({
      url: requestUrl,
      method: "GET",
      headers: {"User-Agent": "overpass-wizard"},
      json: true
    });
  }
  return _request.then(function(data) {
    if (filter)
      data = data.filter(filter);
    if (data.length === 0)
      return Promise.reject(new Error("No result found for geocoding search: "+search));
    else
      return data[0];
  });
}

// geocoding shortcuts
function geocodeArea(instr) {
  function filter(n) {
    return n.osm_type && n.osm_id && n.osm_type!=="node";
  }
  return nominatimRequest(instr,filter).then(function(res) {
    var area_ref = 1*res.osm_id;
    if (res.osm_type == "way")
      area_ref += 2400000000;
    if (res.osm_type == "relation")
      area_ref += 3600000000;
    res = "area("+area_ref+")";
    return res;
  });
}
function geocodeCoords(instr) {
  return nominatimRequest(instr).then(function(res) {
    res = res.lat+','+res.lon;
    return res;
  });
}

var expansions = {
  date: relativeTime,
  geocodeArea: geocodeArea,
  geocodeCoords: geocodeCoords
};

module.exports = function(overpassQuery, bbox, callback) {
  // 1. bbox
  if (bbox) overpassQuery = overpassQuery.replace(/{{bbox}}/g, bbox);
  // 2. constants
  var constantRegexp = "{{([a-zA-Z0-9_]+)=(.+?)}}";
  var constants = overpassQuery.match(new RegExp(constantRegexp, 'g')) || [];
  constants.forEach(function(constant) {
    var constantDefinition = constant.match(new RegExp(constantRegexp)),
        constantShortcut = "{{"+constantDefinition[1]+"}}",
        constantValue = constantDefinition[2];
    while (overpassQuery.indexOf(constantShortcut) >= 0) {
      overpassQuery = overpassQuery.replace(constantShortcut, constantValue);
    }
  });
  // 3. shortcuts
  var shortcutRegexp = "{{(date|geocodeArea|geocodeCoords):([\\s\\S]*?)}}";
  var shortcuts = overpassQuery.match(new RegExp(shortcutRegexp, 'g')) || [];
  return Promise.all(shortcuts.map(function(shortcut) {
    shortcut = shortcut.match(new RegExp(shortcutRegexp));
    return expansions[shortcut[1]](shortcut[2]);
  })).then(function(expansions) {
    expansions.forEach(function(expansion, index) {
      overpassQuery = overpassQuery.replace(shortcuts[index], expansion);
    });
    return overpassQuery;
  }).then(function(overpassQuery) {
    callback(undefined, overpassQuery)
  }).catch(function(err) {
    callback(err);
  });
};