georedis/lib/query.js

Super fast geo queries.

var geohash = require('ngeohash');
var helper = require('./util/helper');


function queryByRanges(client, zSetName, ranges, withValues, callBack) {
  var multi;

  if (typeof client.batch === 'function') {
    multi = client.batch();
  } else {
    multi = client.multi();
  }

  if (withValues !== true) {
    buildMultiWithoutValues(ranges, zSetName, multi);
  } else {
    buildMultiWithValues(ranges, zSetName, multi);
  }

  multi.exec(function(err, replies) {
    if (err) {
      callBack(err, null);
    } else {
      replies = helper.normalizeMultiResponse(client, replies);

      if (withValues) {
        processResultsWithValues(replies, callBack);
      } else {
        processResultsWithoutValues(replies, callBack);
      }
    }
  });
}

function buildMultiWithValues(ranges, zSetName, multi) {
  var range = [];
  var i;

  for (i = 0; i < ranges.length; i++) {
    range = ranges[i];
    multi.zrangebyscore(zSetName, range[0], range[1], 'WITHSCORES');
  }
}

function buildMultiWithoutValues(ranges, zSetName, multi) {
  var range = [];
  var i;

  for (i = 0; i < ranges.length; i++) {
    range = ranges[i];
    multi.zrangebyscore(zSetName, range[0], range[1]);
  }
}

function processResultsWithoutValues(replies, callBack) {
  var concatedReplies = [];
  var i;

  for (i = 0; i < replies.length; i++) {
    concatedReplies = concatedReplies.concat(replies[i]);
  }

  callBack(null, concatedReplies);
}

function processResultsWithValues(replies, callBack) {
  var concatedReplies = {};
  var i;
  var j;
  var decoded;

  for (i = 0; i < replies.length; i++) {
    for (j = 0; j < replies[i].length; j += 2) {
      decoded = geohash.decode_int(replies[i][j + 1], 52);

      concatedReplies[replies[i][j]] = {
        latitude: decoded.latitude,
        longitude: decoded.longitude
      };
    }
  }

  callBack(null, concatedReplies);
}


module.exports = queryByRanges;