OSRM Distance Matrix

distance-matrix.js

var request = require('simple-get'),
    extend = require('extend');

function DistanceMatrix(features, options) {
    this.options = extend({}, { serviceUrl: 'http://router.project-osrm.org/table'}, options);
    this._features = features.features.reduce(function(fs, f, i) {
        if (f.geometry.type !== 'Point') {
            throw 'Feature geometries must be Points.';
        }

        var key = f.geometry.coordinates.toString();
        fs[key] = {
            index: i,
            feature: f
        };

        return fs;
    }, {});
}

DistanceMatrix.prototype.getDistance = function(f1, f2, cb) {
    var getDistance = function() {
        var k1 = f1.geometry.coordinates.toString(),
            k2 = f2.geometry.coordinates.toString(),
            i = this._features[k1].index,
            j = this._features[k2].index;
        console.log(k1, k2, i, j);
        console.log(this._matrix);
        cb(undefined, this._matrix[i][j]);
    }.bind(this);

    if (!this._matrix) {
        this._fetchMatrix(function(err) {
            if (!err) {
                getDistance();
            } else {
                cb(err);
            }
        });
    } else {
        getDistance();
    }
};

DistanceMatrix.prototype._fetchMatrix = function(cb) {
    var locs = Object.keys(this._features).map(function(k) {
            var f = this._features[k].feature,
                cs = f.geometry.coordinates;
            return 'loc=' + cs[1] + ',' + cs[0];
        }.bind(this)),
        url = this.options.serviceUrl + '?' + locs.join('&');

    request.concat(url, function(err, data, res) {
        if (err) {
            cb(err);
        } else {
            if (res.statusCode !== 200) {
                cb({
                    code: 'HTTP_ERROR',
                    statusCode: res.statusCode,
                    response: data.toString()
                });
            } else {
                var dt = JSON.parse(data.toString()).distance_table;
                if (!dt) {
                    cb({
                        code: 'MISSING_DISTANCE_TABLE',
                        message: 'Distance table is missing from server response.',
                        response: data.toString()
                    });
                } else {
                    this._matrix = data.distance_table;
                    cb();
                }
            }
        }
    }.bind(this));
};

module.exports = DistanceMatrix;