var zlib = require('zlib');
var express = require('express');
var mapnik = require('mapnik');
var Promise = require('promise');
var SphericalMercator = require('sphericalmercator');
var geobuf = require('geobuf');
var Pbf = require('pbf');
mapnik.register_default_input_plugins();

var mercator = new SphericalMercator({
    size: 256 //tile size
});

var app = express();

app.get('/vector-tiles/:layerName/:z/:x/:y.pbf', function(req, res) {

var options = {
    x: parseInt(req.params.x),
    y: parseInt(req.params.y),
    z: parseInt(req.params.z),
    layerName: req.params.layerName
};

makeVectorTile(options).then(
    function(vectorTile) {
        zlib.deflate(vectorTile, function(err, data) {
            if (err)
                return res.status(500).send(err.message);
            res.setHeader("Access-Control-Allow-Origin", "*");
            res.setHeader('Content-Encoding', 'deflate');
            res.setHeader('Content-Type', 'application/x-protobuf');
            res.send(data);

        });
    });
});

function makeVectorTile(options) {

var extent = mercator.bbox(options.x, options.y, options.z, false, '3857');
var map = new mapnik.Map(256, 256, '+init=epsg:3857');
map.extent = extent;
var layer = new mapnik.Layer(options.layerName);

layer.datasource = new mapnik.Datasource({
    type: 'postgis',
    dbname: 'db',
    table: "(Select * from planet_osm_" + options.layerName + ") as subquery",
    user: 'user',
    password: 'pass',
    geometry_field: 'way'
});
//layer.styles = ['stylesheet.xml'];

map.add_layer(layer);

return new Promise(function (resolve, reject) {
    var vtile = new mapnik.VectorTile(parseInt(options.z), parseInt(options.x), parseInt(options.y));

    map.render(vtile, function (err, vtile) {
        if (err) return reject(err);
        resolve(vtile.getData());
    });
});
}
app.listen(1234);