'use strict';

const fs = require('fs');
const path = require('path');
const zlib = require('zlib');

const clone = require('clone');
const express = require('express');
const MBTiles = require('@mapbox/mbtiles');
const Pbf = require('pbf');
const VectorTile = require('@mapbox/vector-tile').VectorTile;

const utils = require('./utils');

module.exports = {
  init: (options, repo) => {
    const app = express().disable('x-powered-by');

    app.get('/:id/:z(\\d+)/:x(\\d+)/:y(\\d+).:format([\\w.]+)', (req, res, next) => {
      const item = repo[req.params.id];
      if (!item) {
        return res.sendStatus(404);
      }
      let tileJSONFormat = item.tileJSON.format;
      const z = req.params.z | 0;
      const x = req.params.x | 0;
      const y = req.params.y | 0;
      let format = req.params.format;
      if (format === options.pbfAlias) {
        format = 'pbf';
      }
      if (format !== tileJSONFormat &&
          !(format === 'geojson' && tileJSONFormat === 'pbf')) {
        return res.status(404).send('Invalid format');
      }
      if (z < item.tileJSON.minzoom || 0 || x < 0 || y < 0 ||
          z > item.tileJSON.maxzoom ||
          x >= Math.pow(2, z) || y >= Math.pow(2, z)) {
        return res.status(404).send('Out of bounds');
      }
      item.source.getTile(z, x, y, (err, data, headers) => {
        let isGzipped;
        if (err) {
          if (/does not exist/.test(err.message)) {
            return res.status(204).send();
          } else {
            return res.status(500).send(err.message);
          }
        } else {
          if (data == null) {
            return res.status(404).send('Not found');
          } else {
            if (tileJSONFormat === 'pbf') {
              isGzipped = data.slice(0, 2).indexOf(
                Buffer.from([0x1f, 0x8b])) === 0;
              if (options.dataDecoratorFunc) {
                if (isGzipped) {
                  data = zlib.unzipSync(data);
                  isGzipped = false;
                }
                data = options.dataDecoratorFunc(id, 'data', data, z, x, y);
              }
            }
            if (format === 'pbf') {
              headers['Content-Type'] = 'application/x-protobuf';
            } else if (format === 'geojson') {
              headers['Content-Type'] = 'application/json';

              if (isGzipped) {
                data = zlib.unzipSync(data);
                isGzipped = false;
              }

              const tile = new VectorTile(new Pbf(data));
              const geojson = {
                "type": "FeatureCollection",
                "features": []
              };
              for (let layerName in tile.layers) {
                const layer = tile.layers[layerName];
                for (let i = 0; i < layer.length; i++) {
                  const feature = layer.feature(i);
                  const featureGeoJSON = feature.toGeoJSON(x, y, z);
                  featureGeoJSON.properties.layer = layerName;
                  geojson.features.push(featureGeoJSON);
                }
              }
              data = JSON.stringify(geojson);
            }
            delete headers['ETag']; // do not trust the tile ETag -- regenerate
            headers['Content-Encoding'] = 'gzip';
            res.set(headers);

            if (!isGzipped) {
              data = zlib.gzipSync(data);
              isGzipped = true;
            }

            return res.status(200).send(data);
          }
        }
      });
    });

    app.get('/:id.json', (req, res, next) => {
      const item = repo[req.params.id];
      if (!item) {
        return res.sendStatus(404);
      }
      const info = clone(item.tileJSON);
      info.tiles = utils.getTileUrls(req, info.tiles,
                                     `data/${req.params.id}`, info.format, item.publicUrl, {
                                       'pbf': options.pbfAlias
                                     });
      return res.send(info);
    });

    return app;
  },
  add: (options, repo, params, id, publicUrl) => {
    const mbtilesFile = path.resolve(options.paths.mbtiles, params.mbtiles);
    let tileJSON = {
      'tiles': params.domains || options.domains
    };

    const mbtilesFileStats = fs.statSync(mbtilesFile);
    if (!mbtilesFileStats.isFile() || mbtilesFileStats.size === 0) {
      throw Error(`Not valid MBTiles file: ${mbtilesFile}`);
    }
    let source;
    const sourceInfoPromise = new Promise((resolve, reject) => {
      source = new MBTiles(mbtilesFile, err => {
        if (err) {
          reject(err);
          return;
        }
        source.getInfo((err, info) => {
          if (err) {
            reject(err);
            return;
          }
          tileJSON['name'] = id;
          tileJSON['format'] = 'pbf';

          Object.assign(tileJSON, info);

          tileJSON['tilejson'] = '2.0.0';
          delete tileJSON['filesize'];
          delete tileJSON['mtime'];
          delete tileJSON['scheme'];

          Object.assign(tileJSON, params.tilejson || {});
          utils.fixTileJSONCenter(tileJSON);

          if (options.dataDecoratorFunc) {
            tileJSON = options.dataDecoratorFunc(id, 'tilejson', tileJSON);
          }
          resolve();
        });
      });
    });

    return sourceInfoPromise.then(() => {
      repo[id] = {
        tileJSON,
        publicUrl,
        source
      }
    });
  }
};