tileserver-gl/src/serve_data.js

'use strict';

import fs from 'node:fs';
import path from 'path';
import zlib from 'zlib';

import clone from 'clone';
import express from 'express';
import MBTiles from '@mapbox/mbtiles';
import Pbf from 'pbf';
import { VectorTile } from '@mapbox/vector-tile';

import { getTileUrls, fixTileJSONCenter } from './utils.js';

export const serve_data = {
  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);
        }
        const 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)
                .header('Content-Type', 'text/plain')
                .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 (const 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 = 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 + '?mode=ro', (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 || {});
          fixTileJSONCenter(tileJSON);

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

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