refactor: rework so remote pmtiles may be possible

Signed-off-by: Andrew Calcutt <acalcutt@techidiots.net>

src/main.js

@@ -8,11 +8,7 @@ import { fileURLToPath } from 'url';
 import request from 'request';
 import { server } from './server.js';
 import MBTiles from '@mapbox/mbtiles';
-import {
+import { PMtilesOpen, PMtilesClose, GetPMtilesInfo } from './pmtiles_adapter.js';
-  PMtilesOpen,
-  PMtilesClose,
-  GetPMtilesInfo,
-} from './pmtiles_adapter.js';
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
@@ -120,10 +116,11 @@ const startWithinputFile = async (inputFile) => {
 
   const extension = inputFile.split('.').pop().toLowerCase();
   if (extension === 'pmtiles') {
-    const FileDescriptor = PMtilesOpen(inputFile);
+    let FileOpenInfo = PMtilesOpen(inputFile);
-    const info = await GetPMtilesInfo(FileDescriptor);
+    const info = await GetPMtilesInfo(FileOpenInfo.pmtiles);
     const metadata = info.metadata;
-    PMtilesClose(FileDescriptor);
+    if (FileOpenInfo.fd !== undefined) {PMtilesClose(FileOpenInfo.fd);}
+    FileOpenInfo = null;
 
     if (
       metadata.format === 'pbf' &&

src/pmtiles_adapter.js

@@ -2,15 +2,25 @@ import fs from 'node:fs';
 import PMTiles from 'pmtiles';
 
 export const PMtilesOpen = (FilePath) => {
-  const fd = fs.openSync(FilePath, 'r');
+  let pmtiles = undefined;
-  return fd;
+  let fd = undefined;
+
+  if(isValidHttpUrl(FilePath)) {
+    const source = new PMTiles.FetchSource(FilePath)
+    pmtiles = new PMTiles.PMTiles(source);
+  } else {
+    fd = fs.openSync(FilePath, 'r');
+    const source = new PMTilesFileSource(fd);
+    pmtiles = new PMTiles.PMTiles(source);
+  }
+  return { pmtiles: pmtiles, fd: fd };
 };
 
 export const PMtilesClose = (fd) => {
   fs.closeSync(fd);
 };
 
-const PMTilesFileDescriptorSource = class {
+const PMTilesFileSource = class {
   constructor(fd) {
     this.fd = fd;
   }
@@ -35,9 +45,7 @@ const ReadBytes = async (fd, buffer, offset) => {
   });
 };
 
-export const GetPMtilesInfo = async (fd) => {
+export const GetPMtilesInfo = async (pmtiles) => {
-  const source = new PMTilesFileDescriptorSource(fd);
-  const pmtiles = new PMTiles.PMTiles(source);
   const header = await pmtiles.getHeader();
   const metadata = await pmtiles.getMetadata();
 
@@ -54,9 +62,7 @@ export const GetPMtilesInfo = async (fd) => {
   return { header: header, metadata: metadata };
 };
 
-export const GetPMtilesTile = async (fd, z, x, y) => {
+export const GetPMtilesTile = async (pmtiles, z, x, y) => {
-  const source = new PMTilesFileDescriptorSource(fd);
-  const pmtiles = new PMTiles.PMTiles(source);
   const header = await pmtiles.getHeader();
   const TileType = GetPmtilesTileType(header.tileType);
   let zxyTile = await pmtiles.getZxy(z, x, y);
@@ -116,3 +122,15 @@ const ArrayBufferToBuffer = (array_buffer) => {
   }
   return buffer;
 };
+
+function isValidHttpUrl(string) {
+  let url;
+  
+  try {
+    url = new URL(string);
+  } catch (_) {
+    return false;  
+  }
+
+  return url.protocol === "http:" || url.protocol === "https:";
+}

src/serve_data.js

@@ -11,12 +11,7 @@ import Pbf from 'pbf';
 import { VectorTile } from '@mapbox/vector-tile';
 
 import { getTileUrls, fixTileJSONCenter } from './utils.js';
-import {
+import { PMtilesOpen, GetPMtilesInfo, GetPMtilesTile } from './pmtiles_adapter.js';
-  PMtilesOpen,
-  PMtilesClose,
-  GetPMtilesInfo,
-  GetPMtilesTile,
-} from './pmtiles_adapter.js';
 
 export const serve_data = {
   init: (options, repo) => {
@@ -214,10 +209,10 @@ export const serve_data = {
     let source;
     let source_type;
     if (inputType === 'pmtiles') {
-      const FileDescriptor = PMtilesOpen(inputFile);
+      let FileOpenInfo = PMtilesOpen(inputFile);
-      const info = await GetPMtilesInfo(FileDescriptor);
+      const info = await GetPMtilesInfo(FileOpenInfo.pmtiles);
       const metadata = info.metadata;
-      source = FileDescriptor;
+      source = FileOpenInfo.pmtiles;
       source_type = 'pmtiles';
 
       tileJSON['name'] = id;

src/serve_rendered.js

@@ -19,12 +19,7 @@ import polyline from '@mapbox/polyline';
 import proj4 from 'proj4';
 import request from 'request';
 import { getFontsPbf, getTileUrls, fixTileJSONCenter } from './utils.js';
-import {
+import { PMtilesOpen, GetPMtilesInfo, GetPMtilesTile } from './pmtiles_adapter.js';
-  PMtilesOpen,
-  PMtilesClose,
-  GetPMtilesInfo,
-  GetPMtilesTile,
-} from './pmtiles_adapter.js';
 
 const FLOAT_PATTERN = '[+-]?(?:\\d+|\\d+.?\\d+)';
 const PATH_PATTERN =
@@ -1496,10 +1491,10 @@ export const serve_rendered = {
         }
 
         if (source_type === 'pmtiles') {
-          let FileDescriptor = PMtilesOpen(inputFile);
+          let FileOpenInfo = PMtilesOpen(inputFile);
-          const info = await GetPMtilesInfo(FileDescriptor);
+          const info = await GetPMtilesInfo(FileOpenInfo.pmtiles);
           const metadata = info.metadata;
-          map.sources[metadata.name.toLowerCase()] = FileDescriptor;
+          map.sources[metadata.name.toLowerCase()] = FileOpenInfo.pmtiles;
           map.source_types[metadata.name.toLowerCase()] = 'pmtiles';
 
           if (!repoobj.dataProjWGStoInternalWGS && metadata.proj4) {