From a586ff4f239e231ffc0c1c252f0693b68f027f37 Mon Sep 17 00:00:00 2001
From: Norman Rzepka <code@normanrz.com>
Date: Sat, 4 Aug 2018 14:14:39 +0200
Subject: [PATCH] s3 tileset

---
 index.js                      |   4 +-
 test/{ => N51}/N51E013.hgt.gz | Bin
 tileset.js                    |  73 +++++++++++++++++++++++++++-------
 3 files changed, 61 insertions(+), 16 deletions(-)
 rename test/{ => N51}/N51E013.hgt.gz (100%)

diff --git a/index.js b/index.js
index b6bf3df..2f7f13e 100644
--- a/index.js
+++ b/index.js
@@ -1,11 +1,11 @@
 const { json, send } = require("micro");
-const TileSet = require("./tileset");
+const { S3TileSet } = require("./tileset");
 
 const cacheSize = process.env.TILE_SET_CACHE || 128;
 const tileFolder = process.env.TILE_SET_PATH || __dirname;
 const maxPostSize = process.env.MAX_POST_SIZE || "500kb";
 
-const tiles = new TileSet(tileFolder, { cacheSize });
+const tiles = new S3TileSet({ cacheSize });
 
 module.exports = async (req, res) => {
   if (req.method !== "POST") {
diff --git a/test/N51E013.hgt.gz b/test/N51/N51E013.hgt.gz
similarity index 100%
rename from test/N51E013.hgt.gz
rename to test/N51/N51E013.hgt.gz
diff --git a/tileset.js b/tileset.js
index 42f7b71..3c43a9a 100644
--- a/tileset.js
+++ b/tileset.js
@@ -1,44 +1,89 @@
 const path = require("path");
-const fs = require("fs");
+const { createReadStream } = require("fs");
+const { get } = require("https");
+const { promisify } = require("util");
 const { createGunzip } = require("zlib");
 const memoize = require("lru-memoize").default;
 
 const HGT = require("./hgt");
 
 class TileSet {
-  constructor(folder, options) {
+  constructor(options) {
     this.options = Object.assign(
       {},
       {
-        cacheSize: 128,
-        gzip: true
+        cacheSize: 128
       },
       options
     );
     this.getTile = memoize(this.options.cacheSize)(this._getTile.bind(this));
+  }
+
+  getFilePath(lat, lng) {
+    const latFileName = `${lat < 0 ? "S" : "N"}${String(Math.abs(lat)).padStart(
+      2,
+      "0"
+    )}`;
+    const lngFileName = `${lng < 0 ? "W" : "E"}${String(Math.abs(lng)).padStart(
+      3,
+      "0"
+    )}`;
+    const fileName = `${latFileName}${lngFileName}.hgt.gz`;
+    return `${latFileName}/${fileName}`;
+  }
+
+  async getElevation(latLng) {
+    const tile = await this.getTile(
+      Math.floor(latLng[0]),
+      Math.floor(latLng[1])
+    );
+    return tile.getElevation(latLng);
+  }
+}
+
+class FileTileSet extends TileSet {
+  constructor(folder, options) {
+    super(
+      Object.assign(
+        {},
+        {
+          cacheSize: 128,
+          gzip: true
+        },
+        options
+      )
+    );
     this._folder = folder;
   }
 
   async _getTile(lat, lng) {
-    const fileName =
-      `${lat < 0 ? "S" : "N"}${String(Math.abs(lat)).padStart(2, "0")}` +
-      `${lng < 0 ? "W" : "E"}${String(Math.abs(lng)).padStart(3, "0")}.hgt.gz`;
-
-    let stream = fs.createReadStream(path.join(this._folder, fileName));
+    let stream = fs.createReadStream(
+      path.join(this._folder, this.getFilePath(lat, lng))
+    );
     if (this.options.gzip) {
       stream = stream.pipe(createGunzip());
     }
     const tile = await HGT.loadStream(stream, [lat, lng]);
     return tile;
   }
+}
 
-  async getElevation(latLng) {
-    const tile = await this.getTile(
-      Math.floor(latLng[0]),
-      Math.floor(latLng[1])
+class S3TileSet extends TileSet {
+  async _getTile(lat, lng) {
+    console.log(`${S3TileSet.baseUrl}/${this.getFilePath(lat, lng)}`);
+    let stream = await new Promise(resolve =>
+      get(`${S3TileSet.baseUrl}/${this.getFilePath(lat, lng)}`, resolve)
     );
-    return tile.getElevation(latLng);
+    if (this.options.gzip) {
+      stream = stream.pipe(createGunzip());
+    }
+    const tile = await HGT.loadStream(stream, [lat, lng]);
+    return tile;
   }
 }
+S3TileSet.baseUrl = "https://elevation-tiles-prod.s3.amazonaws.com/skadi";
+
+TileSet.S3TileSet = S3TileSet;
+TileSet.FileTileSet = FileTileSet;
 
 module.exports = TileSet;