From 543b8ef50f32979c1e16189119b781bd8115c521 Mon Sep 17 00:00:00 2001
From: Brandon Liu <bdon@bdon.org>
Date: Wed, 19 Oct 2022 22:36:28 +0800
Subject: [PATCH] tile_path and error handling for lambda

---
 serverless/awsjs/src/index.ts | 138 ++++++++++++++++++++++++++++------
 1 file changed, 117 insertions(+), 21 deletions(-)

diff --git a/serverless/awsjs/src/index.ts b/serverless/awsjs/src/index.ts
index 814b58f..9581f75 100644
--- a/serverless/awsjs/src/index.ts
+++ b/serverless/awsjs/src/index.ts
@@ -1,14 +1,20 @@
 import { Readable } from "stream";
-import { Context, APIGatewayProxyResult, APIGatewayEvent } from "aws-lambda";
+import {
+	Context,
+	APIGatewayProxyResult,
+	APIGatewayProxyEventV2,
+} from "aws-lambda";
 import {
 	PMTiles,
 	ResolvedValueCache,
 	RangeResponse,
 	Source,
+	Compression,
 } from "../../../js";
 
 // @ts-ignore
 import https from "https";
+
 // @ts-ignore
 import s3client from "/var/runtime/node_modules/aws-sdk/clients/s3.js";
 
@@ -21,6 +27,47 @@ const s3 = new s3client({
 // TODO: figure out how much memory to allocate
 const CACHE = new ResolvedValueCache();
 
+export const pmtiles_path = (name: string, setting?: string): string => {
+	if (setting) {
+		return setting.replace("{name}", name);
+	}
+	return name + ".pmtiles";
+};
+
+const TILE =
+	/^\/(?<NAME>[0-9a-zA-Z\/!\-_\.\*\'\(\)]+)\/(?<Z>\d+)\/(?<X>\d+)\/(?<Y>\d+).(?<EXT>[a-z]+)$/;
+
+export const tile_path = (
+	path: string,
+	setting?: string
+): {
+	ok: boolean;
+	name: string;
+	tile: [number, number, number];
+	ext: string;
+} => {
+	let pattern = TILE;
+	if (setting) {
+		// escape regex
+		setting = setting.replace(/[.*+?^$()|[\]\\]/g, "\\$&");
+		setting = setting.replace("{name}", "(?<NAME>[0-9a-zA-Z/!-_.*'()]+)");
+		setting = setting.replace("{z}", "(?<Z>\\d+)");
+		setting = setting.replace("{x}", "(?<X>\\d+)");
+		setting = setting.replace("{y}", "(?<Y>\\d+)");
+		setting = setting.replace("{ext}", "(?<EXT>[a-z]+)");
+		pattern = new RegExp(setting);
+	}
+
+	let match = path.match(pattern);
+
+	if (match) {
+		const g = match.groups!;
+		return { ok: true, name: g.NAME, tile: [+g.Z, +g.X, +g.Y], ext: g.EXT };
+	}
+	return { ok: false, name: "", tile: [0, 0, 0], ext: "" };
+};
+
+
 class S3Source implements Source {
 	archive_name: string;
 
@@ -36,7 +83,7 @@ class S3Source implements Source {
 		const resp = await s3
 			.getObject({
 				Bucket: process.env.BUCKET!,
-				Key: this.archive_name + ".pmtiles",
+				Key: pmtiles_path(this.archive_name, process.env.PMTILES_PATH),
 				Range: "bytes=" + offset + "-" + (offset + length - 1),
 			})
 			.promise();
@@ -45,37 +92,86 @@ class S3Source implements Source {
 	}
 }
 
+interface Headers {
+	[key: string]: string;
+}
+
+const apiResp = (
+	statusCode: number,
+	body: string,
+	isBase64Encoded = false,
+	headers: Headers = {}
+): APIGatewayProxyResult => {
+	return {
+		statusCode: statusCode,
+		body: body,
+		headers: headers,
+		isBase64Encoded: isBase64Encoded,
+	};
+};
+
+// Assumes event is a API Gateway V2 or Lambda Function URL formatted dict
+// and returns API Gateway V2 / Lambda Function dict responses
+// Does not work with CloudFront events/Lambda@Edge; see README
 export const handler = async (
-	event: APIGatewayEvent,
+	event: APIGatewayProxyEventV2,
 	context: Context
 ): Promise<APIGatewayProxyResult> => {
+	var path;
+	var is_api_gateway;
+	if (event.pathParameters) {
+		is_api_gateway = true;
+		if (event.pathParameters.proxy) {
+			path = "/" + event.pathParameters.proxy;
+		} else {
+			return apiResp(500, "Proxy integration missing tile_path parameter");
+		}
+	} else {
+		path = event.rawPath;
+	}
+
+	if (!path) {
+		return apiResp(500, "Invalid event configuration");
+	}
+
+	const { ok, name, tile } = tile_path(path, process.env.TILE_PATH);
+
+	if (!ok) {
+		return apiResp(400, "Invalid tile URL");
+	}
+
+	var headers: Headers = {};
+	if (process.env.CORS) {
+		headers["Access-Control-Allow-Origin"] = process.env.CORS;
+	}
+	// TODO: extension enforcement and MIME types
+
+	const source = new S3Source("stamen_toner_z3");
+	const p = new PMTiles(source, CACHE);
 	try {
-		const source = new S3Source("stamen_toner_z3");
-		const p = new PMTiles(source, CACHE);
+		const header = await p.getHeader();
+		// TODO optimize by checking min/max zoom, return 404
+
+		headers["Content-Type"] = "application/vnd.vector-tile";
 
 		const tile = await p.getZxy(0, 0, 0);
 		if (tile) {
-			return {
-				statusCode: 200,
-				body: Buffer.from(tile.data).toString("base64"),
-			};
+			// return suncompressed response
+			// TODO: may need to special case API gateway to return compressed response with gzip content-encoding header
+			return apiResp(
+				200,
+				Buffer.from(tile.data).toString("base64"),
+				true,
+				headers
+			);
 		} else {
-			return {
-				statusCode: 204,
-				body: "",
-			};
+			return apiResp(204, "", false, headers);
 		}
 	} catch (e) {
 		if ((e as Error).name === "AccessDenied") {
-			return {
-				statusCode: 403,
-				body: "Bucket access failed: Unauthorized",
-			};
+			return apiResp(403, "Bucket access unauthorized");
 		}
 		throw e;
 	}
-	return {
-		statusCode: 404,
-		body: "Invalid URL",
-	};
+	return apiResp(404, "Invalid URL");
 };