Add support for streaming max age

This was previously not implemented, it turns out there's an somewhat unknown API to do it on `awslambda`.

global.d.ts

@@ -1,5 +1,17 @@
+declare type ResponseStream = {
+	setContentType( type: string ): void;
+	write( stream: string | Buffer ): void;
+	end(): void;
+};
+
+declare type StreamifyHandler = ( event: APIGatewayProxyEventV2, response: ResponseStream ) => Promise<any>;
+
 declare var awslambda: {
 	streamifyResponse: (
-		handler: ( event: APIGatewayProxyEventV2, response: ResponseStream ) => Promise<any>
-	) => ( event: APIGatewayProxyEventV2, context: ResponseStream ) => void;
+		handler: StreamifyHandler
+	) => ( event: APIGatewayProxyEventV2, context: ResponseStream ) => void,
+	HttpResponseStream: {
+		from: ( responseStream: ResponseStream, metadata: { statusCode: number, headers: HeadersInit } ) => ResponseStream,
+	},
 };
+

jest.config.js

@@ -1,12 +1,20 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 export default {
-	"preset": "ts-jest/presets/default-esm",
-  testEnvironment: 'node',
-  testMatch: ['**/tests/**/test-*.ts'],
-  globals: {
-	"ts-jest": {
-		useESM: true,
-	}
-  },
-  "extensionsToTreatAsEsm": [".ts"]
+	preset: 'ts-jest/presets/default-esm',
+	testEnvironment: 'node',
+	testMatch: ['**/tests/**/test-*.ts'],
+	extensionsToTreatAsEsm: ['.ts'],
+	moduleNameMapper: {
+		'^(\\.{1,2}/.*)\\.js$': '$1',
+	},
+	transform: {
+		// '^.+\\.[tj]sx?$' to process js/ts with `ts-jest`
+		// '^.+\\.m?[tj]sx?$' to process js/ts/mjs/mts with `ts-jest`
+		'^.+\\.tsx?$': [
+			'ts-jest',
+			{
+				useESM: true,
+			},
+		],
+	},
 };

src/lambda-handler.ts

@@ -1,15 +1,5 @@
-import { APIGatewayProxyEventV2 } from 'aws-lambda';
-
 import { Args, getS3File, resizeBuffer, Config } from './lib.js';
 
-type ResponseStream = {
-	setContentType( type: string ): void;
-	write( stream: string | Buffer ): void;
-	end(): void;
-};
-
-type StreamifyHandler = ( event: APIGatewayProxyEventV2, response: ResponseStream ) => Promise<any>;
-
 /**
  *
  * @param event
@@ -47,8 +37,6 @@ const streamify_handler: StreamifyHandler = async ( event, response ) => {
 
 	let { info, data } = await resizeBuffer( buffer, args );
 	// If this is a signed URL, we need to calculate the max-age of the image.
-	// We don't currently have a way to actually set this header with response
-	// streaming. It doesn't appear streamifyResponse support sending headers.
 	let maxAge = 31536000;
 	if ( args['X-Amz-Expires'] ) {
 		// Date format of X-Amz-Date is YYYYMMDDTHHMMSSZ, which is not parsable by Date.
@@ -65,6 +53,12 @@ const streamify_handler: StreamifyHandler = async ( event, response ) => {
 		// Mage age is the date the URL expires minus the current time.
 		maxAge = Math.round( expires - new Date().getTime() / 1000 ); // eslint-disable-line no-unused-vars
 	}
+	response = awslambda.HttpResponseStream.from( response, {
+		statusCode: 200,
+		headers: {
+			'Cache-Control': `max-age=${maxAge}`,
+		},
+	} );
 	response.setContentType( 'image/' + info.format );
 	response.write( data );
 	response.end();
@@ -79,6 +73,12 @@ if ( typeof awslambda === 'undefined' ) {
 		streamifyResponse( handler: StreamifyHandler ): StreamifyHandler {
 			return handler;
 		},
+
+		HttpResponseStream: {
+			from( stream: ResponseStream, metadata: { statusCode: number, headers: HeadersInit } ): ResponseStream {
+				return stream;
+			},
+		},
 	};
 }