refactor(ext/compress): make extension lighter (#210)

ext/compress.ts

@@ -1,57 +1,82 @@
 // Copyright 2023 Samuel Kopp. All rights reserved. Apache-2.0 license.
-import * as brotli from 'https://deno.land/x/brotli@0.1.7/mod.ts'
-import { deflate, gzip } from 'https://deno.land/x/foras@2.0.8/src/deno/mod.ts'
+import { compress as brotli } from 'https://deno.land/x/brotli@0.1.7/mod.ts'
+import {
+  deflate,
+  gzip,
+  initBundledOnce,
+  InitOutput,
+} from 'https://deno.land/x/foras@2.0.8/src/deno/mod.ts'
 import { createExtension } from '../mod.ts'
 
+type CompressionAlgorithm = {
+  format: 'br' | 'deflate' | 'gzip'
+  compress: (input: Uint8Array) => Uint8Array | Promise<Uint8Array>
+}
+
+let FORAS: InitOutput | undefined
+
+export const BROTLI: CompressionAlgorithm = {
+  format: 'br',
+  compress: brotli,
+}
+
+export const DEFLATE: CompressionAlgorithm = {
+  format: 'deflate',
+  async compress(input) {
+    if (!FORAS) {
+      FORAS = await initBundledOnce()
+    }
+
+    return deflate(input)
+  },
+}
+
+export const GZIP: CompressionAlgorithm = {
+  format: 'gzip',
+  async compress(input) {
+    if (!FORAS) {
+      FORAS = await initBundledOnce()
+    }
+
+    return gzip(input)
+  },
+}
+
 /**
- * An extension to compress the body of the response with [Brotli](https://github.com/google/brotli), [gzip](https://www.gzip.org), or [deflate](https://www.ietf.org/rfc/rfc1951.txt), based on the `Accept-Encoding` header of the incoming request.
+ * An extension to compress the body of the response with [brotli](https://github.com/google/brotli), [gzip](https://www.gzip.org), or [deflate](https://www.ietf.org/rfc/rfc1951.txt), based on the `Accept-Encoding` header of the incoming request.
  *
  * @since v1.0
  */
-export const compress = createExtension({
-  onResponse({ c }) {
+export const compress = createExtension<{
+  algorithm: CompressionAlgorithm | CompressionAlgorithm[]
+}>({
+  async onResponse({ c, _ }) {
+    const alg = _.algorithm instanceof Array ? _.algorithm : [_.algorithm]
+
     const header = c.req.headers['accept-encoding']
 
     if (c.res.body === null || !header || header === 'identity') {
       return
     }
 
-    if (header.includes('br')) {
-      c.res.body = c.res.body instanceof Uint8Array
-        ? brotli.compress(c.res.body)
-        : c.res.body instanceof ArrayBuffer
-        ? brotli.compress(new Uint8Array(c.res.body))
-        : typeof c.res.body === 'string'
-        ? brotli.compress(new TextEncoder().encode(c.res.body))
-        : c.res.body
-
-      if (c.res.body instanceof Uint8Array) {
-        c.res.header('content-encoding', 'br')
+    for (let i = 0; i < alg.length; ++i) {
+      if (!header.includes(alg[i].format)) {
+        continue
       }
-    } else if (header.includes('gzip')) {
-      c.res.body = c.res.body instanceof Uint8Array
-        ? gzip(c.res.body)
-        : c.res.body instanceof ArrayBuffer
-        ? gzip(new Uint8Array(c.res.body))
-        : typeof c.res.body === 'string'
-        ? gzip(new TextEncoder().encode(c.res.body))
-        : c.res.body
 
-      if (c.res.body instanceof Uint8Array) {
-        c.res.header('content-encoding', 'gzip')
-      }
-    } else if (header.includes('deflate')) {
       c.res.body = c.res.body instanceof Uint8Array
-        ? deflate(c.res.body)
+        ? await alg[i].compress(c.res.body)
         : c.res.body instanceof ArrayBuffer
-        ? deflate(new Uint8Array(c.res.body))
+        ? await alg[i].compress(new Uint8Array(c.res.body))
         : typeof c.res.body === 'string'
-        ? deflate(new TextEncoder().encode(c.res.body))
+        ? await alg[i].compress(new TextEncoder().encode(c.res.body))
         : c.res.body
 
       if (c.res.body instanceof Uint8Array) {
-        c.res.header('content-encoding', 'deflate')
+        c.res.header('content-encoding', alg[i].format)
       }
+
+      break
     }
   },
 })