From 9ffc57e63e4f81402e23d584d73ce4fd7bea2a99 Mon Sep 17 00:00:00 2001
From: Dylan Piercey <dpiercey@ebay.com>
Date: Fri, 26 Aug 2022 09:59:57 -0700
Subject: [PATCH] feat: expose ability to override fetch implementation (#6)

---
 README.md                                     |  20 +++
 .../micro-frame/component/node.marko          | 118 ++++++++----------
 .../micro-frame/component/web.component.ts    |  13 +-
 3 files changed, 86 insertions(+), 65 deletions(-)

diff --git a/README.md b/README.md
index 494e28c..0df5b3a 100644
--- a/README.md
+++ b/README.md
@@ -134,6 +134,26 @@ and fallback to the network otherwise
 <micro-frame src="..." cache="force-cache"/>
 ```
 
+## `fetch`
+
+Optionally provide function to override default `fetch` logic.
+
+```marko
+<micro-frame src="..." name="..." fetch(url, options, fetch) {
+  // The 3rd parameter allows us to continue to use micro-frames fetch implementation (which is different server/browser).
+  // We can use this override to do things like a POST request, eg:
+  return fetch(url, {
+    ...options,
+    method: "POST",
+    headers: {
+      ...headers,
+      "Content-Type": "application/json"
+    },
+    body: JSON.stringify({ "some": "json" })
+  });
+}  />
+```
+
 ## `timeout`
 
 A timeout in `ms` (defaults to 30s) that will prematurely abort the request. This will trigger the `<@catch>` if provided.
diff --git a/src/components/micro-frame/component/node.marko b/src/components/micro-frame/component/node.marko
index 6d3149f..8bcae21 100644
--- a/src/components/micro-frame/component/node.marko
+++ b/src/components/micro-frame/component/node.marko
@@ -2,22 +2,9 @@ import path from "path";
 import fetch from "make-fetch-happen";
 
 static const cachePath = path.resolve("node_modules/.cache/fetch");
-static function createDeferredPromise() {
-  let resolve;
-  let reject;
-  const promise = new Promise((_resolve, _reject) => {
-    resolve = _resolve;
-    reject = _reject;
-  });
-  promise.resolve = resolve;
-  promise.reject = reject;
-  return promise;
-}
+static const strictSSL = process.env.NODE_TLS_REJECT_UNAUTHORIZED !== "0";
 
-$ let buf = "";
-$ let hasMore = true;
-$ let sentData = false;
-$ let next = (async () => {
+static async function fetchStream(input, out) {
   const incomingMessage = out.stream && (out.stream.req || out.stream.request);
 
   if (!incomingMessage) {
@@ -25,36 +12,31 @@ $ let next = (async () => {
   }
 
   const url = new URL(input.src, `${incomingMessage.protocol}://${incomingMessage.headers.host}`);
-  const res = await fetch(url, {
-    cachePath,
-    cache: input.cache,
-    strictSSL: process.env.NODE_TLS_REJECT_UNAUTHORIZED !== "0",
-    headers: {
-      ...incomingMessage.headers,
-      ...input.headers,
-      accept: "text/html",
-    }
-  });
+  const { cache } = input;
+  const headers = {
+    ...incomingMessage.headers,
+    ...input.headers,
+    accept: "text/html",
+  };
+
+  const res = await (input.fetch
+    ? input.fetch(url, { cache, headers }, fetch)
+    : fetch(url, {
+      cache,
+      headers,
+      cachePath,
+      strictSSL,
+    })
+  );
 
   if (!res.ok) throw new Error(res.statusText);
-  next = createDeferredPromise();
 
-  res.body
-    .on("data", data => {
-      buf += data.toString();
-      if (next) next = next.resolve();
-    })
-    .on("error", err => {
-      if (next) next = next.reject(err);
-      else out.error(err);
-    })
-    .on("end", () => {
-      hasMore = false;
-      if (next) next = next.resolve();
-    });
+  if (!res.body || !res.body[Symbol.asyncIterator]) {
+    throw new Error("Response body must be a stream.");
+  }
 
-    return next;
-})();
+  return res.body[Symbol.asyncIterator]();
+}
 
 <div id=component.id data-src=input.src>
   <if(input.loading)>
@@ -63,32 +45,42 @@ $ let next = (async () => {
     $!{`<!--${component.id}-->`}
   </if>
 
-  <macro name="wait">
-    <await(next)
-      timeout=input.timeout
-      catch=(!sentData && input.catch)>
-      <@then>
-        $!{buf}
-        <if(hasMore)>
-          $ buf = "";
-          $ sentData = true;
-          $ next = createDeferredPromise();
-          <wait/>
-        </if>
-      </@then>
-    </await>
-  </macro>
-
   <!--
   We put the streamed html in a preserved fragment.
   This allows Marko to avoid diffing that section.
   -->
   $ out.bf("@_", component, true);
-  <wait/>
-  $ out.ef();
+  <await(fetchStream(input, out)) timeout=input.timeout catch=input.catch>
+    <@then|iter|>
+      <macro name="wait">
+        <await(iter.next()) timeout=input.timeout>
+          <@then|{ value, done }|>
+            <if(done)>
+              <if(input.loading)>
+                <!-- Remove all of the <@loading> content after we've received all the data -->
+                $ out.script(`((e,t,d)=>{t=document.getElementById(e);do{t.removeChild(d=t.firstChild)}while(d.data!==e)})(${JSON.stringify(component.id)});`);
+              </if>
+            </if>
+            <else>
+              $!{value}
+              <wait/>
+            </else>
+          </@then>
+          <@catch|err|>
+            <if(input.catch)>
+              <!-- Remove everything in the container and render our catch handler -->
+              <script>document.getElementById(${JSON.stringify(component.id)}).textContent=""</script>
+              <${input.catch}(err)/>
+            </if>
+            <else>
+              $ throw err;
+            </else>
+          </@catch>
+        </await>
+      </macro>
 
-  <if(input.loading)>
-    <!-- Remove all of the <@loading> content after we've received all the data -->
-    $ out.script(`((e,t,d)=>{t=document.getElementById(e);do{t.removeChild(d=t.firstChild)}while(d.data!==e)})(${JSON.stringify(component.id)});`);
-  </if>
+      <wait/>
+    </@then>
+  </await>
+  $ out.ef();
 </div>
diff --git a/src/components/micro-frame/component/web.component.ts b/src/components/micro-frame/component/web.component.ts
index d2ab717..8cd5a19 100644
--- a/src/components/micro-frame/component/web.component.ts
+++ b/src/components/micro-frame/component/web.component.ts
@@ -7,6 +7,11 @@ interface Input {
   loading?: unknown;
   cache?: RequestCache;
   headers?: Record<string, string>;
+  fetch?: (
+    url: string,
+    options: RequestInit,
+    fetch: typeof window.fetch
+  ) => Promise<Response>;
 }
 
 interface State {
@@ -49,11 +54,15 @@ export = {
     let err: Error | undefined;
 
     try {
-      const res = await fetch(this.src, {
+      const options: RequestInit = {
         cache: this.input.cache,
         signal: controller.signal,
         headers: Object.assign({}, this.input.headers, { accept: "text/html" }),
-      });
+      };
+
+      const res = await (this.input.fetch
+        ? this.input.fetch(this.src, options, fetch)
+        : fetch(this.src, options));
       if (!res.ok) throw new Error(res.statusText);
       const reader = res.body!.getReader();
       const decoder = new TextDecoder();