From 5746a510fc569fd464e46b646d4979a976ad769b Mon Sep 17 00:00:00 2001
From: Brian Picciano <mediocregopher@gmail.com>
Date: Sun, 29 Aug 2021 21:34:24 -0600
Subject: [PATCH] generalize api call logic and move it to a module

---
 static/src/assets/api.js | 73 ++++++++++++++++++++++++++++++++++++++
 static/src/follow.md     | 75 +++++++++++-----------------------------
 2 files changed, 93 insertions(+), 55 deletions(-)
 create mode 100644 static/src/assets/api.js

diff --git a/static/src/assets/api.js b/static/src/assets/api.js
new file mode 100644
index 0000000..bec2740
--- /dev/null
+++ b/static/src/assets/api.js
@@ -0,0 +1,73 @@
+
+const doFetch = async (req) => {
+  let res, jsonRes;
+  try {
+    res = await fetch(req);
+    jsonRes = await res.json();
+
+  } catch (e) {
+
+    if (e instanceof SyntaxError)
+      e = new Error(`status ${res.status}, empty (or invalid) response body`);
+
+    console.error(`api call ${req.method} ${req.url}: unexpected error:`, e);
+    throw e;
+  }
+
+  if (jsonRes.error) {
+    console.error(
+      `api call ${req.method} ${req.url}: application error:`,
+      res.status,
+      jsonRes.error,
+    );
+
+    throw jsonRes.error;
+  }
+
+  return jsonRes;
+}
+
+// may throw
+const solvePow = async () => {
+
+  const res = await call('GET', '/api/pow/challenge');
+
+  const worker = new Worker('/assets/solvePow.js');
+
+  const p = new Promise((resolve, reject) => {
+    worker.postMessage({seedHex: res.seed, target: res.target});
+    worker.onmessage = resolve;
+  });
+
+  const powSol = (await p).data;
+  worker.terminate();
+
+  return {seed: res.seed, solution: powSol};
+}
+
+const call = async (method, route, opts = {}) => {
+  const { body = {}, requiresPow = false } = opts;
+
+  const reqOpts = { method };
+
+  if (requiresPow) {
+    const {seed, solution} = await solvePow();
+    body.powSeed = seed;
+    body.powSolution = solution;
+  }
+
+  if (Object.keys(body).length > 0) {
+
+    const form = new FormData();
+    for (const key in body) form.append(key, body[key]);
+
+    reqOpts.body = form;
+  }
+
+  const req = new Request(route, reqOpts);
+  return doFetch(req);
+}
+
+export {
+  call,
+}
diff --git a/static/src/follow.md b/static/src/follow.md
index 4e949dd..b02e7f0 100644
--- a/static/src/follow.md
+++ b/static/src/follow.md
@@ -4,6 +4,8 @@ title: "Follow the Blog"
 nofollow: true
 ---
 
+<script async type="module" src="/assets/api.js"></script>
+
 Here's your options for receiving updates about new blog posts:
 
 ## Option 1: Email
@@ -40,82 +42,45 @@ is published then input your email below and smash that subscribe button!
 <span id="emailStatus"></span>
 
 <script>
+
 const emailAddress = document.getElementById("emailAddress");
 const emailSubscribe = document.getElementById("emailSubscribe");
 const emailSubscribeOrigValue = emailSubscribe.value;
 const emailStatus = document.getElementById("emailStatus");
 
-const solvePow = async (seedHex, target) => {
-
-    const worker = new Worker('/assets/solvePow.js');
-
-    const p = new Promise((resolve, reject) => {
-        worker.postMessage({seedHex, target});
-        worker.onmessage = resolve;
-    });
-
-    const solutionHex = (await p).data;
-    worker.terminate();
-
-    return solutionHex;
-}
-
 emailSubscribe.onclick = async () => {
 
+    const api = await import("/assets/api.js");
+
     emailSubscribe.disabled = true;
     emailSubscribe.className = "";
     emailSubscribe.value = "Please hold...";
+    emailStatus.innerHTML = '';
 
-    await (async () => {
-
-        setErr = (errStr, retry) => {
-            emailStatus.className = "fail";
-            emailStatus.innerHTML = errStr
-            if (retry) emailStatus.innerHTML += "  (please try again)";
-        };
+    try {
 
         if (!window.isSecureContext) {
-            setErr("The browser environment is not secure.", false);
-            return;
+            throw "The browser environment is not secure.";
         }
 
-        const getPowReq = new Request('/api/pow/challenge');
-        const res = await fetch(getPowReq)
-            .then(response => response.json())
-
-        if (res.error) {
-            setErr(res.error, true);
-            return;
-        }
-
-        const powSol = await solvePow(res.seed, res.target);
-
-        const subscribeForm = new FormData();
-        subscribeForm.append('powSeed', res.seed);
-        subscribeForm.append('powSolution', powSol);
-        subscribeForm.append('email', emailAddress.value);
-
-        const subscribeReq = new Request('/api/mailinglist/subscribe', {
-            method: 'POST',
-            body: subscribeForm,
+        await api.call('POST', '/api/mailinglist/subscribe', {
+            body: { email: emailAddress.value },
+            requiresPow: true,
         });
 
-        const subRes = await fetch(subscribeReq)
-            .then(response => response.json());
-
-        if (subRes.error) {
-            setErr(subRes.error, true);
-            return;
-        }
-
         emailStatus.className = "success";
         emailStatus.innerHTML = "Verification email sent (check your spam folder)";
 
-    })();
+    } catch (e) {
+        emailStatus.className = "fail";
+        emailStatus.innerHTML = e;
+
+    } finally {
+        emailSubscribe.disabled = false;
+        emailSubscribe.className = "button-primary";
+        emailSubscribe.value = emailSubscribeOrigValue;
+    }
 
-    emailSubscribe.disabled = false;
-    emailSubscribe.className = "button-primary";
-    emailSubscribe.value = emailSubscribeOrigValue;
 };
 
 </script>