feat: Respect req.accept header. Support application/json and text/pl…

…ain.

src/middleware/res-goodbye.js

@@ -1,26 +1,46 @@
 const debug = require("debug")("Blocks:GoodbyeMiddleware")
 
-import { forEach, is } from "@mutantlove/m"
+import { get, isEmpty } from "@mutantlove/m"
+import accepts from "accepts"
+
+const toNowInMs = start => {
+  const end = process.hrtime(start)
+
+  return end[0] * 1000 + end[1] / 1000000
+}
+
+const bodyByAccept = ({ accept, res }) => {
+  const payload = get(["ctx", "payload"])(res)
+
+  switch (accept.type(["json", "text"])) {
+    case "json":
+      res.setHeader("Content-Type", "application/json")
+
+      return JSON.stringify(isEmpty(payload) ? {} : payload)
+    default:
+      // the fallback is text/plain, so no need to specify it above
+      res.setHeader("Content-Type", "text/plain")
+
+      return isEmpty(payload) ? "" : payload
+  }
+}
 
 module.exports = () => (req, res) => {
   debug(`${req.method}:${req.url} responding with ${res.ctx.status}`)
 
-  const payload = is(res.ctx.payload) ? res.ctx.payload : {}
-  const isObject = typeof payload === "object"
-  const endAt = process.hrtime(req.ctx.startAt)
+  const body = bodyByAccept({
+    accept: accepts(req),
+    res,
+  })
+  const startAt = get(["ctx", "startAt"])(req)
+  const status = get(["ctx", "status"])(res)
 
-  const body = isObject ? JSON.stringify(payload) : payload
-  const contentType = isObject
-    ? "application/json; charset=utf-8"
-    : "text/plain; charset=utf-8"
+  // time to respond in miliseconds
+  res.setHeader("X-Response-Time", `${toNowInMs(startAt)} ms`)
 
-  forEach(([name, value]) => res.setHeader(name, value))([
-    // from the first middleware to now
-    ["X-Response-Time", `${endAt[0]}s ${endAt[1] / 1000000}ms`],
-    ["Content-Type", contentType],
-    ["Content-Length", Buffer.byteLength(body, "utf8")],
-  ])
+  // count the number of octets, not chars
+  res.setHeader("Content-Length", Buffer.byteLength(body, "utf8"))
 
-  res.writeHead(res.ctx.status)
+  res.writeHead(status)
   res.end(body, "utf8")
 }