From 377b79eb8551500bbc63afb1d88dfc86fe578c0f Mon Sep 17 00:00:00 2001
From: tjjfvi <t6@t6.fyi>
Date: Mon, 20 Mar 2023 15:16:51 -0400
Subject: [PATCH] ...

---
 server/capi.dev/delegator.ts | 46 +++++++++++++++++++++++-------------
 1 file changed, 29 insertions(+), 17 deletions(-)

diff --git a/server/capi.dev/delegator.ts b/server/capi.dev/delegator.ts
index d999b7480..1329afaa3 100644
--- a/server/capi.dev/delegator.ts
+++ b/server/capi.dev/delegator.ts
@@ -4,23 +4,22 @@ import { f, handleErrors } from "../mod.ts"
 
 serve(handleErrors(handler))
 
-const delegateeProjectId = "70eddd08-c9b0-4cb3-b100-8c6facf52f1e"
-
+const ttl = 60_000
 const shaAbbrevLength = 8
 
-const GITHUB_API_REPO = "https://api.github.com/repos/paritytech/capi"
-
 const rTagVersion = /^v(\d+\.\d+\.\d+(?:-.+)?)$/
 const rPrVersion = /^pr:(\d+)$/
-
 const rVersionedUrl = /^(?:\/@(.+?))?(\/.*)?$/
 
+const delegateeProjectId = "70eddd08-c9b0-4cb3-b100-8c6facf52f1e"
+const githubApiBase = "https://api.github.com/repos/paritytech/capi"
+
 const { signal } = new AbortController()
 
 async function handler(request: Request) {
   const url = new URL(request.url)
   const [, version, path = "/"] = rVersionedUrl.exec(url.pathname)!
-  if (!version) throw f.notFound()
+  if (!version) return f.redirect(`/@${await defaultVersion()}${path}`)
   const sha = await getSha(version)
   let normalizedVersion
   if (rTagVersion.test(version)) {
@@ -39,8 +38,16 @@ async function handler(request: Request) {
   })
 }
 
-const shaTtl = 60_000
-const shaMemo = new TimedMemo<string, string>(shaTtl, signal)
+const defaultVersionMemo = new TimedMemo<void, string>(ttl, signal)
+async function defaultVersion() {
+  return await defaultVersionMemo.run(undefined, async () => {
+    const release = (await github<GithubRelease>(`releases/latest`))
+      ?? (await github<GithubRelease[]>(`releases`))[0]
+    return release.tag_name
+  })
+}
+
+const shaMemo = new TimedMemo<string, string>(ttl, signal)
 async function getSha(version: string): Promise<string> {
   const ref = version
     .replace(rPrVersion, "pull/$1/head")
@@ -48,28 +55,25 @@ async function getSha(version: string): Promise<string> {
     .replace(/:/g, "/")
   return await shaMemo.run(
     ref,
-    async () => (await json(`${GITHUB_API_REPO}/commits/${ref}`)).sha,
+    async () => (await github<GithubCommit>(`commits/${ref}`)).sha,
   )
 }
 
-const deploymentTtl = 60_000
-const deploymentMemo = new TimedMemo<string, string>(deploymentTtl, signal)
+const deploymentMemo = new TimedMemo<string, string>(ttl, signal)
 async function getDeployment(sha: string) {
   return await deploymentMemo.run(sha, async () => {
-    const deployments: GithubDeployment[] = await json(
-      `${GITHUB_API_REPO}/deployments?sha=${sha}`,
-    )
+    const deployments = await github<GithubDeployment[]>(`deployments?sha=${sha}`)
     const deployment = deployments.find((x) => x.payload.project_id === delegateeProjectId)
     if (!deployment) throw f.notFound()
-    const statuses: GithubStatus[] = await json(deployment.statuses_url)
+    const statuses = await github<GithubStatus[]>(deployment.statuses_url)
     const url = statuses.map((x) => x.environment_url).find((x) => x)
     if (!url) throw f.notFound()
     return url
   })
 }
 
-async function json(url: string) {
-  const response = await fetch(url)
+async function github<T>(url: string): Promise<T> {
+  const response = await fetch(new URL(url, githubApiBase))
   if (!response.ok) throw new Error(`${url}: invalid response`)
   return await response.json()
 }
@@ -82,3 +86,11 @@ interface GithubDeployment {
 interface GithubStatus {
   environment_url?: string
 }
+
+interface GithubRelease {
+  tag_name: string
+}
+
+interface GithubCommit {
+  sha: string
+}