feat: Add nf-core website API wrapper

Basically, a stand-in for OctoKit, but smarter.

src/nf-core-api-wrapper.ts

@@ -0,0 +1,45 @@
+import { info } from "@actions/core"
+import { downloadTool } from "@actions/tool-cache"
+import retry from "async-retry"
+import { readFileSync } from "fs"
+
+import { NextflowRelease } from "./nextflow-release"
+
+async function fetch_nextflow_versions_data(): Promise<object> {
+  // Occasionally the connection is reset for unknown reasons
+  // In those cases, retry the download
+  const versionsFile = await retry(
+    async () => {
+      return await downloadTool("https://nf-co.re/nextflow_version")
+    },
+    {
+      retries: 5,
+      onRetry: (err: Error) => {
+        info(`Download of versions.json failed, trying again. Error: ${err}`)
+      }
+    }
+  )
+
+  return JSON.parse(readFileSync(versionsFile).toString())
+}
+
+export async function get_nextflow_versions(): Promise<NextflowRelease[]> {
+  const version_dataset = await fetch_nextflow_versions_data()
+  const versions = version_dataset["versions"]
+  const nextflow_releases: NextflowRelease[] = []
+  // eslint-disable-next-line github/array-foreach
+  versions.array.forEach(element => {
+    const release = element as NextflowRelease
+    nextflow_releases.push(release)
+  })
+  return nextflow_releases
+}
+
+export async function get_latest_nextflow_version(
+  flavor: string
+): Promise<NextflowRelease> {
+  const version_dataset = await fetch_nextflow_versions_data()
+  const latest_versions = version_dataset["latest"]
+  const latest_version = latest_versions[flavor] as NextflowRelease
+  return latest_version
+}