chore: migrate code to ESM (#73)

src/version.mjs

@@ -0,0 +1,209 @@
+import semver from "semver";
+import { fetch } from "undici";
+import * as fs from "node:fs";
+
+const GIT_HASH_RE = /^[0-9a-fA-F]{40}$/;
+
+/**
+ * @typedef VersionRange
+ * @property {string} range
+ * @property {"canary" | "rc" | "release"} kind
+ */
+
+/**
+ * @typedef Version
+ * @property {string} version
+ * @property {"canary" | "rc" | "release"} kind
+ */
+
+/**
+ * Parses the version from the user into a structure.
+ *
+ * @param {string | undefined} version
+ * @returns {VersionRange | null}
+ */
+export function parseVersionRange(version) {
+  version = String(version) || "1.x";
+  version = version.trim();
+
+  if (version === "canary") {
+    return { range: "latest", kind: "canary" };
+  }
+
+  if (version === "rc") {
+    return { range: "latest", kind: "rc" };
+  }
+
+  if (version === "latest") {
+    return { range: "latest", kind: "release" };
+  }
+
+  if (GIT_HASH_RE.test(version)) {
+    return { range: version, kind: "canary" };
+  }
+
+  const range = semver.validRange(version);
+  if (range !== null) {
+    return { range, kind: "release" };
+  }
+
+  return null;
+}
+
+/**
+ * Parses the version from the version file
+ *
+ * @param {string} versionFilePath
+ * @returns {string | undefined}
+ */
+export function getDenoVersionFromFile(versionFilePath) {
+  if (!fs.existsSync(versionFilePath)) {
+    throw new Error(
+      `The specified node version file at: ${versionFilePath} does not exist`,
+    );
+  }
+
+  const contents = fs.readFileSync(versionFilePath, "utf8");
+
+  // .tool-versions typically looks like
+  // ```
+  // ruby 2.6.5
+  // deno 1.43.1
+  // node 20.0.0
+  // ```
+  // This parses the version of Deno from the file
+  const denoVersionInToolVersions = contents.match(
+    /^deno\s+v?(?<version>[^\s]+)$/m,
+  );
+
+  return denoVersionInToolVersions?.groups?.version || contents.trim();
+}
+
+/**
+ * @param {VersionRange} range
+ * @returns {Promise<Version | null>}
+ */
+export function resolveVersion({ range, kind }) {
+  if (kind === "canary") {
+    return resolveCanary(range);
+  } else if (kind === "rc") {
+    // range is always "latest"
+    return resolveReleaseCandidate();
+  } else {
+    return resolveRelease(range);
+  }
+}
+
+/**
+ * @param {string} range
+ * @returns {Promise<Version | null>}
+ */
+async function resolveCanary(range) {
+  if (range === "latest") {
+    const res = await fetchWithRetries(
+      "https://dl.deno.land/canary-latest.txt",
+    );
+    if (res.status !== 200) {
+      throw new Error(
+        "Failed to fetch canary version info from dl.deno.land. Please try again later.",
+      );
+    }
+    const version = (await res.text()).trim();
+    return { version, kind: "canary" };
+  } else {
+    return { version: range, kind: "canary" };
+  }
+}
+
+/**
+ * @returns {Promise<Version | null>}
+ */
+async function resolveReleaseCandidate() {
+  const res = await fetchWithRetries(
+    "https://dl.deno.land/release-rc-latest.txt",
+  );
+  if (res.status !== 200) {
+    throw new Error(
+      "Failed to fetch release candidate version info from dl.deno.land. Please try again later.",
+    );
+  }
+  const version = semver.clean((await res.text()).trim());
+  if (version === null) {
+    throw new Error("Failed to parse release candidate version.");
+  }
+  return { version, kind: "rc" };
+}
+
+/**
+ * @param {string} range
+ * @returns {Promise<Version | null>}
+ */
+async function resolveRelease(range) {
+  if (range === "latest") {
+    const res = await fetchWithRetries(
+      "https://dl.deno.land/release-latest.txt",
+    );
+    if (res.status !== 200) {
+      throw new Error(
+        "Failed to fetch release version info from dl.deno.land. Please try again later.",
+      );
+    }
+    /** @type {string | null} */
+    let version = (await res.text()).trim();
+    version = semver.clean(version);
+    if (version === null) {
+      throw new Error("Failed to parse release version.");
+    }
+    return { version, kind: "release" };
+  } else {
+    const res = await fetchWithRetries("https://deno.com/versions.json");
+    if (res.status !== 200) {
+      throw new Error(
+        "Failed to fetch stable version info from deno.com/versions.json. Please try again later.",
+      );
+    }
+    const versionJson = await res.json();
+    if (typeof versionJson !== "object" || versionJson === null) {
+      throw new Error("Fetched stable version info is invalid.");
+    }
+    if (!("cli" in versionJson)) {
+      throw new Error("Fetched stable version info is invalid.");
+    }
+    if (!Array.isArray(versionJson.cli)) {
+      throw new Error("Fetched stable version info is invalid.");
+    }
+    /** @type {string[]} */
+    const versions = versionJson.cli;
+
+    let version = semver.maxSatisfying(versions, range);
+    if (version === null) {
+      return null;
+    }
+    version = semver.clean(version);
+    if (version === null) throw new Error("UNREACHABLE");
+
+    return { version, kind: "release" };
+  }
+}
+
+/** @param {string} url */
+async function fetchWithRetries(url, maxRetries = 5) {
+  let sleepMs = 250;
+  let iterationCount = 0;
+  while (true) {
+    iterationCount++;
+    try {
+      const res = await fetch(url);
+      if (res.status === 200 || iterationCount > maxRetries) {
+        return res;
+      }
+    } catch (err) {
+      if (iterationCount > maxRetries) {
+        throw err;
+      }
+    }
+    console.warn(`Failed fetching. Retrying in ${sleepMs}ms...`);
+    await new Promise((resolve) => setTimeout(resolve, sleepMs));
+    sleepMs = Math.min(sleepMs * 2, 10_000);
+  }
+}