chore: migrate code to ESM (#73)

main.mjs

@@ -0,0 +1,53 @@
+import process from "node:process";
+import core from "@actions/core";
+import {
+  getDenoVersionFromFile,
+  parseVersionRange,
+  resolveVersion,
+} from "./src/version.mjs";
+import { install } from "./src/install.mjs";
+
+/**
+ * @param {string} message
+ * @returns {never}
+ */
+function exit(message) {
+  core.setFailed(message);
+  process.exit();
+}
+
+async function main() {
+  try {
+    const denoVersionFile = core.getInput("deno-version-file");
+    const range = parseVersionRange(
+      denoVersionFile
+        ? getDenoVersionFromFile(denoVersionFile)
+        : core.getInput("deno-version"),
+    );
+
+    if (range === null) {
+      exit("The passed version range is not valid.");
+    }
+
+    const version = await resolveVersion(range);
+    if (version === null) {
+      exit("Could not resolve a version for the given range.");
+    }
+
+    core.info(`Going to install ${version.kind} version ${version.version}.`);
+
+    await install(version);
+
+    core.setOutput("deno-version", version.version);
+    // TODO(@crowlKats): remove in 2.0
+    core.setOutput("is-canary", version.kind === "canary");
+    core.setOutput("release-channel", version.kind);
+
+    core.info("Installation complete.");
+  } catch (err) {
+    core.setFailed((err instanceof Error) ? err : String(err));
+    process.exit();
+  }
+}
+
+main();