Initial pass

main.js

@@ -0,0 +1,46 @@
+const process = require("process");
+const core = require("@actions/core");
+
+const { parseVersionRange, resolveVersion } = require("./src/version.js");
+const { install } = require("./src/install.js");
+
+/**
+ * @param {string} message
+ * @returns {never} 
+ */
+function exit(message) {
+  core.setFailed(message);
+  process.exit();
+}
+
+async function main() {
+  try {
+    const range = parseVersionRange(core.getInput("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.isCanary ? "canary" : "stable"
+      } version ${version.version}.`,
+    );
+
+    await install(version);
+
+    core.setOutput("version", version.version);
+    core.setOutput("is-canary", version.isCanary);
+
+    core.info("Installation complete.");
+  } catch (err) {
+    core.setFailed(err);
+    process.exit();
+  }
+}
+
+main();