Making postinstall.mjs more robust

packages/util/postinstall.mjs

@@ -1,41 +1,85 @@
-import { writeFile } from "fs/promises";
-
-let firebaseConfig = {};
-if (process.env.FIREBASE_CONFIG?.startsWith("{")) {
-    // TODO probably want a more robust yaml parse
-    firebaseConfig = Object.fromEntries(process.env.FIREBASE_CONFIG.match(/[^(\:\{\},)]+\:[^(,})]+/g).map(it => {
-        const parts = it.split(":");
-        return [parts[0], parts.slice(1).join(":")]
-    }));
-}
+import { writeFile, readFile } from "node:fs/promises";
+import { pathToFileURL } from "node:url";
+import { isAbsolute, join } from "node:path";
 
-const projectId = firebaseConfig.projectId;
-const appId = firebaseConfig.appId;
-const apiKey = firebaseConfig.apiKey;
+async function getWebConfig() {
+    let configFromEnvironment = undefined;
+    // $FIREBASE_WEBAPP_CONFIG can be either a JSON representation of FirebaseOptions or the path
+    // to a filename
+    if (process.env.FIREBASE_WEBAPP_CONFIG) {
+        if (process.env.FIREBASE_WEBAPP_CONFIG.startsWith("{")) {
+            try {
+                configFromEnvironment = JSON.parse(process.env.FIREBASE_WEBAPP_CONFIG);
+            } catch(e) {
+                console.error("FIREBASE_WEBAPP_CONFIG could not be parsed.", e);
+            }
+        } else {
+            const fileName = process.env.FIREBASE_WEBAPP_CONFIG;
+            const fileURL = pathToFileURL(isAbsolute(fileName) ? fileName : join(process.cwd(), fileName));
+            const fileContents = await readFile(fileURL, "utf-8").catch((err) => {
+                console.error(err);
+                return undefined;
+            });
+            if (fileContents) {
+                try {
+                    configFromEnvironment = JSON.parse(fileContents);
+                } catch(e) {
+                    console.error(`Contents of ${fileName} could not be parsed.`, e);
+                }
+            }
+        }
+    }
 
-const config = projectId && appId && apiKey && await (await fetch(
-    `https://firebase.googleapis.com/v1alpha/projects/${projectId}/apps/${appId}/webConfig`,
-    { headers: { "x-goog-api-key": apiKey } }
-)).json();
+    // In Firebase App Hosting the config provided to the environment variable is up-to-date and
+    // "complete" we should not reach out to the webConfig endpoint to freshen it
+    if (process.env.X_GOOGLE_TARGET_PLATFORM === "fah") {
+        return configFromEnvironment;
+    }
 
-if (config) {
-    config.apiKey = apiKey;
+    if (!configFromEnvironment) {
+        return undefined;
+    }
+    const projectId = configFromEnvironment.projectId || "-";
+    const appId = configFromEnvironment.appId;
+    const apiKey = configFromEnvironment.apiKey;
+    if (!appId || !apiKey) {
+        console.error("appId and apiKey are needed");
+        return undefined;
+    }
+    const response = await fetch(
+        `https://firebase.googleapis.com/v1alpha/projects/${projectId}/apps/${appId}/webConfig`,
+        { headers: { "x-goog-api-key": apiKey } }
+    );
+    if (!response.ok) {
+        // TODO add sensible error
+        console.error("yikes.");
+        return undefined;
+    }
+    const json = await response.json().catch(() => {
+        // TODO add sensible error
+        console.error("also yikes.");
+        return undefined;
+    });
+    return { ...json, apiKey };
 }
 
-let emulatorHosts = {
+const config = await getWebConfig();
+
+const emulatorHosts = {
+    // TODO: remote config, functions, and data connect emulators?
     firestore: process.env.FIRESTORE_EMULATOR_HOST,
     database: process.env.FIREBASE_DATABASE_EMULATOR_HOST,
     storage: process.env.FIREBASE_STORAGE_EMULATOR_HOST,
     auth: process.env.FIREBASE_AUTH_EMULATOR_HOST,
 };
 
-if (!Object.values(emulatorHosts).filter(it => it).length) {
-    emulatorHosts = undefined;
-}
+const anyEmulatorHosts = Object.values(emulatorHosts).filter(it => it).length > 0;
 
-const defaults = (config || emulatorHosts) && { config, emulatorHosts };
+// getDefaults() will use this object, rather than fallback to other autoinit suppliers, if it's
+// truthy—if we've done nothing here, make it falsy.
+const defaults = (config || anyEmulatorHosts) ? { config, emulatorHosts } : undefined;
 
 await Promise.all([
-    writeFile("./defaults.js", `module.exports = ${JSON.stringify(defaults)}`),
-    writeFile("./defaults.mjs", `export default ${JSON.stringify(defaults)}`),
+    writeFile(join(import.meta.dirname, "defaults.js"), `module.exports = ${JSON.stringify(defaults)}`),
+    writeFile(join(import.meta.dirname, "defaults.mjs"), `export default ${JSON.stringify(defaults)}`),
 ]);