update path prefix file (#127)

Author: louisachu

.github/scripts/get-path-prefix.js

@@ -0,0 +1,49 @@
+// This script retrieves the pathPrefix from the gatsby-config.js file.
+// It serves as an example for how to set up external javascript functions
+// outside workflow .yml files when they get too big or complex to keep them inline.
+
+// Documentation for the actions/github-script:
+// https://github.com/actions/github-script#run-a-separate-file
+
+module.exports = async ({ core }) => {
+  const { pathPrefix } = await require('../../gatsby-config.js');
+
+  if (!pathPrefix) {
+    core.setFailed(
+      `The pathPrefix in the site's gatsby-config.js file is missing.
+
+      To fix this, open your gatsby-config.js file, and add it to the config object:
+
+      module.exports = {
+        pathPrefix: "/commerce/frontend-core/",
+        ...
+      }`
+    );
+  } else if (pathPrefix === '/') {
+    core.setFailed(
+      `The pathPrefix in the site's gatsby-config.js file is set to "/". This is not allowed.
+
+      To fix this, change the pathPrefix to include a name that starts and ends with "/":
+
+      pathPrefix: "/commerce/frontend - core/"
+
+      This name identifies the site within the developer.adobe.com domain:
+      https://developer.adobe.com/document-services/<PATH_TO_FILES>.
+      `
+    );
+  } else {
+    if (!pathPrefix.startsWith('/') || !pathPrefix.endsWith('/')) {
+      core.setFailed(
+        `The pathPrefix in the site's gatsby-config.js file does not start or end with "/".
+
+        To fix this, change the pathPrefix to include a name that starts and ends with "/".
+        For example: "/document-services/" or "/commerce/cloud-tools/".
+
+        This is required by convention because of the way we construct site URLs.
+        For example: https://developer.adobe.com + /document-services/ + path/to/files/.
+        `
+      );
+    }
+  }
+  core.setOutput('path_prefix', pathPrefix);
+};