Add support to deploy preview other releases

bin/playbook-changer.js

@@ -15,11 +15,39 @@ let url;
 
 console.log(process.env);
 
-if (process.env.CI === "true") {
-  headRef = process.env.HEAD;
-  // FIXME: change this depending on the branch
-  baseRef = "develop";
+// Infers base branch reference according to the head reference
+//
+// If the head reference starts with the version number (i.e. "v0.26/fix/preview"), returns the base branch reference (i.e. "release/0.26-stable")
+// If not, then returns "develop"
+//
+// @param {string} headRef - The head reference. Examples: "v0.26/fix/preview" or "fix/preview"
+// @returns {string} The base reference. Examples "release/0.26-stable" or "develop"
+function baseFromHead(headRef) {
+  let baseRef;
+
+  if (headRef.startsWith("v0.")) {
+    const version = headRef.split("/")[0].replace("v");
+    baseRef = `release/${version}-stable`;
+  } else {
+    baseRef = "develop";
+  };
+
+  return baseRef;
+}
+
+if (process.env.CONTEXT === "deploy-preview" || process.env.RUNNER_ENVIRONMENT == "github-hosted") {
+  // We're in CI and we need to adapt the head of the playbook
+  headRef = process.env.HEAD || process.env.GITHUB_HEAD_REF;
+  if (process.env.GITHUB_BASE_REF != undefined) {
+    baseRef = process.env.GITHUB_BASE_REF
+  } else {
+    baseRef = baseFromHead(headRef);
+  }
+} else if (process.env.CI === "true") {
+  // We're in production so we don't need to change anything
+  return;
 } else {
+  // We're in development and we need to adapt the head and also the URL
   headRef = "HEAD";
   baseRef = "develop";
   url = ".";