Move validateExclusiveModes before getBody for fail-fast validation (#1663)

* Initial plan

* feat: refactor option validation to list-based approach and add delete+hide_and_recreate check

Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

* feat: add only_update to exclusive modes validation list

Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

* refactor: extract validation logic into src/validate.ts

Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

* refactor: move validateExclusiveModes before getBody in run()

Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

* test: assert getBody is not called when validateExclusiveModes fails

Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: marocchino <128431+marocchino@users.noreply.github.com>

src/main.ts

@@ -27,6 +27,7 @@ import {
   repo,
   skipUnchanged,
 } from "./config"
+import {validateBody, validateExclusiveModes} from "./validate"
 
 async function run(): Promise<undefined> {
   if (Number.isNaN(pullRequestNumber) || pullRequestNumber < 1) {
@@ -35,6 +36,15 @@ async function run(): Promise<undefined> {
   }
 
   try {
+    validateExclusiveModes(
+      deleteOldComment,
+      recreate,
+      onlyCreateComment,
+      onlyUpdateComment,
+      hideOldComment,
+      hideAndRecreate,
+    )
+
     const body = await getBody()
 
     if (!body && ignoreEmpty) {
@@ -42,29 +52,7 @@ async function run(): Promise<undefined> {
       return
     }
 
-    if (!deleteOldComment && !hideOldComment && !body) {
-      throw new Error("Either message or path input is required")
-    }
-
-    if (deleteOldComment && recreate) {
-      throw new Error("delete and recreate cannot be both set to true")
-    }
-
-    if (deleteOldComment && onlyCreateComment) {
-      throw new Error("delete and only_create cannot be both set to true")
-    }
-
-    if (deleteOldComment && hideOldComment) {
-      throw new Error("delete and hide cannot be both set to true")
-    }
-
-    if (onlyCreateComment && onlyUpdateComment) {
-      throw new Error("only_create and only_update cannot be both set to true")
-    }
-
-    if (hideOldComment && hideAndRecreate) {
-      throw new Error("hide and hide_and_recreate cannot be both set to true")
-    }
+    validateBody(body, deleteOldComment, hideOldComment)
 
     const octokit = github.getOctokit(githubToken)
     const previous = await findPreviousComment(octokit, repo, pullRequestNumber, header)

src/validate.ts

@@ -0,0 +1,35 @@
+export function validateBody(
+  body: string,
+  deleteOldComment: boolean,
+  hideOldComment: boolean,
+): void {
+  if (!deleteOldComment && !hideOldComment && !body) {
+    throw new Error("Either message or path input is required")
+  }
+}
+
+export function validateExclusiveModes(
+  deleteOldComment: boolean,
+  recreate: boolean,
+  onlyCreateComment: boolean,
+  onlyUpdateComment: boolean,
+  hideOldComment: boolean,
+  hideAndRecreate: boolean,
+): void {
+  const exclusiveModes: [string, boolean][] = [
+    ["delete", deleteOldComment],
+    ["recreate", recreate],
+    ["only_create", onlyCreateComment],
+    ["only_update", onlyUpdateComment],
+    ["hide", hideOldComment],
+    ["hide_and_recreate", hideAndRecreate],
+  ]
+  const enabledModes = exclusiveModes.filter(([, flag]) => flag).map(([name]) => name)
+  if (enabledModes.length > 1) {
+    const last = enabledModes[enabledModes.length - 1]
+    const rest = enabledModes.slice(0, -1)
+    const joined =
+      enabledModes.length === 2 ? `${rest[0]} and ${last}` : `${rest.join(", ")}, and ${last}`
+    throw new Error(`${joined} cannot be set to true simultaneously`)
+  }
+}