add auto gemini review comment workflow (#38309)

* add auto gemini review comment workflow

* add workflow dispatch

* add pr number input option

* remove comment

* make pull request target

* add back opened type

Author: derrickaw

.github/workflows/gemini-review-comment.yml

@@ -0,0 +1,49 @@
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: Gemini Review Comment
+
+on:
+  workflow_dispatch:
+    inputs:
+      pr_number:
+        description: 'The Pull Request number to review'
+        required: true
+        type: string
+  pull_request_target:
+    types: [ opened ]
+    branches: [ master ]
+
+jobs:
+  add-comment:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+    steps:
+      - uses: actions/github-script@v8
+        with:
+          script: |
+            const prNumber = context.payload.pull_request?.number || context.payload.inputs?.pr_number;
+
+            if (!prNumber) {
+              throw new Error("Could not find a PR number from context or inputs.");
+            }
+
+            await github.rest.issues.createComment({
+              issue_number: parseInt(prNumber),
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: '/gemini review'
+            });