add an action to remove trailing spaces when opening a PR

.github/workflows/formt-pr-files.yml

@@ -0,0 +1,58 @@
+name: Format PR Files
+
+on:
+  pull_request:
+    types:
+      - opened
+    paths:
+      - '**/*.md'  # Trigger workflow only when .md files are modified in the PR
+
+jobs:
+  whitespace:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Git config
+        run: |
+          git config --global user.name "miyaliu666"
+          git config --global user.email "[email protected]"
+
+      - name: Remove trailing whitespaces from Markdown files
+        run: |
+          echo "Target branch: ${{ github.event.pull_request.base.ref }}"
+          echo "Head branch: ${{ github.event.pull_request.head.ref }}"
+
+          # Get the base commit between the target branch (main) and the source branch (HEAD)
+          base_branch="${{ github.event.pull_request.base.ref }}"
+          head_branch="${{ github.event.pull_request.head.ref }}"
+
+          git fetch origin $base_branch
+          git fetch origin $head_branch
+
+          base_commit=$(git merge-base origin/$base_branch origin/$head_branch)
+          echo "Base commit: $base_commit"
+
+           # Get the changed files in the current PR
+          echo "Checking changes in PR..."
+          files=$(git diff --name-only $base_commit origin/$head_branch)
+          echo "Changed files: $files"
+
+          # Filter out .md files
+          file=$(echo "$files" | grep '\.md$')
+          echo "Filtered .md file: $file"
+
+          if [ -n "$file" ]; then
+            echo "Processing file: $file"
+            # Remove trailing spaces from each line in the file
+            sed -i 's/ $//g' "$file"
+            # Switch to the source branch and push the changes
+            git checkout $head_branch
+            git add "$file"
+            git commit -m "Remove trailing spaces from $file"
+            git push origin $head_branch
+          else
+            echo "No .md files found or no changes to commit."
+          fi