Introduce REST API fallback

Switch to using the GitHub REST API as a fallback when HTML parsing
fails to retrieve the commit hash from the GitHub commits page. This
ensures that the script continues to work even under rate limit
conditions and improves reliability. Optionally, authentication can
be used to further mitigate rate limits.

Co-authored-by: Po-Ying Chiu <charlie910417@gmail.com>
Change-Id: I248793f475525af192944f892641169ee3320517

Author: EricccTaiwan

scripts/check-repo.sh

@@ -85,6 +85,30 @@ upstream_hash=$(
 
 rm -f "$temp_file"
 
+# If HTML parsing fails, fallback to using GitHub REST API
+if [ -z "$upstream_hash" ]; then
+  echo "HTML retrieval failed, falling back to GitHub REST API..."
+  API_URL="https://api.github.com/repos/${REPO_OWNER}/${REPO_NAME}/commits"
+  
+  # Try to use cached GitHub credentials from GitHub CLI
+  # https://docs.github.com/en/get-started/git-basics/caching-your-github-credentials-in-git
+  if command -v gh >/dev/null 2>&1; then
+    TOKEN=$(gh auth token 2>/dev/null)
+    if [ -n "$TOKEN" ]; then
+      echo "Using token from GitHub CLI..."
+      response=$(curl -sSL -H "Authorization: token $TOKEN" "$API_URL")
+    fi
+  fi
+
+  # If response is empty (i.e. token not available or failed), use unauthenticated request.
+  if [ -z "$response" ]; then
+    response=$(curl -sSL "$API_URL")
+  fi
+
+  # Extract the latest commit SHA from the JSON response
+  upstream_hash=$(echo "$response" | grep -m 1 '"sha":' | sed -E 's/.*"sha": "([^"]+)".*/\1/')
+fi
+
 if [ -z "$upstream_hash" ]; then
   throw "Failed to retrieve upstream commit hash from GitHub.\n"
 fi