diff --git a/git-auto-comment.py b/git-auto-comment.py
index 415e1f2..92551ee 100755
--- a/git-auto-comment.py
+++ b/git-auto-comment.py
@@ -4,20 +4,47 @@ import re
 import json
 import requests
 
+# Read inputs from environment variables
 platform = os.environ.get("PLATFORM", "github").lower()
 token = os.environ["TOKEN"]
-owner = os.environ["REPO_OWNER"]
-repo = os.environ["REPO_NAME"]
+owner = os.environ.get("REPO_OWNER", os.environ.get("GITHUB_REPOSITORY_OWNER"))
+repo = os.environ.get("REPO_NAME", os.environ.get("GITHUB_REPOSITORY"))
 pr_index = os.environ["PR_INDEX"]
-api_url = os.environ.get("API_URL")
-diff_text = os.environ.get("DIFF")
-comment_template = os.environ.get("COMMENT_TEMPLATE", "")
+api_url = os.environ.get("API_URL", os.environ.get("GITHUB_API_URL"))
+diff_text = os.environ.get("DIFF")  # optional
+comment_template = os.environ.get("COMMENT_TEMPLATE", "Auto-comment: changed line -> {line}")
 
-if not diff_text:
-    print("No diff provided", file=sys.stderr)
+if not token or not pr_index:
+    print("TOKEN and PR_INDEX are required.", file=sys.stderr)
     sys.exit(1)
 
-# Parse diff
+# If diff_text is empty, just post a general PR comment
+if not diff_text:
+    body = comment_template.replace("{line}", "").replace("{lines}", "")
+    if platform == "github":
+        url = f"https://api.github.com/repos/{owner}/{repo}/issues/{pr_index}/comments"
+        payload = {"body": body}
+    elif platform == "gitea":
+        if not api_url:
+            print("Gitea API URL required for Gitea platform", file=sys.stderr)
+            sys.exit(1)
+        url = f"{api_url}/repos/{owner}/{repo}/pulls/{pr_index}/comments"
+        payload = {"body": body}
+    else:
+        print(f"Unsupported platform: {platform}", file=sys.stderr)
+        sys.exit(1)
+
+    headers = {"Authorization": f"token {token}", "Content-Type": "application/json"}
+    resp = requests.post(url, headers=headers, json=payload)
+    if resp.status_code in (200, 201):
+        print("General comment posted successfully!")
+        sys.exit(0)
+    else:
+        print(f"Failed to post comment: {resp.status_code}", file=sys.stderr)
+        print(resp.text, file=sys.stderr)
+        sys.exit(1)
+
+# --- If diff_text exists, parse diff normally ---
 diff_files = {}
 current_file = None
 new_line_num = None
@@ -38,7 +65,7 @@ for line in diff_text.splitlines():
     elif not line.startswith("-"):
         new_line_num += 1
 
-# Post comments
+# Post comments for each added line
 for file_path, lines in diff_files.items():
     if not lines:
         continue
@@ -47,37 +74,21 @@ for file_path, lines in diff_files.items():
         body = comment_template.replace("{line}", line_content).replace("{lines}", all_lines_content)
 
         if platform == "github":
-            url = f"https://api.github.com/repos/{owner}/{repo}/issues/{pr_index}/comments"
-            payload = {"body": body}
-            if file_path and line_number:
-                url = f"https://api.github.com/repos/{owner}/{repo}/pulls/{pr_index}/comments"
-                payload.update({
-                    "body": body,
-                    "path": file_path,
-                    "position": line_number
-                })
+            url = f"https://api.github.com/repos/{owner}/{repo}/pulls/{pr_index}/comments"
+            payload = {"body": body, "path": file_path, "position": line_number}
         elif platform == "gitea":
             if not api_url:
                 print("Gitea API URL required", file=sys.stderr)
                 sys.exit(1)
             url = f"{api_url}/repos/{owner}/{repo}/pulls/{pr_index}/comments"
-            payload = {"body": body}
-            if file_path and line_number:
-                payload.update({
-                    "path": file_path,
-                    "position": line_number
-                })
+            payload = {"body": body, "path": file_path, "position": line_number}
         else:
             print(f"Unsupported platform: {platform}", file=sys.stderr)
             sys.exit(1)
 
-        headers = {
-            "Authorization": f"token {token}",
-            "Content-Type": "application/json",
-        }
-
+        headers = {"Authorization": f"token {token}", "Content-Type": "application/json"}
         resp = requests.post(url, headers=headers, json=payload)
-        if resp.status_code in (201, 200):
+        if resp.status_code in (200, 201):
             print(f"Comment posted on {file_path}:{line_number}")
         else:
             print(f"Failed to post comment on {file_path}:{line_number} ({resp.status_code})", file=sys.stderr)