Python script to compare source files with decomp (#1635)

* Python script to compare source files with decomp

* Remove unused function

1 files changed, 92 insertions, 0 deletions

diff --git a/decomp_diff.py b/decomp_diff.py
new file mode 100644
index 000000000..cbcde1dd0
--- /dev/null
+++ b/decomp_diff.py
@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+"""
+Generate a git-style patch that shows changes in decompilation between 2Ship (new)
+and the official decomp repo (old).
+"""
+import difflib
+import os
+import sys
+
+ZELDARET_URL = "https://raw.githubusercontent.com/zeldaret/mm/master/"
+
+OLD_DISPLAY = "zeldaret/mm"
+NEW_DISPLAY = "2Ship"
+
+try:
+    # Prefer requests if available for nicer error handling
+    import requests
+except Exception:
+    requests = None
+    import urllib.request
+
+def read_file(path):
+    with open(path, "r", encoding="utf-8", errors="surrogateescape") as f:
+        return f.read().splitlines(keepends=False)
+
+def fetch_url(url):
+    if requests:
+        r = requests.get(url)
+        r.raise_for_status()
+        return r.text.splitlines(keepends=False)
+    else:
+        with urllib.request.urlopen(url) as resp:
+            data = resp.read()
+            # decode with utf-8 fallback
+            text = data.decode("utf-8", errors="surrogateescape")
+            return text.splitlines(keepends=False)
+
+def main():
+    if len(sys.argv) < 2:
+        print("Usage: python decomp_diff.py <local_file> [decomp_relative_path]", file=sys.stderr)
+        sys.exit(2)
+
+    local_path = sys.argv[1]
+    if not os.path.exists(local_path):
+        print(f"Local file not found: {local_path}", file=sys.stderr)
+        sys.exit(2)
+
+    if not local_path.endswith((".c", ".h")):
+        print("Can only compare .c and .h files", file=sys.stderr)
+        sys.exit(2)
+
+    # Read local file (new)
+    local_path = os.path.abspath(local_path)
+    new_lines = read_file(local_path)
+
+    repo_path = os.path.join(os.path.dirname(__file__), "mm")
+    relative_path = os.path.relpath(local_path, repo_path)
+
+    if len(sys.argv) > 2:
+        decomp_url = sys.argv[2]
+    else:
+        decomp_url = None
+
+    print(f"Comparing '{relative_path}' to{f" '{decomp_url}' in" if decomp_url else ""} zeldaret's decomp...")
+
+    if not decomp_url:
+        decomp_url = relative_path.replace("\\", "/")
+
+    # Read zeldaret file (old)
+    try:
+        old_lines = fetch_url(ZELDARET_URL + decomp_url)
+    except Exception as e:
+        print(f"Failed to fetch URL {ZELDARET_URL + decomp_url}: {e}", file=sys.stderr)
+        sys.exit(3)
+
+    # produce unified diff (old -> new)
+    patch_lines = list(difflib.unified_diff(old_lines, new_lines,
+                                   fromfile=f"{OLD_DISPLAY} ({decomp_url})",
+                                   tofile=f"{NEW_DISPLAY} ({relative_path})",
+                                   lineterm=""))
+
+    # append --- and +++ lines are already present in unified diff output; but ensure they exist
+    # if unified_diff returned an empty list and files are identical, print nothing
+    if not patch_lines:
+        print("No differences found.")
+        return
+
+    out_text = "\n".join(patch_lines) + "\n"
+    sys.stdout.write(out_text)
+
+if __name__ == "__main__":
+    main()