From 8fe3e1938580fb41af293fbf37b72f215f241023 Mon Sep 17 00:00:00 2001
From: Nathan McRae <nathanm@electroimpact.com>
Date: Sun, 7 Jul 2024 20:06:28 -0700
Subject: [PATCH] Add check-ignore

---
 libwyag.py | 107 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)

diff --git a/libwyag.py b/libwyag.py
index d9e106b..a208d02 100644
--- a/libwyag.py
+++ b/libwyag.py
@@ -957,3 +957,110 @@ def cmd_ls_files(args):
             print(f"  uid: {e.uid} group: {e.gid}")
             print(f"  flags: stage={e.flag_stage} assume_valid={e.flag_assume_valid}")
 
+argsp = argsubparsers.add_parser("check-ignore", help="Check path(s) against ignore rules.")
+argsp.add_argument("path", nargs="+", help="Paths to check")
+
+def cmd_check_ignore(args):
+    repo = repo_find()
+    rules = gitignore_read(repo)
+    for path in args.path:
+        if check_ignore(rules, path):
+            print(path)
+
+def gitignore_parse1(raw):
+    raw = raw.strip()
+
+    if not raw or raw[0] == "#":
+        return None
+    elif raw[0] == "!":
+        return (raw[1:], False)
+    elif raw[0] == "\\":
+        return (raw[1:], True)
+    else:
+        return (raw, True)
+
+def gitignore_parse(lines):
+    ret = list()
+
+    for line in lines:
+        parsed = gitignore_parse1(line)
+        if parsed:
+            ret.append(parsed)
+
+    return ret
+
+class GitIgnore(object):
+    absolute = None
+    scoped = None
+
+    def __init__(self, absolute, scoped):
+        self.absolute = absolute
+        self.scoped = scoped
+
+def gitignore_read(repo):
+    ret = GitIgnore(absolute=list(), scoped=dict())
+
+    # Read local configuration
+    repo_file = os.path.join(repo.gitdir, "info/exclude")
+    if os.path.exists(repo_file):
+        with open(repo_file, "r") as f:
+            ret.absolute.append(gitignore_parse(f.readlines()))
+
+    # Global configuration
+    if "XDG_CONFIG_HOME" in os.environ:
+        config_home == os.environ["XDG_CONFIG_HOME"]
+    else:
+        config_home = os.path.expanduser("~/.config")
+    global_file = os.path.join(config_home, "git/ignore")
+
+    if os.path.exists(global_file):
+        with open(global_file, "r") as f:
+            ret.absolute.append(gitignore_parse(f.readlines()))
+
+    # .gitignore files in the index
+    index = index_read(repo)
+
+    for entry in index.entries:
+        if entry.name == ".gitignore" or entry.name.endswith("/.gitignore"):
+            dir_name = os.path.dirname(entry.name)
+            contents = object_read(repo, entry.sha)
+            lines = contents.blobdata.decode("utf8").splitlines()
+            ret.scoped[dirname] = gitignore_parse(lines)
+    return ret
+
+def check_ignore1(rules, path):
+    result = None
+    for (pattern, value) in rules:
+        if fnmatch(path, pattern):
+            result = value
+    return result
+
+def check_ignore_scoped(rules, path):
+    parent = os.path.dirname(path)
+    while True:
+        if parent in rules:
+            result = check_ignore1(rules[parent], path)
+            if result != None:
+                return result
+        if parent == "":
+            break
+        parent = os.path.dirname(parent)
+    return None
+
+def check_ignore_absolute(rules, path):
+    parent = os.path.dirname(path)
+    for ruleset in rules:
+        result = check_ignore1(ruleset, path)
+        if result != None:
+            return result
+    return False
+
+def check_ignore(rules, path):
+    if os.path.isabs(path):
+        raise Exception("This function requires path to be relative to the repository's root")
+
+    result = check_ignore_scoped(rules.scoped, path)
+    if result != None:
+        return result
+
+    return check_ignore_absolute(rules.absolute, path)