#!/bin/bash

if ! command -v python3 >/dev/null 2>&1; then
  printf '%s\n' 'BLOCKED: Python 3 is required to inspect this command.' >&2
  exit 2
fi

exec python3 -c '
import itertools
import json
import shlex
import sys

def block(reason):
    print("BLOCKED: " + reason, file=sys.stderr)
    sys.exit(2)

try:
    command = json.load(sys.stdin)["tool_input"]["command"]
    if not isinstance(command, str) or not command.strip():
        raise ValueError("missing command")
    lexer = shlex.shlex(command.replace("\\\n", ""), posix=True, punctuation_chars=";&|()\n")
    lexer.whitespace = " \t\r"
    lexer.whitespace_split = True
    tokens = list(lexer)
except (ValueError, KeyError, TypeError):
    block("Cannot parse the command input.")

value_options = {"-C", "-c", "--git-dir", "--work-tree", "--namespace", "--config-env"}
flag_options = {"-p", "--paginate", "-P", "--no-pager", "--bare", "--literal-pathspecs"}
# ponytail: conservative token inspection; shell expansion and aliases require sandbox enforcement.
for separator, group in itertools.groupby(tokens, lambda token: bool(token) and token[0] in ";&|()\n"):
    if separator:
        continue
    words = list(group)
    for index, word in enumerate(words):
        if word.rsplit("/", 1)[-1] != "git":
            continue
        args = words[index + 1:]
        while args and args[0].startswith("-"):
            option = args.pop(0)
            if option in value_options:
                if not args:
                    block("Missing Git option value.")
                args.pop(0)
            elif option in flag_options or option.split("=", 1)[0] in value_options:
                continue
            else:
                block("Unsupported Git option; inspect this command manually.")
        if not args:
            continue
        operation, *args = args
        short_flags = "".join(arg[1:] for arg in args if arg.startswith("-") and not arg.startswith("--"))
        force = "--force" in args or "f" in short_flags
        dangerous = (
            operation == "push"
            or operation == "reset" and "--hard" in args
            or operation == "clean" and force
            or operation == "branch" and ("D" in short_flags or force and ("d" in short_flags or "--delete" in args))
            or operation in {"checkout", "restore"} and "." in args
        )
        if dangerous:
            block("Git " + operation + " is disabled by this hook.")
'