import json
import subprocess
import sys
from pathlib import Path


SOURCE_SUFFIXES = {".ts", ".tsx", ".js", ".jsx"}
TEST_SUFFIXES = ("ts", "tsx", "js", "jsx")
CONFIG_SUFFIXES = {".json", ".css", ".scss", ".md", ".yml", ".yaml"}
NEXT_SPECIAL_FILES = {
    "layout.ts",
    "layout.tsx",
    "page.ts",
    "page.tsx",
    "loading.tsx",
    "error.tsx",
    "not-found.tsx",
    "globals.css",
}


def _repo_root(cwd: Path) -> Path:
    try:
        root = subprocess.check_output(
            ["git", "rev-parse", "--show-toplevel"],
            cwd=cwd,
            text=True,
            stderr=subprocess.DEVNULL,
        ).strip()
    except (subprocess.CalledProcessError, FileNotFoundError):
        return cwd
    return Path(root)


def _extract_patch_paths(command: str) -> list[str]:
    prefixes = (
        "*** Add File: ",
        "*** Update File: ",
        "*** Delete File: ",
        "*** Move to: ",
    )
    paths: list[str] = []
    for raw_line in command.splitlines():
        line = raw_line.strip()
        for prefix in prefixes:
            if line.startswith(prefix):
                paths.append(line[len(prefix) :].strip())
                break
    return paths


def _touched_paths(payload: dict) -> list[str]:
    tool_input = payload.get("tool_input", {})
    if not isinstance(tool_input, dict):
        return []

    file_path = tool_input.get("file_path")
    if isinstance(file_path, str) and file_path:
        return [file_path]

    command = tool_input.get("command")
    if isinstance(command, str):
        return _extract_patch_paths(command)

    return []


def _normalize(path_text: str) -> str:
    return path_text.replace("\\", "/").lower()


def _is_test_path(path_text: str) -> bool:
    normalized = _normalize(path_text)
    name = normalized.rsplit("/", 1)[-1]
    return (
        "__tests__/" in normalized
        or ".test." in name
        or ".spec." in name
        or "test" in name
        or "spec" in name
    )


def _is_exempt(path_text: str) -> bool:
    normalized = _normalize(path_text)
    path = Path(path_text)
    name = path.name.lower()

    if _is_test_path(path_text):
        return True
    if name in NEXT_SPECIAL_FILES:
        return True
    if path.suffix.lower() in CONFIG_SUFFIXES:
        return True
    if ".env" in name or ".config." in name:
        return True
    if any(token in name for token in ("tailwind", "postcss", "next.config", "tsconfig")):
        return True
    if "/types/" in normalized or name in {"types.ts", "types.d.ts"}:
        return True

    return False


def _resolve_path(path_text: str, cwd: Path) -> Path:
    path = Path(path_text)
    if path.is_absolute():
        return path
    return (cwd / path).resolve()


def _base_name(path: Path) -> str:
    for suffix in (".tsx", ".ts", ".jsx", ".js"):
        if path.name.endswith(suffix):
            return path.name[: -len(suffix)]
    return path.stem


def _has_existing_test(path: Path, root: Path) -> bool:
    directory = path.parent
    parent = directory.parent
    base = _base_name(path)

    for ext in TEST_SUFFIXES:
        if (directory / f"{base}.test.{ext}").exists():
            return True
        if (directory / f"{base}.spec.{ext}").exists():
            return True

    for ext in TEST_SUFFIXES:
        if (parent / "__tests__" / f"{base}.test.{ext}").exists():
            return True
        if (directory / "__tests__" / f"{base}.test.{ext}").exists():
            return True

    for ext in TEST_SUFFIXES:
        if (root / "src" / "__tests__" / f"{base}.test.{ext}").exists():
            return True

    return False


def _guarded_paths(paths: list[str], cwd: Path, root: Path) -> list[str]:
    missing_tests: list[str] = []
    for path_text in paths:
        if _is_exempt(path_text):
            continue

        path = _resolve_path(path_text, cwd)
        if path.suffix.lower() not in SOURCE_SUFFIXES:
            continue
        if not _has_existing_test(path, root):
            missing_tests.append(_base_name(path))

    return missing_tests


def main() -> int:
    try:
        payload = json.load(sys.stdin)
    except json.JSONDecodeError:
        return 0

    cwd = Path(payload.get("cwd") or Path.cwd())
    root = _repo_root(cwd)
    missing_tests = _guarded_paths(_touched_paths(payload), cwd, root)
    if not missing_tests:
        return 0

    names = ", ".join(sorted(set(missing_tests)))
    print(
        json.dumps(
            {
                "hookSpecificOutput": {
                    "hookEventName": "PreToolUse",
                    "permissionDecision": "deny",
                    "permissionDecisionReason": (
                        "TDD GUARD: missing test file for "
                        f"{names}. Write or add the test first."
                    ),
                }
            }
        )
    )
    return 0


if __name__ == "__main__":
    raise SystemExit(main())