#!/usr/bin/env python3
import os
import subprocess
import sys
from pathlib import Path

ROOT = Path(".").resolve()
TEST_DIRS = [ROOT / "tests", ROOT / "test"]
CPP_EXTENSIONS = {".c", ".cc", ".cpp", ".cxx", ".h", ".hh", ".hpp", ".hxx"}

TEST_PATTERNS = [
    "test_{name}.cpp",
    "test_{name}.h",
    "{name}_test.cpp",
    "{name}_test.h",
    "{name}test.cpp",
    "{name}test.h",
    "{name}gtest.cpp",
    "{name}gtest.h",
]

def run(cmd: str) -> str:
    return subprocess.check_output(cmd, shell=True, text=True).strip()

def git_ref_exists(ref: str) -> bool:
    try:
        subprocess.check_call(
            f"git rev-parse --verify --quiet '{ref}'",
            shell=True,
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
        )
        return True
    except subprocess.CalledProcessError:
        return False

def is_pull_request_build() -> bool:
    return bool(os.environ.get("CHANGE_ID"))

def resolve_target_ref() -> str | None:
    raw = os.environ.get("CHANGE_TARGET", "").strip()

    candidates = []
    if raw:
        candidates.append(raw)
        if not raw.startswith("origin/"):
            candidates.append(f"origin/{raw}")

    candidates.extend(["origin/main", "main"])

    seen = set()
    for ref in candidates:
        if ref and ref not in seen:
            seen.add(ref)
            if git_ref_exists(ref):
                return ref

    return None

def changed_files():
    target = resolve_target_ref()

    if target:
        print(f"Vergleiche gegen Ziel-Ref: {target}")
        out = run(f"git diff --name-only {target}...HEAD")
        return [line.strip() for line in out.splitlines() if line.strip()]

    if is_pull_request_build():
        print("ERROR: Kein gültiger Ziel-Branch-Ref für PR-Build gefunden.")
        sys.exit(1)

    if git_ref_exists("HEAD~1"):
        print("Kein Ziel-Branch-Ref gefunden, verwende HEAD~1 für Branch-Build.")
        out = run("git diff --name-only HEAD~1..HEAD")
        return [line.strip() for line in out.splitlines() if line.strip()]

    print("Keine Vergleichsbasis gefunden, behandle alle versionierten Dateien als geändert.")
    out = run("git ls-files")
    return [line.strip() for line in out.splitlines() if line.strip()]

def is_cpp_file(path: Path) -> bool:
    return path.suffix.lower() in CPP_EXTENSIONS

def require_clang_format():
    if not (ROOT / ".clang-format").exists():
        print("ERROR: .clang-format fehlt im Repository-Root.")
        sys.exit(1)

def check_format(path: Path):
    subprocess.check_call(f"clang-format --dry-run --Werror '{path}'", shell=True)

def candidate_names(path: Path):
    stem = path.stem.lower()
    names = {stem}
    for suffix in ["_p", "_impl", "_private", "_priv", "_ui"]:
        if stem.endswith(suffix):
            names.add(stem[:-len(suffix)])
    return sorted(n for n in names if n)

def iter_test_files():
    for test_dir in TEST_DIRS:
        if test_dir.exists():
            yield from (p for p in test_dir.rglob("*") if p.is_file())

def has_related_test(path: Path) -> bool:
    test_files = list(iter_test_files())
    if not test_files:
        return False

    test_names = [p.name.lower() for p in test_files]

    for name in candidate_names(path):
        for pattern in TEST_PATTERNS:
            if pattern.format(name=name).lower() in test_names:
                return True
        for test_name in test_names:
            if name in test_name and ("test" in test_name or "gtest" in test_name):
                return True
    return False

def main():
    require_clang_format()

    files = changed_files()
    if not files:
        print("Keine geänderten Dateien erkannt.")
        return

    for rel in files:
        path = ROOT / rel
        if not path.exists():
            continue
        if is_cpp_file(path):
            print(f"Prüfe: {rel}")
            try:
                check_format(path)
            except subprocess.CalledProcessError:
                print(f"ERROR: Formatfehler in {rel}")
                sys.exit(1)

            if not has_related_test(path):
                print(f"ERROR: Kein passender Test unter tests/ oder test/ für {rel} gefunden.")
                sys.exit(1)

    print("Policy-Checks erfolgreich.")

if __name__ == "__main__":
    main()