"""YakPanel - Utility functions (ported from legacy panel public module)"""
import os
import re
import hashlib
import asyncio
import subprocess
import html
from typing import Tuple, Optional

regex_safe_path = re.compile(r"^[\w\s./\-]*$")

# systemd often sets PATH to venv-only; subprocess shells then miss /usr/bin (dnf, apt-get, …).
_SYSTEM_PATH = "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"


def ensure_system_path(env: dict[str, str]) -> None:
    """Append standard locations to PATH if /usr/bin is missing."""
    cur = (env.get("PATH") or "").strip()
    if "/usr/bin" in cur:
        return
    env["PATH"] = f"{cur}:{_SYSTEM_PATH}" if cur else _SYSTEM_PATH


def environment_with_system_path(base: Optional[dict[str, str]] = None) -> dict[str, str]:
    """Copy of process env (or base) with PATH guaranteed to include system bin dirs."""
    env = dict(base) if base is not None else os.environ.copy()
    ensure_system_path(env)
    return env


def md5(strings: str | bytes) -> str:
    """Generate MD5 hash"""
    if isinstance(strings, str):
        strings = strings.encode("utf-8")
    return hashlib.md5(strings).hexdigest()


def read_file(filename: str, mode: str = "r") -> str | bytes | None:
    """Read file contents"""
    if not os.path.exists(filename):
        return None
    try:
        with open(filename, mode, encoding="utf-8" if "b" not in mode else None) as f:
            return f.read()
    except Exception:
        try:
            with open(filename, mode) as f:
                return f.read()
        except Exception:
            return None


def write_file(filename: str, content: str | bytes, mode: str = "w+") -> bool:
    """Write content to file"""
    try:
        os.makedirs(os.path.dirname(filename) or ".", exist_ok=True)
        with open(filename, mode, encoding="utf-8" if "b" not in mode else None) as f:
            f.write(content)
        return True
    except Exception:
        return False


def xss_decode(text: str) -> str:
    """Decode XSS-encoded text"""
    try:
        cs = {""": '"', "&quot": '"', "'": "'", "&#x27": "'"}
        for k, v in cs.items():
            text = text.replace(k, v)
        return html.unescape(text)
    except Exception:
        return text


def path_safe_check(path: str, force: bool = True) -> bool:
    """Validate path for security (no traversal, no dangerous chars)"""
    if len(path) > 256:
        return False
    checks = ["..", "./", "\\", "%", "$", "^", "&", "*", "~", '"', "'", ";", "|", "{", "}", "`"]
    for c in checks:
        if c in path:
            return False
    if force and not regex_safe_path.match(path):
        return False
    return True


async def exec_shell(
    cmd: str,
    timeout: Optional[float] = None,
    cwd: Optional[str] = None,
) -> Tuple[str, str]:
    """Execute shell command asynchronously. Returns (stdout, stderr)."""
    proc = await asyncio.create_subprocess_shell(
        cmd,
        stdout=asyncio.subprocess.PIPE,
        stderr=asyncio.subprocess.PIPE,
        cwd=cwd,
        env=environment_with_system_path(),
    )
    try:
        stdout, stderr = await asyncio.wait_for(
            proc.communicate(),
            timeout=timeout or 300,
        )
    except asyncio.TimeoutError:
        proc.kill()
        await proc.wait()
        return "", "Timed out"
    out = stdout.decode("utf-8", errors="replace") if stdout else ""
    err = stderr.decode("utf-8", errors="replace") if stderr else ""
    return out, err


def exec_shell_sync(cmd: str, timeout: Optional[float] = None, cwd: Optional[str] = None) -> Tuple[str, str]:
    """Execute shell command synchronously. Returns (stdout, stderr)."""
    try:
        result = subprocess.run(
            cmd,
            shell=True,
            capture_output=True,
            timeout=timeout or 300,
            cwd=cwd,
            env=environment_with_system_path(),
        )
        out = result.stdout.decode("utf-8", errors="replace") if result.stdout else ""
        err = result.stderr.decode("utf-8", errors="replace") if result.stderr else ""
        return out, err
    except subprocess.TimeoutExpired:
        return "", "Timed out"
    except Exception as e:
        return "", str(e)