"""Cloudflared binary discovery and download helpers."""

import os
import platform
import shutil
import stat
from urllib import error as urlerror
from urllib import request

from ..logging import debug_log


def _get_project_root():
    return os.path.dirname(os.path.dirname(os.path.dirname(__file__)))


def _get_cloudflared_dir():
    return os.path.join(_get_project_root(), "bin")


def _get_platform_binary_name():
    system = platform.system().lower()
    machine = platform.machine().lower()

    if system == "windows":
        if "arm" in machine:
            return "cloudflared-windows-arm64.exe"
        return "cloudflared-windows-amd64.exe"
    if system == "darwin":
        if machine in ("arm64", "aarch64"):
            return "cloudflared-darwin-arm64"
        return "cloudflared-darwin-amd64"
    if system == "linux":
        if machine in ("arm64", "aarch64"):
            return "cloudflared-linux-arm64"
        return "cloudflared-linux-amd64"

    raise RuntimeError(f"Unsupported platform for cloudflared: {system}/{machine}")


def _get_binary_path(bin_dir=None):
    bin_dir = bin_dir or _get_cloudflared_dir()
    binary_name = "cloudflared.exe" if platform.system().lower() == "windows" else "cloudflared"
    return os.path.join(bin_dir, binary_name)


def _download_cloudflared():
    asset = _get_platform_binary_name()
    url = f"https://github.com/cloudflare/cloudflared/releases/latest/download/{asset}"

    bin_dir = _get_cloudflared_dir()
    os.makedirs(bin_dir, exist_ok=True)
    target_path = _get_binary_path(bin_dir)

    debug_log(f"Downloading cloudflared from {url}")
    try:
        with request.urlopen(url, timeout=30) as resp:
            with open(target_path, "wb") as f:
                shutil.copyfileobj(resp, f)
    except urlerror.URLError as exc:
        raise RuntimeError(f"Failed to download cloudflared: {exc}") from exc

    st = os.stat(target_path)
    os.chmod(target_path, st.st_mode | stat.S_IEXEC)
    debug_log(f"Downloaded cloudflared to {target_path}")
    return target_path


def ensure_binary() -> str:
    """Return a usable cloudflared binary path, downloading if necessary."""
    env_path = os.environ.get("CLOUDFLARED_PATH")
    if env_path and os.path.exists(env_path):
        return env_path

    local_candidate = _get_binary_path()
    if os.path.exists(local_candidate):
        return local_candidate

    path_binary = shutil.which("cloudflared")
    if path_binary:
        return path_binary

    return _download_cloudflared()