"""Launch external applications (currently PPSSPP)."""
import os
import shutil
import subprocess
from pathlib import Path


def find_ppsspp():
    """Return a candidate PPSSPP executable path, or None."""
    for name in ("ppsspp", "PPSSPP", "PPSSPPSDL", "PPSSPPQt"):
        p = shutil.which(name)
        if p:
            return p
    home = Path.home()
    for cand in (
        home / ".local" / "bin" / "ppsspp",
        home / ".local" / "bin" / "PPSSPPSDL",
        home / "Applications" / "PPSSPP" / "PPSSPP",
        Path("/usr/games/ppsspp"),
        Path("/usr/bin/ppsspp"),
        Path("/usr/bin/PPSSPPSDL"),
        Path("/snap/bin/ppsspp"),
    ):
        if cand.is_file():
            return str(cand)
    return None


def _env():
    env = dict(os.environ)
    # PPSSPPSDL (the SDL build) frequently crashes on Wayland; route it through
    # XWayland instead. Kept local to PPSSPP so nothing else is affected.
    env["SDL_VIDEODRIVER"] = "x11"
    env.setdefault("SDL_AUDIODRIVER", "pulseaudio")
    return env


def launch_ppsspp(iso, exe=""):
    """Launch PPSSPP with the given ISO. Returns ``(ok, message)``."""
    iso = str(iso)
    exe = (exe or "").strip()
    if exe:
        cmd = [exe, iso]
    else:
        found = find_ppsspp()
        if found:
            cmd = [found, iso]
        else:
            return False, "PPSSPP not found. Install it or set its path in Settings → Saves."
    try:
        kwargs = {"env": _env(), "stdout": subprocess.DEVNULL, "stderr": subprocess.DEVNULL}
        if os.name != "nt":
            kwargs["start_new_session"] = True  # POSIX-only: detach from our process group
        subprocess.Popen(cmd, **kwargs)
        return True, ""
    except OSError as exc:
        return False, str(exc)