"""Predator key listener.

The PH16-71 Predator key produces no input event: its keyboard usage (0xC9) is outside the
range the keyboard declares, so the kernel drops it. The key is also reported on the
vendor report 4 of USB interface 2: `04 81 ff` on press, `04 00 00` on release.
"""

import os
import pwd
import select
import subprocess
import threading
import time

from .keyboard import HOTKEY_INTERFACE, find_hidraw

PRESS_PREFIX = b"\x04\x81"


def active_session_user():
    """(uid, name) of the active graphical session, or None."""
    out = subprocess.run(["loginctl", "list-sessions", "--no-legend"],
                         capture_output=True, text=True).stdout
    for line in out.splitlines():
        sid = line.split()[0] if line.split() else None
        if not sid:
            continue
        props = dict(l.split("=", 1) for l in subprocess.run(
            ["loginctl", "show-session", sid, "-p", "Active", "-p", "Type", "-p", "User", "-p", "Name"],
            capture_output=True, text=True).stdout.splitlines() if "=" in l)
        if props.get("Active") == "yes" and props.get("Type") in ("wayland", "x11"):
            return int(props["User"]), props["Name"]
    return None


def launch_in_session(args):
    sess = active_session_user()
    if not sess:
        return False
    uid, name = sess
    # runs in the user's systemd manager, which carries WAYLAND_DISPLAY/DISPLAY on Plasma
    r = subprocess.run(["systemd-run", "--quiet", "--user", "--machine=%s@.host" % name, "--collect",
                        "--unit=predator-control-launch-%d" % int(time.time() * 1000)] + args,
                       capture_output=True, text=True)
    return r.returncode == 0


class HotkeyListener(threading.Thread):
    def __init__(self, on_press, log):
        super().__init__(daemon=True)
        self.on_press = on_press
        self.log = log

    def run(self):
        while True:
            path = find_hidraw(HOTKEY_INTERFACE)
            if not path:
                time.sleep(5)
                continue
            try:
                fd = os.open(path, os.O_RDONLY)
            except OSError as e:
                self.log("hotkey: cannot open %s: %s" % (path, e))
                time.sleep(5)
                continue
            last = 0.0
            try:
                while True:
                    select.select([fd], [], [])
                    data = os.read(fd, 64)
                    if not data:
                        break
                    if data.startswith(PRESS_PREFIX) and time.monotonic() - last > 0.4:
                        last = time.monotonic()
                        try:
                            self.on_press()
                        except Exception as e:
                            self.log("hotkey: %s" % e)
            except OSError:
                pass  # device vanished (suspend/replug) – reopen
            finally:
                os.close(fd)
            time.sleep(1)