"""Real GUI service fault/restart acceptance, inside a disposable Computer container.

Run via scripts/test-runtime-gui.py; never targets an existing Computer.
"""
import json
import os
from pathlib import Path
import signal
import resource
import subprocess
import tempfile
import time

source = Path('/fixture/runtime_probe.py')
def probe(slot):
    # Match the production helper's limits and clean environment, so a healthy
    # service cannot pass only because the acceptance process has more resources.
    def limits():
        resource.setrlimit(resource.RLIMIT_AS, (256 * 1024 * 1024,) * 2)
        resource.setrlimit(resource.RLIMIT_CPU, (20, 20))
        resource.setrlimit(resource.RLIMIT_NOFILE, (64, 64))
        resource.setrlimit(resource.RLIMIT_CORE, (0, 0))
    result = subprocess.run(['python3', '-I', str(source), json.dumps(slot)],
                            env={'PATH': '/usr/local/bin:/usr/bin:/bin',
                                 'HOME': '/home/lazyboy', 'LANG': 'C.UTF-8'},
                            capture_output=True, timeout=8, preexec_fn=limits, check=True)
    assert len(result.stdout) <= 4096
    return json.loads(result.stdout)


def main():
    assert os.getuid() == 1000
    processes = {}
    with tempfile.TemporaryDirectory(prefix='runtime-gui-') as directory:
        root = Path(directory)
        env = dict(os.environ, DISPLAY=':8', HOME=directory,
                   DBUS_SESSION_BUS_ADDRESS=f'unix:path={root / "bus"}')
        commands = {
            'bus': ['dbus-daemon', '--session', '--nofork', f'--address=unix:path={root / "bus"}'],
            'x': ['Xvfb', ':8', '-screen', '0', '1024x768x24', '-ac', '-nolisten', 'tcp'],
            'wm': ['xfwm4', '--replace', '--compositor=off'],
            'browser': ['chromium', '--no-sandbox', '--disable-dev-shm-usage',
                        '--no-first-run', '--disable-background-networking',
                        '--remote-debugging-port=9229', f'--user-data-dir={root / "profile"}', 'about:blank'],
            'rfb': ['x11vnc', '-display', ':8', '-forever', '-shared', '-nopw',
                    '-listen', '127.0.0.1', '-rfbport', '5907'],
            'viewer': ['websockify', '--web=/usr/share/novnc', '127.0.0.1:6087', '127.0.0.1:5907'],
        }

        def start(name):
            with (root / f'{name}.log').open('ab') as log:
                processes[name] = subprocess.Popen(commands[name], env=env, stdout=log,
                                                   stderr=subprocess.STDOUT, start_new_session=True)

        def stop(name):
            process = processes.pop(name)
            try:
                os.killpg(process.pid, signal.SIGTERM)
                process.wait(timeout=5)
            except ProcessLookupError:
                pass
            except subprocess.TimeoutExpired:
                os.killpg(process.pid, signal.SIGKILL)
                process.wait(timeout=5)

        def expect(label, desktop, browser, viewer):
            wanted = dict(version=1, slot=7, runner=True, desktop=desktop, browser=browser, viewer=viewer)
            deadline = time.monotonic() + 20
            while True:
                actual = probe(7)
                if actual == wanted:
                    print(json.dumps({'case': label, 'observation': actual}), flush=True)
                    return
                if time.monotonic() >= deadline:
                    logs = {p.name: p.read_text(errors='replace')[-5000:] for p in root.glob('*.log')}
                    raise AssertionError((label, wanted, actual, logs))
                time.sleep(.2)

        try:
            assert probe(None) == dict(version=1, slot=None, runner=True, desktop=None, browser=None, viewer=None)
            expect('cold', False, False, False)
            start('x')
            deadline = time.monotonic() + 10
            while subprocess.run(['xdpyinfo', '-display', ':8'], stdout=subprocess.DEVNULL,
                                 stderr=subprocess.DEVNULL).returncode:
                assert time.monotonic() < deadline, 'Xvfb startup timeout'
                time.sleep(.1)
            start('bus')
            deadline = time.monotonic() + 5
            while not (root / 'bus').exists():
                assert time.monotonic() < deadline, 'session bus startup timeout'
                time.sleep(.1)
            for name in ['wm', 'browser', 'rfb', 'viewer']:
                start(name)
            expect('all-real-services', True, True, True)
            for service, expected in [('browser', (True, False, True)),
                                      ('viewer', (True, True, False)),
                                      ('rfb', (True, True, False)),
                                      ('wm', (False, True, True))]:
                stop(service)
                expect(f'{service}-stopped', *expected)
                start(service)
                expect(f'{service}-restarted', True, True, True)
            assert probe(None)['desktop'] is None, 'unassigned probe must not borrow the live screen'
        finally:
            for name in list(reversed(processes)):
                stop(name)


if __name__ == '__main__':
    main()