"""Start Gyre from a desktop icon: run the web page in the background (no terminal window) and
open it in the browser. Used by the Gyre icon (`install-desktop` puts it in the app grid and on
the desktop):
    python3 -m sandtable launch     start if needed, then open the page
    python3 -m sandtable quit       stop any design, motors off, close Gyre
"""
import json
import os
import shutil
import subprocess
import sys
import time
import urllib.request
import webbrowser

SOFTWARE = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
ICON = os.path.join(SOFTWARE, 'sandtable', 'static', 'gyre.svg')
LOG = os.path.join(SOFTWARE, '.cache', 'server.log')


def status(port):
    """The running Gyre page's status, or None if nothing (or something else) answers."""
    try:
        with urllib.request.urlopen(f'http://127.0.0.1:{port}/api/status', timeout=1.5) as r:
            d = json.load(r)
        return d if 'machine' in d else None
    except Exception:
        return None


def say(title, msg, error=False):
    """Tell the person at the desktop: a dialog if possible, else a notification."""
    print(f'{title}: {msg}', flush=True)
    if shutil.which('zenity'):
        subprocess.run(['zenity', '--error' if error else '--info', '--title', title, '--width', '420',
                        '--text', msg], stderr=subprocess.DEVNULL)
    elif shutil.which('notify-send'):
        subprocess.run(['notify-send', '-a', 'Gyre', title, msg])


def launch(port=8765):
    if status(port) is None:
        os.makedirs(os.path.dirname(LOG), exist_ok=True)
        log = open(LOG, 'a')
        log.write(time.strftime('\n=== %Y-%m-%d %H:%M:%S starting from the Gyre icon\n'))
        log.flush()
        subprocess.Popen([sys.executable, '-m', 'sandtable', 'web', '--no-browser', '--http-port', str(port)],
                         cwd=SOFTWARE, stdout=log, stderr=subprocess.STDOUT, stdin=subprocess.DEVNULL,
                         start_new_session=True)        # keeps running after this launcher exits
        t_end = time.time() + 25
        while time.time() < t_end and status(port) is None:
            time.sleep(0.4)
        if status(port) is None:
            with open(LOG) as f:
                tail = ''.join(f.readlines()[-12:])
            say('Gyre could not start', f'The page did not come up. The last lines of its log:\n\n{tail}', error=True)
            return 1
    webbrowser.open(f'http://127.0.0.1:{port}/')
    return 0


def quit_gyre(port=8765):
    try:
        req = urllib.request.Request(f'http://127.0.0.1:{port}/api/quit', data=b'{}', method='POST',
                                     headers={'Content-Type': 'application/json'})
        with urllib.request.urlopen(req, timeout=40) as r:
            ok = json.load(r).get('ok')
    except Exception:
        ok = False
    if not ok:
        say('Gyre', 'Gyre is not running.')
    return 0


def install_desktop():
    """Put a Gyre icon in the app grid and on the desktop (Linux desktops that follow the
    freedesktop.org standard: GNOME, KDE, Cinnamon, Xfce...)."""
    entry = f"""[Desktop Entry]
Type=Application
Name=Gyre
GenericName=Sand art table
Comment=Draw designs on the Gyre sand table
Exec={sys.executable} -m sandtable launch
Path={SOFTWARE}
Icon={ICON}
Terminal=false
Categories=Utility;
StartupNotify=false
Actions=quit;

[Desktop Action quit]
Name=Quit Gyre
Exec={sys.executable} -m sandtable quit
"""
    apps = os.path.expanduser('~/.local/share/applications')
    os.makedirs(apps, exist_ok=True)
    places = [os.path.join(apps, 'gyre.desktop')]
    desktop = subprocess.run(['xdg-user-dir', 'DESKTOP'], capture_output=True, text=True).stdout.strip() \
        if shutil.which('xdg-user-dir') else os.path.expanduser('~/Desktop')
    if desktop and os.path.isdir(desktop) and desktop != os.path.expanduser('~'):
        places.append(os.path.join(desktop, 'Gyre.desktop'))
    for p in places:
        with open(p, 'w') as f:
            f.write(entry)
        os.chmod(p, 0o755)
        if shutil.which('gio'):                         # GNOME: allow launching from the desktop
            subprocess.run(['gio', 'set', p, 'metadata::trusted', 'true'], stderr=subprocess.DEVNULL)
    if shutil.which('update-desktop-database'):
        subprocess.run(['update-desktop-database', apps], stderr=subprocess.DEVNULL)
    for p in places:
        print('  wrote', p)
    return places