#!/usr/bin/env python3
'Read gestures from libinput touchpad and action shell commands.'
# Mark Blakeney, Sep 2015
import os, sys, argparse, subprocess, shlex, re, getpass, fcntl, platform, math
from time import monotonic
from collections import OrderedDict
from pathlib import Path
from distutils.version import LooseVersion as Version

PROGPATH = Path(sys.argv[0])
PROGNAME = PROGPATH.stem

# Conf file containing gesture commands.
# Search first for user file then system file.
CONFNAME = '{}.conf'.format(PROGNAME)
USERDIR = os.getenv('XDG_CONFIG_HOME', os.path.expanduser('~/.config'))
CONFDIRS = (USERDIR, '/etc')

# Ratio of X/Y (or Y/X) at which we consider an oblique swipe gesture.
# The number is the trigger angle in degrees and set to 360/8/2.
OBLIQUE_RATIO = math.tan(math.radians(22.5))

# Default minimum significant distance to move for swipes, in dots.
# Can be changed using configuration command.
swipe_min_threshold = 0

# Timeout on gesture action from start to end. 0 = no timeout. In secs.
# Can be changed using configuration command.
DEFAULT_TIMEOUT = 1.5
timeoutv = DEFAULT_TIMEOUT

# Rotation threshold in degrees to discriminate pinch rotate from in/out
ROTATE_ANGLE = 15.0

# Set up command line arguments
opt = argparse.ArgumentParser(description=__doc__)
opt.add_argument('-c', '--conffile',
        help='alternative configuration file')
opt.add_argument('-v', '--verbose', action='store_true',
        help='output diagnostic messages')
opt.add_argument('-d', '--debug', action='store_true',
        help='output diagnostic messages only, do not action gestures')
opt.add_argument('-r', '--raw', action='store_true',
        help='output raw libinput debug-event messages only, '
        'do not action gestures')
opt.add_argument('-l', '--list', action='store_true',
        help='just list out environment and configuration')
opt.add_argument('--device',
        help='explicit device name to use (or path if starts with /)')
# Test/diag hidden option to specify a file containing libinput list
# device output to parse
opt.add_argument('--device-list', help=argparse.SUPPRESS)
args = opt.parse_args()

if args.debug or args.raw or args.list:
    args.verbose = True

def open_lock(*args):
    'Create a lock based on given list of arguments'
    # We use exclusive assess to a file for this
    fp = Path('/tmp', '-'.join(args) + '.lock').open('w')
    try:
        fcntl.lockf(fp, fcntl.LOCK_EX | fcntl.LOCK_NB)
    except IOError:
        return None

    return fp

def run(cmd, check=True):
    'Run subprocess function and return standard output or None'
    # Maintain subprocess compatibility with python 3.4 so use
    # check_output() rather than run().
    try:
        stdout = subprocess.check_output(cmd, universal_newlines=True,
                stderr=(None if check else subprocess.DEVNULL))
    except Exception as e:
        stdout = None
        if check:
            print(str(e), file=sys.stderr)

    return stdout

def get_libinput_vers():
    'Return the libinput installed version number string'
    # Try to use newer libinput interface then fall back to old
    # (depreciated) interface.
    res = run(('libinput', '--version'), check=False)
    return res.strip() if res else \
            run(('libinput-list-devices', '--version'), check=False)

# Libinput changed the way in which it's utilities are called
libvers = get_libinput_vers()
if not libvers:
    sys.exit('libinput helper tools do not seem to be installed?')

if Version(libvers) >= Version('1.8'):
    cmd_debug_events = 'libinput debug-events'
    cmd_list_devices = 'libinput list-devices'
else:
    cmd_debug_events = 'libinput-debug-events'
    cmd_list_devices = 'libinput-list-devices'

def get_devices_list():
    'Get list of devices and their attributes (as a dict) from libinput'
    if args.device_list:
        with open(args.device_list) as fd:
            stdout = fd.read()
    else:
        stdout = run(cmd_list_devices.split())

    if stdout:
        dev = {}
        for line in stdout.splitlines():
            line = line.strip()
            if line and ':' in line:
                key, value = line.split(':', maxsplit=1)
                dev[key.strip().lower()] = value.strip()
            elif dev:
                yield dev
                dev = {}

        # Ensure we include last device
        if dev:
            yield dev

def get_device(name):
    'Determine libinput touchpad device'
    devices = list(get_devices_list())

    if not devices:
        print('Can not see any devices, did you add yourself to the '
                'input group and log out/in?', file=sys.stderr)
        return None

    # If a specific device name was asked for then return that device
    # This is the "Device" name from libinput list-devices command.
    if name:
        kdev = str(Path(name).resolve()) if name[0] == '/' else None
        for d in devices:
            # If the device name starts with a '/' then it is instead
            # considered as the explicit device path although since
            # device paths can change through reboots this is best to be
            # a symlink. E.g. use the corresponding full path link under
            # /dev/input/by-path/*.
            if kdev:
                if d.get('kernel') == kdev:
                    return d
            elif d.get('device') == name:
                return d
        return None

    # Otherwise look for 1st device with touchpad capabilities
    for d in devices:
        if 'size' in d and 'pointer' in d.get('capabilities'):
            return d

    # Otherwise look for 1st device with touchpad in it's name
    for d in devices:
        if re.search(r'touch ?pad', d.get('device', ''), re.I):
            return d

    # Give up
    return None

class COMMAND:
    'Generic command handler'
    def __init__(self, args):
        self.reprstr = ' '.join(args)

        # Expand '~' and env vars in executable command name
        args[0] = os.path.expandvars(os.path.expanduser(args[0]))
        self.argslist = args

    def run(self):
        'Run this command + arguments'
        run(self.argslist)

    def __str__(self):
        'Return string representation'
        return self.reprstr

# Table of internal commands
internal_commands = OrderedDict()

def add_internal_command(cls):
    'Add configuration command to command lookup table based on name'
    internal_commands[re.sub('^COMMAND', '', cls.__name__)] = cls

@add_internal_command
class COMMAND_internal(COMMAND):
    'Internal command handler.'
    def __init__(self, args):
        'Action internal swipe commands'
        super().__init__(args)

        # Commands currently supported are:
        commands = (
            'ws_up',
            'ws_down',
        )
        # Set up command line arguments
        opt = argparse.ArgumentParser(prog=self.argslist[0],
                description=self.__doc__)
        opt.add_argument('-w', '--wrap', action='store_true',
                help='Wrap workspaces when switching to/from start/end')
        opt.add_argument('--row', type=int,
                help='Step along the row for this number in a row')
        opt.add_argument('--col', type=int,
                help='Step along the column for this number in a column')
        opt.add_argument('action', choices=commands,
                help='Internal command to action')
        self.args = opt.parse_args(self.argslist[1:])
        self.is_up = self.args.action == commands[0]

    def run(self):
        'Get list of current workspaces and select next one'
        stdout = run(('wmctrl', '-d'), check=False)
        if not stdout:
            # This command can fail on GNOME when you have only a single
            # dynamic workspace using Xorg (probably a GNOME bug) so let's
            # just ignore it given there is no other workspace to switch to
            # anyhow.
            return

        args = self.args
        out = stdout.strip().splitlines()
        lines = [l.split(maxsplit=3)[1] for l in out]
        index = lines.index('*')

        if args.row:
            minindex = index - (index % args.row)
            maxindex = minindex + args.row
            count = 1
        else:
            minindex = 0
            maxindex = len(lines)
            count = (maxindex // args.col) if args.col else 1

        # Work out desired workspace
        index += count if self.is_up else -count
        if args.wrap:
            if index == minindex - count:
                index = maxindex - count
            elif index >= maxindex:
                index += minindex - maxindex
            elif index < minindex:
                index += maxindex - minindex

        # Switch to desired workspace
        if index >= minindex and index < maxindex:
            run(('wmctrl', '-s', str(index)))

# Table of gesture handlers
handlers = OrderedDict()

def add_gesture_handler(cls):
    'Create gesture handler instance and add to lookup table based on name'
    handlers[cls.__name__] = cls()

class GESTURE:
    'Abstract base class for handling for gestures'
    def __init__(self):
        'Initialise this gesture at program start'
        self.name = type(self).__name__
        self.motions = OrderedDict()
        self.has_extended = False

    def add(self, motion, fingers, command):
        'Add a configured motion command for this gesture'
        if motion not in self.SUPPORTED_MOTIONS:
            return 'Gesture {} does not support motion "{}".\n' \
                    'Must be "{}"'.format(self.name.lower(), motion,
                            '" or "'.join(self.SUPPORTED_MOTIONS))
        if not command:
            return 'No command configured'

        # If any extended gestures configured then set flag to enable
        # their discrimination
        if self.extended_text in motion:
            self.has_extended = True

        key = (motion, fingers) if fingers else motion

        try:
            cmds = shlex.split(command)
        except Exception as e:
            return str(e)

        cls = internal_commands.get(cmds[0], COMMAND)
        self.motions[key] = cls(cmds)
        return None

    def begin(self, fingers):
        'Initialise this gesture at the start of motion'
        self.fingers = fingers
        self.data = [0.0, 0.0]
        self.starttime = monotonic()

    def action(self, motion):
        'Action a motion command for this gesture'
        command = self.motions.get((motion, self.fingers)) or \
                self.motions.get(motion)

        if args.verbose:
            print('{}: {} {} {} {}'.format(PROGNAME, self.name, motion,
                self.fingers, self.data))
            if command:
                print('  ', command)

        if timeoutv > 0 and (self.starttime + timeoutv) < monotonic():
            if args.verbose:
                print('  ', 'timeout - no action')
            return

        if command and not args.debug:
            command.run()

@add_gesture_handler
class SWIPE(GESTURE):
    'Class to handle this type of gesture'
    SUPPORTED_MOTIONS = ('left', 'right', 'up', 'down',
            'left_up', 'right_up', 'left_down', 'right_down')
    extended_text = '_'

    def update(self, coords):
        'Update this gesture for a motion'
        # Ignore this update if we can not parse the numbers we expect
        try:
            x = float(coords[2])
            y = float(coords[3])
        except (ValueError, IndexError):
            return False

        self.data[0] += x
        self.data[1] += y
        return True

    def end(self):
        'Action this gesture at the end of a motion sequence'
        x, y = self.data
        abx = abs(x)
        aby = abs(y)

        # Require absolute distance movement beyond a small thresh-hold.
        if abx**2 + aby**2 < abzsquare:
            return

        # Discriminate left/right or up/down.
        # If significant movement in both planes the consider it a
        # oblique swipe (but only if any are configured)
        if abx > aby:
            motion = 'left' if x < 0 else 'right'
            if self.has_extended and abx > 0 and aby / abx > OBLIQUE_RATIO:
                motion += '_up' if y < 0 else '_down'
        else:
            motion = 'up' if y < 0 else 'down'
            if self.has_extended and aby > 0 and abx / aby > OBLIQUE_RATIO:
                motion = ('left_' if x < 0 else 'right_') + motion

        self.action(motion)

@add_gesture_handler
class PINCH(GESTURE):
    'Class to handle this type of gesture'
    SUPPORTED_MOTIONS = ('in', 'out', 'clockwise', 'anticlockwise')
    extended_text = 'clock'

    def update(self, coords):
        'Update this gesture for a motion'
        # Ignore this update if we can not parse the numbers we expect
        try:
            x = float(coords[4])
            y = float(coords[5])
        except (ValueError, IndexError):
            return False

        self.data[0] += x - 1.0
        self.data[1] += y
        return True

    def end(self):
        'Action this gesture at the end of a motion sequence'
        ratio, angle = self.data

        if self.has_extended and abs(angle) > ROTATE_ANGLE:
            self.action('clockwise' if angle >= 0.0 else 'anticlockwise')
        elif ratio != 0.0:
            self.action('in' if ratio <= 0.0 else 'out')

# Table of configuration commands
conf_commands = OrderedDict()

def add_conf_command(func):
    'Add configuration command to command lookup table based on name'
    conf_commands[re.sub('^conf_', '', func.__name__)] = func

@add_conf_command
def conf_gesture(lineargs):
    'Process a single gesture line in conf file'
    fields = lineargs.split(maxsplit=2)

    # Look for configured gesture. Sanity check the line.
    if len(fields) < 3:
        return 'Invalid gesture line - not enough fields'

    gesture, motion, command = fields
    handler = handlers.get(gesture.upper())

    if not handler:
        return 'Gesture "{}" is not supported.\nMust be "{}"'.format(
                gesture, '" or "'.join([h.lower() for h in handlers]))

    # Gesture command can be configured with optional specific finger
    # count so look for that
    fingers, *fcommand = command.split(maxsplit=1)
    if fingers.isdigit() and len(fingers) == 1:
        command = fcommand[0] if fcommand else ''
    else:
        fingers = None

    # Add the configured gesture
    return handler.add(motion.lower(), fingers, command)

@add_conf_command
def conf_device(lineargs):
    'Process a single device line in conf file'
    # Command line overrides configuration file
    if not args.device:
        args.device = lineargs

    return None if args.device else 'No device specified'

@add_conf_command
def swipe_threshold(lineargs):
    'Change swipe threshold'
    global swipe_min_threshold
    try:
        swipe_min_threshold = int(lineargs)
    except Exception:
        return 'Must be integer value'

    return None if swipe_min_threshold >= 0 else 'Must be >= 0'

@add_conf_command
def timeout(lineargs):
    'Change gesture timeout'
    global timeoutv
    try:
        timeoutv = float(lineargs)
    except Exception:
        return 'Must be float value'

    return None if timeoutv >= 0 else 'Must be >= 0'

def get_conf_line(line):
    'Process a single line in conf file'
    key, *argslist = line.split(maxsplit=1)

    # Old format conf files may have a ":" appended to the key
    key = key.rstrip(':')
    conf_func = conf_commands.get(key)

    if not conf_func:
        return 'Configuration command "{}" is not supported.\n' \
                'Must be "{}"'.format(key, '" or "'.join(conf_commands))

    return conf_func(argslist[0] if argslist else '')

def get_conf(conffile, confname):
    'Read given configuration file and store internal actions etc'
    with conffile.open() as fp:
        for num, line in enumerate(fp, 1):
            line = line.strip()
            if not line or line[0] == '#':
                continue

            errmsg = get_conf_line(line)
            if errmsg:
                sys.exit('Error at line {} in file {}:\n>> {} <<\n{}.'.format(
                    num, confname, line, errmsg))

def unexpanduser(cfile):
    'Return absolute path name, with $HOME replaced by ~'
    relslash = Path(os.path.abspath(str(cfile)))
    try:
        relhome = relslash.relative_to(os.getenv('HOME'))
    except (ValueError, TypeError):
        relhome = None

    return ('~/' + str(relhome)) if relhome else str(relslash)

if args.verbose:
    # Output various info/version info
    xsession = os.getenv('XDG_SESSION_DESKTOP') or \
            os.getenv('DESKTOP_SESSION') or 'unknown'
    xtype = os.getenv('XDG_SESSION_TYPE') or 'unknown'
    print('{}: session {}+{} on {}, python {}, libinput {}'.format(
        PROGNAME, xsession, xtype, platform.platform(),
        platform.python_version(), libvers))

    # Output hash version/checksum of this program
    vers = run(('md5sum', str(PROGPATH)), check=False)
    vers = str(vers.split()[0]) if vers else '?'
    print('{}: hash {}'.format(PROGPATH, vers))

# Search for configuration file. Use file given as command line
# argument, else look for file in search dir order.
if args.conffile:
    conffile = Path(args.conffile)
    if not conffile.exists():
        sys.exit('Conf file "{}" does not exist.'.format(conffile))
else:
    for confdir in CONFDIRS:
        conffile = Path(confdir, CONFNAME)
        if conffile.exists():
            break
    else:
        sys.exit('No file {} in {}.'.format(CONFNAME, ' or '.join(
            [unexpanduser(Path(c)) for c in CONFDIRS])))

# Hide any personal user dir/names from diag output
confname = unexpanduser(conffile)

# Read and process the conf file
get_conf(conffile, confname)

# List out available gestures if that is asked for
if args.verbose and not args.raw:
    print('Gestures configured in {}:'.format(confname))
    for h in handlers.values():
        for mpair, cmd in h.motions.items():
            motion, fingers = (mpair, '') if isinstance(mpair, str) else mpair
            print('{} {:10}{:>2} {}'.format(h.name.lower(), motion,
                fingers, cmd))
    if args.device:
        print('device {}'.format(args.device))
    if swipe_min_threshold:
        print('swipe_threshold {}'.format(swipe_min_threshold))
    if timeoutv != DEFAULT_TIMEOUT:
        print('timeout {}'.format(timeoutv))

# Get touchpad device
if not args.device or args.device.lower() != "all":
    device = get_device(args.device)
    if not device:
        sys.exit('Could not determine touchpad device.')
else:
    device = None

if args.verbose:
    if device:
        print('{}: device {}: {}'.format(PROGNAME, device.get('kernel'),
            device.get('device')))
    else:
        print('{}: monitoring all devices'.format(PROGNAME))

# If just called to list out above environment info then exit now
if args.list:
    sys.exit()

# Make sure only one instance running for current user
user = getpass.getuser()
proglock = open_lock(PROGNAME, user)
if not proglock:
    sys.exit('{} is already running for {}, terminating ..'.format(
        PROGNAME, user))

# Set up square of swipe threshold
abzsquare = swipe_min_threshold**2

# Note your must "sudo gpasswd -a $USER input" then log out/in for
# permission to access the device.
devstr = ' --device {}'.format(device.get('kernel')) if device else ''
command = 'stdbuf -oL -- {}{}'.format(cmd_debug_events, devstr)

cmd = subprocess.Popen(shlex.split(command), stdout=subprocess.PIPE,
        bufsize=1, universal_newlines=True)

# Sit in a loop forever reading the libinput messages ..
handler = None
for line in cmd.stdout:

    # Just output raw messages if in that mode
    if args.raw:
        print(line.strip())
        continue

    # Only interested in gestures
    if 'GESTURE_' not in line:
        continue

    # Split received message line into relevant fields
    dev, gevent, time, other = line.strip().split(maxsplit=3)
    gesture, event = gevent[8:].split('_')
    fingers, *argslist = other.split(maxsplit=1)
    params = argslist[0] if argslist else ''

    # Action each type of event
    if event == 'UPDATE':
        if handler:
            # Split parameters into list of clean numbers
            if not handler.update(re.split(r'[^-.\d]+', params)):
                print('Could not parse {} {}: {}'.format(gesture, event,
                    params), file=sys.stderr)

    elif event == 'BEGIN':
        handler = handlers.get(gesture)
        if handler:
            handler.begin(fingers)
        else:
            print('Unknown gesture received: {}.'.format(gesture),
                    file=sys.stderr)
    elif event == 'END':
        # Ignore gesture if final action is cancelled
        if handler:
            if params != 'cancelled':
                handler.end()
            handler = None
    else:
        print('Unknown gesture + event received: {} + {}.'.format(gesture,
            event), file=sys.stderr)
