#!/usr/bin/env python3
#
# Copyright 2024 David Vazgenovich Shakaryan

import os
import queue
import subprocess
import threading

from datetime import datetime
from zoneinfo import ZoneInfo

class Fmt:
    @classmethod
    def fg(cls, col, s):
        return f'%{{F{col}}}{s}%{{F-}}'

    @classmethod
    def bg(cls, col, s):
        return f'%{{B{col}}}{s}%{{B-}}'

    @classmethod
    def ul(cls, col, s):
        return f'%{{U{col}}}%{{+u}}{s}%{{-u}}%{{U-}}'

    @classmethod
    def bold(cls, s):
        return f'%{{T2}}{s}%{{T-}}'

    @classmethod
    def label(cls, s):
        return cls.fg('#7b51ca', s)

    @classmethod
    def spacer(cls, n=1):
        return f'%{{O{n * 7}}}'

    @classmethod
    def pad(cls, s, n=1):
        sp = cls.spacer(n)
        return f'{sp}{s}{sp}'

    @classmethod
    def clickable(cls, btn, cmd, s):
        return f'%{{A{btn}:{cmd}:}}{s}%{{A}}'

class Mod:
    def __init__(self, spacing=1, spacing_l=None, spacing_r=None):
        self.e_repaint = None

        self.spacing_l = spacing_l if spacing_l is not None else spacing
        self.spacing_r = spacing_r if spacing_r is not None else spacing

        # changes should be applied atomically, as the main thread may read
        # this at any time.
        self.out = None

    def repaint(self):
        self.e_repaint.set()

    def run(self):
        if callable(getattr(self, 'work', None)):
            threading.Thread(target=self.work, daemon=True).start()

    def to_paint(self):
        if (buf := self.out):
            if self.spacing_l:
                buf = Fmt.spacer(self.spacing_l) + buf
            if self.spacing_r:
                buf += Fmt.spacer(self.spacing_r)
            return buf

    def process_cmd(self, cmd):
        pass

class ModRight(Mod):
    def __init__(self, **kwargs):
        kwargs.setdefault('spacing', 0)
        super().__init__(**kwargs)
        self.out = '%{r}'

class ModSpacer(Mod):
    def __init__(self, n=1, **kwargs):
        kwargs.setdefault('spacing', 0)
        super().__init__(**kwargs)
        self.out = Fmt.spacer(n)

class ModDate(Mod):
    def __init__(self, fmts=None, tzs=None, **kwargs):
        super().__init__(**kwargs)
        self.e = threading.Event()

        self.fmts = fmts or ('%H:%M',)
        self.fmt = 0
        self.tzs = tzs or ({'id': None},)
        self.tz = 0

    def work(self):
        while True:
            fmt = self.fmts[self.fmt]
            tz = self.tzs[self.tz]
            tz_id = tz['id']
            tz_label = tz.get('label')

            dt = datetime.now().astimezone(ZoneInfo(tz_id) if tz_id else None)
            label = tz_label or dt.strftime('%Z')

            self.out = Fmt.clickable(
                4, f'{id(self)} tz +1',
                Fmt.clickable(
                    5, f'{id(self)} tz -1',
                    Fmt.clickable('', f'{id(self)} tz', Fmt.label(label))
                        + Fmt.spacer()
                        + Fmt.clickable(
                            '', f'{id(self)} fmt', dt.strftime(fmt))))
            self.repaint()

            self.e.wait(1 - (dt.microsecond / 1000000))
            self.e.clear()

    def process_cmd(self, cmd):
        if cmd == 'fmt':
            self.fmt = (self.fmt + 1) % len(self.fmts)
            self.e.set()
        elif cmd.startswith('tz'):
            self.tz = (self.tz + int(cmd[3:] or 1)) % len(self.tzs)
            self.e.set()

class HLWMClient():
    def __init__(self):
        self.t = None
        self.lock = threading.Lock()
        self.listeners = {}

    def run(self):
        with self.lock:
            if self.t is None:
                self.t = threading.Thread(target=self.work, daemon=True)
                self.t.start()

    def work(self):
        p = subprocess.Popen(
            ('herbstclient', '--idle'),
            stdout=subprocess.PIPE, text=True)

        for line in iter(p.stdout.readline, ''):
            for hook, arr in self.listeners.items():
                if line.startswith(hook):
                    for q, cb_index in arr:
                        q.put((cb_index, line))

    def listen(self, hook, q, cb_index):
        d = (q, cb_index)
        if hook in self.listeners:
            self.listeners[hook].append(d)
        else:
            self.listeners[hook] = [d]

    def exec(self, *args):
        res = subprocess.run(
            ('herbstclient', *args),
            stdout=subprocess.PIPE, stderr=subprocess.DEVNULL, text=True)
        return res.stdout.rstrip()

class ModHLWMBase(Mod):
    client = HLWMClient()

    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.q = queue.Queue()
        self.cbs = []

    def post_start(self):
        pass

    def listen(self, hook, cb):
        self.client.listen(hook, self.q, len(self.cbs))
        self.cbs.append(cb)

    def work(self):
        self.client.run()
        self.post_start()
        while True:
            cb_index, line = self.q.get()
            self.cbs[cb_index]()

    def hc(self, *args):
        return self.client.exec(*args);

class ModHLWMTags(ModHLWMBase):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.listen('tag_', self.refresh)

    def post_start(self):
        self.refresh()

    def fmt_tag(self, sym, tag, focused):
        disp = Fmt.pad(tag)
        match sym:
            case '.':
                buf = Fmt.fg('#777777', disp)
            case '#':
                buf = Fmt.bg('#333333', Fmt.ul('#7b51ca', Fmt.bold(disp)))
            case '!':
                buf = Fmt.bg(
                    '#a03000',
                    Fmt.ul('#7b51ca', Fmt.bold(disp))
                        if tag == focused
                        else Fmt.ul('#000000', disp))
            case ':':
                buf = disp

        return Fmt.clickable('', f'{id(self)} use {tag}', buf)

    def refresh(self):
        tags = self.hc('tag_status').lstrip('\t').split('\t')
        focused = self.hc('attr', 'tags.focus.name')

        self.out = Fmt.clickable(
            4, f'{id(self)} use_index +1',
            Fmt.clickable(
                5, f'{id(self)} use_index -1',
                ''.join(
                    self.fmt_tag(tag[0], tag[1:], focused) for tag in tags)))
        self.repaint()

    def process_cmd(self, cmd):
        subprocess.run(('herbstclient', *cmd.split()))

class ModHLWMTitle(ModHLWMBase):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.listen('focus_changed', self.refresh)
        self.listen('window_title_changed', self.refresh)

    def post_start(self):
        self.refresh()

    def refresh(self):
        title = self.hc('attr', 'clients.focus.title')
        self.out = title if len(title) < 65 else title[0:63] + '…'
        self.repaint()

class ModInputUnavail(Mod):
    def __init__(self, path, label='', **kwargs):
        super().__init__(**kwargs)
        self.path = path
        self.label = label

    def work(self):
        p = subprocess.Popen(
            ('udevadm', 'monitor', '-ups', 'input'),
            stdout=subprocess.PIPE, text=True)

        self._update_state(os.path.exists(self.path))

        building = False
        for line in iter(p.stdout.readline, ''):
            line = line.rstrip()

            if not building and line.startswith('UDEV'):
                building = True
                e = {}
            elif building:
                if '=' in line:
                    k, v = line.split('=', 1)
                    e[k] = v
                else:
                    building = False
                    if e:
                        self._process_event(e)

    def _process_event(self, e):
        if (action := e.get('ACTION')) and (paths := e.get('DEVLINKS')):
            if self.path in paths.split(' '):
                if action == 'add':
                    self._update_state(True)
                elif action == 'remove':
                    self._update_state(False)

    def _update_state(self, avail):
        if avail:
            self.out = None
        else:
            self.out = Fmt.bg('#a03000', Fmt.pad(self.label))
        self.repaint()

class Panel:
    def __init__(self, *mods):
        self.e_repaint = threading.Event()
        self.mods = mods
        for m in self.mods:
            m.e_repaint = self.e_repaint
        self.mod_by_id = {id(m): m for m in self.mods}

    def process_cmds(self, pipe):
        while True:
            line = pipe.readline()
            if not line:
                break
            mod_id, cmd = line.rstrip().split(' ', 1)
            if mod := self.mod_by_id.get(int(mod_id)):
                mod.process_cmd(cmd)

    def run(self):
        for mod in self.mods:
            mod.run()

        self.panel = subprocess.Popen(
            ('/home/david/lemonbar-xft/lemonbar',
                '-bf', 'Monospace:size=10:dpi=96',
                '-f', 'Monospace:size=10:dpi=96:bold',
                '-u', '2', '-g', '1920x22', '-a', '100'),
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            text=True)

        threading.Thread(
            target=self.process_cmds,
            args=(self.panel.stdout,),
            daemon=True
        ).start()

        while True:
                self.e_repaint.wait()
                self.e_repaint.clear()
                print(''.join([s for m in self.mods if (s := m.to_paint())]),
                    file=self.panel.stdin, flush=True)

Panel(
    ModHLWMTags(spacing=0),
    ModHLWMTitle(),
    ModRight(),
    ModInputUnavail(
        '/dev/input/by-id/usb-HID_Keyboard_HID_Keyboard-event-kbd',
        label='NO KEYBOARD'),
    ModDate(
        fmts=('%Y-%m-%d %H:%M:%S', '%H:%M'),
        tzs=({'id': None}, {'id': 'UTC'},
            {'id': 'Asia/Yerevan', 'label': 'AMT'}))
).run()