import React, { useEffect, useLayoutEffect, useMemo, useRef, useState } from 'react';
import { api } from '../api.js';
import {
  byteString,
  formatByteString,
  formatLastSeen,
  sortDevicesByTraffic,
} from '../utils/format.js';

const AUTO_REFRESH_MS = 15_000;
const DEVICE_MOVE_MS = 520;

function Tooltip({ children }) {
  return <span className="client-tooltip" role="tooltip">{children}</span>;
}

function TextMorph({ from, to }) {
  const anchor = from.length >= to.length ? from : to;
  return <span className="client-text-morph" aria-hidden="true">
    <span className="client-text-morph-anchor">{anchor}</span>
    <span className="client-text-morph-value is-date">{from}</span>
    <span className="client-text-morph-value is-relative">{to}</span>
  </span>;
}

export function DevicesPanel({ open, panelRef, closeRef, onClose }) {
  const [snapshot, setSnapshot] = useState(null);
  const [status, setStatus] = useState('idle');
  const [error, setError] = useState(null);
  const [editingId, setEditingId] = useState('');
  const [alias, setAlias] = useState('');
  const [savingId, setSavingId] = useState('');
  const [refreshing, setRefreshing] = useState(false);
  const [refreshCycle, setRefreshCycle] = useState(0);
  const [sortDirection, setSortDirection] = useState('desc');
  const deviceNodes = useRef(new Map());
  const previousPositions = useRef(new Map());
  const devices = useMemo(
    () => sortDevicesByTraffic(snapshot?.devices, sortDirection),
    [snapshot?.devices, sortDirection],
  );

  async function load(quiet = false, discover = false) {
    if (!quiet) setStatus(snapshot ? 'refreshing' : 'loading');
    setRefreshing(true);
    try {
      const next = await (discover ? api.devices.refresh() : api.devices.list());
      setSnapshot((current) => !current || next.revision >= current.revision ? next : current);
      setError(null);
      setStatus('ready');
    } catch (requestError) {
      setError(requestError);
      setStatus('error');
    } finally {
      setRefreshing(false);
      setRefreshCycle((cycle) => cycle + 1);
    }
  }

  useEffect(() => {
    if (!open) return undefined;
    load();
    return undefined;
  }, [open]);

  useEffect(() => {
    if (!open || refreshing || status === 'loading') return undefined;
    const timer = setTimeout(() => load(true), AUTO_REFRESH_MS);
    return () => clearTimeout(timer);
  }, [open, refreshCycle, refreshing, status]);

  useLayoutEffect(() => {
    if (!open) {
      previousPositions.current.clear();
      return;
    }
    const positions = new Map();
    for (const [id, node] of deviceNodes.current) {
      node.getAnimations().forEach((animation) => animation.cancel());
      positions.set(id, node.getBoundingClientRect());
    }
    if (!window.matchMedia('(prefers-reduced-motion: reduce)').matches) {
      for (const [id, after] of positions) {
        const before = previousPositions.current.get(id);
        const deltaY = before ? before.top - after.top : 0;
        if (Math.abs(deltaY) < 1) continue;
        deviceNodes.current.get(id)?.animate([
          { transform: `translateY(${deltaY}px)` },
          { transform: 'translateY(0)' },
        ], { duration: DEVICE_MOVE_MS, easing: 'cubic-bezier(0.16, 1, 0.3, 1)' });
      }
    }
    previousPositions.current = positions;
  }, [devices, open]);

  async function updateDevice(device, patch) {
    setSavingId(device.id);
    try {
      let next;
      try {
        next = await api.devices.update(device.id, patch, snapshot.revision);
      } catch (requestError) {
        if (requestError.code !== 'STATE_CONFLICT') throw requestError;
        const latest = await api.devices.list();
        setSnapshot((current) => !current || latest.revision >= current.revision ? latest : current);
        const latestDevice = latest.devices.find((candidate) => candidate.id === device.id);
        if (!latestDevice || Object.keys(patch).some((key) => latestDevice[key] !== device[key])) {
          throw requestError;
        }
        next = await api.devices.update(device.id, patch, latest.revision);
      }
      setSnapshot((current) => !current || next.revision >= current.revision ? next : current);
      setError(null);
      return true;
    } catch (requestError) {
      setError(requestError);
      return false;
    } finally {
      setSavingId('');
    }
  }

  async function saveAlias(event, device) {
    event.preventDefault();
    if (!await updateDevice(device, { alias })) return;
    setEditingId('');
  }

  async function updatePolicy(device, mode) {
    setSavingId(device.id);
    try {
      let next;
      try {
        next = await api.devices.setPolicy(device.id, mode, snapshot.revision);
      } catch (requestError) {
        if (requestError.code !== 'STATE_CONFLICT') throw requestError;
        const latest = await api.devices.list();
        setSnapshot((current) => !current || latest.revision >= current.revision ? latest : current);
        const latestDevice = latest.devices.find((candidate) => candidate.id === device.id);
        if (!latestDevice || latestDevice.desiredPolicy !== device.desiredPolicy) throw requestError;
        next = await api.devices.setPolicy(device.id, mode, latest.revision);
      }
      setSnapshot((current) => !current || next.revision >= current.revision ? next : current);
      setError(null);
    } catch (requestError) {
      if (requestError.code === 'DEVICE_POLICY_APPLY_FAILED') {
        try {
          const latest = await api.devices.list();
          setSnapshot((current) => !current || latest.revision >= current.revision ? latest : current);
        } catch {
          // Keep the policy error as the actionable result.
        }
      }
      setError(requestError);
    } finally {
      setSavingId('');
    }
  }

  return (
    <aside
      ref={panelRef}
      id="client-devices"
      className={`client-drawer client-instructions client-devices${open ? ' is-open' : ''}`}
      aria-labelledby="client-devices-title"
      aria-hidden={!open}
      inert={!open ? true : undefined}
    >
      <div className="client-drawer-sheet client-instructions-sheet client-devices-sheet">
        <button
          ref={closeRef}
          className="client-drawer-close"
          type="button"
          aria-label="Закрыть устройства"
          onClick={onClose}
        >×</button>
        <header className="client-instructions-header client-devices-header">
          <div className="client-devices-kicker">
            <span>Gateway · {devices.length}</span>
            <span className="client-devices-refresh-wrap client-tooltip-anchor">
              <button
                className={`client-devices-refresh${refreshing ? ' is-refreshing' : ''}`}
                type="button"
                aria-label={refreshing ? 'Обновляем устройства' : 'Обновить устройства сейчас'}
                aria-busy={refreshing}
                disabled={refreshing}
                onClick={() => load(true, true)}
              >
                <svg key={refreshCycle} className="client-devices-refresh-ring" viewBox="0 0 24 24" aria-hidden="true">
                  <circle cx="12" cy="12" r="10" pathLength="1" />
                </svg>
                <svg className="client-devices-refresh-icon" viewBox="0 0 24 24" aria-hidden="true">
                  <path d="M20 11a8 8 0 1 0-2.3 6.7M20 5v6h-6" />
                </svg>
              </button>
              <Tooltip>{refreshing ? 'Обновляем устройства…' : 'Обновить сейчас · автоматически каждые 15 с'}</Tooltip>
            </span>
            <span className="client-devices-sort-wrap client-tooltip-anchor">
              <button
                className="client-devices-sort"
                type="button"
                aria-label={`Сортировка по трафику: сначала ${sortDirection === 'desc' ? 'больше' : 'меньше'}. Изменить направление`}
                onClick={() => setSortDirection((direction) => direction === 'desc' ? 'asc' : 'desc')}
              >
                <span>Трафик</span>
                <span aria-hidden="true">{sortDirection === 'desc' ? '↓' : '↑'}</span>
              </button>
              <Tooltip>Сначала {sortDirection === 'desc' ? 'больше' : 'меньше'} трафика</Tooltip>
            </span>
          </div>
          <h2 id="client-devices-title">Устройства</h2>
          <div className="client-instructions-intro">
            <p>Устройства, которые Gateway видит в локальной таблице соседей.</p>
            <p>Учитывается только трафик, который прошёл через Harbor.</p>
          </div>
        </header>

        {snapshot?.source?.error && (
          <p className="client-devices-source" role="status">
            Список временно не обновляется. Показаны последние сохранённые данные.
          </p>
        )}
        {snapshot?.source?.traffic?.error && (
          <p className="client-devices-source" role="status">
            Трафик временно не обновляется. Показаны последние сохранённые значения.
          </p>
        )}
        {snapshot?.source?.traffic?.proxy?.error && (
          <p className="client-devices-source" role="status">
            Прокси-трафик временно не обновляется. Показаны последние сохранённые значения.
          </p>
        )}
        {snapshot?.source?.policy?.error && (
          <p className="client-devices-source" role="status">
            Маршруты устройств временно не обновляются. Показано последнее подтверждённое состояние.
          </p>
        )}
        {error && (
          <div className="client-devices-error" role="alert">
            <span>{error.message}</span>
            <button type="button" onClick={() => load()}>Повторить</button>
          </div>
        )}
        {status === 'loading' && <p className="client-devices-empty" role="status">Ищем устройства…</p>}
        {status !== 'loading' && !devices.length && !error && (
          <p className="client-devices-empty">Gateway пока не видит устройств.</p>
        )}

        <div className="client-devices-list" aria-live="polite" aria-busy={status === 'loading' || status === 'refreshing'}>
          {devices.map((device) => {
            const title = device.alias || device.hostname || device.ip || 'Неизвестное устройство';
            const editing = editingId === device.id;
            const saving = savingId === device.id;
            const seen = formatLastSeen(device.lastSeenAt);
            const online = device.status === 'online';
            const download = formatByteString(device.downloadBytes);
            const upload = formatByteString(device.uploadBytes);
            const proxyDownload = formatByteString(device.proxyDownloadBytes);
            const proxyUpload = formatByteString(device.proxyUploadBytes);
            const gatewayTotal = byteString(device.downloadBytes) + byteString(device.uploadBytes);
            const proxyTotal = byteString(device.proxyDownloadBytes) + byteString(device.proxyUploadBytes);
            const gatewayTraffic = formatByteString(gatewayTotal.toString());
            const proxyTraffic = formatByteString(proxyTotal.toString());
            const trafficLabel = [
              gatewayTotal > 0n ? `Gateway: получено ${download}, отдано ${upload}` : '',
              proxyTotal > 0n ? `Прокси: получено ${proxyDownload}, отдано ${proxyUpload}` : '',
            ].filter(Boolean).join('. ');
            const policyBusy = device.policyStatus === 'applying';
            const policyFailed = device.policyStatus === 'failed';
            const policyPending = device.policyStatus === 'pending';
            const displayPolicy = device.appliedPolicy;
            const policyTarget = device.policyStatus === 'applied'
              ? device.appliedPolicy === 'direct' ? 'vpn' : 'direct'
              : device.appliedPolicy;
            const cannotEnableDirect = device.policyStatus === 'applied'
              && device.appliedPolicy !== 'direct'
              && (!device.pinned || device.confidence === 'ambiguous');
            const policyTooltip = policyBusy
              ? `Применяем: ${device.desiredPolicy === 'direct' ? 'полностью напрямую' : 'через правила Gateway'}`
              : policyFailed
                ? `${device.policyError || 'Маршрут не применён'}. Сейчас: ${device.appliedPolicy === 'direct' ? 'напрямую' : 'через Gateway'}. Нажмите, чтобы оставить текущий маршрут`
                : policyPending
                  ? 'Gateway должен однозначно распознать устройство. Нажмите, чтобы отменить ожидание'
                  : !device.pinned
                    ? 'Закрепите устройство, чтобы изменить маршрут'
                    : device.confidence === 'ambiguous' && device.desiredPolicy !== 'direct'
                      ? 'Маршрут недоступен, пока Gateway видит несколько сетевых адресов одного устройства'
                      : displayPolicy === 'direct'
                        ? 'Полностью обходит sing-box. Нажмите, чтобы вернуть обработку Gateway'
                        : 'Проходит через sing-box и правила Gateway. Нажмите, чтобы пустить полностью напрямую';
            return <article
              ref={(node) => {
                if (node) deviceNodes.current.set(device.id, node);
                else deviceNodes.current.delete(device.id);
              }}
              className={`client-device is-${device.status}`}
              key={device.id}
            >
              <div className="client-device-heading">
                {editing ? (
                  <form className="client-device-alias" onSubmit={(event) => saveAlias(event, device)}>
                    <input
                      value={alias}
                      maxLength="64"
                      autoFocus
                      aria-label="Название устройства"
                      onChange={(event) => setAlias(event.target.value)}
                    />
                    <button type="submit" aria-label="Сохранить название" disabled={saving}>✓</button>
                    <button type="button" aria-label="Отменить изменение" disabled={saving} onClick={() => setEditingId('')}>×</button>
                  </form>
                ) : (
                  <div className="client-device-title">
                    <h3>{title}</h3>
                    <span className="client-device-edit-wrap client-tooltip-anchor">
                      <button
                        className="client-device-edit"
                        type="button"
                        aria-label={`Изменить название ${title}`}
                        onClick={() => {
                          setEditingId(device.id);
                          setAlias(device.alias || '');
                        }}
                      >
                        <svg viewBox="0 0 24 24" aria-hidden="true">
                          <path d="m4 20 4.2-1 10.3-10.3a2 2 0 0 0-2.8-2.8L5.4 16.2 4 20ZM14.5 7.1l2.8 2.8" />
                        </svg>
                      </button>
                      <Tooltip>Изменить название</Tooltip>
                    </span>
                  </div>
                )}
                <span className="client-device-traffic-slot">
                  {(gatewayTotal > 0n || proxyTotal > 0n) && <span
                    className="client-device-traffic client-tooltip-anchor"
                    tabIndex="0"
                    aria-label={trafficLabel}
                  >
                    <span className="client-device-traffic-sources" aria-hidden="true">
                      {gatewayTotal > 0n && <span>Gateway {gatewayTraffic}</span>}
                      {proxyTotal > 0n && <span className="is-proxy">Прокси {proxyTraffic}</span>}
                    </span>
                    <Tooltip>{trafficLabel}</Tooltip>
                  </span>}
                </span>
                <span className="client-device-pin-wrap client-tooltip-anchor">
                  <button
                    className="client-device-pin"
                    type="button"
                    aria-pressed={device.pinned}
                    aria-label={device.pinned ? `Открепить ${title}` : `Закрепить ${title}`}
                    disabled={saving || device.desiredPolicy === 'direct' || device.appliedPolicy === 'direct'}
                    onClick={() => updateDevice(device, { pinned: !device.pinned })}
                  >
                    <svg viewBox="0 0 24 24" aria-hidden="true">
                      <path d="M9 3h6l-1 5 3 3v2H7v-2l3-3-1-5ZM12 13v8" />
                    </svg>
                  </button>
                  <Tooltip>{device.desiredPolicy === 'direct' || device.appliedPolicy === 'direct'
                    ? 'Сначала верните маршрут через Gateway'
                    : device.pinned ? 'Открепить' : 'Закрепить'}</Tooltip>
                </span>
              </div>

              <div className="client-device-meta">
                <div className="client-device-addresses">
                  {title !== device.ip && device.ip && <span>{device.ip}</span>}
                  {device.manufacturer && <span className="client-device-manufacturer">{device.manufacturer}</span>}
                </div>
                <span className="client-device-policy-wrap client-tooltip-anchor">
                  <button
                    className={`client-device-policy is-${displayPolicy}${policyFailed ? ' is-failed' : ''}${policyPending ? ' is-pending' : ''}`}
                    type="button"
                    aria-label={`Маршрут устройства: ${displayPolicy === 'direct' ? 'полностью напрямую' : 'через правила Gateway'}. ${policyTooltip}`}
                    aria-pressed={displayPolicy === 'direct'}
                    aria-busy={policyBusy}
                    disabled={saving || policyBusy || cannotEnableDirect}
                    onClick={() => updatePolicy(device, policyTarget)}
                  >
                    {displayPolicy === 'direct' ? 'Напрямую' : 'VPN'}
                  </button>
                  <Tooltip>{policyTooltip}</Tooltip>
                </span>
                <span className={`client-device-last-seen${online ? ' is-online' : ''}`} tabIndex="0">
                  <time
                    dateTime={device.lastSeenAt}
                    aria-label={`${online ? 'В сети' : 'Не в сети'}. Последний контакт: ${seen.tooltip}`}
                  >
                    {online ? 'В сети' : <TextMorph from={seen.label} to={seen.relative} />}
                  </time>
                </span>
              </div>
            </article>;
          })}
        </div>
      </div>
    </aside>
  );
}