'use client';

import { useState, useEffect } from 'react';
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
import { Input } from '@/components/ui/input';
import { Label } from '@/components/ui/label';
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from '@/components/ui/select';
import { Button } from '@/components/ui/button';
import { Separator } from '@/components/ui/separator';
import { Tabs, TabsList, TabsTrigger, TabsContent } from '@/components/ui/tabs';
import { useSettingsStore } from '@/stores/settings-store';
import { getApiBaseUrl, getWsBaseUrl, getBackendUrl, setBackendUrl } from '@/lib/constants';
import { showSuccess } from '@/lib/toast';
import { useTranslation } from '@/lib/i18n';
import { ServerLogViewer } from '@/components/server-log-viewer';
import { ServerStatusDashboard } from '@/components/server-status-dashboard';

// TODO(M2+): read actual values from the backend via /api/system/info.
// 暫時用 userAgent 判斷平台顯示對應路徑。
function getPlatformDataDir(): string {
  if (typeof navigator === 'undefined') return '(unknown)';
  if (/Windows/i.test(navigator.userAgent)) return '%APPDATA%\\visiona-local';
  if (/Linux/i.test(navigator.userAgent)) return '~/.local/share/visiona-local';
  return '~/Library/Application Support/visiona-local';
}
const DATA_DIR_PLACEHOLDER = getPlatformDataDir();
const MODELS_UPLOAD_PATH_PLACEHOLDER = DATA_DIR_PLACEHOLDER + (DATA_DIR_PLACEHOLDER.includes('\\') ? '\\models' : '/models');
const BUNDLED_PYTHON_PLACEHOLDER = 'Bundled Python 3.12 (ready)';

export default function SettingsPage() {
  const { t } = useTranslation();
  const { theme, language, setLanguage, resetToDefaults } = useSettingsStore();
  const [backendUrlInput, setBackendUrlInput] = useState('');
  const [apiUrl, setApiUrl] = useState('');
  const [wsUrl, setWsUrl] = useState('');

  useEffect(() => {
    setBackendUrlInput(getBackendUrl());
    setApiUrl(getApiBaseUrl());
    setWsUrl(getWsBaseUrl());
  }, []);

  function handleSaveBackendUrl() {
    setBackendUrl(backendUrlInput);
    setApiUrl(getApiBaseUrl());
    setWsUrl(getWsBaseUrl());
    showSuccess(t('settings.backendUrlSaved'));
  }

  // Derived port for Advanced tab — parsed from backend URL if possible.
  let serverPortDisplay = '3721';
  try {
    const u = new URL(apiUrl || 'http://localhost:3721');
    if (u.port) serverPortDisplay = u.port;
  } catch {
    /* ignore */
  }

  return (
    <div className="space-y-6">
      <div>
        <h1 className="text-2xl font-bold">{t('settings.title')}</h1>
        <p className="text-muted-foreground">{t('settings.subtitle')}</p>
      </div>

      <Tabs defaultValue="general" className="w-full">
        <TabsList>
          <TabsTrigger value="general">{t('settings.tabs.general')}</TabsTrigger>
          <TabsTrigger value="hardware">{t('settings.tabs.hardware')}</TabsTrigger>
          <TabsTrigger value="models">{t('settings.tabs.models')}</TabsTrigger>
          <TabsTrigger value="advanced">{t('settings.tabs.advanced')}</TabsTrigger>
        </TabsList>

        {/* ─────────── General ─────────── */}
        <TabsContent value="general" className="space-y-6">
          <Card>
            <CardHeader>
              <CardTitle className="text-base">{t('settings.general.title')}</CardTitle>
            </CardHeader>
            <CardContent className="space-y-6">
              <div className="space-y-2">
                <Label>{t('settings.general.language')}</Label>
                <Select value={language} onValueChange={(v) => setLanguage(v as 'zh-TW' | 'en')}>
                  <SelectTrigger className="w-60">
                    <SelectValue />
                  </SelectTrigger>
                  <SelectContent>
                    <SelectItem value="zh-TW">{t('settings.languageZhTW')}</SelectItem>
                    <SelectItem value="en">{t('settings.languageEn')}</SelectItem>
                  </SelectContent>
                </Select>
                <p className="text-xs text-muted-foreground">
                  {t('settings.general.languageRestartHint')}
                </p>
              </div>

              <Separator />

              <div className="space-y-2">
                <Label>{t('settings.general.theme')}</Label>
                <Input
                  value={
                    theme === 'dark'
                      ? `${t('settings.general.themeFollowSystem')} — ${t('settings.general.themeCurrentDark')}`
                      : `${t('settings.general.themeFollowSystem')} — ${t('settings.general.themeCurrentLight')}`
                  }
                  readOnly
                  className="bg-muted w-80"
                />
                <p className="text-xs text-muted-foreground">
                  {t('settings.general.themeFollowSystemHint')}
                </p>
              </div>

              <Separator />

              <div className="space-y-2">
                <Label>{t('settings.general.dataDirectory')}</Label>
                <Input value={DATA_DIR_PLACEHOLDER} readOnly className="bg-muted font-mono text-sm" />
                <p className="text-xs text-muted-foreground">
                  {t('settings.general.dataDirectoryHint')}
                </p>
              </div>
            </CardContent>
          </Card>
        </TabsContent>

        {/* ─────────── Hardware ─────────── */}
        <TabsContent value="hardware" className="space-y-6">
          <Card>
            <CardHeader>
              <CardTitle className="text-base">{t('settings.hardware.title')}</CardTitle>
            </CardHeader>
            <CardContent className="space-y-6">
              <div className="space-y-2">
                <Label>{t('settings.hardware.runtimeMode')}</Label>
                {/* TODO: 連接 backend GET /api/system/config 讀實際 mode，現階段只顯示預設值 real */}
                <Select value="real" disabled>
                  <SelectTrigger className="w-[420px]">
                    <SelectValue />
                  </SelectTrigger>
                  <SelectContent>
                    <SelectItem value="mock">{t('settings.hardware.runtimeModeMock')}</SelectItem>
                    <SelectItem value="real">{t('settings.hardware.runtimeModeReal')}</SelectItem>
                  </SelectContent>
                </Select>
                <p className="text-xs text-muted-foreground">
                  {t('settings.hardware.runtimeModeHint')}
                </p>
              </div>

              <Separator />

              <div className="space-y-2">
                <Label>{t('settings.hardware.pythonMode')}</Label>
                <Input value={BUNDLED_PYTHON_PLACEHOLDER} readOnly className="bg-muted w-80" />
                <p className="text-xs text-muted-foreground">
                  {t('settings.hardware.pythonModeHint')}
                </p>
              </div>
            </CardContent>
          </Card>
        </TabsContent>

        {/* ─────────── Models ─────────── */}
        <TabsContent value="models" className="space-y-6">
          <Card>
            <CardHeader>
              <CardTitle className="text-base">{t('settings.models.title')}</CardTitle>
            </CardHeader>
            <CardContent className="space-y-6">
              <div className="space-y-2">
                <Label>{t('settings.models.presetModels')}</Label>
                {/* TODO(M2+): fetch /api/models and list preset models here */}
                <p className="text-sm text-muted-foreground">
                  {t('settings.models.presetModelsEmpty')}
                </p>
              </div>

              <Separator />

              <div className="space-y-2">
                <Label>{t('settings.models.uploadPath')}</Label>
                <Input
                  value={MODELS_UPLOAD_PATH_PLACEHOLDER}
                  readOnly
                  className="bg-muted font-mono text-sm"
                />
                <p className="text-xs text-muted-foreground">
                  {t('settings.models.uploadPathHint')}
                </p>
              </div>
            </CardContent>
          </Card>
        </TabsContent>

        {/* ─────────── Advanced ─────────── */}
        <TabsContent value="advanced" className="space-y-6">
          <Card>
            <CardHeader>
              <CardTitle className="text-base">{t('settings.serverConfig')}</CardTitle>
            </CardHeader>
            <CardContent className="space-y-4">
              <div className="space-y-2">
                <Label>{t('settings.backendUrl')}</Label>
                <div className="flex gap-2">
                  <Input
                    value={backendUrlInput}
                    onChange={(e) => setBackendUrlInput(e.target.value)}
                    placeholder={t('settings.backendUrlPlaceholder')}
                    className="flex-1"
                  />
                  <Button onClick={handleSaveBackendUrl} size="sm">
                    {t('settings.saveBackendUrl')}
                  </Button>
                </div>
                <p className="text-xs text-muted-foreground">
                  {t('settings.backendUrlHint')}
                </p>
              </div>
              <Separator />
              <div className="space-y-2">
                <Label>{t('settings.hardware.serverPort')}</Label>
                <Input value={serverPortDisplay} readOnly className="bg-muted w-32" />
                <p className="text-xs text-muted-foreground">
                  {t('settings.hardware.serverPortHint')}
                </p>
              </div>
              <div className="space-y-2">
                <Label>{t('settings.apiUrl')}</Label>
                <Input value={apiUrl} readOnly className="bg-muted" />
              </div>
              <div className="space-y-2">
                <Label>{t('settings.wsUrl')}</Label>
                <Input value={wsUrl} readOnly className="bg-muted" />
              </div>
            </CardContent>
          </Card>

          <ServerStatusDashboard />

          <ServerLogViewer />

          <Card>
            <CardHeader>
              <CardTitle className="text-base">{t('settings.advanced.about')}</CardTitle>
            </CardHeader>
            <CardContent className="space-y-3">
              <div className="flex justify-between text-sm">
                <span className="text-muted-foreground">{t('settings.versionLabel')}</span>
                <span className="font-medium">v0.1.0</span>
              </div>
              <div className="flex justify-between text-sm">
                <span className="text-muted-foreground">{t('settings.platform')}</span>
                <span className="font-medium">visionA Local</span>
              </div>
            </CardContent>
          </Card>

          <Card>
            <CardHeader>
              <CardTitle className="text-base">{t('settings.advanced.resetAll')}</CardTitle>
            </CardHeader>
            <CardContent className="space-y-3">
              <p className="text-xs text-muted-foreground">
                {t('settings.advanced.resetAllHint')}
              </p>
              <Button
                variant="outline"
                onClick={() => {
                  resetToDefaults();
                  showSuccess(t('settings.resetSuccess'));
                }}
              >
                {t('settings.resetToDefaults')}
              </Button>
            </CardContent>
          </Card>
        </TabsContent>
      </Tabs>
    </div>
  );
}