import { useCallback } from 'react';
import { Menu, Sparkles, LogOut, Volume2, VolumeOff, Cpu, Bot, Download } from 'lucide-react';
import type { ConnectionStatus, Session, ChatMessage } from '../types';
import { useT } from '../hooks/useLocale';
import { LanguageSelector } from './LanguageSelector';
import { ThemeSwitcher } from './ThemeSwitcher';
import { sessionDisplayName } from '../lib/sessionName';
import { messagesToMarkdown, downloadFile } from '../lib/exportChat';

interface Props {
  status: ConnectionStatus;
  sessionKey: string;
  onToggleSidebar: () => void;
  activeSessionData?: Session;
  onLogout?: () => void;
  soundEnabled?: boolean;
  onToggleSound?: () => void;
  messages?: ChatMessage[];
  agentAvatarUrl?: string;
}

export function Header({ status, sessionKey, onToggleSidebar, activeSessionData, onLogout, soundEnabled, onToggleSound, messages, agentAvatarUrl }: Props) {
  const t = useT();
  const sessionLabel = activeSessionData ? sessionDisplayName(activeSessionData) : (sessionKey.split(':').pop() || sessionKey);

  const handleExport = useCallback(() => {
    if (!messages || messages.length === 0) return;
    const md = messagesToMarkdown(messages, sessionLabel);
    const safeLabel = sessionLabel.replace(/[^a-zA-Z0-9_-]/g, '_').slice(0, 50);
    const date = new Date().toISOString().slice(0, 10);
    downloadFile(md, `${safeLabel}_${date}.md`);
  }, [messages, sessionLabel]);

  return (
    <>
    <header className="h-14 border-b border-pc-border bg-[var(--pc-bg-surface)]/90 backdrop-blur-xl flex items-center px-4 gap-3 shrink-0" role="banner">
      <button onClick={onToggleSidebar} aria-label={t('header.toggleSidebar')} className="lg:hidden p-2 rounded-2xl hover:bg-[var(--pc-hover)] text-pc-text-secondary transition-colors">
        <Menu size={20} />
      </button>
      <div className="flex items-center gap-3 flex-1 min-w-0">
        <img src={agentAvatarUrl || '/logo.png'} alt="PinchChat" className="h-9 w-9 rounded-2xl object-cover" />
        <div className="min-w-0">
          <div className="flex items-center gap-2">
            <span className="font-semibold text-pc-text text-sm tracking-wide">{t('header.title')}</span>
            <Sparkles className="h-3.5 w-3.5 text-pc-accent-light/60" />
          </div>
          <span className="text-xs text-pc-text-muted truncate flex items-center gap-1.5">
            {activeSessionData?.agentId && (
              <span className="inline-flex items-center gap-0.5 text-pc-accent/70 font-medium">
                <Bot className="h-3 w-3" />
                {activeSessionData.agentId}
                <span className="text-pc-text-faint mx-0.5">·</span>
              </span>
            )}
            {sessionLabel}
          </span>
        </div>
      </div>
      <div className="flex items-center gap-2 text-sm">
        {onToggleSound && (
          <button
            onClick={onToggleSound}
            aria-label={soundEnabled ? t('header.soundOff') : t('header.soundOn')}
            className="p-2 rounded-2xl hover:bg-[var(--pc-hover)] text-pc-text-muted hover:text-pc-text transition-colors"
            title={soundEnabled ? t('header.soundOff') : t('header.soundOn')}
          >
            {soundEnabled ? <Volume2 size={16} /> : <VolumeOff size={16} />}
          </button>
        )}
        {messages && messages.length > 0 && (
          <button
            onClick={handleExport}
            aria-label={t('header.export')}
            className="p-2 rounded-2xl hover:bg-[var(--pc-hover)] text-pc-text-muted hover:text-pc-text transition-colors"
            title={t('header.export')}
          >
            <Download size={16} />
          </button>
        )}
        <ThemeSwitcher />
        <LanguageSelector />
        {status === 'connected' ? (
          <div className="flex items-center gap-2 rounded-2xl border border-pc-border bg-pc-elevated/30 px-3 py-1.5">
            <span className="w-2 h-2 rounded-full bg-[var(--pc-accent)] shadow-[0_0_12px_var(--pc-accent-dim)]" />
            <span className="text-xs text-pc-text hidden sm:inline">{t('header.connected')}</span>
          </div>
        ) : status === 'connecting' ? (
          <div className="flex items-center gap-2 rounded-2xl border border-pc-border bg-pc-elevated/30 px-3 py-1.5">
            <span className="w-2 h-2 rounded-full bg-yellow-400/80 pulse-dot" />
            <span className="text-xs text-pc-text hidden sm:inline">{t('login.connecting')}</span>
          </div>
        ) : (
          <div className="flex items-center gap-2 rounded-2xl border border-pc-border bg-pc-elevated/30 px-3 py-1.5">
            <span className="w-2 h-2 rounded-full bg-red-400/80" />
            <span className="text-xs text-pc-text hidden sm:inline">{t('header.disconnected')}</span>
          </div>
        )}
        {onLogout && (
          <button
            onClick={onLogout}
            aria-label={t('header.logout')}
            className="p-2 rounded-2xl hover:bg-[var(--pc-hover)] text-pc-text-muted hover:text-pc-text transition-colors"
            title={t('header.logout')}
          >
            <LogOut size={16} />
          </button>
        )}
      </div>
    </header>
      {(() => {
        const ctx = activeSessionData?.contextTokens;
        const total = activeSessionData?.totalTokens || 0;
        if (!ctx) return null;
        const pct = Math.min(100, (total / ctx) * 100);
        const opacity = Math.max(0.35, Math.min(1, pct / 100));
        const barStyle = { width: `${pct}%`, backgroundColor: `rgba(56, 189, 248, ${opacity})` };
        return (
          <div className="px-4 py-1.5 bg-[var(--pc-bg-surface)]/60 border-b border-pc-border flex items-center gap-3">
            {activeSessionData?.model && (
              <span className="inline-flex items-center gap-1 text-[10px] text-pc-text-muted shrink-0" title={`Model: ${activeSessionData.model}${activeSessionData.agentId ? ` · Agent: ${activeSessionData.agentId}` : ''}`}>
                <Cpu className="h-2.5 w-2.5" />
                <span className="truncate max-w-[120px]">{activeSessionData.model.replace(/^.*\//, '')}</span>
              </span>
            )}
            <div className="flex-1 h-[5px] rounded-full bg-[var(--pc-hover)] overflow-hidden">
              <div className="h-full rounded-full transition-all duration-500" style={barStyle} />
            </div>
            <span className="text-[11px] text-pc-text-secondary tabular-nums shrink-0 whitespace-nowrap">
              {(total / 1000).toFixed(1)}k / {(ctx / 1000).toFixed(0)}k tokens
            </span>
          </div>
        );
      })()}
    </>
  );
}
