import { useState, useRef, useEffect } from 'react';
import { cn } from '@/lib/utils';
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
import { Button } from '@/components/ui/button';
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from '@/components/ui/select';
import {
  Dialog,
  DialogContent,
  DialogDescription,
  DialogFooter,
  DialogHeader,
  DialogTitle,
  DialogTrigger,
} from '@/components/ui/dialog';
import {
  Terminal,
  Plus,
  X,
  Server,
  Maximize2,
  Minimize2,
} from 'lucide-react';
import { Terminal as XTerm } from 'xterm';
import { FitAddon } from 'xterm-addon-fit';
import 'xterm/css/xterm.css';
import { serverApi } from '@/services/api';
import { useUserStore } from '@/store';

interface TerminalSession {
  id: string;
  serverId: string;
  serverName: string;
  serverIp: string;
  connected: boolean;
}

interface TermEntry {
  term: XTerm;
  ws: WebSocket;
  fit: FitAddon;
  opened: boolean;
}

export function WebShell() {
  const [servers, setServers] = useState<any[]>([]);
  const [sessions, setSessions] = useState<TerminalSession[]>([]);
  const [activeSession, setActiveSession] = useState<string | null>(null);
  const [selectedServer, setSelectedServer] = useState<string>('');
  const [isFullscreen, setIsFullscreen] = useState(false);
  const [dialogOpen, setDialogOpen] = useState(false);

  // 每个会话的终端实例：sessionId -> { term, ws, fit, opened }
  const termsRef = useRef<Map<string, TermEntry>>(new Map());
  // 每个会话的容器 DOM
  const containerRef = useRef<Map<string, HTMLDivElement>>(new Map());

  const loadServers = async () => {
    try {
      const res: any = await serverApi.getServers();
      setServers(res?.list || []);
    } catch (e) {
      console.error('加载服务器列表失败:', e);
      setServers([]);
    }
  };

  useEffect(() => {
    loadServers();
  }, []);

  // 卸载时关闭所有连接
  useEffect(() => {
    return () => {
      termsRef.current.forEach(({ ws, term }) => {
        try {
          ws.close();
          term.dispose();
        } catch {
          /* noop */
        }
      });
      termsRef.current.clear();
    };
  }, []);

  const runningServers = servers.filter((s) => s.status === 'running');

  const createSession = () => {
    if (!selectedServer) return;
    const server = servers.find((s) => s.id === selectedServer);
    if (!server) return;

    const sessionId = `session-${Date.now()}`;
    const cols = 80;
    const rows = 24;

    const term = new XTerm({
      cursorBlink: true,
      fontSize: 13,
      fontFamily: 'Menlo, Monaco, "Courier New", monospace',
      allowProposedApi: true,
      theme: {
        background: '#0a0e14',
        foreground: '#d6d6d6',
        cursor: '#d6d6d6',
        selectionBackground: 'rgba(255,255,255,0.2)',
      },
    });

    const fit = new FitAddon();
    term.loadAddon(fit);

    const proto = typeof location !== 'undefined' && location.protocol === 'https:' ? 'wss' : 'ws';
    const token = useUserStore.getState().token || '';
    const wsUrl = `${proto}://${location.host}/ws/terminal?id=${server.id}&cols=${cols}&rows=${rows}&token=${encodeURIComponent(token)}`;
    const ws = new WebSocket(wsUrl);

    // 终端输入 -> WebSocket
    term.onData((data) => {
      if (ws.readyState === WebSocket.OPEN) {
        ws.send(JSON.stringify({ status: 0, data }));
      }
    });

    // WebSocket 输出 -> 终端
    ws.onmessage = (event) => {
      try {
        const msg = JSON.parse(event.data);
        if (msg.status === 0 && typeof msg.data === 'string') {
          term.write(msg.data);
        }
      } catch {
        // 非 JSON，直接写入原始数据
        term.write(typeof event.data === 'string' ? event.data : '');
      }
    };

    ws.onopen = () => {
      term.write(`\x1b[32m正在连接 ${server.hostname} (${server.ip})...\x1b[0m\r\n`);
    };

    ws.onclose = () => {
      term.write('\r\n\x1b[31m[连接已关闭]\x1b[0m\r\n');
      setSessions((prev) =>
        prev.map((s) => (s.id === sessionId ? { ...s, connected: false } : s))
      );
    };

    ws.onerror = () => {
      term.write('\r\n\x1b[31m[连接发生错误]\x1b[0m\r\n');
    };

    termsRef.current.set(sessionId, { term, ws, fit, opened: false });

    const newSession: TerminalSession = {
      id: sessionId,
      serverId: server.id,
      serverName: server.hostname,
      serverIp: server.ip,
      connected: true,
    };
    setSessions((prev) => [...prev, newSession]);
    setActiveSession(sessionId);
    setSelectedServer('');
    setDialogOpen(false);
  };

  const closeSession = (sessionId: string) => {
    const entry = termsRef.current.get(sessionId);
    if (entry) {
      try {
        if (entry.ws.readyState === WebSocket.OPEN || entry.ws.readyState === WebSocket.CONNECTING) {
          entry.ws.close();
        }
        entry.term.dispose();
      } catch {
        /* noop */
      }
      termsRef.current.delete(sessionId);
    }
    containerRef.current.delete(sessionId);
    const newSessions = sessions.filter((s) => s.id !== sessionId);
    setSessions(newSessions);
    if (activeSession === sessionId) {
      setActiveSession(newSessions.length > 0 ? newSessions[0].id : null);
    }
  };

  // 窗口 resize 时适配当前激活的终端
  useEffect(() => {
    const handleResize = () => {
      if (!activeSession) return;
      const entry = termsRef.current.get(activeSession);
      if (!entry || !entry.opened) return;
      try {
        entry.fit.fit();
        const { cols, rows } = entry.term;
        entry.term.resize(cols, rows);
        if (entry.ws.readyState === WebSocket.OPEN) {
          entry.ws.send(JSON.stringify({ status: 1, cols, rows }));
        }
      } catch {
        /* noop */
      }
    };
    window.addEventListener('resize', handleResize);
    return () => window.removeEventListener('resize', handleResize);
  }, [activeSession, isFullscreen]);

  // 激活会话切换后重新 fit
  useEffect(() => {
    if (!activeSession) return;
    const entry = termsRef.current.get(activeSession);
    if (entry && entry.opened) {
      requestAnimationFrame(() => {
        try {
          entry.fit.fit();
          entry.term.focus();
        } catch {
          /* noop */
        }
      });
    }
  }, [activeSession, isFullscreen]);

  // 快捷命令：直接发送到当前激活的 WebSocket
  const sendCommand = (cmd: string) => {
    if (!activeSession) return;
    const entry = termsRef.current.get(activeSession);
    if (entry && entry.ws.readyState === WebSocket.OPEN) {
      entry.ws.send(JSON.stringify({ status: 0, data: cmd + '\n' }));
      entry.term.focus();
    }
  };

  // 注册容器并首次挂载终端
  const registerContainer = (sessionId: string, el: HTMLDivElement | null) => {
    if (el) {
      containerRef.current.set(sessionId, el);
      const entry = termsRef.current.get(sessionId);
      if (entry && !entry.opened) {
        try {
          entry.term.open(el);
          entry.opened = true;
          requestAnimationFrame(() => {
            try {
              entry.fit.fit();
              entry.term.focus();
            } catch {
              /* noop */
            }
          });
        } catch (e) {
          console.error('打开终端失败:', e);
        }
      }
    } else {
      containerRef.current.delete(sessionId);
    }
  };

  const activeSessionData = sessions.find((s) => s.id === activeSession);
  const terminalHeight = isFullscreen ? 'calc(100vh - 140px)' : '500px';

  return (
    <div className={cn('space-y-4', isFullscreen && 'fixed inset-0 z-50 p-4')} style={isFullscreen ? { background: 'var(--dg-bg-primary)' } : undefined}>
      {/* Page Header */}
      {!isFullscreen && (
        <div className="flex items-center justify-between">
          <div>
            <h1 className="text-2xl font-bold text-[var(--dg-text-primary)]">WebShell</h1>
            <p className="text-sm text-[var(--dg-text-secondary)] mt-1">远程服务器终端管理</p>
          </div>
          <div className="flex items-center gap-2">
            <Dialog open={dialogOpen} onOpenChange={setDialogOpen}>
              <DialogTrigger asChild>
                <Button className="bg-[var(--dg-blue)] hover:opacity-90 text-white">
                  <Plus className="h-4 w-4 mr-2" />
                  新建连接
                </Button>
              </DialogTrigger>
              <DialogContent className="bg-[var(--dg-bg-secondary)] border-[var(--dg-border)]">
                <DialogHeader>
                  <DialogTitle className="text-[var(--dg-text-primary)]">新建终端连接</DialogTitle>
                  <DialogDescription className="text-[var(--dg-text-secondary)]">
                    选择要连接的服务器
                  </DialogDescription>
                </DialogHeader>
                <div className="space-y-4 py-4">
                  <div className="space-y-2">
                    <label className="text-sm font-medium text-[var(--dg-text-secondary)]">选择服务器</label>
                    <Select value={selectedServer} onValueChange={setSelectedServer}>
                      <SelectTrigger className="bg-[var(--dg-bg-tertiary)] border-[var(--dg-border)] text-[var(--dg-text-primary)]">
                        <SelectValue placeholder="选择服务器" />
                      </SelectTrigger>
                      <SelectContent className="bg-[var(--dg-bg-tertiary)] border-[var(--dg-border)]">
                        {runningServers.length === 0 ? (
                          <SelectItem value="__none" disabled>暂无运行中的服务器</SelectItem>
                        ) : (
                          runningServers.map((server) => (
                            <SelectItem key={server.id} value={server.id}>
                              <div className="flex items-center gap-2">
                                <Server className="h-4 w-4" />
                                <span>{server.hostname}</span>
                                <span className="text-[var(--dg-text-muted)]">({server.ip})</span>
                              </div>
                            </SelectItem>
                          ))
                        )}
                      </SelectContent>
                    </Select>
                  </div>
                </div>
                <DialogFooter>
                  <Button
                    onClick={createSession}
                    disabled={!selectedServer || selectedServer === '__none'}
                    className="bg-[var(--dg-blue)] hover:opacity-90 text-white"
                  >
                    <Terminal className="h-4 w-4 mr-2" />
                    连接
                  </Button>
                </DialogFooter>
              </DialogContent>
            </Dialog>
          </div>
        </div>
      )}

      {/* Terminal Container */}
      <Card className="bg-[var(--dg-bg-secondary)] border-[var(--dg-border)] flex-1">
        <CardHeader className="pb-2 border-b border-[var(--dg-border)]">
          <div className="flex items-center justify-between">
            <div className="flex items-center gap-4">
              {sessions.length > 0 ? (
                <div className="flex items-center gap-1">
                  {sessions.map((session) => (
                    <button
                      key={session.id}
                      onClick={() => setActiveSession(session.id)}
                      className={cn(
                        'flex items-center gap-2 px-3 py-1.5 text-sm rounded-md transition-colors',
                        activeSession === session.id
                          ? 'bg-[var(--dg-bg-tertiary)] text-[var(--dg-text-primary)]'
                          : 'text-[var(--dg-text-secondary)] hover:text-[var(--dg-text-primary)]'
                      )}
                    >
                      <div
                        className={cn(
                          'w-2 h-2 rounded-full',
                          session.connected ? 'bg-emerald-400' : 'bg-red-400'
                        )}
                      />
                      <span className="max-w-[120px] truncate">{session.serverName}</span>
                      <span
                        onClick={(e) => {
                          e.stopPropagation();
                          closeSession(session.id);
                        }}
                        className="ml-1 p-0.5 rounded hover:bg-[var(--dg-bg-hover)] cursor-pointer"
                      >
                        <X className="h-3 w-3" />
                      </span>
                    </button>
                  ))}
                </div>
              ) : (
                <span className="text-sm text-[var(--dg-text-secondary)]">暂无连接</span>
              )}
            </div>
            <div className="flex items-center gap-1">
              {activeSessionData && (
                <span className="text-xs text-[var(--dg-text-muted)] mr-2">
                  {activeSessionData.serverIp}
                </span>
              )}
              <Button
                variant="ghost"
                size="icon"
                className="h-8 w-8 text-[var(--dg-text-secondary)] hover:text-[var(--dg-text-primary)]"
                onClick={() => setIsFullscreen(!isFullscreen)}
              >
                {isFullscreen ? <Minimize2 className="h-4 w-4" /> : <Maximize2 className="h-4 w-4" />}
              </Button>
            </div>
          </div>
        </CardHeader>
        <CardContent className="p-0">
          {sessions.length > 0 ? (
            <div className="relative bg-[#0a0e14]" style={{ height: terminalHeight }}>
              {sessions.map((session) => (
                <div
                  key={session.id}
                  ref={(el) => registerContainer(session.id, el)}
                  className={cn(
                    'absolute inset-0 p-1',
                    activeSession === session.id ? 'block' : 'hidden'
                  )}
                />
              ))}
            </div>
          ) : (
            <div
              className="flex flex-col items-center justify-center text-[var(--dg-text-secondary)]"
              style={{ height: terminalHeight }}
            >
              <Terminal className="h-16 w-16 mb-4 opacity-50" />
              <p className="text-lg font-medium">暂无活动连接</p>
              <p className="text-sm mt-1">点击“新建连接”开始远程会话</p>
            </div>
          )}
        </CardContent>
      </Card>

      {/* Quick Commands */}
      {activeSessionData && (
        <Card className="bg-[var(--dg-bg-secondary)] border-[var(--dg-border)]">
          <CardHeader className="pb-2">
            <CardTitle className="text-sm text-[var(--dg-text-secondary)]">快捷命令</CardTitle>
          </CardHeader>
          <CardContent>
            <div className="flex flex-wrap gap-2">
              {['ls -la', 'pwd', 'df -h', 'free -m', 'ps aux', 'top', 'netstat -tlnp', 'systemctl status'].map(
                (cmd) => (
                  <Button
                    key={cmd}
                    variant="outline"
                    size="sm"
                    className="border-[var(--dg-border)] text-[var(--dg-text-secondary)] hover:text-[var(--dg-text-primary)] hover:bg-[var(--dg-bg-hover)]"
                    onClick={() => sendCommand(cmd)}
                  >
                    {cmd}
                  </Button>
                )
              )}
            </div>
          </CardContent>
        </Card>
      )}
    </div>
  );
}