import { useState, useEffect, useCallback, useRef } from 'react';
import { Card } from '@/components/ui/Card';
import { Button } from '@/components/ui/Button';
import { Badge } from '@/components/ui/Badge';
import { Spinner } from '@/components/ui/Spinner';
import { useLoginStatus } from '@/hooks/useLoginStatus';
import { useToast } from '@/context/ToastContext';
import { getLoginQRCode, deleteCookies, getLoginStatus } from '@/api/endpoints';

export function LoginPage() {
  const { status, loading: statusLoading, refresh: refreshStatus } = useLoginStatus();
  const { toast } = useToast();

  const [qrData, setQrData] = useState<string | null>(null);
  const [qrLoading, setQrLoading] = useState(false);
  const [polling, setPolling] = useState(false);
  const [countdown, setCountdown] = useState(0);
  const [logoutLoading, setLogoutLoading] = useState(false);

  const pollRef = useRef<ReturnType<typeof setInterval> | undefined>(undefined);
  const countdownRef = useRef<ReturnType<typeof setInterval> | undefined>(undefined);

  const stopPolling = useCallback(() => {
    setPolling(false);
    if (pollRef.current) clearInterval(pollRef.current);
    if (countdownRef.current) clearInterval(countdownRef.current);
  }, []);

  const handleGetQR = useCallback(async () => {
    stopPolling();
    setQrLoading(true);
    setQrData(null);
    try {
      const res = await getLoginQRCode();
      if (res.success && res.data) {
        if (res.data.alreadyLoggedIn) {
          toast('info', 'Already logged in!');
          void refreshStatus();
          return;
        }
        setQrData(res.data.qrcodeData);
        // Start polling
        setPolling(true);
        setCountdown(240); // 4 min
        pollRef.current = setInterval(async () => {
          try {
            const statusRes = await getLoginStatus();
            if (statusRes.success && statusRes.data?.loggedIn) {
              stopPolling();
              setQrData(null);
              toast('success', `Logged in as ${statusRes.data.username || 'user'}`);
              void refreshStatus();
            }
          } catch {
            // ignore poll errors
          }
        }, 3000);
        countdownRef.current = setInterval(() => {
          setCountdown((prev) => {
            if (prev <= 1) {
              stopPolling();
              setQrData(null);
              toast('warning', 'QR code expired');
              return 0;
            }
            return prev - 1;
          });
        }, 1000);
      } else {
        toast('error', res.error?.message || 'Failed to get QR code');
      }
    } catch (err) {
      toast('error', err instanceof Error ? err.message : 'Failed to get QR code');
    } finally {
      setQrLoading(false);
    }
  }, [stopPolling, toast, refreshStatus]);

  const handleLogout = useCallback(async () => {
    setLogoutLoading(true);
    try {
      const res = await deleteCookies();
      if (res.success) {
        toast('success', 'Logged out successfully');
        void refreshStatus();
      } else {
        toast('error', res.error?.message || 'Failed to logout');
      }
    } catch (err) {
      toast('error', err instanceof Error ? err.message : 'Failed to logout');
    } finally {
      setLogoutLoading(false);
    }
  }, [toast, refreshStatus]);

  useEffect(() => {
    return () => stopPolling();
  }, [stopPolling]);

  const formatCountdown = (secs: number) => {
    const m = Math.floor(secs / 60);
    const s = secs % 60;
    return `${m}:${s.toString().padStart(2, '0')}`;
  };

  return (
    <div className="max-w-2xl space-y-6">
      <h1 className="text-2xl font-bold">Xiaohongshu Login</h1>

      {/* Current Status */}
      <Card>
        <div className="flex items-center justify-between">
          <div>
            <h2 className="text-sm font-semibold text-dark-muted uppercase tracking-wider mb-2">
              Current Status
            </h2>
            {statusLoading ? (
              <Spinner size="sm" />
            ) : status ? (
              <div className="flex items-center gap-3">
                <Badge variant={status.loggedIn ? 'success' : 'warning'}>
                  {status.loggedIn ? 'Logged In' : 'Not Logged In'}
                </Badge>
                {status.username && <span className="text-sm">{status.username}</span>}
              </div>
            ) : (
              <Badge variant="danger">Unable to check</Badge>
            )}
          </div>
          <div className="flex gap-2">
            <Button variant="ghost" size="sm" onClick={() => void refreshStatus()}>
              Refresh
            </Button>
            {status?.loggedIn && (
              <Button variant="danger" size="sm" onClick={() => void handleLogout()} loading={logoutLoading}>
                Logout
              </Button>
            )}
          </div>
        </div>
      </Card>

      {/* QR Code Login */}
      <Card>
        <h2 className="text-sm font-semibold text-dark-muted uppercase tracking-wider mb-4">
          QR Code Login
        </h2>

        {!qrData && !qrLoading && (
          <div className="text-center py-8">
            <p className="text-dark-muted mb-4">Click the button to generate a QR code for login</p>
            <Button onClick={() => void handleGetQR()} disabled={status?.loggedIn}>
              Get QR Code
            </Button>
          </div>
        )}

        {qrLoading && (
          <div className="flex flex-col items-center py-8 gap-3">
            <Spinner size="lg" />
            <p className="text-sm text-dark-muted">Generating QR code...</p>
          </div>
        )}

        {qrData && (
          <div className="flex flex-col items-center gap-4">
            <div className="bg-white rounded-xl p-4">
              <img src={qrData} alt="Login QR Code" className="w-64 h-64" />
            </div>
            <p className="text-sm text-dark-muted">Scan with Xiaohongshu app to login</p>
            {polling && (
              <div className="flex items-center gap-3">
                <Spinner size="sm" />
                <span className="text-sm text-dark-accent">
                  Waiting for scan... {formatCountdown(countdown)}
                </span>
              </div>
            )}
            <div className="flex gap-2">
              <Button variant="ghost" size="sm" onClick={() => void handleGetQR()}>
                Refresh QR
              </Button>
              <Button variant="ghost" size="sm" onClick={stopPolling}>
                Cancel
              </Button>
            </div>
          </div>
        )}
      </Card>
    </div>
  );
}