import { useEffect, useState } from 'react';
import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from './ui/tooltip';
import { checkBackendHealth, type HealthStatus, type HealthCheckResult } from '@/services';
import { Circle, Loader2 } from 'lucide-react';

interface HealthIndicatorProps {
  /** How often to check health in milliseconds (default: 30000 = 30s) */
  interval?: number;
}

function formatRelativeTime(isoString: string): string {
  const date = new Date(isoString);
  const now = new Date();
  const diffMs = now.getTime() - date.getTime();
  const diffMins = Math.floor(diffMs / 60000);
  const diffHours = Math.floor(diffMs / 3600000);
  const diffDays = Math.floor(diffMs / 86400000);

  if (diffMins < 1) return 'just now';
  if (diffMins < 60) return `${diffMins}m ago`;
  if (diffHours < 24) return `${diffHours}h ago`;
  return `${diffDays}d ago`;
}

export function HealthIndicator({ interval = 30000 }: HealthIndicatorProps) {
  const [health, setHealth] = useState<HealthCheckResult>({ status: 'checking' });

  useEffect(() => {
    // Initial check
    checkBackendHealth().then(setHealth);

    // Periodic checks
    const intervalId = setInterval(() => {
      checkBackendHealth().then(setHealth);
    }, interval);

    return () => clearInterval(intervalId);
  }, [interval]);

  const getStatusColor = (status: HealthStatus) => {
    switch (status) {
      case 'healthy':
        return 'text-green-500';
      case 'unhealthy':
        return 'text-red-500';
      case 'checking':
        return 'text-muted-foreground';
    }
  };

  const getStatusLabel = (status: HealthStatus) => {
    switch (status) {
      case 'healthy':
        return 'Connected';
      case 'unhealthy':
        return 'Disconnected';
      case 'checking':
        return 'Checking...';
    }
  };

  const getTooltipContent = () => {
    const lines: string[] = [];

    if (health.status === 'checking') {
      return 'Checking backend connection...';
    }

    if (health.status === 'healthy') {
      lines.push(`Backend connected (${health.latencyMs}ms)`);
      if (health.lastUpdated) {
        const date = new Date(health.lastUpdated);
        lines.push(`Last update: ${date.toLocaleString()}`);
      }
      return lines.join('\n');
    }

    return `Backend unavailable: ${health.error || 'Unknown error'}`;
  };

  return (
    <TooltipProvider>
      <Tooltip>
        <TooltipTrigger asChild>
          <div className="flex items-center gap-1.5 cursor-default">
            {health.status === 'checking' ? (
              <Loader2 className="h-3 w-3 animate-spin text-muted-foreground" />
            ) : (
              <Circle
                className={`h-2.5 w-2.5 fill-current ${getStatusColor(health.status)}`}
              />
            )}
            <span className={`text-xs ${getStatusColor(health.status)} hidden sm:inline`}>
              {getStatusLabel(health.status)}
            </span>
            {health.status === 'healthy' && health.lastUpdated && (
              <span className="text-xs text-muted-foreground hidden sm:inline">
                · {formatRelativeTime(health.lastUpdated)}
              </span>
            )}
          </div>
        </TooltipTrigger>
        <TooltipContent side="bottom">
          <p className="whitespace-pre-line">{getTooltipContent()}</p>
        </TooltipContent>
      </Tooltip>
    </TooltipProvider>
  );
}