import React, { useState, useEffect, useCallback } from 'react';
import { performanceService } from '../services/performanceService.ts';

const PerformanceDebug: React.FC = () => {
  const [isOpen, setIsOpen] = useState(false);
  const [metrics, setMetrics] = useState(() => performanceService.getMetrics());
  const [apiTimings, setApiTimings] = useState(() => performanceService.getApiTimings());
  const [componentTimings, setComponentTimings] = useState(() =>
    performanceService.getComponentTimings()
  );

  const refreshMetrics = useCallback(() => {
    setMetrics(performanceService.getMetrics());
    setApiTimings(performanceService.getApiTimings());
    setComponentTimings(performanceService.getComponentTimings());
  }, []);

  useEffect(() => {
    if (!isOpen) return undefined;
    refreshMetrics(); // Refresh immediately on open
    const interval = setInterval(refreshMetrics, 2000);
    return () => clearInterval(interval);
  }, [isOpen, refreshMetrics]);

  const formatMs = (value: number | null) => (value === null ? 'N/A' : `${Math.round(value)} ms`);
  const formatCls = (value: number | null) => (value === null ? 'N/A' : value.toFixed(4));

  if (!isOpen) {
    return (
      <button
        onClick={() => setIsOpen(true)}
        className="fixed bottom-6 right-24 bg-indigo-600 text-white w-16 h-16 rounded-full shadow-lg flex items-center justify-center hover:bg-indigo-700 transition-transform hover:scale-110 focus:outline-none focus:ring-2 focus:ring-offset-2 focus:ring-indigo-500 z-40"
        aria-label="Open Performance Debug"
      >
        <i className="fa-solid fa-tachometer-alt-fast text-2xl"></i>
      </button>
    );
  }

  return (
    <div className="fixed bottom-6 right-6 w-96 bg-white rounded-2xl shadow-2xl z-40 border border-gray-200 transform transition-all text-sm font-sans">
      <div className="p-4 border-b flex justify-between items-center bg-gray-50 rounded-t-2xl">
        <h3 className="font-bold text-gray-800 flex items-center">
          <i className="fa-solid fa-tachometer-alt-fast mr-2 text-indigo-600"></i> Performance Debug
        </h3>
        <div className="flex items-center gap-2">
          <button
            onClick={refreshMetrics}
            className="text-gray-500 hover:text-indigo-600"
            title="Refresh Metrics"
          >
            <i className="fa-solid fa-sync"></i>
          </button>
          <button
            onClick={() => setIsOpen(false)}
            className="text-gray-400 hover:text-gray-600 text-xl"
            aria-label="Close"
          >
            &times;
          </button>
        </div>
      </div>
      <div className="p-4 space-y-3 max-h-96 overflow-y-auto">
        <div>
          <h4 className="font-semibold text-gray-700 mb-1">Core Web Vitals & Loading</h4>
          <ul className="space-y-1 pl-2 text-gray-600">
            <li className="flex justify-between">
              <span>Page Load Time:</span>{' '}
              <span className="font-mono bg-gray-100 px-2 rounded">
                {formatMs(metrics.pageLoad)}
              </span>
            </li>
            <li className="flex justify-between">
              <span>Time to First Byte (TTFB):</span>{' '}
              <span className="font-mono bg-gray-100 px-2 rounded">{formatMs(metrics.ttfb)}</span>
            </li>
            <li className="flex justify-between">
              <span>First Contentful Paint (FCP):</span>{' '}
              <span className="font-mono bg-gray-100 px-2 rounded">{formatMs(metrics.fcp)}</span>
            </li>
            <li className="flex justify-between">
              <span>Largest Contentful Paint (LCP):</span>{' '}
              <span className="font-mono bg-gray-100 px-2 rounded">{formatMs(metrics.lcp)}</span>
            </li>
            <li className="flex justify-between">
              <span>First Input Delay (FID):</span>{' '}
              <span className="font-mono bg-gray-100 px-2 rounded">{formatMs(metrics.fid)}</span>
            </li>
            <li className="flex justify-between">
              <span>Cumulative Layout Shift (CLS):</span>{' '}
              <span className="font-mono bg-gray-100 px-2 rounded">{formatCls(metrics.cls)}</span>
            </li>
          </ul>
        </div>

        <div>
          <h4 className="font-semibold text-gray-700 mb-1 pt-2 border-t mt-3">
            Component Mount Timings
          </h4>
          <ul className="space-y-1 pl-2 text-gray-600">
            {componentTimings.length > 0 ? (
              componentTimings.map((timing) => (
                <li key={timing.timestamp} className="flex justify-between">
                  <span>{timing.name}:</span>
                  <span className="font-mono bg-gray-100 px-2 rounded">
                    {formatMs(timing.duration)}
                  </span>
                </li>
              ))
            ) : (
              <li>No components timed yet.</li>
            )}
          </ul>
        </div>

        <div>
          <h4 className="font-semibold text-gray-700 mb-1 pt-2 border-t mt-3">
            API Timings (Last 10)
          </h4>
          <ul className="space-y-1 pl-2 text-gray-600">
            {apiTimings.length > 0 ? (
              apiTimings.map((timing) => (
                <li key={timing.timestamp} className="flex justify-between">
                  <span>{timing.name}:</span>
                  <span className="font-mono bg-gray-100 px-2 rounded">
                    {formatMs(timing.duration)}
                  </span>
                </li>
              ))
            ) : (
              <li>No API calls recorded yet.</li>
            )}
          </ul>
        </div>
      </div>
    </div>
  );
};

export default PerformanceDebug;