import { useState } from 'react';
import { motion, AnimatePresence } from 'framer-motion';

// ---------------------------------------------------------------------------
// TokenMeter — circular SVG gauge showing token usage
// Inspired by DeerFlow's token usage display
// ---------------------------------------------------------------------------

interface TokenMeterProps {
  inputTokens: number;
  outputTokens: number;
  model?: string;
  className?: string;
}

// Color thresholds
function getUsageColor(percent: number): string {
  if (percent >= 80) return '#ef4444'; // red
  if (percent >= 50) return '#eab308'; // yellow
  return '#22c55e'; // green
}

// Format token count for display
function formatTokens(n: number): string {
  if (n >= 1_000_000) return `${(n / 1_000_000).toFixed(1)}M`;
  if (n >= 1_000) return `${(n / 1_000).toFixed(1)}K`;
  return String(n);
}

export function TokenMeter({ inputTokens, outputTokens, model, className = '' }: TokenMeterProps) {
  const [showDetail, setShowDetail] = useState(false);
  const total = inputTokens + outputTokens;
  // Assume ~128K context window as budget for percentage calculation
  const budget = 128_000;
  const percent = Math.min(100, (total / budget) * 100);
  const color = getUsageColor(percent);

  // SVG circular gauge parameters
  const size = 28;
  const strokeWidth = 3;
  const radius = (size - strokeWidth) / 2;
  const circumference = 2 * Math.PI * radius;
  const offset = circumference - (percent / 100) * circumference;

  if (total === 0) return null;

  return (
    <div className={`relative ${className}`}>
      <button
        onClick={() => setShowDetail(!showDetail)}
        onMouseEnter={() => setShowDetail(true)}
        onMouseLeave={() => setShowDetail(false)}
        className="focus:outline-none"
        title="Token 用量"
      >
        <svg width={size} height={size} className="transform -rotate-90">
          {/* Background circle */}
          <circle
            cx={size / 2}
            cy={size / 2}
            r={radius}
            fill="none"
            stroke="currentColor"
            strokeWidth={strokeWidth}
            className="text-gray-200 dark:text-gray-700"
          />
          {/* Usage arc */}
          <circle
            cx={size / 2}
            cy={size / 2}
            r={radius}
            fill="none"
            stroke={color}
            strokeWidth={strokeWidth}
            strokeDasharray={circumference}
            strokeDashoffset={offset}
            strokeLinecap="round"
            className="transition-all duration-500"
          />
        </svg>
        {/* Center text */}
        <span className="absolute inset-0 flex items-center justify-center text-[9px] font-medium text-gray-500 dark:text-gray-400">
          {percent >= 1 ? `${Math.round(percent)}` : '<1'}
        </span>
      </button>

      {/* Hover detail card */}
      <AnimatePresence>
        {showDetail && (
          <motion.div
            initial={{ opacity: 0, y: 4, scale: 0.95 }}
            animate={{ opacity: 1, y: 0, scale: 1 }}
            exit={{ opacity: 0, y: 4, scale: 0.95 }}
            transition={{ duration: 0.15 }}
            className="absolute bottom-full right-0 mb-2 w-44 p-3 rounded-lg bg-white dark:bg-gray-800 border border-gray-200 dark:border-gray-700 shadow-lg z-50"
          >
            <div className="space-y-2">
              <div className="flex items-center justify-between">
                <span className="text-[11px] text-gray-500 dark:text-gray-400">Input</span>
                <span className="text-[11px] font-medium text-gray-700 dark:text-gray-200">{formatTokens(inputTokens)}</span>
              </div>
              <div className="flex items-center justify-between">
                <span className="text-[11px] text-gray-500 dark:text-gray-400">Output</span>
                <span className="text-[11px] font-medium text-gray-700 dark:text-gray-200">{formatTokens(outputTokens)}</span>
              </div>
              <div className="border-t border-gray-100 dark:border-gray-700 pt-1.5 flex items-center justify-between">
                <span className="text-[11px] text-gray-500 dark:text-gray-400">Total</span>
                <span className="text-[11px] font-bold text-gray-800 dark:text-gray-100">{formatTokens(total)}</span>
              </div>
              {model && (
                <div className="border-t border-gray-100 dark:border-gray-700 pt-1.5">
                  <span className="text-[10px] text-gray-400 dark:text-gray-500 truncate block">{model}</span>
                </div>
              )}
            </div>
          </motion.div>
        )}
      </AnimatePresence>
    </div>
  );
}