"use client";

import { useTheme } from "next-themes";
import { useEffect, useState } from "react";

export default function ThemeToggle() {
  const { theme, setTheme } = useTheme();
  const [mounted, setMounted] = useState(false);

  useEffect(() => setMounted(true), []);

  if (!mounted) {
    return (
      <button className="btn btn-ghost btn-sm w-9 h-9 rounded-full p-0" aria-label="Toggle theme">
        <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
          <circle cx="12" cy="12" r="4" />
        </svg>
      </button>
    );
  }

  const cycleTheme = () => {
    if (theme === "dark") setTheme("light");
    else if (theme === "light") setTheme("system");
    else setTheme("dark");
  };

  return (
    <button
      onClick={cycleTheme}
      className="btn btn-ghost btn-sm w-9 h-9 rounded-full p-0 text-base transition-transform hover:scale-110"
      aria-label={`Current theme: ${theme}. Click to cycle.`}
      title={theme === "dark" ? "深色模式" : theme === "light" ? "浅色模式" : "跟随系统"}
    >
      {theme === "dark" ? (
        // Moon icon
        <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
          <path d="M21 12.79A9 9 0 1 1 11.21 3 7 7 0 0 0 21 12.79z" />
        </svg>
      ) : theme === "light" ? (
        // Sun icon
        <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
          <circle cx="12" cy="12" r="5" />
          <line x1="12" y1="1" x2="12" y2="3" />
          <line x1="12" y1="21" x2="12" y2="23" />
          <line x1="4.22" y1="4.22" x2="5.64" y2="5.64" />
          <line x1="18.36" y1="18.36" x2="19.78" y2="19.78" />
          <line x1="1" y1="12" x2="3" y2="12" />
          <line x1="21" y1="12" x2="23" y2="12" />
          <line x1="4.22" y1="19.78" x2="5.64" y2="18.36" />
          <line x1="18.36" y1="5.64" x2="19.78" y2="4.22" />
        </svg>
      ) : (
        // System/auto icon
        <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
          <rect x="2" y="3" width="20" height="14" rx="2" ry="2" />
          <line x1="8" y1="21" x2="16" y2="21" />
          <line x1="12" y1="17" x2="12" y2="21" />
        </svg>
      )}
    </button>
  );
}
