"use client";

import { useEffect, useState } from "react";
import { Moon, Sun } from "lucide-react";

type Theme = "light" | "dark";

export default function ThemeToggle() {
  const [theme, setTheme] = useState<Theme>("light");

  useEffect(() => {
    const saved = localStorage.getItem("write-theme");
    const nextTheme: Theme = saved === "dark" ? "dark" : "light";
    setTheme(nextTheme);
    if (nextTheme === "dark") {
      document.documentElement.dataset.theme = "dark";
    } else {
      delete document.documentElement.dataset.theme;
    }
  }, []);

  const toggleTheme = () => {
    const nextTheme: Theme = theme === "dark" ? "light" : "dark";
    setTheme(nextTheme);
    localStorage.setItem("write-theme", nextTheme);
    if (nextTheme === "dark") {
      document.documentElement.dataset.theme = "dark";
    } else {
      delete document.documentElement.dataset.theme;
    }
  };

  const isDark = theme === "dark";
  const Icon = isDark ? Sun : Moon;

  return (
    <button
      type="button"
      onClick={toggleTheme}
      className="mb-3 flex w-full items-center justify-between rounded-md border border-line px-3 py-2 text-[12px] text-muted transition-colors hover:bg-bg hover:text-accent"
      title={isDark ? "切换到浅色模式" : "切换到夜间模式"}
      aria-label={isDark ? "切换到浅色模式" : "切换到夜间模式"}
    >
      <span>{isDark ? "浅色模式" : "夜间模式"}</span>
      <Icon size={14} />
    </button>
  );
}