"use client";

import { Check, Copy } from "lucide-react";
import { isValidElement, useEffect, useRef, useState, type ReactNode } from "react";

/** The fenced language, from the `language-xxx` class react-markdown puts on <code>. */
export function fencedLanguage(node: ReactNode): string {
  if (!isValidElement<{ className?: string }>(node)) return "";
  return /language-([\w+-]+)/.exec(node.props.className ?? "")?.[1] ?? "";
}

/** The raw source inside the fence, for the copy button. */
export function fencedSource(node: ReactNode): string {
  if (typeof node === "string") return node;
  if (Array.isArray(node)) return node.map(fencedSource).join("");
  if (isValidElement<{ children?: ReactNode }>(node)) return fencedSource(node.props.children);
  return "";
}

export function MarkdownCodeBlock({ children }: { readonly children?: ReactNode }) {
  const [copied, setCopied] = useState(false);
  const resetTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const language = fencedLanguage(children);
  const source = fencedSource(children);

  useEffect(() => () => {
    if (resetTimer.current) clearTimeout(resetTimer.current);
  }, []);

  async function copy() {
    try {
      await navigator.clipboard.writeText(source);
    } catch {
      return;
    }
    setCopied(true);
    if (resetTimer.current) clearTimeout(resetTimer.current);
    resetTimer.current = setTimeout(() => setCopied(false), 1600);
  }

  return (
    <div className="markdown-code">
      <div className="markdown-code-bar">
        <span className="markdown-code-language">{language || "代码"}</span>
        <button
          aria-label={copied ? "已复制代码" : "复制代码"}
          className="markdown-code-copy"
          onClick={() => void copy()}
          type="button"
        >
          {copied ? <Check aria-hidden="true" /> : <Copy aria-hidden="true" />}
          <span>{copied ? "已复制" : "复制"}</span>
        </button>
      </div>
      <pre>{children}</pre>
    </div>
  );
}