import ReactMarkdown from "react-markdown";
import remarkGfm from "remark-gfm";
import remarkMath from "remark-math";
import rehypeKatex from "rehype-katex";
import { Prism as SyntaxHighlighter } from "react-syntax-highlighter";
import {
  oneDark,
  oneLight,
} from "react-syntax-highlighter/dist/esm/styles/prism";
import { useState } from "react";
import { Copy, Check } from "lucide-react";
import { cn } from "@/lib/utils";
import "katex/dist/katex.min.css";

interface MessageBubbleProps {
  content: string;
  role: "human" | "ai";
}

function CodeBlock({
  language,
  children,
}: {
  language: string;
  children: string;
}) {
  const [copied, setCopied] = useState(false);

  const handleCopy = () => {
    navigator.clipboard.writeText(children).then(() => {
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    });
  };

  // Detect dark mode via document class
  const isDark =
    typeof document !== "undefined" &&
    document.documentElement.classList.contains("dark");

  return (
    <div className="relative group my-2 rounded-lg overflow-hidden border border-border">
      {/* Language label + copy button */}
      <div className="flex items-center justify-between px-3 py-1.5 bg-muted border-b border-border">
        <span className="text-xs font-mono text-muted-foreground">
          {language || "text"}
        </span>
        <button
          type="button"
          onClick={handleCopy}
          className="inline-flex items-center gap-1 text-xs text-muted-foreground hover:text-foreground transition-colors"
        >
          {copied ? (
            <Check className="size-3.5 text-green-500" />
          ) : (
            <Copy className="size-3.5" />
          )}
          {copied ? "已复制" : "复制"}
        </button>
      </div>
      <SyntaxHighlighter
        language={language || "text"}
        style={isDark ? oneDark : oneLight}
        customStyle={{
          margin: 0,
          borderRadius: 0,
          fontSize: "0.75rem",
          background: "transparent",
        }}
        PreTag="div"
      >
        {children}
      </SyntaxHighlighter>
    </div>
  );
}

export default function MessageBubble({ content }: MessageBubbleProps) {
  return (
    <ReactMarkdown
      remarkPlugins={[remarkGfm, remarkMath]}
      rehypePlugins={[rehypeKatex]}
      components={{
        // Code blocks
        code({ className, children, ...props }) {
          const match = /language-(\w+)/.exec(className ?? "");
          const isInline = !match && !className;
          const codeStr = String(children).replace(/\n$/, "");

          if (isInline) {
            return (
              <code
                className="bg-muted px-1 rounded text-xs font-mono"
                {...props}
              >
                {children}
              </code>
            );
          }

          return (
            <CodeBlock language={match ? match[1] : ""}>{codeStr}</CodeBlock>
          );
        },

        // Tables
        table({ children }) {
          return (
            <div className="overflow-x-auto my-2">
              <table className="min-w-full text-xs border-collapse border border-border">
                {children}
              </table>
            </div>
          );
        },
        th({ children }) {
          return (
            <th className="border border-border px-3 py-1.5 bg-muted text-left font-medium text-foreground">
              {children}
            </th>
          );
        },
        td({ children }) {
          return (
            <td className="border border-border px-3 py-1.5 text-foreground">
              {children}
            </td>
          );
        },

        // Headings
        h1({ children }) {
          return (
            <h1 className="text-base font-bold mt-3 mb-1 text-foreground">
              {children}
            </h1>
          );
        },
        h2({ children }) {
          return (
            <h2 className="text-sm font-semibold mt-3 mb-1 text-foreground">
              {children}
            </h2>
          );
        },
        h3({ children }) {
          return (
            <h3 className="text-sm font-medium mt-2 mb-1 text-foreground">
              {children}
            </h3>
          );
        },

        // Lists
        ul({ children }) {
          return (
            <ul className="list-disc list-inside space-y-0.5 my-1 text-foreground">
              {children}
            </ul>
          );
        },
        ol({ children }) {
          return (
            <ol className="list-decimal list-inside space-y-0.5 my-1 text-foreground">
              {children}
            </ol>
          );
        },

        // Paragraphs
        p({ children }) {
          return <p className="my-1 leading-relaxed text-foreground">{children}</p>;
        },

        // Links
        a({ href, children }) {
          return (
            <a
              href={href}
              target="_blank"
              rel="noopener noreferrer"
              className={cn(
                "underline underline-offset-2 text-foreground",
                "hover:opacity-80 transition-opacity",
              )}
            >
              {children}
            </a>
          );
        },

        // Blockquote
        blockquote({ children }) {
          return (
            <blockquote className="border-l-2 border-border pl-3 my-2 text-muted-foreground italic">
              {children}
            </blockquote>
          );
        },

        // Horizontal rule
        hr() {
          return <hr className="my-3 border-border" />;
        },

        // Strong / em
        strong({ children }) {
          return (
            <strong className="font-semibold text-foreground">{children}</strong>
          );
        },
        em({ children }) {
          return <em className="italic text-foreground">{children}</em>;
        },
      }}
    >
      {content}
    </ReactMarkdown>
  );
}