import { memo, useCallback, useRef, useState } from "react";
import ReactMarkdown, { type Components } from "react-markdown";
import remarkGfm from "remark-gfm";
import "./markdown.web.css";
import { type ChatMarkdownProps, closeUnterminatedFence, sanitizeMarkdownUrl } from "./markdown";

function CopyIcon() {
  return (
    <svg width="14" height="14" viewBox="0 0 24 24" fill="none" aria-hidden="true">
      <rect
        x="9"
        y="9"
        width="12"
        height="12"
        rx="2"
        stroke="currentColor"
        strokeWidth="2"
        strokeLinejoin="round"
      />
      <path
        d="M5 15H4a1 1 0 0 1-1-1V4a1 1 0 0 1 1-1h10a1 1 0 0 1 1 1v1"
        stroke="currentColor"
        strokeWidth="2"
        strokeLinecap="round"
        strokeLinejoin="round"
      />
    </svg>
  );
}

function CheckIcon() {
  return (
    <svg width="14" height="14" viewBox="0 0 24 24" fill="none" aria-hidden="true">
      <path
        d="M4 12.5 9.5 18 20 6"
        stroke="currentColor"
        strokeWidth="2.25"
        strokeLinecap="round"
        strokeLinejoin="round"
      />
    </svg>
  );
}

function CodeBlock(props: React.ComponentPropsWithoutRef<"pre">) {
  const preRef = useRef<HTMLPreElement>(null);
  const resetTimerRef = useRef<number | undefined>(undefined);
  const [copied, setCopied] = useState(false);

  const handleCopy = useCallback(() => {
    if (!navigator.clipboard) return;
    const text = preRef.current?.textContent ?? "";
    navigator.clipboard
      .writeText(text)
      .then(() => {
        setCopied(true);
        window.clearTimeout(resetTimerRef.current);
        resetTimerRef.current = window.setTimeout(() => setCopied(false), 1500);
      })
      .catch(() => {});
  }, []);

  return (
    <div className="rk-chat-markdown-pre-wrap">
      <pre {...props} ref={preRef} />
      <button
        type="button"
        className="rk-chat-markdown-copy"
        onClick={handleCopy}
        aria-label={copied ? "Copied" : "Copy code"}
      >
        {copied ? <CheckIcon /> : <CopyIcon />}
      </button>
    </div>
  );
}

const components: Components = {
  a({ node: _node, ...props }) {
    return <a {...props} target="_blank" rel="noreferrer noopener" />;
  },
  img({ node: _node, ...props }) {
    return <img {...props} alt={props.alt ?? ""} loading="lazy" />;
  },
  pre({ node: _node, ...props }) {
    return <CodeBlock {...props} />;
  },
};

export const ChatMarkdown = memo(function ChatMarkdown({
  children,
  streaming = false,
}: ChatMarkdownProps) {
  const source = streaming ? closeUnterminatedFence(children) : children;

  return (
    <div className={streaming ? "rk-chat-markdown rk-chat-markdown-streaming" : "rk-chat-markdown"}>
      <ReactMarkdown
        components={components}
        remarkPlugins={[remarkGfm]}
        skipHtml
        urlTransform={(url) => sanitizeMarkdownUrl(url, true) ?? ""}
      >
        {source}
      </ReactMarkdown>
      {streaming ? <span aria-hidden="true" className="rk-chat-markdown-cursor" /> : null}
    </div>
  );
});

export type { ChatMarkdownProps } from "./markdown";