import { memo, useCallback, useEffect, useRef, useState } from "react";
import type { Components } from "react-markdown";
import ReactMarkdown from "react-markdown";
import remarkGfm from "remark-gfm";
import "./markdown.web.css";
import type { ChatMarkdownProps } from "./markdown";
import {
  citationDomainLabel,
  closeUnterminatedFence,
  isExternalMarkdownUrl,
  parseCitationBadgeLabel,
  parseHexColorToken,
  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 ExternalLinkArrowIcon() {
  return (
    <svg
      className="rk-chat-markdown-external-icon"
      width="11"
      height="11"
      viewBox="0 0 12 12"
      fill="none"
      aria-hidden="true"
    >
      <path
        d="M3.5 8.5L8.5 3.5M8.5 3.5H4.25M8.5 3.5V7.75"
        stroke="currentColor"
        strokeWidth="1.65"
        strokeLinecap="round"
        strokeLinejoin="round"
      />
    </svg>
  );
}

function ColorSwatchCode({ hex, children }: { hex: string; children: React.ReactNode }) {
  const [copied, setCopied] = useState(false);
  const timerRef = useRef<number | undefined>(undefined);

  useEffect(() => () => window.clearTimeout(timerRef.current), []);

  const handleCopy = useCallback(() => {
    if (!navigator.clipboard) return;
    navigator.clipboard
      .writeText(hex)
      .then(() => {
        setCopied(true);
        window.clearTimeout(timerRef.current);
        timerRef.current = window.setTimeout(() => setCopied(false), 1200);
      })
      .catch(() => {});
  }, [hex]);

  return (
    <button
      type="button"
      onClick={handleCopy}
      title={copied ? `${hex} ✓` : hex}
      aria-label={hex}
      data-testid="markdown-color-swatch"
      data-color={hex}
      className="rk-chat-markdown-swatch"
    >
      <span
        aria-hidden="true"
        className="rk-chat-markdown-swatch-dot"
        style={{ backgroundColor: hex }}
      />
      <code>{children}</code>
    </button>
  );
}

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, children, href, className, ...props }) {
    const external = isExternalMarkdownUrl(href);
    const childText =
      typeof children === "string"
        ? children
        : Array.isArray(children) && children.length === 1 && typeof children[0] === "string"
          ? children[0]
          : undefined;
    const citationNum = parseCitationBadgeLabel(childText, href);
    if (citationNum) {
      const domain = citationDomainLabel(href);
      return (
        <a
          {...props}
          href={href}
          target="_blank"
          rel="noreferrer noopener"
          title={domain ? `${domain} — ${href}` : href}
          data-external-link=""
          data-citation-badge={citationNum}
          className={
            className ? `${className} rk-chat-markdown-citation` : "rk-chat-markdown-citation"
          }
        >
          {citationNum}
        </a>
      );
    }
    const linkClass = external
      ? className
        ? `${className} rk-chat-markdown-external-link`
        : "rk-chat-markdown-external-link"
      : className;
    return (
      <a
        {...props}
        href={href}
        target="_blank"
        rel="noreferrer noopener"
        data-external-link={external ? "" : undefined}
        className={linkClass}
      >
        {children}
        {external ? <ExternalLinkArrowIcon /> : null}
      </a>
    );
  },
  code({ node: _node, className, children, ...props }) {
    const rawText = typeof children === "string" ? children : undefined;
    const hex = !className ? parseHexColorToken(rawText) : undefined;
    if (hex) {
      return <ColorSwatchCode hex={hex}>{children}</ColorSwatchCode>;
    }
    return (
      <code {...props} className={className}>
        {children}
      </code>
    );
  },
  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";