import { memo, useState, type ReactNode } from "react";
import ReactMarkdown from "react-markdown";
import remarkGfm from "remark-gfm";
import rehypeHighlight from "rehype-highlight";
import { FileChip, FileFigure } from "./FileFigure";

export const IMAGE_EXT = /\.(png|jpe?g|gif|webp|bmp|svg)$/i;

/** URL for a file in the project (absolute or relative to baseDir). */
export function projectFileUrl(src: string, baseDir?: string): string | undefined {
  if (/^(https?:|data:|blob:)/i.test(src)) return src;
  if (!baseDir && !src.startsWith("/")) return undefined;
  const parts = (src.startsWith("/") ? src : `${baseDir}/${src}`).split("/");
  const out: string[] = [];
  for (const p of parts) {
    if (p === "..") out.pop();
    else if (p && p !== ".") out.push(p);
  }
  return `/api/files/raw?path=${encodeURIComponent("/" + out.join("/"))}`;
}

function textOf(node: ReactNode): string {
  if (typeof node === "string") return node;
  if (Array.isArray(node)) return node.map(textOf).join("");
  if (node && typeof node === "object" && "props" in node) return textOf((node as any).props.children);
  return "";
}

/** SVG code shown as an image (img context: scripts never run), code on demand. */
export function SvgBlock({ code, children }: { code: string; children?: ReactNode }) {
  const [showCode, setShowCode] = useState(false);
  const url = `data:image/svg+xml;base64,${btoa(unescape(encodeURIComponent(code)))}`;
  return (
    <div className="svg-block">
      <FileFigure name="inline.svg" size={new Blob([code]).size} mime="image/svg+xml">
        <img src={url} alt="SVG" />
      </FileFigure>
      <button className="small ghost" onClick={() => setShowCode(!showCode)}>
        {showCode ? "▾ SVG" : "▸ SVG"}
      </button>
      {showCode && children}
    </div>
  );
}

export const Markdown = memo(function Markdown({ text, baseDir }: { text: string; baseDir?: string }) {
  return (
    <div className="markdown">
      <ReactMarkdown
        remarkPlugins={[remarkGfm]}
        rehypePlugins={[[rehypeHighlight, { detect: false, ignoreMissing: true }]]}
        components={{
          a: (props) => <a {...props} target="_blank" rel="noreferrer" />,
          img: ({ src, alt }) => {
            const url = typeof src === "string" ? projectFileUrl(src, baseDir) : undefined;
            if (!url) return <span>{alt}</span>;
            // Non-image files (3D models, documents) become links.
            if (typeof src === "string" && !/^(data:|https?:)/i.test(src) && !IMAGE_EXT.test(src)) {
              return <FileChip url={url} name={src} />;
            }
            const name = typeof src === "string" && !src.startsWith("data:") ? decodeURIComponent(src.split("?")[0]) : alt || undefined;
            return (
              <FileFigure url={url} name={name} mime={typeof src === "string" ? src.match(/^data:([^;,]+)/)?.[1] : undefined}>
                <img className="inline-image" src={url} alt={alt ?? ""} loading="lazy" />
              </FileFigure>
            );
          },
          pre: ({ children }) => {
            const code = textOf(children);
            const child: any = Array.isArray(children) ? children[0] : children;
            const cls = String(child?.props?.className ?? "");
            if (/language-svg/.test(cls) || (/language-(xml|html)/.test(cls) && code.trim().startsWith("<svg"))) {
              return (
                <SvgBlock code={code}>
                  <pre>{children}</pre>
                </SvgBlock>
              );
            }
            return <pre>{children}</pre>;
          },
        }}
      >
        {text}
      </ReactMarkdown>
    </div>
  );
});

/** Image files mentioned in a text (paths in backticks or plain). */
export function imagePathsIn(text: string): string[] {
  const found = new Set<string>();
  const re = /(?:^|[\s`(\["'])((?:\.{0,2}\/)?[\w\-./]+\.(?:png|jpe?g|gif|webp|bmp|svg))(?=$|[\s`)\]"',.:;!?])/gim;
  for (const m of text.matchAll(re)) {
    // Skip URLs and markdown images (rendered anyway).
    const idx = m.index ?? 0;
    const before = text.slice(Math.max(0, idx - 2), idx + 1);
    if (m[1].includes("://") || before.includes("](") || text.slice(Math.max(0, idx - 10), idx + 1).includes("http")) continue;
    found.add(m[1]);
  }
  return [...found].slice(0, 8);
}

/** Thumbnails for image files mentioned in a message; missing files hide themselves. */
export function ImageRefs({ text, baseDir }: { text: string; baseDir?: string }) {
  const paths = imagePathsIn(text.replace(/!\[[^\]]*\]\([^)]*\)/g, ""));
  if (paths.length === 0 || !baseDir) return null;
  return (
    <div className="image-refs">
      {paths.map((p) => {
        const url = projectFileUrl(p, baseDir)!;
        return (
          <FileFigure key={p} url={url} name={p} className="thumb">
            <img src={url} alt={p} loading="lazy" onError={(e) => ((e.currentTarget.closest("figure") as HTMLElement).style.display = "none")} />
          </FileFigure>
        );
      })}
    </div>
  );
}