co-mono/packages/web-ui/src/tools/artifacts/MarkdownArtifact.ts

import { CopyButton, DownloadButton, PreviewCodeToggle } from "@mariozechner/mini-lit";
import hljs from "highlight.js";
import { html } from "lit";
import { customElement, property, state } from "lit/decorators.js";
import { unsafeHTML } from "lit/directives/unsafe-html.js";
import { i18n } from "../../utils/i18n.js";
import "@mariozechner/mini-lit/dist/MarkdownBlock.js";
import { ArtifactElement } from "./ArtifactElement.js";

@customElement("markdown-artifact")
export class MarkdownArtifact extends ArtifactElement {
	@property() override filename = "";

	private _content = "";
	override get content(): string {
		return this._content;
	}
	override set content(value: string) {
		this._content = value;
		this.requestUpdate();
	}

	@state() private viewMode: "preview" | "code" = "preview";

	protected override createRenderRoot(): HTMLElement | DocumentFragment {
		return this; // light DOM
	}

	private setViewMode(mode: "preview" | "code") {
		this.viewMode = mode;
	}

	public getHeaderButtons() {
		const toggle = new PreviewCodeToggle();
		toggle.mode = this.viewMode;
		toggle.addEventListener("mode-change", (e: Event) => {
			this.setViewMode((e as CustomEvent).detail);
		});

		const copyButton = new CopyButton();
		copyButton.text = this._content;
		copyButton.title = i18n("Copy Markdown");
		copyButton.showText = false;

		return html`
			<div class="flex items-center gap-2">
				${toggle}
				${copyButton}
				${DownloadButton({
					content: this._content,
					filename: this.filename,
					mimeType: "text/markdown",
					title: i18n("Download Markdown"),
				})}
			</div>
		`;
	}

	override render() {
		return html`
			<div class="h-full flex flex-col">
				<div class="flex-1 overflow-auto">
					${
						this.viewMode === "preview"
							? html`<div class="p-4"><markdown-block .content=${this.content}></markdown-block></div>`
							: html`<pre class="m-0 p-4 text-xs whitespace-pre-wrap break-words"><code class="hljs language-markdown">${unsafeHTML(
									hljs.highlight(this.content, { language: "markdown", ignoreIllegals: true }).value,
								)}</code></pre>`
					}
				</div>
			</div>
		`;
	}
}

declare global {
	interface HTMLElementTagNameMap {
		"markdown-artifact": MarkdownArtifact;
	}
}