src/lib/components/chat/ChatMessage.svelte

<script lang="ts">
	import { marked } from "marked";
	import type { Message } from "$lib/types/Message";
	import { afterUpdate } from "svelte";
	import { deepestChild } from "$lib/utils/deepestChild";

	import CodeBlock from "../CodeBlock.svelte";
	import IconLoading from "../icons/IconLoading.svelte";

	function sanitizeMd(md: string) {
		return md.replaceAll("&", "&amp;").replaceAll("<", "&lt;");
	}
	function unsanitizeMd(md: string) {
		return md.replaceAll("&lt;", "<").replaceAll("&amp;", "&");
	}

	export let message: Message;
	export let loading: boolean = false;

	let contentEl: HTMLElement;
	let loadingEl: any;
	let pendingTimeout: NodeJS.Timeout;

	const renderer = new marked.Renderer();

	// For code blocks with simple backticks
	renderer.codespan = (code) => {
		// Unsanitize double-sanitized code
		return `<code>${code.replaceAll("&amp;", "&")}</code>`;
	};

	const options: marked.MarkedOptions = {
		...marked.getDefaults(),
		gfm: true,
		renderer,
	};

	$: tokens = marked.lexer(sanitizeMd(message.content));

	afterUpdate(() => {
		loadingEl?.$destroy();
		clearTimeout(pendingTimeout);

		// Add loading animation to the last message if update takes more than 600ms
		if (loading) {
			pendingTimeout = setTimeout(() => {
				if (contentEl) {
					loadingEl = new IconLoading({
						target: deepestChild(contentEl),
						props: { classNames: "loading inline ml-2" },
					});
				}
			}, 600);
		}
	});
</script>

{#if message.from === "assistant"}
	<div class="flex items-start justify-start gap-4 leading-relaxed">
		<img
			alt=""
			src="https://huggingface.co/avatars/2edb18bd0206c16b433841a47f53fa8e.svg"
			class="mt-5 w-3 h-3 flex-none rounded-full shadow-lg"
		/>
		<div
			class="relative rounded-2xl prose-pre:my-2 px-5 py-3.5 border border-gray-100 bg-gradient-to-br from-gray-50 dark:from-gray-800/40 dark:border-gray-800 text-gray-600 dark:text-gray-300 min-h-[calc(2rem+theme(spacing[3.5])*2)] min-w-[100px]"
		>
			{#if !message.content}
				<IconLoading classNames="absolute inset-0 m-auto" />
			{/if}
			<div
				class="prose dark:prose-invert prose-pre:bg-gray-800 dark:prose-pre:bg-gray-900 prose-h1:text-lg prose-h2:text-base prose-h3:text-base prose-headings:font-semibold max-w-none"
				bind:this={contentEl}
			>
				{#each tokens as token}
					{#if token.type === "code"}
						<CodeBlock lang={token.lang} code={unsanitizeMd(token.text)} />
					{:else}
						{@html marked.parser([token], options)}
					{/if}
				{/each}
			</div>
		</div>
	</div>
{/if}
{#if message.from === "user"}
	<div class="flex items-start justify-start gap-4">
		<div class="mt-5 w-3 h-3 flex-none rounded-full" />
		<div class="rounded-2xl px-5 py-3.5 text-gray-500 dark:text-gray-400 whitespace-break-spaces">
			{message.content.trim()}
		</div>
	</div>
{/if}