fix: wasm loading on cloudflare (#12)

website/src/lib/markdown.ts

@@ -18,15 +18,26 @@ import remarkGfm from "remark-gfm"
 import remarkGithubAdmonitionsToDirectives from "remark-github-admonitions-to-directives"
 import remarkParse from "remark-parse"
 import remarkRehype from "remark-rehype"
-import { createCssVariablesTheme, createHighlighter } from "shiki"
+import { createCssVariablesTheme, createHighlighter, loadWasm } from "shiki"
 import { unified } from "unified"
 import type { Node } from "unist"
 import { map } from "unist-util-map"
 
-const highlighter = createHighlighter({
+// @ts-expect-error - typescript doesn't like the wasm import
+import onigWasm from "shiki/onig.wasm"
+
+const loadOnigWasm = (async () => {
+	await loadWasm(onigWasm())
+})()
+
+const highlighter = (async () => {
+	await loadOnigWasm
+
+	return await createHighlighter({
 		themes: [],
 		langs: [],
-})
+	})
+})()
 
 const ADMONITION_TYPES = {
 	note: {

website/vite.config.ts

@@ -1,6 +1,89 @@
 import { sveltekit } from "@sveltejs/kit/vite"
-import { defineConfig } from "vite"
+import { readFile } from "node:fs/promises"
+import path from "node:path"
+import { defineConfig, type Plugin, type ResolvedConfig } from "vite"
 
 export default defineConfig({
-	plugins: [sveltekit()],
+	plugins: [sveltekit(), cloudflareWasmImport()],
 })
+
+// This plugin allows us to import WebAssembly modules and have them work in
+// both the browser, Node.js, and Cloudflare Workers.
+function cloudflareWasmImport(): Plugin {
+	const wasmPostfix = ".wasm"
+	const importMetaPrefix = "___WASM_IMPORT_PATH___"
+
+	let config: ResolvedConfig
+
+	return {
+		name: "cloudflare-wasm-import",
+		configResolved(resolvedConfig) {
+			config = resolvedConfig
+		},
+		async load(id) {
+			if (!id.endsWith(wasmPostfix)) return
+
+			if (config.command === "serve") {
+				// Running dev server
+
+				// We generate a module that on the browser will fetch the WASM file
+				// (through a Vite `?url` import), and on the server will read the file
+				// from the file system.
+
+				return `
+					import WASM_URL from ${JSON.stringify(`${id}?url`)}
+
+					let promise
+					export default function() {
+						if (import.meta.env.SSR) {
+							return promise ?? (promise = import("node:fs/promises")
+								.then(({ readFile }) => readFile(${JSON.stringify(id)})))
+						} else {
+							return promise ?? (promise = fetch(WASM_URL).then(r => r.arrayBuffer()))
+						}
+					}
+				`
+			}
+
+			// When building, we emit the WASM file as an asset and generate a module
+			// that will fetch the asset in the browser, import the WASM file when in
+			// a Cloudflare Worker, and read the file from the file system when in
+			// Node.js.
+
+			const wasmSource = await readFile(id)
+
+			const refId = this.emitFile({
+				type: "asset",
+				name: path.basename(id),
+				source: wasmSource,
+			})
+
+			return `
+				import WASM_URL from ${JSON.stringify(`${id}?url`)}
+
+				let promise
+				export default function() {
+					if (import.meta.env.SSR) {
+						if (typeof navigator !== "undefined" && navigator.userAgent === "Cloudflare-Workers") {
+							return promise ?? (promise = import(import.meta.${importMetaPrefix}${refId}))
+						} else {
+							return promise ?? (promise = import(\`\${"node:fs/promises"}\`)
+								.then(({ readFile }) => readFile(new URL(import.meta.ROLLUP_FILE_URL_${refId}))))
+						}
+					} else {
+						return promise ?? (promise = fetch(WASM_URL).then(r => r.arrayBuffer()))
+					}
+				}
+			`
+		},
+		resolveImportMeta(property, { chunkId }) {
+			if (!property?.startsWith(importMetaPrefix)) return
+
+			const refId = property.slice(importMetaPrefix.length)
+			const fileName = this.getFileName(refId)
+			const relativePath = path.relative(path.dirname(chunkId), fileName)
+
+			return JSON.stringify(relativePath)
+		},
+	}
+}