fix(images): Simpler logic for collecting images in Markdown (#6744)

7 files changed, 54 insertions, 42 deletions

diff --git a/.changeset/green-turtles-jump.md b/.changeset/green-turtles-jump.md
new file mode 100644
index 000000000..22c670c17
--- /dev/null
+++ b/.changeset/green-turtles-jump.md
@@ -0,0 +1,6 @@
+---
+'astro': patch
+'@astrojs/markdown-remark': patch
+---
+
+Fix remote images in Markdown throwing errors when using `experimental.assets`
diff --git a/packages/astro/src/vite-plugin-markdown/index.ts b/packages/astro/src/vite-plugin-markdown/index.ts
index ed2779da9..1afeca8f7 100644
--- a/packages/astro/src/vite-plugin-markdown/index.ts
+++ b/packages/astro/src/vite-plugin-markdown/index.ts
@@ -86,18 +86,17 @@ export default function markdown({ settings, logging }: AstroPluginOptions): Plu
 
 				let html = renderResult.code;
 				const { headings } = renderResult.metadata;
+
+				// Resolve all the extracted images from the content
 				let imagePaths: { raw: string; resolved: string }[] = [];
-				if (settings.config.experimental.assets) {
-					let paths = (renderResult.vfile.data.imagePaths as string[]) ?? [];
-					imagePaths = await Promise.all(
-						paths.map(async (imagePath) => {
-							return {
-								raw: imagePath,
-								resolved:
-									(await this.resolve(imagePath, id))?.id ?? path.join(path.dirname(id), imagePath),
-							};
-						})
-					);
+				if (settings.config.experimental.assets && renderResult.vfile.data.imagePaths) {
+					for (let imagePath of renderResult.vfile.data.imagePaths.values()) {
+						imagePaths.push({
+							raw: imagePath,
+							resolved:
+								(await this.resolve(imagePath, id))?.id ?? path.join(path.dirname(id), imagePath),
+						});
+					}
 				}
 
 				const astroData = safelyGetAstroData(renderResult.vfile.data);
diff --git a/packages/astro/test/core-image.test.js b/packages/astro/test/core-image.test.js
index 7baf8bcb8..4b444708e 100644
--- a/packages/astro/test/core-image.test.js
+++ b/packages/astro/test/core-image.test.js
@@ -218,6 +218,19 @@ describe('astro:image', () => {
 				let $img = $('img');
 				expect($img.attr('src').startsWith('/_image')).to.equal(true);
 			});
+
+			it('properly handles remote images', async () => {
+				let res = await fixture.fetch('/httpImage');
+				let html = await res.text();
+				$ = cheerio.load(html);
+
+				let $img = $('img');
+				expect($img).to.have.a.lengthOf(2);
+				const remoteUrls = ['https://example.com/image.png', '/image.png'];
+				$img.each((index, element) => {
+					expect(element.attribs['src']).to.equal(remoteUrls[index]);
+				});
+			});
 		});
 
 		describe('getImage', () => {
diff --git a/packages/astro/test/fixtures/core-image/src/pages/httpImage.md b/packages/astro/test/fixtures/core-image/src/pages/httpImage.md
new file mode 100644
index 000000000..441b74f3e
--- /dev/null
+++ b/packages/astro/test/fixtures/core-image/src/pages/httpImage.md
@@ -0,0 +1,2 @@
+![Remote image](https://example.com/image.png)
+![/public image](/image.png)
diff --git a/packages/markdown/remark/src/rehype-images.ts b/packages/markdown/remark/src/rehype-images.ts
index 72f475700..fd1e8f70f 100644
--- a/packages/markdown/remark/src/rehype-images.ts
+++ b/packages/markdown/remark/src/rehype-images.ts
@@ -9,9 +9,7 @@ export function rehypeImages() {
 				if (node.tagName !== 'img') return;
 
 				if (node.properties?.src) {
-					if (file.dirname) {
-						if (!isRelativePath(node.properties.src) && !isAliasedPath(node.properties.src)) return;
-
+					if (file.data.imagePaths?.has(node.properties.src)) {
 						node.properties['__ASTRO_IMAGE_'] = node.properties.src;
 						delete node.properties.src;
 					}
@@ -19,24 +17,3 @@ export function rehypeImages() {
 			});
 		};
 }
-
-function isAliasedPath(path: string) {
-	return path.startsWith('~/assets');
-}
-
-function isRelativePath(path: string) {
-	return startsWithDotDotSlash(path) || startsWithDotSlash(path);
-}
-
-function startsWithDotDotSlash(path: string) {
-	const c1 = path[0];
-	const c2 = path[1];
-	const c3 = path[2];
-	return c1 === '.' && c2 === '.' && c3 === '/';
-}
-
-function startsWithDotSlash(path: string) {
-	const c1 = path[0];
-	const c2 = path[1];
-	return c1 === '.' && c2 === '/';
-}
diff --git a/packages/markdown/remark/src/remark-collect-images.ts b/packages/markdown/remark/src/remark-collect-images.ts
index afc61c468..470b770ed 100644
--- a/packages/markdown/remark/src/remark-collect-images.ts
+++ b/packages/markdown/remark/src/remark-collect-images.ts
@@ -1,17 +1,31 @@
 import type { Image } from 'mdast';
 import { visit } from 'unist-util-visit';
-import type { VFile } from 'vfile';
+import type { MarkdownVFile } from './types';
 
 export default function toRemarkCollectImages() {
 	return () =>
-		async function (tree: any, vfile: VFile) {
+		async function (tree: any, vfile: MarkdownVFile) {
 			if (typeof vfile?.path !== 'string') return;
 
 			const imagePaths = new Set<string>();
-			visit(tree, 'image', function raiseError(node: Image) {
-				imagePaths.add(node.url);
+			visit(tree, 'image', (node: Image) => {
+				if (shouldOptimizeImage(node.url)) imagePaths.add(node.url);
 			});
 
-			vfile.data.imagePaths = Array.from(imagePaths);
+			vfile.data.imagePaths = imagePaths;
 		};
 }
+
+function shouldOptimizeImage(src: string) {
+	// Optimize anything that is NOT external or an absolute path to `public/`
+	return !isValidUrl(src) && !src.startsWith('/');
+}
+
+function isValidUrl(str: string): boolean {
+	try {
+		new URL(str);
+		return true;
+	} catch {
+		return false;
+	}
+}
diff --git a/packages/markdown/remark/src/types.ts b/packages/markdown/remark/src/types.ts
index dc3bbce32..2f2d36de7 100644
--- a/packages/markdown/remark/src/types.ts
+++ b/packages/markdown/remark/src/types.ts
@@ -1,8 +1,8 @@
 import type * as hast from 'hast';
 import type * as mdast from 'mdast';
 import type {
-	all as Handlers,
 	one as Handler,
+	all as Handlers,
 	Options as RemarkRehypeOptions,
 } from 'remark-rehype';
 import type { ILanguageRegistration, IThemeRegistration, Theme } from 'shiki';
@@ -85,11 +85,12 @@ export interface MarkdownMetadata {
 export interface MarkdownVFile extends VFile {
 	data: {
 		__astroHeadings?: MarkdownHeading[];
+		imagePaths?: Set<string>;
 	};
 }
 
 export interface MarkdownRenderingResult {
 	metadata: MarkdownMetadata;
-	vfile: VFile;
+	vfile: MarkdownVFile;
 	code: string;
 }