feat: adds fallback image

__snapshots__/mod_test.ts.snap

@@ -8,3 +8,12 @@ snapshot[`should archive a markdown file with all images 1`] = `
 <img 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" alt="Google Logo 2006" />
 '
 `;
+
+snapshot[`should use a fallback image if downloading the image failed 1`] = `
+'# Testing
+
+![](data:image/png;base64,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)
+
+<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAADAAAAAwCAYAAABXAvmHAAAACXBIWXMAAAsTAAALEwEAmpwYAAADN0lEQVR4nO2Y3U9SYRzH+T/qstq6sYv+gmKkKaAmaLalazJNjdNoikAo0PSyteWFF3mRlk0Kp64ZDGsElq/LeLtpxYbrwoZ4lq04cG5+7XnwIfDEi43ToTy/7bs9nPNs5/N5Xsb2k0jEEkssscQqdzVq9cebKNMzldb0TUWZQNBoMcPMJcp8snR4rXFXcHAqN4hJrTMdKyqAV54ygW10HCLRLaBpWtBEoltgHX1AROxFBcixqQR4OksC7wJl+lpcYH/LhIamD4RwHV2B0y8SfzW0KED/Zzug8CVA4WPgvIeBKtfvP4qeo/dortzHgLTAXJTrKwH4EhuG7Z1h6FwJ8itQv8RkQuCQkNzLwDkPA2fdaejseWRulZMLf8aVgFh8GGBPjxOLj+TM41XgsKnzpkUOysazBHbiI+kF8aV3sKIE8sXmD2IJBI/G2e94FVB6PoNsSgOyJxo85kOO5k3Al4AL9j6QPqzGaXDcAksoCcYAC+1ryRyIlmUGdO9TMBRiYSiUAt1mCprfCiRgCLBgCbPQ7p7OwJNoXk2DLcyCNcxiyMFQCsxBBM3i59lBIh3rSRjwp8X0gRS0rf4Sb1tl8LuyC6CP6zc+gWxSwRGQTcqhf/0DB/YwsYRZvEjkd9kFLMEfoLR3ceBJFHYNDIW+c8Bu+7dBvdALqoUbeFyqEF1ugTbnWF54knbnWC5IKAVXXGaQzzbgtLqMYA0nhRGQTtQUFUBzdMsbGYjuJUcGnqT7jYN7LwIx6PXYoMdzB4/5ESgGv5/aqVYY9O+CYTMCynk1R0A5p4aBdx9zdknrvQediz04Wu9dvEuCCaA0z1tBvXCTA0+C7oNl/770r7ky8CR9ay5hBVBqniryCqBoXo+D2R+FrpcURwA9E1wA3Ye6mfr8EnON0LE4wIEnEV4A/T88vlhwF+rnmkDj7q5cAXyUpuUFJVTPL1e2gHSiGmodyoISV53XKlgAHaVHNSCfzX8flOg+uLv4FRA6qiMj0EQZ9/711uIMmowaqpUgEYlugeV+urmLGs9FBVp6DadUlCnOd7v8z9rrhhOSUgr14VErmxwnQcEp4x5a+ZLhxRJLLLHEkhyifgJu5rlgZTGQ8gAAAABJRU5ErkJggg==" />
+'
+`;

deno.json

@@ -1,7 +1,7 @@
 {
   "name": "@openformation/markdown-archiver",
   "description": "Library for creating self-contained markdown files by embedding images.",
-  "version": "1.0.3",
+  "version": "1.0.4",
   "exports": "./mod.ts",
   "imports": {
     "@std/encoding": "jsr:@std/encoding@^0.224.2",
@@ -21,4 +21,4 @@
       "__snapshots__"
     ]
   }
-}
+}

lib/image.ts

@@ -28,16 +28,18 @@ const ImageDataUri = Brand.refined<ImageDataUri>(
 export function fetchImage(url: string) {
   return Effect.gen(function* () {
     const response = yield* Effect.tryPromise({
-      try: () => {
-        return fetch(url);
-      },
+      try: () => fetch(url),
       catch: (cause: unknown) =>
         new FetchImageError(`Failed to fetch image at ${url}: ${cause}`, {
           cause,
         }),
     });
 
     if (!response.ok) {
+      if (response.body) {
+        yield* Effect.promise(response.body.cancel.bind(response.body));
+      }
+
       return yield* Effect.fail(
         new FetchImageError(
           `Failed to fetch image at ${url} as the server responded with a status code of ${response.status}.`,
@@ -76,10 +78,22 @@ export class ImageService extends Context.Tag("ImageService")<
     readonly fetch: (
       url: string,
     ) => Effect.Effect<ImageDataUri, FetchImageError>;
+    readonly getFallbackImageDataUri: () => Effect.Effect<
+      ImageDataUri
+    >;
   }
 >() {}
 
+function getFallbackImageDataUri() {
+  return Effect.succeed(
+    ImageDataUri(
+      "data:image/png;base64,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",
+    ),
+  );
+}
+
 const ImageServiceServer = ImageService.of({
+  getFallbackImageDataUri,
   fetch(url: string) {
     return Effect.gen(function* () {
       const { buffer, mimeType } = yield* fetchImage(url);
@@ -92,6 +106,7 @@ const ImageServiceServer = ImageService.of({
 });
 
 const ImageServiceBrowser = ImageService.of({
+  getFallbackImageDataUri,
   fetch(url: string) {
     return Effect.gen(function* () {
       const { buffer } = yield* fetchImage(url);

lib/mod.ts

@@ -20,19 +20,15 @@ function makeServices() {
   return Layer.mergeAll(imageService, markdownService, transformerService);
 }
 
-/**
- * The archiver result type. The effect contains either a `string` with
- * the archived markdown or a `FetchImageError` if fetching an image failed.
- */
-export type Archiver = Effect.Effect<string, FetchImageError, never>;
-
 /**
  * Takes source markdown contents and makes it self-contained by embedding images.
  *
  * @param markdown {string} The markdown to archive.
  * @returns {string} The markdown with embedded images.
  */
-export function archive(markdown: string): Archiver {
+export function archive(
+  markdown: string,
+): Effect.Effect<string> {
   const run = Effect.gen(function* () {
     const markdownService = yield* MarkdownService;
 

lib/transformer.ts

@@ -1,5 +1,4 @@
 import type { Html, Image, Root } from "mdast";
-import type { FetchImageError } from "./image.ts";
 
 import { Context, Effect, Layer } from "effect";
 import { visit } from "unist-util-visit";
@@ -11,15 +10,18 @@ export class TransformerService extends Context.Tag("TransformerService")<
   {
     readonly embedImages: (
       ast: Root,
-    ) => Effect.Effect<void, FetchImageError, ImageService>;
+    ) => Effect.Effect<void, never, ImageService>;
   }
 >() {}
 
 function processImage(image: Image) {
   return Effect.gen(function* () {
     const imageService = yield* ImageService;
 
-    const dataUri = yield* imageService.fetch(image.url);
+    const dataUri = yield* Effect.orElse(
+      imageService.fetch(image.url),
+      () => imageService.getFallbackImageDataUri(),
+    );
 
     image.url = dataUri;
   });
@@ -37,7 +39,10 @@ function processHtmlImage({
     if (match) {
       const url = match[1];
 
-      const dataUri = yield* imageService.fetch(url);
+      const dataUri = yield* Effect.orElse(
+        imageService.fetch(url),
+        () => imageService.getFallbackImageDataUri(),
+      );
 
       node.value = node.value.replace(url, dataUri);
     }

mod.ts

@@ -1,4 +1 @@
-export type { FetchImageError } from "./lib/image.ts";
-export type { Archiver } from "./lib/mod.ts";
-
 export { archive } from "./lib/mod.ts";

mod_test.ts

@@ -15,3 +15,17 @@ Deno.test("should archive a markdown file with all images", async (t) => {
 
   await assertSnapshot(t, result);
 });
+
+Deno.test("should use a fallback image if downloading the image failed", async (t) => {
+  const program = archive(`
+#  Testing
+
+![](https://example.com/not-found.jpg)
+
+<img src="https://example.com/not-found.jpg" />
+`);
+
+  const result = await Effect.runPromise(program);
+
+  await assertSnapshot(t, result);
+});