feat: add image URL fetching service with tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/server/services/image.service.ts

@@ -0,0 +1,82 @@
+import { randomUUID } from "node:crypto";
+import { mkdir } from "node:fs/promises";
+import { join } from "node:path";
+
+const ALLOWED_TYPES = ["image/jpeg", "image/png", "image/webp"];
+const MAX_SIZE = 5 * 1024 * 1024; // 5MB
+const FETCH_TIMEOUT = 10_000; // 10 seconds
+
+interface FetchImageResult {
+	filename: string;
+	sourceUrl: string;
+}
+
+export async function fetchImageFromUrl(
+	url: string,
+	uploadsDir = "uploads",
+): Promise<FetchImageResult> {
+	// Validate URL format
+	let parsedUrl: URL;
+	try {
+		parsedUrl = new URL(url);
+	} catch {
+		throw new Error("Invalid URL format");
+	}
+
+	if (!["http:", "https:"].includes(parsedUrl.protocol)) {
+		throw new Error("URL must use HTTP or HTTPS");
+	}
+
+	// Fetch with timeout
+	const controller = new AbortController();
+	const timeout = setTimeout(() => controller.abort(), FETCH_TIMEOUT);
+
+	let response: Response;
+	try {
+		response = await fetch(url, { signal: controller.signal });
+	} catch (err) {
+		if (err instanceof DOMException && err.name === "AbortError") {
+			throw new Error("Request timed out");
+		}
+		throw new Error(`Failed to fetch image: ${(err as Error).message}`);
+	} finally {
+		clearTimeout(timeout);
+	}
+
+	if (!response.ok) {
+		throw new Error(`HTTP ${response.status}: Failed to fetch image`);
+	}
+
+	// Validate content type
+	const contentType = response.headers
+		.get("content-type")
+		?.split(";")[0]
+		.trim();
+	if (!contentType || !ALLOWED_TYPES.includes(contentType)) {
+		throw new Error(
+			`Invalid content type: ${contentType ?? "unknown"}. Accepted: jpeg, png, webp`,
+		);
+	}
+
+	// Check content length if available
+	const contentLength = response.headers.get("content-length");
+	if (contentLength && Number.parseInt(contentLength, 10) > MAX_SIZE) {
+		throw new Error("File too large. Maximum size is 5MB");
+	}
+
+	// Read body and check actual size
+	const buffer = await response.arrayBuffer();
+	if (buffer.byteLength > MAX_SIZE) {
+		throw new Error("File too large. Maximum size is 5MB");
+	}
+
+	// Determine extension
+	const ext = contentType === "image/jpeg" ? "jpg" : contentType.split("/")[1];
+	const filename = `${Date.now()}-${randomUUID()}.${ext}`;
+
+	// Ensure directory exists and write
+	await mkdir(uploadsDir, { recursive: true });
+	await Bun.write(join(uploadsDir, filename), buffer);
+
+	return { filename, sourceUrl: url };
+}