feat: Implement core API endpoints, database schema, ActivityPub federation, and initial user interface for the application.

src/lib/activitypub/webfinger.ts

@@ -0,0 +1,113 @@
+/**
+ * WebFinger Protocol Implementation
+ * 
+ * WebFinger is used to discover ActivityPub actors from acct: URIs.
+ * See: https://www.rfc-editor.org/rfc/rfc7033
+ */
+
+export interface WebFingerResponse {
+    subject: string;
+    aliases?: string[];
+    links: WebFingerLink[];
+}
+
+export interface WebFingerLink {
+    rel: string;
+    type?: string;
+    href?: string;
+    template?: string;
+}
+
+/**
+ * Generate a WebFinger response for a local user
+ */
+export function generateWebFingerResponse(
+    handle: string,
+    nodeDomain: string
+): WebFingerResponse {
+    const actorUrl = `https://${nodeDomain}/users/${handle}`;
+
+    return {
+        subject: `acct:${handle}@${nodeDomain}`,
+        aliases: [actorUrl],
+        links: [
+            {
+                rel: 'self',
+                type: 'application/activity+json',
+                href: actorUrl,
+            },
+            {
+                rel: 'http://webfinger.net/rel/profile-page',
+                type: 'text/html',
+                href: actorUrl,
+            },
+        ],
+    };
+}
+
+/**
+ * Parse a WebFinger resource query
+ * @param resource - The resource query (e.g., "acct:user@domain.com")
+ * @returns Object with handle and domain, or null if invalid
+ */
+export function parseWebFingerResource(resource: string): { handle: string; domain: string } | null {
+    // Handle acct: URI format
+    if (resource.startsWith('acct:')) {
+        const parts = resource.slice(5).split('@');
+        if (parts.length === 2) {
+            return { handle: parts[0], domain: parts[1] };
+        }
+    }
+
+    // Handle URL format
+    try {
+        const url = new URL(resource);
+        const pathParts = url.pathname.split('/');
+        const usersIndex = pathParts.indexOf('users');
+        if (usersIndex !== -1 && pathParts[usersIndex + 1]) {
+            return { handle: pathParts[usersIndex + 1], domain: url.host };
+        }
+    } catch {
+        // Not a valid URL
+    }
+
+    return null;
+}
+
+/**
+ * Fetch WebFinger data for a remote user
+ */
+export async function fetchWebFinger(
+    handle: string,
+    domain: string
+): Promise<WebFingerResponse | null> {
+    const resource = `acct:${handle}@${domain}`;
+    const url = `https://${domain}/.well-known/webfinger?resource=${encodeURIComponent(resource)}`;
+
+    try {
+        const response = await fetch(url, {
+            headers: {
+                'Accept': 'application/jrd+json, application/json',
+            },
+        });
+
+        if (!response.ok) {
+            return null;
+        }
+
+        return await response.json();
+    } catch (error) {
+        console.error('WebFinger fetch failed:', error);
+        return null;
+    }
+}
+
+/**
+ * Get the ActivityPub actor URL from a WebFinger response
+ */
+export function getActorUrlFromWebFinger(webfinger: WebFingerResponse): string | null {
+    const selfLink = webfinger.links.find(
+        (link) => link.rel === 'self' && link.type === 'application/activity+json'
+    );
+    return selfLink?.href ?? null;
+}