Step 10: MCP Resources — Browseable Workspaces & Collections

import { registerSnippetTools }     from "./tools/snippets.ts";
import { registerWorkspaceTools }   from "./tools/workspaces.ts";
import { registerSnippetResources } from "./resources/snippets.ts";
 
// ... inside the route handler, after registering tools:
registerSnippetResources(server, { user, supabase });

import { ResourceTemplate } from "@modelcontextprotocol/sdk/server/mcp.js";
import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import type { Variables } from "@modelcontextprotocol/sdk/shared/uriTemplate.js";
import type { SupabaseClient } from "@supabase/supabase-js";
import type { AuthedUser } from "../auth.ts";
 
type Ctx = { user: AuthedUser; supabase: SupabaseClient };
 
export function registerSnippetResources(server: McpServer, ctx: Ctx) {
  const { supabase } = ctx;
 
  // ---------------------------------------------------------------------
  // workspace://<id> — metadata about one workspace.
  // The template's `list` callback is what fills the client's
  // resources/list catalog; the read callback serves resources/read.
  // ---------------------------------------------------------------------
  server.registerResource(
    "workspace",
    new ResourceTemplate("workspace://{id}", {
      list: async () => {
        const { data, error } = await supabase
          .from("workspaces")
          .select("id, name");
 
        if (error) throw new Error(error.message);
 
        return {
          resources: (data ?? []).map((w) => ({
            uri:         `workspace://${w.id}`,
            name:        `Workspace: ${w.name}`,
            description: `Metadata for workspace ${w.name}.`,
            mimeType:    "application/json",
          })),
        };
      },
    }),
    {
      description: "Metadata for one workspace the caller belongs to.",
      mimeType: "application/json",
    },
    async (uri: URL, { id }: Variables) => {
      const workspaceId = String(id);
      const { data: ws, error: wsErr } = await supabase
        .from("workspaces")
        .select("id, name, created_at")
        .eq("id", workspaceId)
        .maybeSingle();
 
      if (wsErr)  throw new Error(wsErr.message);
      if (!ws)    throw new Error(`workspace ${workspaceId} not found or not visible to you`);
 
      const { count } = await supabase
        .from("snippets")
        .select("id", { count: "exact", head: true })
        .eq("workspace_id", workspaceId);
 
      return {
        contents: [{
          uri: uri.href,
          mimeType: "application/json",
          text: JSON.stringify({ ...ws, snippet_count: count ?? 0 }, null, 2),
        }],
      };
    }
  );
 
  // ---------------------------------------------------------------------
  // workspace://<id>/snippets — a workspace's snippet listing
  // ---------------------------------------------------------------------
  server.registerResource(
    "workspace-snippets",
    new ResourceTemplate("workspace://{id}/snippets", {
      list: async () => {
        const { data, error } = await supabase
          .from("workspaces")
          .select("id, name");
 
        if (error) throw new Error(error.message);
 
        return {
          resources: (data ?? []).map((w) => ({
            uri:         `workspace://${w.id}/snippets`,
            name:        `Snippets in ${w.name}`,
            description: `Browseable list of snippets the caller can see in ${w.name}.`,
            mimeType:    "application/json",
          })),
        };
      },
    }),
    {
      description: "Snippets the caller can see in one workspace.",
      mimeType: "application/json",
    },
    async (uri: URL, { id }: Variables) => {
      const workspaceId = String(id);
      const { data, error } = await supabase
        .from("snippets")
        .select("id, title, tags, visibility, updated_at")
        .eq("workspace_id", workspaceId)
        .order("updated_at", { ascending: false });
 
      if (error) throw new Error(error.message);
 
      return {
        contents: [{
          uri: uri.href,
          mimeType: "application/json",
          text: JSON.stringify(data ?? [], null, 2),
        }],
      };
    }
  );
 
  // ---------------------------------------------------------------------
  // snippet://<id> — one snippet's full body, as markdown
  // ---------------------------------------------------------------------
  server.registerResource(
    "snippet",
    new ResourceTemplate("snippet://{id}", {
      // We cap the listing to the 50 most recently updated snippets so a
      // big workspace doesn't blow up the catalog.
      list: async () => {
        const { data, error } = await supabase
          .from("snippets")
          .select("id, title, workspace_id")
          .order("updated_at", { ascending: false })
          .limit(50);
 
        if (error) throw new Error(error.message);
 
        return {
          resources: (data ?? []).map((s) => ({
            uri:         `snippet://${s.id}`,
            name:        s.title,
            description: `Snippet "${s.title}" (workspace ${s.workspace_id}).`,
            mimeType:    "text/markdown",
          })),
        };
      },
    }),
    {
      description: "One snippet's full body.",
      mimeType: "text/markdown",
    },
    async (uri: URL, { id }: Variables) => {
      const snippetId = String(id);
      const { data, error } = await supabase
        .from("snippets")
        .select("title, body, tags, visibility, updated_at")
        .eq("id", snippetId)
        .maybeSingle();
 
      if (error)  throw new Error(error.message);
      if (!data)  throw new Error(`snippet ${snippetId} not found or not visible to you`);
 
      // Return as markdown so Claude renders it cleanly.
      const md = [
        `# ${data.title}`,
        ``,
        `_tags: ${data.tags.join(", ") || "(none)"} · visibility: ${data.visibility} · updated: ${data.updated_at}_`,
        ``,
        data.body,
      ].join("\n");
 
      return {
        contents: [{ uri: uri.href, mimeType: "text/markdown", text: md }],
      };
    }
  );
}