implement demo mode

server/demo/demo-provision.js

@@ -0,0 +1,149 @@
+// Vault provisioning for demo sessions.
+//
+// Copies the template into a session-prefixed dir, installs the bridge plugin, and registers the vault on the session.
+// Re-provisions if disk was wiped under an existing session.
+
+const fs = require("fs");
+const fsp = fs.promises;
+const path = require("path");
+
+const config = require("../config");
+const { installBridgePlugin } = require("../bridge-plugin");
+const bootstrapRoutes = require("../routes/bootstrap");
+
+const { sessions, makeStorageName } = require("./demo-sessions");
+
+const DEFAULT_VAULT_NAME = "Welcome";
+
+async function dirSize(dir) {
+  let total = 0;
+
+  async function walk(d) {
+    let entries;
+
+    try {
+      entries = await fsp.readdir(d, { withFileTypes: true });
+    } catch {
+      return;
+    }
+
+    for (const e of entries) {
+      const full = path.join(d, e.name);
+
+      if (e.isDirectory()) {
+        await walk(full);
+      } else {
+        try {
+          const st = await fsp.stat(full);
+          total += st.size;
+        } catch {}
+      }
+    }
+  }
+
+  await walk(dir);
+  return total;
+}
+
+async function recomputeBytes(sessionId) {
+  const s = sessions.get(sessionId);
+
+  if (!s) {
+    return 0;
+  }
+
+  let total = 0;
+
+  for (const userVaultName of s.vaults) {
+    const storageName = makeStorageName(sessionId, userVaultName);
+    const vaultPath = config.getVaultPath(storageName);
+
+    if (vaultPath) {
+      total += await dirSize(vaultPath);
+    }
+  }
+
+  s.bytesUsed = total;
+  return total;
+}
+
+async function provisionVault(sessionId, userVaultName) {
+  const s = sessions.get(sessionId);
+
+  if (!s) {
+    return null;
+  }
+
+  if (s.vaults.size >= config.demoVaultsPerSession) {
+    return { error: "vaults-per-session-limit" };
+  }
+
+  const storageName = makeStorageName(sessionId, userVaultName);
+  const vaultPath = path.join(config.vaultRoot, storageName);
+
+  await fsp.mkdir(config.vaultRoot, { recursive: true });
+
+  try {
+    await fsp.mkdir(vaultPath, { recursive: false });
+  } catch (e) {
+    if (e.code === "EEXIST") {
+      return { error: "vault-exists" };
+    }
+
+    throw e;
+  }
+
+  // Copy template (default: Welcome.md, Getting Started.md, .obsidian/*).
+  await fsp.cp(config.demoTemplateDir, vaultPath, { recursive: true });
+
+  // Install bridge plugin
+  await installBridgePlugin(vaultPath);
+
+  config.refreshVaults();
+  bootstrapRoutes.invalidateVault(storageName);
+
+  s.vaults.add(userVaultName);
+  await recomputeBytes(sessionId);
+
+  return { storageName, userVaultName };
+}
+
+async function ensureDefaultVault(sessionId) {
+  const s = sessions.get(sessionId);
+
+  if (!s) {
+    return null;
+  }
+
+  const storageName = makeStorageName(sessionId, DEFAULT_VAULT_NAME);
+  const vaultPath = config.getVaultPath(storageName);
+  const onDisk = vaultPath && fs.existsSync(vaultPath);
+
+  if (s.vaults.has(DEFAULT_VAULT_NAME) && onDisk) {
+    return DEFAULT_VAULT_NAME;
+  }
+
+  if (onDisk) {
+    // Disk has it but session forgot (cookie outlived in-memory session).
+    s.vaults.add(DEFAULT_VAULT_NAME);
+    return DEFAULT_VAULT_NAME;
+  }
+
+  // Disk wiped under us; clear stale Set entry before re-provisioning.
+  s.vaults.delete(DEFAULT_VAULT_NAME);
+
+  const result = await provisionVault(sessionId, DEFAULT_VAULT_NAME);
+
+  if (result && result.userVaultName) {
+    return result.userVaultName;
+  }
+
+  return null;
+}
+
+module.exports = {
+  DEFAULT_VAULT_NAME,
+  provisionVault,
+  ensureDefaultVault,
+  recomputeBytes,
+};