feat: add user conversion count to admin panel (#1150)

Displays the count of users who signed up after signing at least one
document in the admin panel

packages/lib/server-only/user/get-signer-conversion.ts

@@ -0,0 +1,34 @@
+import { DateTime } from 'luxon';
+
+import { kyselyPrisma, sql } from '@documenso/prisma';
+
+export const getSignerConversionMonthly = async () => {
+  const qb = kyselyPrisma.$kysely
+    .selectFrom('Recipient')
+    .innerJoin('User', 'Recipient.email', 'User.email')
+    .select(({ fn }) => [
+      fn<Date>('DATE_TRUNC', [sql.lit('MONTH'), 'User.createdAt']).as('month'),
+      fn.count('Recipient.email').distinct().as('count'),
+      fn
+        .sum(fn.count('Recipient.email').distinct())
+        // eslint-disable-next-line @typescript-eslint/consistent-type-assertions, @typescript-eslint/no-explicit-any
+        .over((ob) => ob.orderBy(fn('DATE_TRUNC', [sql.lit('MONTH'), 'User.createdAt']) as any))
+        .as('cume_count'),
+    ])
+    .where('Recipient.signedAt', 'is not', null)
+    .where('Recipient.signedAt', '<', (eb) => eb.ref('User.createdAt'))
+    .groupBy(({ fn }) => fn('DATE_TRUNC', [sql.lit('MONTH'), 'User.createdAt']))
+    .orderBy('month', 'desc');
+
+  const result = await qb.execute();
+
+  return result.map((row) => ({
+    month: DateTime.fromJSDate(row.month).toFormat('yyyy-MM'),
+    count: Number(row.count),
+    cume_count: Number(row.cume_count),
+  }));
+};
+
+export type GetSignerConversionMonthlyResult = Awaited<
+  ReturnType<typeof getSignerConversionMonthly>
+>;