WIP: Compute balances in database

.eslintignore

@@ -0,0 +1 @@
+src/prisma/client/

.gitignore

@@ -11,6 +11,7 @@
 # database
 /prisma/db.sqlite
 /prisma/db.sqlite-journal
+/src/prisma/client
 
 # next.js
 /.next/

prisma/schema.prisma

@@ -3,7 +3,8 @@
 
 generator client {
     provider        = "prisma-client-js"
-    previewFeatures = ["relationJoins"]
+    output = "../src/prisma/client"
+    previewFeatures = ["relationJoins", "typedSQL"]
 }
 
 datasource db {

prisma/seed.ts

@@ -1,4 +1,4 @@
-import { PrismaClient } from '@prisma/client';
+import { PrismaClient } from '~/prisma/client';
 
 const prisma = new PrismaClient();
 

prisma/sql/getAllBalancesForGroup.sql

@@ -0,0 +1,6 @@
+-- @param {Int} $1:id of the group
+select "groupId", "userId" as "borrowedBy", "paidBy", "currency", Coalesce(-1 * sum("ExpenseParticipant".amount),0) as amount FROM "Expense"
+JOIN "ExpenseParticipant" ON "ExpenseParticipant"."expenseId" = "Expense".id
+WhERE "groupId" = $1 AND "userId" != "paidBy"
+GROUP BY "userId", "paidBy", "currency", "groupId"
+ORDER By "currency"

prisma/sql/getGroupsWithBalances.sql

@@ -0,0 +1,9 @@
+-- @param {Int} $1:id of the user
+SELECT "Group"."id", "Group".name, Coalesce(sum("ExpenseParticipant".amount),0) as balance, Coalesce("Expense".currency, "Group"."defaultCurrency") as currency
+FROM "GroupUser"
+JOIN "Group" ON "GroupUser"."groupId" = "Group".id
+LEFT JOIN "Expense" ON "Expense"."groupId" = "Group".id
+LEFT JOIN "ExpenseParticipant" ON "Expense".id = "ExpenseParticipant"."expenseId"
+WHERE "GroupUser"."userId" = $1 AND "deletedAt" IS NULL AND ("ExpenseParticipant"."userId" = $1 OR "Expense".id is null)
+GROUP BY "Group".id, "Group".name, "Expense".currency
+ORDER BY "Group"."createdAt" DESC, balance DESC

src/components/AddExpense/SelectUserOrGroup.tsx

@@ -1,12 +1,12 @@
 import { CheckIcon } from '@heroicons/react/24/outline';
 import { UserPlusIcon } from '@heroicons/react/24/solid';
-import { type Group, type GroupUser, type User } from '@prisma/client';
 import { motion } from 'framer-motion';
 import { SendIcon } from 'lucide-react';
 import Image from 'next/image';
 import React from 'react';
 import { z } from 'zod';
 
+import { type Group, type GroupUser, type User } from '~/prisma/client';
 import { useAddExpenseStore } from '~/store/addStore';
 import { api } from '~/utils/api';
 

src/components/AddExpense/SplitTypeSection.tsx

@@ -1,4 +1,3 @@
-import { SplitType } from '@prisma/client';
 import clsx from 'clsx';
 import {
   BarChart2,
@@ -12,6 +11,7 @@ import {
 } from 'lucide-react';
 import { type ChangeEvent, useCallback, useMemo } from 'react';
 
+import { SplitType } from '~/prisma/client';
 import { type AddExpenseState, type Participant, useAddExpenseStore } from '~/store/addStore';
 import { removeTrailingZeros, toSafeBigInt, toUIString } from '~/utils/numbers';
 

src/components/Expense/BalanceList.tsx

@@ -1,9 +1,10 @@
-import type { GroupBalance, User } from '@prisma/client';
 import clsx from 'clsx';
 import { Info } from 'lucide-react';
 import { useMemo } from 'react';
 
 import { UserAvatar } from '~/components/ui/avatar';
+import type { User } from '~/prisma/client';
+import { type getAllBalancesForGroup } from '~/prisma/client/sql';
 import { api } from '~/utils/api';
 import { BigMath, toUIString } from '~/utils/numbers';
 import { displayName } from '~/utils/strings';
@@ -18,7 +19,7 @@
 }
 
 export const BalanceList: React.FC<{
-  groupBalances: GroupBalance[];
+  groupBalances: getAllBalancesForGroup.Result[];
   users: User[];
 }> = ({ groupBalances, users }) => {
   const userQuery = api.user.me.useQuery();
@@ -32,16 +33,17 @@
       {} as Record<number, UserWithBalance>,
     );
     groupBalances
-      .filter(({ amount }) => BigMath.abs(amount) > 0)
+      .filter(({ amount }) => amount != null && BigMath.abs(amount) > 0)
       .forEach((balance) => {
-        if (!res[balance.userId]!.balances[balance.firendId]) {
-          res[balance.userId]!.balances[balance.firendId] = {};
+        if (!res[balance.paidBy]!.balances[balance.borrowedBy]) {
+          res[balance.paidBy]!.balances[balance.borrowedBy] = {};
         }
-        const friendBalance = res[balance.userId]!.balances[balance.firendId]!;
-        friendBalance[balance.currency] = (friendBalance[balance.currency] ?? 0n) + balance.amount;
+        const friendBalance = res[balance.paidBy]!.balances[balance.borrowedBy]!;
+        friendBalance[balance.currency] =
+          (friendBalance[balance.currency] ?? 0n) + (balance.amount ?? 0n);
 
-        res[balance.userId]!.total[balance.currency] =
-          (res[balance.userId]!.total[balance.currency] ?? 0n) + balance.amount;
+        res[balance.paidBy]!.total[balance.currency] =
+          (res[balance.paidBy]!.total[balance.currency] ?? 0n) + (balance.amount ?? 0n);
       });
 
     return res;
@@ -109,7 +111,7 @@
                           user={user}
                           amount={amount}
                           currency={currency}
                           groupId={groupBalances[0]!.groupId}
                         >
                           <div className="mb-4 ml-5 flex cursor-pointer items-center gap-3 text-sm">
                             <UserAvatar user={friend} size={20} />

src/components/Expense/ExpenseList.tsx

@@ -1,11 +1,11 @@
-import { SplitType } from '@prisma/client';
 import { type inferRouterOutputs } from '@trpc/server';
 import { format } from 'date-fns';
 import Image from 'next/image';
 import Link from 'next/link';
 import React from 'react';
 
 import { CategoryIcon } from '~/components/ui/categoryIcons';
+import { SplitType } from '~/prisma/client';
 import { type GroupRouter } from '~/server/api/routers/group';
 import { type UserRouter } from '~/server/api/routers/user';
 import { toUIString } from '~/utils/numbers';

src/components/Expense/ExpensePage.tsx

@@ -1,10 +1,10 @@
-import { type Expense, type ExpenseParticipant, type User } from '@prisma/client';
 import { format, isSameDay } from 'date-fns';
 import { Banknote } from 'lucide-react';
 import Image from 'next/image';
 import { type User as NextUser } from 'next-auth';
 import React from 'react';
 
+import { type Expense, type ExpenseParticipant, type User } from '~/prisma/client';
 import { toUIString } from '~/utils/numbers';
 
 import { UserAvatar } from '../ui/avatar';

src/components/Friend/Export.tsx

@@ -1,9 +1,9 @@
-import { type Expense, type ExpenseParticipant, SplitType } from '@prisma/client';
 import { format } from 'date-fns';
 import { Download } from 'lucide-react';
 import React from 'react';
 
 import { Button } from '~/components/ui/button';
+import { type Expense, type ExpenseParticipant, SplitType } from '~/prisma/client';
 import { toUIString } from '~/utils/numbers';
 
 interface ExportCSVProps {

src/components/Friend/FirendBalance.tsx

@@ -1,6 +1,6 @@
-import { type Balance, type User } from '@prisma/client';
 import clsx from 'clsx';
 
+import { type Balance, type User } from '~/prisma/client';
 import { toUIString } from '~/utils/numbers';
 
 import { UserAvatar } from '../ui/avatar';

src/components/Friend/GroupSettleup.tsx

@@ -1,8 +1,8 @@
-import { SplitType, type User } from '@prisma/client';
 import { ArrowRightIcon } from 'lucide-react';
 import React, { type ReactNode, useCallback, useState } from 'react';
 import { toast } from 'sonner';
 
+import { SplitType, type User } from '~/prisma/client';
 import { api } from '~/utils/api';
 import { toSafeBigInt, toUIString } from '~/utils/numbers';
 import { displayName } from '~/utils/strings';

src/components/Friend/Settleup.tsx

@@ -1,9 +1,9 @@
-import { type Balance, SplitType, type User } from '@prisma/client';
 import { ArrowRightIcon } from 'lucide-react';
 import { type User as NextUser } from 'next-auth';
 import React, { useState } from 'react';
 import { toast } from 'sonner';
 
+import { type Balance, SplitType, type User } from '~/prisma/client';
 import { api } from '~/utils/api';
 import { BigMath, toSafeBigInt, toUIString } from '~/utils/numbers';
 

src/components/group/AddMembers.tsx

@@ -1,12 +1,12 @@
 import { UserPlusIcon } from '@heroicons/react/24/solid';
-import { type Group, type GroupUser } from '@prisma/client';
 import clsx from 'clsx';
 import { CheckIcon, SendIcon } from 'lucide-react';
 import React, { useState } from 'react';
 import { z } from 'zod';
 
 import { Button } from '~/components/ui/button';
 import { AppDrawer } from '~/components/ui/drawer';
+import { type Group, type GroupUser } from '~/prisma/client';
 import { api } from '~/utils/api';
 
 import { UserAvatar } from '../ui/avatar';

src/components/group/GroupMyBalance.tsx

@@ -1,6 +1,6 @@
-import { type GroupBalance, type User } from '@prisma/client';
 import React from 'react';
 
+import { type GroupBalance, type User } from '~/prisma/client';
 import { BigMath, toUIString } from '~/utils/numbers';
 
 type GroupMyBalanceProps = {

src/components/group/NoMembers.tsx

@@ -1,8 +1,8 @@
-import { type Group, type GroupUser } from '@prisma/client';
 import { Share, UserPlus } from 'lucide-react';
 import React, { useState } from 'react';
 
 import { Button } from '~/components/ui/button';
+import { type Group, type GroupUser } from '~/prisma/client';
 
 import AddMembers from './AddMembers';
 

src/lib/simplify.test.ts

@@ -1,5 +1,4 @@
-import { type GroupBalance } from '@prisma/client';
-import { addHours } from 'date-fns';
+import { type getAllBalancesForGroup } from '~/prisma/client/sql';
 
 import { simplifyDebts } from './simplify';
 
@@ -9,46 +8,45 @@ type MinimalEdge = {
   amount: bigint;
 };
 
-const sortByIds = (a: GroupBalance, b: GroupBalance) => {
-  if (a.userId === b.userId) {
-    return a.firendId - b.firendId;
+const sortByIds = (a: getAllBalancesForGroup.Result, b: getAllBalancesForGroup.Result) => {
+  if (a.paidBy === b.paidBy) {
+    return a.borrowedBy - b.borrowedBy;
   }
-  return a.userId - b.userId;
+  return a.paidBy - b.paidBy;
 };
 
-let dateCounter = 0;
-
-const edgeToGroupBalance = (edge: MinimalEdge): [GroupBalance, GroupBalance] => {
+const edgeToGroupBalance = (
+  edge: MinimalEdge,
+): [getAllBalancesForGroup.Result, getAllBalancesForGroup.Result] => {
   const base = {
     groupId: 0,
     currency: 'USD',
-    updatedAt: addHours(new Date(), dateCounter++),
   };
   return [
     {
-      userId: edge.userOne,
-      firendId: edge.userTwo,
+      paidBy: edge.userOne,
+      borrowedBy: edge.userTwo,
       amount: edge.amount,
       ...base,
     },
     {
-      userId: edge.userTwo,
-      firendId: edge.userOne,
+      paidBy: edge.userTwo,
+      borrowedBy: edge.userOne,
       amount: edge.amount === 0n ? 0n : -edge.amount,
       ...base,
     },
   ];
 };
 
-const padWithZeroBalances: (balances: GroupBalance[], userCount: number) => GroupBalance[] = (
-  balances,
-  userCount,
-) => {
+const padWithZeroBalances: (
+  balances: getAllBalancesForGroup.Result[],
+  userCount: number,
+) => getAllBalancesForGroup.Result[] = (balances, userCount) => {
   const result = [...balances];
   for (let userId = 0; userId < userCount; userId++) {
     for (let friendId = userId + 1; friendId < userCount; friendId++) {
       const found = balances.find(
-        (balance) => balance.userId === userId && balance.firendId === friendId,
+        (balance) => balance.paidBy === userId && balance.borrowedBy === friendId,
       );
 
       if (!found) {
@@ -59,14 +57,17 @@ const padWithZeroBalances: (balances: GroupBalance[], userCount: number) => Grou
   return result;
 };
 
-const getFullBalanceGraph = (edges: MinimalEdge[], userCount: number): GroupBalance[] => {
+const getFullBalanceGraph = (
+  edges: MinimalEdge[],
+  userCount: number,
+): getAllBalancesForGroup.Result[] => {
   const arr = padWithZeroBalances(edges.flatMap(edgeToGroupBalance), userCount);
   arr.sort(sortByIds);
   return arr;
 };
 
 // taken from https://www.geeksforgeeks.org/minimize-cash-flow-among-given-set-friends-borrowed-money/
-const smallGraph: GroupBalance[] = getFullBalanceGraph(
+const smallGraph: getAllBalancesForGroup.Result[] = getFullBalanceGraph(
   [
     { userOne: 0, userTwo: 1, amount: 1000n },
     { userOne: 1, userTwo: 2, amount: 5000n },
@@ -75,19 +76,16 @@ const smallGraph: GroupBalance[] = getFullBalanceGraph(
   3,
 );
 
-const smallGraphResult: GroupBalance[] = getFullBalanceGraph(
+const smallGraphResult: getAllBalancesForGroup.Result[] = getFullBalanceGraph(
   [
     { userOne: 1, userTwo: 2, amount: 4000n },
     { userOne: 2, userTwo: 0, amount: -3000n },
   ],
   3,
-).map((resultBalance, idx) => ({
-  ...resultBalance,
-  updatedAt: smallGraph[idx]!.updatedAt,
-}));
+);
 
 // taken from https://medium.com/@mithunmk93/algorithm-behind-splitwises-debt-simplification-feature-8ac485e97688
-const largeGraph: GroupBalance[] = getFullBalanceGraph(
+const largeGraph: getAllBalancesForGroup.Result[] = getFullBalanceGraph(
   [
     { userOne: 1, userTwo: 2, amount: 4000n },
     { userOne: 1, userTwo: 5, amount: -1000n },
@@ -105,7 +103,7 @@ const largeGraph: GroupBalance[] = getFullBalanceGraph(
   7,
 );
 
-const denseGraph: GroupBalance[] = getFullBalanceGraph(
+const denseGraph: getAllBalancesForGroup.Result[] = getFullBalanceGraph(
   [
     { userOne: 0, userTwo: 1, amount: 895795n },
     { userOne: 0, userTwo: 2, amount: 328043n },
@@ -142,23 +140,25 @@ describe('simplifyDebts', () => {
     { graph: largeGraph, expected: 3 },
     { graph: denseGraph, expected: 5 },
   ])('gets the optimal operation count', ({ graph, expected }) => {
-    expect(simplifyDebts(graph).filter((balance) => balance.amount > 0).length).toBe(expected);
+    expect(simplifyDebts(graph).filter((balance) => (balance.amount ?? 0n) > 0).length).toBe(
+      expected,
+    );
   });
 
   it.each([{ graph: smallGraph }, { graph: largeGraph }, { graph: denseGraph }])(
     'preserves the total balance per user',
     ({ graph }) => {
       const startingBalances = graph.reduce(
         (acc, balance) => {
-          acc[balance.userId] = (acc[balance.userId] ?? 0n) + balance.amount;
+          acc[balance.paidBy] = (acc[balance.paidBy] ?? 0n) + (balance.amount ?? 0n);
           return acc;
         },
         {} as Record<number, bigint>,
       );
 
       const userBalances = simplifyDebts(graph).reduce(
         (acc, balance) => {
-          acc[balance.userId] = (acc[balance.userId] ?? 0n) + balance.amount;
+          acc[balance.paidBy] = (acc[balance.paidBy] ?? 0n) + (balance.amount ?? 0n);
           return acc;
         },
         {} as Record<number, bigint>,