- Added a simple bank system. Users can deposit, withdraw and check the balance of their currency in the bank.

- Users can't check other user's bank balances.
- Added a button on a .$ command which, when clicked, sends you a message with your bank balance that only you can see.
- Updated pagination, it now uses buttons instead of reactions
- using .h <command group> (atm only .bank is a proper group) will list commands with their descriptions in that group

src/NadekoBot/Modules/Gambling/Bank/BankService.cs

@@ -0,0 +1,77 @@
+using LinqToDB;
+using LinqToDB.EntityFrameworkCore;
+
+namespace NadekoBot.Modules.Gambling.Bank;
+
+public sealed class BankService : IBankService, INService
+{
+    private readonly ICurrencyService _cur;
+    private readonly DbService _db;
+
+    public BankService(ICurrencyService cur, DbService db)
+    {
+        _cur = cur;
+        _db = db;
+    }
+
+    public async Task<bool> DepositAsync(ulong userId, long amount)
+    {
+        if (amount <= 0)
+            throw new ArgumentOutOfRangeException(nameof(amount));
+        
+        if (!await _cur.RemoveAsync(userId, amount, new("bank", "deposit")))
+            return false;
+
+        await using var ctx = _db.GetDbContext();
+        await ctx.BankUsers
+                 .ToLinqToDBTable()
+                 .InsertOrUpdateAsync(() => new()
+                     {
+                         UserId = userId,
+                         Balance = amount
+                     },
+                     (old) => new()
+                     {
+                         Balance = old.Balance + amount
+                     },
+                     () => new()
+                     {
+                         UserId = userId
+                     });
+
+        return true;
+    }
+
+    public async Task<bool> WithdrawAsync(ulong userId, long amount)
+    {
+        if (amount <= 0)
+            throw new ArgumentOutOfRangeException(nameof(amount));
+        
+        await using var ctx = _db.GetDbContext();
+        var rows = await ctx.BankUsers
+                 .ToLinqToDBTable()
+                 .Where(x => x.UserId == userId && x.Balance >= amount)
+                 .UpdateAsync((old) => new()
+                 {
+                     Balance = old.Balance - amount
+                 });
+
+        if (rows > 0)
+        {
+            await _cur.AddAsync(userId, amount, new("bank", "withdraw"));
+            return true;
+        }
+
+        return false;
+    }
+
+    public async Task<long> GetBalanceAsync(ulong userId)
+    {
+        await using var ctx = _db.GetDbContext();
+        return (await ctx.BankUsers
+                         .ToLinqToDBTable()
+                         .FirstOrDefaultAsync(x => x.UserId == userId))
+               ?.Balance
+               ?? 0;
+    }
+}