Implemented user transactions

src/IO.Swagger/Repositories/TransactionRepository.cs

@@ -1,4 +1,5 @@
 using IO.Swagger.Models.db;
+using IO.Swagger.Models.dto;
 using IO.Swagger.Services;
 using Microsoft.EntityFrameworkCore;
 using System;
@@ -8,6 +9,7 @@ using System.Threading.Tasks;
 
 namespace IO.Swagger.Repositories
 {
+
     public class TransactionRepository : ITransactionRepository
     {
         BankDbContext context;
@@ -31,5 +33,48 @@ namespace IO.Swagger.Repositories
                     t.Amount *= -1;
             return transactions;
         }
+
+        public async Task<List<Tuple<Currency, float>>> GetBalancesForUser(int userId)
+        {
+            var transactions = await context.Transactions.Where(t => t.ToUserId == userId || t.FromUserId == userId)
+                                .Include(t => t.Currency)
+                                .GroupBy(t => t.Currency)
+                                .Select(g => Tuple.Create(
+                                        g.Key,
+                                        g.Sum(t =>t.ToUserId != t.FromUserId && t.FromUserId == userId
+                                                ? -t.Amount
+                                                : t.Amount
+                                        )
+                                    )
+                                )
+                                .ToListAsync();
+
+            return transactions;
+        }
+
+        public async Task<TransactionReturnCode> TransferPhysical(WalletTransferPhysicalBody request, int fromUserId)
+        {
+            var trimmedDest = request.DestUserEmail.Trim().ToLower();
+            var destUser = await context.Users.FirstOrDefaultAsync(u => u.Email == trimmedDest);
+            if (destUser == null)
+                return TransactionReturnCode.UnknownDestinationUser;
+            
+            var balances = await GetBalancesForUser(fromUserId);
+            var balance = balances.FirstOrDefault(b => b.Item1.CurrencyId == request.CurrencyId);
+            if (balance == null || balance.Item2 < request.Amount)
+                return TransactionReturnCode.InsufficientFunds;
+
+
+            await context.Transactions.AddAsync(new Transaction
+            {
+                Amount = request.Amount,
+                CurrencyId = request.CurrencyId,
+                ToUserId = destUser.Id,
+                FromUserId = fromUserId,
+                Memo = request.Memo
+            });
+            return await context.SaveChangesAsync() > 0 ? TransactionReturnCode.Success : TransactionReturnCode.DbError;
+        }
+
     }
 }