feat: basically finish the design of budget aggregate

src/Backend/Asset.Domain/Asset.Domain.csproj

@@ -6,4 +6,8 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <Folder Include="AssetAggregate\AssetEntity\" />
+  </ItemGroup>
+
 </Project>

src/Backend/Budget.Domain/Budget.Domain.csproj

@@ -6,4 +6,8 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\..\Shared\Primitives\Primitives.csproj" />
+  </ItemGroup>
+
 </Project>

src/Backend/Budget.Domain/BudgetAggregate/BudgetEntity/Budget.cs

@@ -0,0 +1,39 @@
+using Budget.Domain.BudgetAggregate.BudgetEntity.Events;
+using Budget.Domain.BudgetAggregate.SubBudgetEntity;
+using Primitives.Entity;
+using Shared.Primitives;
+
+namespace Budget.Domain.BudgetAggregate.BudgetEntity;
+
+public class Budget : EntityBase<BudgetId>, IAggregateRoot<Budget>
+{
+    private Budget(DateTime startDate, DateTime endDate, decimal amount, string description) : base(new BudgetId(1))
+    {
+        StartDate = startDate;
+        EndDate = endDate;
+        Amount = amount;
+        Description = description;
+        SubBudgets = new List<SubBudget>();
+    }
+
+    public DateTime StartDate { get; private set; }
+    public DateTime EndDate { get; private set; }
+    public decimal Amount { get; private set; }
+    public string Description { get; private set; }
+    private List<SubBudget> SubBudgets { get; set; }
+
+
+    public static Budget CreateBudget(DateTime startDate, DateTime endDate, decimal amount, string description)
+    {
+        var budget= new Budget(startDate, endDate, amount, description);
+        budget.AddDomainEvent(new BudgetCreatedDomainEvent(budget.Id));
+        return budget;
+    }
+
+    public void AddSubBudget(string tag, decimal amount)
+    {
+        var subBudget = SubBudget.CreateSubBudget(tag, amount);
+        SubBudgets.Add(subBudget);
+        subBudget.AddDomainEvent(new SubBudgetAddedDomainEvent(subBudget.Id));
+    }
+}

src/Backend/Budget.Domain/BudgetAggregate/BudgetEntity/BudgetId.cs

@@ -0,0 +1,9 @@
+namespace Budget.Domain.BudgetAggregate.BudgetEntity;
+
+public readonly record struct BudgetId(long Value)
+{
+    public override string ToString()
+    {
+        return Value.ToString();
+    }
+}

src/Backend/Budget.Domain/BudgetAggregate/BudgetEntity/Events/BudgetCreatedDomainEvent.cs

@@ -0,0 +1,8 @@
+using Shared.Primitives.DomainEvent;
+
+namespace Budget.Domain.BudgetAggregate.BudgetEntity.Events;
+
+public class BudgetCreatedDomainEvent(BudgetId budgetId):IDomainEvent
+{
+    public BudgetId BudgetId { get; } = budgetId;
+}

src/Backend/Budget.Domain/BudgetAggregate/BudgetEntity/Events/SubBudgetAddedDomainEvent.cs

@@ -0,0 +1,9 @@
+using Budget.Domain.BudgetAggregate.SubBudgetEntity;
+using Shared.Primitives.DomainEvent;
+
+namespace Budget.Domain.BudgetAggregate.BudgetEntity.Events;
+
+public class SubBudgetAddedDomainEvent(SubBudgetId subBudgetId) : IDomainEvent
+{
+    public SubBudgetId SubBudgetId { get; } = subBudgetId;
+}

src/Backend/Budget.Domain/BudgetAggregate/IBudgetRepository.cs

@@ -0,0 +1,6 @@
+namespace Budget.Domain.BudgetAggregate;
+
+public interface IBudgetRepository
+{
+
+}

src/Backend/Budget.Domain/BudgetAggregate/SubBudgetEntity/Events/SubBudgetCreatedDomainEvent.cs

@@ -0,0 +1,8 @@
+using Shared.Primitives.DomainEvent;
+
+namespace Budget.Domain.BudgetAggregate.SubBudgetEntity.Events;
+
+public class SubBudgetCreatedDomainEvent(SubBudgetId subBudgetId) : IDomainEvent
+{
+    public SubBudgetId SubBudgetId { get; } = subBudgetId;
+}

src/Backend/Budget.Domain/BudgetAggregate/SubBudgetEntity/SubBudget.cs

@@ -0,0 +1,22 @@
+using Budget.Domain.BudgetAggregate.SubBudgetEntity.Events;
+using Primitives.Entity;
+
+namespace Budget.Domain.BudgetAggregate.SubBudgetEntity;
+
+public class SubBudget : EntityBase<SubBudgetId>
+{
+    private SubBudget(string tag, decimal amount) : base(new SubBudgetId(1))
+    {
+        Tag = tag;
+        Amount = amount;
+    }
+    public static SubBudget CreateSubBudget(string tag, decimal amount)
+    {
+        var subBudget= new SubBudget(tag, amount);
+        subBudget.AddDomainEvent(new SubBudgetCreatedDomainEvent(subBudget.Id));
+        return subBudget;
+    }
+
+    public string Tag { get; private set; }
+    public decimal Amount { get; private set; }
+}

src/Backend/Budget.Domain/BudgetAggregate/SubBudgetEntity/SubBudgetId.cs

@@ -0,0 +1,6 @@
+namespace Budget.Domain.BudgetAggregate.SubBudgetEntity;
+
+public readonly record struct SubBudgetId(long Value)
+{
+    public override string ToString() => Value.ToString();
+}