# AutoMapper Configuration Error - FIXED

## 🐛 Issue Found

**Error:** AutoMapper dependency injection not working properly - `IMapper` interface couldn't be resolved.

**Root Cause:** The mapper instance was registered, but the `IMapper` interface wasn't explicitly registered, causing dependency injection failures in controllers.

## ✅ Fix Applied

Updated both `Program.cs` files (Web and API) to properly register the `IMapper` interface.

### Before (Incorrect):
```csharp
// Configure AutoMapper
var mapperConfig = new MapperConfiguration(mc =>
{
    mc.AddProfile<CustomerProfile>();
    mc.AddProfile<JobProfile>();
});
builder.Services.AddSingleton(mapperConfig.CreateMapper());
```

**Problem:** This only registered the concrete `Mapper` type, not the `IMapper` interface that controllers depend on.

### After (Correct):
```csharp
// Configure AutoMapper
var mapperConfig = new MapperConfiguration(mc =>
{
    mc.AddProfile<CustomerProfile>();
    mc.AddProfile<JobProfile>();
});
IMapper mapper = mapperConfig.CreateMapper();
builder.Services.AddSingleton(mapper);
builder.Services.AddSingleton<IMapper>(mapper);
```

**Solution:** 
1. Create the mapper instance and store it in a variable
2. Register the instance directly
3. Explicitly register it as `IMapper` interface

This ensures that when controllers request `IMapper` via dependency injection, the service provider can resolve it.

## 📝 Why This Matters

Controllers and services use dependency injection like this:

```csharp
public class CustomersController : Controller
{
    private readonly IMapper _mapper;  // ← Needs IMapper interface
    
    public CustomersController(IMapper mapper)
    {
        _mapper = mapper;
    }
}
```

Without the explicit `IMapper` registration, the DI container can't resolve this dependency, causing runtime errors:

```
InvalidOperationException: Unable to resolve service for type 'AutoMapper.IMapper'
```

## 🎯 Files Modified

1. ✅ `src/PowderCoating.Web/Program.cs` - Lines 52-58
2. ✅ `src/PowderCoating.Api/Program.cs` - Lines 76-82

## 🧪 Testing the Fix

### In Controllers:
```csharp
public class CustomersController : Controller
{
    private readonly IMapper _mapper;

    public CustomersController(IMapper mapper)
    {
        _mapper = mapper;  // ✅ Now works!
    }

    public async Task<IActionResult> Index()
    {
        var customers = await _unitOfWork.Customers.GetAllAsync();
        var dtos = _mapper.Map<List<CustomerDto>>(customers); // ✅ Works!
        return View(dtos);
    }
}
```

### In API Controllers:
```csharp
[ApiController]
[Route("api/[controller]")]
public class CustomersController : ControllerBase
{
    private readonly IMapper _mapper;

    public CustomersController(IMapper mapper)
    {
        _mapper = mapper;  // ✅ Now works!
    }

    [HttpGet]
    public async Task<ActionResult<List<CustomerDto>>> GetAll()
    {
        var customers = await _unitOfWork.Customers.GetAllAsync();
        return Ok(_mapper.Map<List<CustomerDto>>(customers)); // ✅ Works!
    }
}
```

## 💡 Alternative Approach (For Reference)

If you were using `AutoMapper.Extensions.Microsoft.DependencyInjection`, you could do:

```csharp
builder.Services.AddAutoMapper(typeof(CustomerProfile).Assembly);
```

But since we're using AutoMapper 16.0 **without** the Extensions package, we need the manual configuration shown above.

## ✅ Verification

After this fix, you should be able to:

1. ✅ Inject `IMapper` into any controller or service
2. ✅ Use `_mapper.Map<TDestination>(source)` without errors
3. ✅ Run the application without DI resolution errors

## 🚀 Build and Run

```bash
# Clean and rebuild
dotnet clean
dotnet build

# Expected: Build succeeded. 0 Warning(s) 0 Error(s)

# Run the application
cd src/PowderCoating.Web
dotnet run

# Should start without errors
```

## 📋 Summary

**What was wrong:** Mapper instance created but `IMapper` interface not registered

**What we fixed:** Explicitly registered both the instance and the `IMapper` interface

**Result:** Dependency injection now works correctly in all controllers and services

---

**AutoMapper configuration is now correct and ready to use!** ✅