# ExcelIO Consolidation Design

## Problem

After the architecture cleanup, Excel file I/O code is scattered across multiple projects:
- `JdeScoping.ExcelExport` - search result report generation
- `JdeScoping.Api/Controllers/FileIOController.*.cs` - upload parsing and template downloads
- `JdeScoping.Api/Helpers/ExcelTemplateGenerator.cs` - template generation helper

The project name "ExcelExport" no longer reflects its broader responsibility for all Excel I/O operations.

## Goal

1. Rename `JdeScoping.ExcelExport` to `JdeScoping.ExcelIO`
2. Consolidate ALL Excel file I/O into the ExcelIO project
3. Integrate with search processor for report generation
4. Move related tests to `JdeScoping.ExcelIO.Tests`

## Design Decisions

| Decision | Choice | Rationale |
|----------|--------|-----------|
| Parser scope | Pure I/O only | ExcelIO parses/writes files; API handles database lookups |
| Integration point | In ExcelIO | IExcelExportService takes search results, returns byte[] |
| Service structure | Separate services | IExcelExportService, IExcelTemplateService, IExcelParserService |
| Interface location | Core project | Follows existing pattern, enables dependency inversion |

## Target Structure

### JdeScoping.ExcelIO Project

```
ExcelIO/
├── Export/
│   ├── ExcelExportService.cs
│   ├── Generators/
│   │   ├── AttributeTableWriter.cs
│   │   ├── CriteriaSheetGenerator.cs
│   │   └── DataEntryTemplateGenerator.cs
│   └── Formatting/
│       ├── ColumnFormatter.cs
│       ├── ExcelFormats.cs
│       ├── HeaderFormatter.cs
│       └── WorksheetProtector.cs
├── Templates/
│   └── ExcelTemplateService.cs
├── Parsing/
│   ├── ExcelParserService.cs
│   └── Parsers/
│       ├── WorkOrderParser.cs
│       ├── ItemParser.cs
│       ├── ComponentLotParser.cs
│       └── PartOperationParser.cs
├── Shared/
│   ├── Attributes/
│   ├── Helpers/
│   └── Models/
└── ServiceCollectionExtensions.cs
```

### Interfaces in Core/Interfaces

```csharp
// Existing, moved from ExcelIO
public interface IExcelExportService
{
    Task<byte[]> GenerateAsync(SearchModel search, CancellationToken ct);
}

// New
public interface IExcelTemplateService
{
    byte[] GenerateSingleColumn<T>(IEnumerable<T> data, string headerText);
    byte[] GenerateMultiColumn(object?[][] data, string[] headers);
}

// New
public interface IExcelParserService
{
    List<long> ParseWorkOrders(Stream fileStream);
    List<string> ParseItems(Stream fileStream);
    List<(string LotNumber, string ItemNumber)> ParseComponentLots(Stream fileStream);
    List<PartOperationViewModel> ParsePartOperations(Stream fileStream);
}
```

## Code Movement

### From Api to ExcelIO

| From | To |
|------|-----|
| `Api/Helpers/ExcelTemplateGenerator.cs` | `ExcelIO/Templates/ExcelTemplateService.cs` |
| Excel parsing logic from FileIOController.*.cs | `ExcelIO/Parsing/ExcelParserService.cs` |

### FileIOController Changes

The 5 partial class files become thin wrappers:
- Inject `IExcelParserService` and `IExcelTemplateService`
- Call parser for uploads, then repository for DB lookups
- Call template service for downloads

### Api Project Reference Changes

- Remove: `ClosedXML` package reference
- Add: Project reference to `JdeScoping.ExcelIO`

## Test Movement

| From | To | Reason |
|------|-----|--------|
| `Api.Tests/FileControllerTests.cs` (parsing tests) | `ExcelIO.Tests/Parsing/` | Tests Excel parsing logic |
| `Api.Tests/FileControllerTests.cs` (controller tests) | Keep in Api.Tests | Tests HTTP behavior |

### ExcelIO.Tests Structure

```
ExcelIO.Tests/
├── Export/           (existing tests, reorganized)
├── Templates/
│   └── ExcelTemplateServiceTests.cs
└── Parsing/
    └── ExcelParserServiceTests.cs
```

## Search Processor Integration

The search processor will:
1. Execute search query → get results
2. Call `IExcelExportService.GenerateAsync(searchModel)` → get `byte[]`
3. Call repository to store `byte[]` in `Search.Results` column

Host project will:
- Reference `JdeScoping.ExcelIO`
- Register services via `services.AddExcelIO()`
- Inject and call the export service

## Verification

1. **Build:** `dotnet build` succeeds, no ClosedXML in Api
2. **Tests:** All tests pass, count preserved (~49 in ExcelIO.Tests)
3. **Functional:** Templates download, uploads parse, exports generate
4. **Structure:** Solution file updated with renamed projects