Feature: MS Excel (xlsx) Import/Export

Microsoft Excel files can be used to import/export devices. Several
import bugs were also fixed in the process.

Disco.Models/Services/Devices/Importing/IDeviceImportColumn.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace Disco.Models.Services.Devices.Importing
+{
+    public interface IDeviceImportColumn
+    {
+        int Index { get; }
+        string Name { get; }
+        DeviceImportFieldTypes Type { get; }
+        Type Handler { get; }
+
+        IDeviceImportField GetHandlerInstance();
+    }
+}

Disco.Models/Services/Devices/Importing/IDeviceImportContext.cs

@@ -1,8 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 
 namespace Disco.Models.Services.Devices.Importing
 {
@@ -10,11 +7,19 @@ namespace Disco.Models.Services.Devices.Importing
     {
         string SessionId { get; }
         string Filename { get; }
-        List<Tuple<string, DeviceImportFieldTypes>> Header { get; }
-        List<Tuple<string, DeviceImportFieldTypes, Func<string[], string>, Type>> ParsedHeaders { get; }
-        List<string[]> RawData { get; }
+        string DatasetName { get; }
+        int ColumnCount { get; }
+        IEnumerable<IDeviceImportColumn> Columns { get; }
+        IDeviceImportColumn GetColumn(int Index);
+        void SetColumnType(int Index, DeviceImportFieldTypes Type);
+        int? GetColumnByType(DeviceImportFieldTypes FieldType);
 
-        List<IDeviceImportRecord> Records { get; }
-        int AffectedRecords { get; }
+        int RecordCount { get; }
+
+        IDeviceImportDataReader GetDataReader();
+        IEnumerable<KeyValuePair<DeviceImportFieldTypes, Type>> GetFieldHandlers();
+
+        List<IDeviceImportRecord> Records { get; set; }
+        int AffectedRecords { get; set; }
     }
 }

Disco.Models/Services/Devices/Importing/IDeviceImportDataReader.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Disco.Models.Services.Devices.Importing
+{
+    public interface IDeviceImportDataReader : IDisposable
+    {
+        void Reset();
+        bool Read();
+
+        int Index { get; }
+
+        int GetRowNumber(int Index);
+
+        string GetString(int ColumnIndex);
+        IEnumerable<string> GetStrings(int ColumnIndex);
+
+        bool TryGetNullableInt(int ColumnIndex, out int? value);
+
+        bool TryGetNullableBool(int ColumnIndex, out bool? value);
+
+        bool TryGetNullableDateTime(int ColumnIndex, out DateTime? value);
+
+        bool TestAllNotEmpty(int ColumnIndex);
+        bool TestAllNullableInt(int ColumnIndex);
+        bool TestAllInt(int ColumnIndex);
+        bool TestAllNullableBool(int ColumnIndex);
+        bool TestAllNullableDateTime(int ColumnIndex);
+    }
+}

Disco.Models/Services/Devices/Importing/IDeviceImportField.cs

@@ -1,9 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Data;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using System.Data;
 
 namespace Disco.Models.Services.Devices.Importing
 {

Disco.Models/Services/Devices/Importing/IDeviceImportRecord.cs

@@ -9,6 +9,7 @@ namespace Disco.Models.Services.Devices.Importing
 {
     public interface IDeviceImportRecord
     {
+        int Index { get; }
         string DeviceSerialNumber { get; }
 
         IEnumerable<IDeviceImportField> Fields { get; }