feature/edit/subset (#283)

* Changing query/subset API to only use Result on success, Error on error

* Creating an interservice API for getting query result subsets

* Updates to subset API

* RowStartIndex is now long
* Output of query/subset is a 2D array of DbCellValue
* Adding LongSkip method to LongList to allow skipping ahead by longs
* Moving LongList back to ServiceLayer utilities. Move refactoring

* Stubbing out request for edit/subset

* Initial implementation of getting edit rows

* Unit tests for RowEdit and RowDelete .GetEditRow

* Fixing major bugs in LongList implementation, adding much more thorough tests

* Adding some more unit tests and fixes to make unit tests pass

* Fixing comment

src/Microsoft.SqlTools.ServiceLayer/EditData/Contracts/EditRow.cs

@@ -0,0 +1,45 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts;
+
+namespace Microsoft.SqlTools.ServiceLayer.EditData.Contracts
+{
+    /// <summary>
+    /// A way to return a row in a result set that is being edited. It contains state about whether
+    /// or not the row is dirty
+    /// </summary>
+    public class EditRow
+    {
+        public enum EditRowState
+        {
+            Clean = 0,
+            DirtyInsert = 1,
+            DirtyDelete = 2,
+            DirtyUpdate = 3
+        }
+
+        /// <summary>
+        /// The cells in the row. If the row has pending changes, they will be represented in
+        /// this list
+        /// </summary>
+        public DbCellValue[] Cells { get; set; }
+
+        /// <summary>
+        /// Internal ID of the row. This should be used whenever referencing a row in row edit operations.
+        /// </summary>
+        public long Id { get; set; }
+
+        /// <summary>
+        /// Whether or not the row has changes pending
+        /// </summary>
+        public bool IsDirty => State != EditRowState.Clean;
+
+        /// <summary>
+        /// What type of dirty state (or lack thereof) the row is
+        /// </summary>
+        public EditRowState State { get; set; }
+    }
+}

src/Microsoft.SqlTools.ServiceLayer/EditData/Contracts/EditSubsetRequest.cs

@@ -0,0 +1,52 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using Microsoft.SqlTools.Hosting.Protocol.Contracts;
+
+namespace Microsoft.SqlTools.ServiceLayer.EditData.Contracts
+{
+    /// <summary>
+    /// Parameters for a subset retrieval request
+    /// </summary>
+    public class EditSubsetParams : SessionOperationParams
+    {
+        /// <summary>
+        /// Beginning index of the rows to return from the selected resultset. This index will be
+        /// included in the results.
+        /// </summary>
+        public long RowStartIndex { get; set; }
+
+        /// <summary>
+        /// Number of rows to include in the result of this request. If the number of the rows
+        /// exceeds the number of rows available after the start index, all available rows after
+        /// the start index will be returned.
+        /// </summary>
+        public int RowCount { get; set; }
+    }
+
+    /// <summary>
+    /// Parameters for the result of a subset retrieval request
+    /// </summary>
+    public class EditSubsetResult
+    {
+        /// <summary>
+        /// The number of rows returned from result set, useful for determining if less rows were
+        /// returned than requested.
+        /// </summary>
+        public int RowCount { get; set; }
+
+        /// <summary>
+        /// The requested subset of rows, with information about whether or not the rows are dirty
+        /// </summary>
+        public EditRow[] Subset { get; set; }
+    }
+
+    public class EditSubsetRequest
+    {
+        public static readonly
+            RequestType<EditSubsetParams, EditSubsetResult> Type =
+            RequestType<EditSubsetParams, EditSubsetResult>.Create("edit/subset");
+    }
+}

src/Microsoft.SqlTools.ServiceLayer/EditData/EditDataService.cs

@@ -91,6 +91,7 @@ namespace Microsoft.SqlTools.ServiceLayer.EditData
             serviceHost.SetRequestHandler(EditInitializeRequest.Type, HandleInitializeRequest);
             serviceHost.SetRequestHandler(EditRevertCellRequest.Type, HandleRevertCellRequest);
             serviceHost.SetRequestHandler(EditRevertRowRequest.Type, HandleRevertRowRequest);
+            serviceHost.SetRequestHandler(EditSubsetRequest.Type, HandleSubsetRequest);
             serviceHost.SetRequestHandler(EditUpdateCellRequest.Type, HandleUpdateCellRequest);
         }
 
@@ -241,6 +242,20 @@ namespace Microsoft.SqlTools.ServiceLayer.EditData
             });
         }
 
+        internal Task HandleSubsetRequest(EditSubsetParams subsetParams,
+            RequestContext<EditSubsetResult> requestContext)
+        {
+            return HandleSessionRequest(subsetParams, requestContext, session =>
+            {
+                EditRow[] rows = session.GetRows(subsetParams.RowStartIndex, subsetParams.RowCount).Result;
+                return new EditSubsetResult
+                {
+                    RowCount = rows.Length,
+                    Subset = rows
+                };
+            });
+        }
+
         internal Task HandleUpdateCellRequest(EditUpdateCellParams updateParams,
             RequestContext<EditUpdateCellResult> requestContext)
         {

src/Microsoft.SqlTools.ServiceLayer/EditData/EditSession.cs

@@ -13,6 +13,7 @@ using System.Threading.Tasks;
 using Microsoft.SqlTools.ServiceLayer.EditData.Contracts;
 using Microsoft.SqlTools.ServiceLayer.EditData.UpdateManagement;
 using Microsoft.SqlTools.ServiceLayer.QueryExecution;
+using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts;
 using Microsoft.SqlTools.Utility;
 
 namespace Microsoft.SqlTools.ServiceLayer.EditData
@@ -186,6 +187,60 @@ namespace Microsoft.SqlTools.ServiceLayer.EditData
             }
         }
 
+        /// <summary>
+        /// Retrieves a subset of rows with the pending updates applied. If more rows than exist
+        /// are requested, only the rows that exist will be returned.
+        /// </summary>
+        /// <param name="startIndex">Index to start returning rows from</param>
+        /// <param name="rowCount">The number of rows to return.</param>
+        /// <returns>An array of rows with pending edits applied</returns>
+        public async Task<EditRow[]> GetRows(long startIndex, int rowCount)
+        {
+            // Get the cached rows from the result set
+            ResultSetSubset cachedRows = startIndex < associatedResultSet.RowCount
+                ? await associatedResultSet.GetSubset(startIndex, rowCount)
+                : new ResultSetSubset
+                {
+                    RowCount = 0,
+                    Rows = new DbCellValue[][] { }
+                };
+
+            // Convert the rows into EditRows and apply the changes we have
+            List<EditRow> editRows = new List<EditRow>();
+            for (int i = 0; i < cachedRows.RowCount; i++)
+            {
+                long rowId = i + startIndex;
+                RowEditBase edr;
+                if (EditCache.TryGetValue(rowId, out edr))
+                {
+                    // Ask the edit object to generate an edit row
+                    editRows.Add(edr.GetEditRow(cachedRows.Rows[i]));
+                }
+                else
+                {
+                    // Package up the existing row into a clean edit row
+                    EditRow er = new EditRow
+                    {
+                        Id = rowId,
+                        Cells = cachedRows.Rows[i],
+                        State = EditRow.EditRowState.Clean
+                    };
+                    editRows.Add(er);
+                }
+            }
+
+            // If the requested range of rows was at the end of the original cell set and we have
+            // added new rows, we need to reflect those changes
+            if (rowCount > cachedRows.RowCount)
+            {
+                long endIndex = startIndex + cachedRows.RowCount;
+                var newRows = EditCache.Where(edit => edit.Key >= endIndex).Take(rowCount - cachedRows.RowCount);
+                editRows.AddRange(newRows.Select(newRow => newRow.Value.GetEditRow(null)));
+            }
+
+            return editRows.ToArray();
+        }
+
         /// <summary>
         /// Reverts a cell in a pending edit
         /// </summary>

src/Microsoft.SqlTools.ServiceLayer/EditData/UpdateManagement/CellUpdate.cs

@@ -85,6 +85,22 @@ namespace Microsoft.SqlTools.ServiceLayer.EditData.UpdateManagement
 
         #region Properties
 
+        /// <summary>
+        /// Converts the cell update to a DbCellValue
+        /// </summary>
+        public DbCellValue AsDbCellValue
+        {
+            get
+            {
+                return new DbCellValue
+                {
+                    DisplayValue = ValueAsString,
+                    IsNull = Value == DBNull.Value,
+                    RawObject = Value
+                };
+            }
+        }
+
         /// <summary>
         /// The column that the cell will be placed in
         /// </summary>

src/Microsoft.SqlTools.ServiceLayer/EditData/UpdateManagement/RowCreate.cs

@@ -122,6 +122,26 @@ namespace Microsoft.SqlTools.ServiceLayer.EditData.UpdateManagement
             return command;
         }
 
+        /// <summary>
+        /// Generates a edit row that represents a row pending insertion
+        /// </summary>
+        /// <param name="cachedRow">Original, cached cell contents. (Should be null in this case)</param>
+        /// <returns>EditRow of pending update</returns>
+        public override EditRow GetEditRow(DbCellValue[] cachedRow)
+        {
+            // Iterate over the new cells. If they are null, generate a blank value
+            DbCellValue[] editCells = newCells.Select(cell => cell == null
+                    ? new DbCellValue {DisplayValue = string.Empty, IsNull = false, RawObject = null}
+                    : cell.AsDbCellValue)
+                .ToArray();
+            return new EditRow
+            {
+                Id = RowId,
+                Cells = editCells,
+                State = EditRow.EditRowState.DirtyInsert
+            };
+        }
+
         /// <summary>
         /// Generates the INSERT INTO statement that will apply the row creation
         /// </summary>

src/Microsoft.SqlTools.ServiceLayer/EditData/UpdateManagement/RowDelete.cs

@@ -9,6 +9,7 @@ using System.Globalization;
 using System.Threading.Tasks;
 using Microsoft.SqlTools.ServiceLayer.EditData.Contracts;
 using Microsoft.SqlTools.ServiceLayer.QueryExecution;
+using Microsoft.SqlTools.ServiceLayer.QueryExecution.Contracts;
 using Microsoft.SqlTools.Utility;
 
 namespace Microsoft.SqlTools.ServiceLayer.EditData.UpdateManagement
@@ -72,6 +73,24 @@ namespace Microsoft.SqlTools.ServiceLayer.EditData.UpdateManagement
             return command;
         }
 
+        /// <summary>
+        /// Generates a edit row that represents a row pending deletion. All the original cells are
+        /// intact but the state is dirty.
+        /// </summary>
+        /// <param name="cachedRow">Original, cached cell contents</param>
+        /// <returns>EditRow that is pending deletion</returns>
+        public override EditRow GetEditRow(DbCellValue[] cachedRow)
+        {
+            Validate.IsNotNull(nameof(cachedRow), cachedRow);
+
+            return new EditRow
+            {
+                Id = RowId,
+                Cells = cachedRow,
+                State = EditRow.EditRowState.DirtyDelete
+            };
+        }
+
         /// <summary>
         /// Generates a DELETE statement to delete this row
         /// </summary>

src/Microsoft.SqlTools.ServiceLayer/EditData/UpdateManagement/RowEdit.cs

@@ -85,6 +85,14 @@ namespace Microsoft.SqlTools.ServiceLayer.EditData.UpdateManagement
         /// <returns>Command to commit the change to the db</returns>
         public abstract DbCommand GetCommand(DbConnection connection);
 
+        /// <summary>
+        /// Generates a row that has the pending update applied. The dirty status of the row is
+        /// reflected in the returned EditRow.
+        /// </summary>
+        /// <param name="cachedRow">The original, cached row values</param>
+        /// <returns>An EditRow with the pending changes applied</returns>
+        public abstract EditRow GetEditRow(DbCellValue[] cachedRow);
+
         /// <summary>
         /// Converts the row edit into a SQL statement
         /// </summary>

src/Microsoft.SqlTools.ServiceLayer/EditData/UpdateManagement/RowUpdate.cs

@@ -113,6 +113,30 @@ namespace Microsoft.SqlTools.ServiceLayer.EditData.UpdateManagement
             return command;
         }
 
+        /// <summary>
+        /// Generates a edit row that represents a row with pending update. The cells pending
+        /// updates are merged into the unchanged cells.
+        /// </summary>
+        /// <param name="cachedRow">Original, cached cell contents</param>
+        /// <returns>EditRow with pending updates</returns>
+        public override EditRow GetEditRow(DbCellValue[] cachedRow)
+        {
+            Validate.IsNotNull(nameof(cachedRow), cachedRow);
+
+            // For each cell that is pending update, replace the db cell value with a new one
+            foreach (var cellUpdate in cellUpdates)
+            {
+                cachedRow[cellUpdate.Key] = cellUpdate.Value.AsDbCellValue;
+            }
+
+            return new EditRow
+            {
+                Id = RowId,
+                Cells = cachedRow,
+                State = EditRow.EditRowState.DirtyUpdate
+            };
+        }
+
         /// <summary>
         /// Constructs an update statement to change the associated row.
         /// </summary>