//---------------------------------------------------------------------
// <copyright file="Row.cs" company="Microsoft">
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
//
// @owner  [....]
// @backupOwner [....]
//---------------------------------------------------------------------

using System.Collections.Generic;
using System.Data.Common.CommandTrees;
using System.Data.Common.Utils;

namespace System.Data.Common.CommandTrees.ExpressionBuilder
{
    /// <summary>
    /// The Row class is intended to provide a constructor-like means of calling <see cref="DbExpressionBuilder.NewRow"/>.
    /// </summary>
    public sealed class Row
    {
        private readonly System.Collections.ObjectModel.ReadOnlyCollection<KeyValuePair<string, DbExpression>> arguments;

        /// <summary>
        /// Constructs a new Row with the specified first column value and optional successive column values
        /// </summary>
        /// <param name="columnValue">A key-value pair that provides the first column in the new row instance (required)</param>
        /// <param name="columnValues">Key-value pairs that provide any subsequent columns in the new row instance (optional)</param>
        public Row(KeyValuePair<string, DbExpression> columnValue, params KeyValuePair<string, DbExpression>[] columnValues)
        {
            this.arguments = new System.Collections.ObjectModel.ReadOnlyCollection<KeyValuePair<string, DbExpression>>(Helpers.Prepend(columnValues, columnValue));
        }

        /// <summary>
        /// Creates a new <see cref="DbNewInstanceExpression"/> that constructs a new row based on the columns
        /// contained in this Row instance. 
        /// </summary>
        /// <returns>A new DbNewInstanceExpression that constructs a row with the same column names and DbExpression values as this Row instance</returns>
        /// <seealso cref="DbExpressionBuilder.NewRow"/>
        public DbNewInstanceExpression ToExpression()
        {
            return DbExpressionBuilder.NewRow(this.arguments);
        }

        /// <summary>
        /// Converts the given Row instance into an instance of <see cref="DbExpression"/>
        /// </summary>
        /// <param name="row"></param>
        /// <returns>A DbExpression based on the Row instance</returns>
        /// <exception cref="ArgumentNullException"><paramref name="row"/> is null.</exception>
        /// <seealso cref="ToExpression"/>
        public static implicit operator DbExpression(Row row)
        {
            EntityUtil.CheckArgumentNull(row, "row");
            return row.ToExpression();
        }
    }
}