#if NET20 || NET30 || !NET_4_6

// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Dynamic.Utils;
using LinqInternal.Collections;

namespace System.Linq.Expressions.Reimplement
{
    /// <summary>
    /// Represents one case of a <see cref="SwitchExpression"/>.
    /// </summary>
    [DebuggerTypeProxy(typeof(SwitchCaseProxy))]
    public sealed class SwitchCase
    {
        private readonly ReadOnlyCollection<Expression> _testValues;
        private readonly Expression _body;

        internal SwitchCase(Expression body, ReadOnlyCollection<Expression> testValues)
        {
            _body = body;
            _testValues = testValues;
        }

        /// <summary>
        /// Gets the values of this case. This case is selected for execution when the <see cref="SwitchExpression.SwitchValue"/> matches any of these values.
        /// </summary>
        public ReadOnlyCollection<Expression> TestValues
        {
            get { return _testValues; }
        }

        /// <summary>
        /// Gets the body of this case.
        /// </summary>
        public Expression Body
        {
            get { return _body; }
        }

        /// <summary>
        /// Returns a <see cref="string"/> that represents the current <see cref="object"/>.
        /// </summary>
        /// <returns>A <see cref="string"/> that represents the current <see cref="object"/>. </returns>
        public override string ToString()
        {
            return ExpressionStringBuilder.SwitchCaseToString(this);
        }

        /// <summary>
        /// Creates a new expression that is like this one, but using the
        /// supplied children. If all of the children are the same, it will
        /// return this expression.
        /// </summary>
        /// <param name="testValues">The <see cref="TestValues" /> property of the result.</param>
        /// <param name="body">The <see cref="Body" /> property of the result.</param>
        /// <returns>This expression if no children changed, or an expression with the updated children.</returns>
        public SwitchCase Update(IEnumerable<Expression> testValues, Expression body)
        {
            if (testValues == TestValues && body == Body)
            {
                return this;
            }
            return Expression.SwitchCase(body, testValues);
        }
    }

    public partial class Expression
    {
        /// <summary>
        /// Creates a <see cref="T:SwitchCase">SwitchCase</see> for use in a <see cref="SwitchExpression"/>.
        /// </summary>
        /// <param name="body">The body of the case.</param>
        /// <param name="testValues">The test values of the case.</param>
        /// <returns>The created <see cref="T:SwitchCase">SwitchCase</see>.</returns>
        public static SwitchCase SwitchCase(Expression body, params Expression[] testValues)
        {
            return SwitchCase(body, (IEnumerable<Expression>)testValues);
        }

        /// <summary>
        /// Creates a <see cref="T:SwitchCase">SwitchCase</see> for use in a <see cref="SwitchExpression"/>.
        /// </summary>
        /// <param name="body">The body of the case.</param>
        /// <param name="testValues">The test values of the case.</param>
        /// <returns>The created <see cref="T:SwitchCase">SwitchCase</see>.</returns>
        public static SwitchCase SwitchCase(Expression body, IEnumerable<Expression> testValues)
        {
            RequiresCanRead(body, "body");

            var values = testValues.ToReadOnly();
            RequiresCanRead(values, "testValues");
            ContractUtils.RequiresNotEmpty(values, "testValues");

            return new SwitchCase(body, values);
        }
    }
}

#endif