// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.Text
{
    /// <summary>
    /// Represents state for a TextChanged event.
    /// </summary>
    public class TextChangeEventArgs : EventArgs
    {
        /// <summary>
        /// Initializes an instance of <see cref="TextChangeEventArgs"/>.
        /// </summary>
        /// <param name="oldText">The text before the change.</param>
        /// <param name="newText">The text after the change.</param>
        /// <param name="changes">A set of ranges for the change.</param>
        public TextChangeEventArgs(SourceText oldText, SourceText newText, IEnumerable<TextChangeRange> changes)
        {
            if (changes == null)
            {
                throw new ArgumentNullException(nameof(changes));
            }

            this.OldText = oldText;
            this.NewText = newText;
            this.Changes = changes.ToImmutableArray();
        }

        /// <summary>
        /// Initializes an instance of <see cref="TextChangeEventArgs"/>.
        /// </summary>
        /// <param name="oldText">The text before the change.</param>
        /// <param name="newText">The text after the change.</param>
        /// <param name="changes">A set of ranges for the change.</param>
        public TextChangeEventArgs(SourceText oldText, SourceText newText, params TextChangeRange[] changes)
            : this(oldText, newText, (IEnumerable<TextChangeRange>)changes)
        {
        }

        /// <summary>
        /// Gets the text before the change.
        /// </summary>
        public SourceText OldText { get; }

        /// <summary>
        /// Gets the text after the change.
        /// </summary>
        public SourceText NewText { get; }

        /// <summary>
        /// Gets the set of ranges for the change.
        /// </summary>
        public IReadOnlyList<TextChangeRange> Changes { get; }
    }
}