// 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.

#nullable disable

using System.Collections.Generic;
using System.Diagnostics;

namespace Microsoft.CodeAnalysis.Differencing;

public partial class Match<TNode>
{
    internal sealed class LongestCommonSubsequence : LongestCommonSubsequence<IReadOnlyList<TNode>>
    {
        private readonly Match<TNode> _match;

        internal LongestCommonSubsequence(Match<TNode> match)
        {
            Debug.Assert(match != null);
            _match = match;
        }

        protected override bool ItemsEqual(IReadOnlyList<TNode> oldSequence, int oldIndex, IReadOnlyList<TNode> newSequence, int newIndex)
            => _match.Contains(oldSequence[oldIndex], newSequence[newIndex]);

        internal Dictionary<TNode, TNode> GetMatchingNodes(IReadOnlyList<TNode> oldNodes, IReadOnlyList<TNode> newNodes)
        {
            var result = new Dictionary<TNode, TNode>();

            foreach (var pair in GetMatchingPairs(oldNodes, oldNodes.Count, newNodes, newNodes.Count))
            {
                result.Add(oldNodes[pair.Key], newNodes[pair.Value]);
            }

            return result;
        }

        internal IEnumerable<Edit<TNode>> GetEdits(IReadOnlyList<TNode> oldNodes, IReadOnlyList<TNode> newNodes)
        {
            foreach (var edit in GetEdits(oldNodes, oldNodes.Count, newNodes, newNodes.Count))
            {
                yield return new Edit<TNode>(edit.Kind, _match.Comparer,
                    edit.OldIndex >= 0 ? oldNodes[edit.OldIndex] : default,
                    edit.NewIndex >= 0 ? newNodes[edit.NewIndex] : default);
            }
        }
    }
}