// 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.Concurrent;
using System.Collections.Immutable;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Internal.Log;
using Microsoft.CodeAnalysis.Shared;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;

namespace Microsoft.CodeAnalysis.CaseCorrection;

internal abstract partial class AbstractCaseCorrectionService : ICaseCorrectionService
{
    protected abstract void AddReplacements(SemanticModel? semanticModel, SyntaxNode root, ImmutableArray<TextSpan> spans, ConcurrentDictionary<SyntaxToken, SyntaxToken> replacements, CancellationToken cancellationToken);

    public async Task<Document> CaseCorrectAsync(Document document, ImmutableArray<TextSpan> spans, CancellationToken cancellationToken)
    {
        if (!spans.Any())
        {
            return document;
        }

        var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
        if (root is null)
        {
            throw new NotSupportedException(WorkspaceExtensionsResources.Document_does_not_support_syntax_trees);
        }

        var semanticModel = await document.ReuseExistingSpeculativeModelAsync(spans.Collapse(), cancellationToken).ConfigureAwait(false);

        var newRoot = CaseCorrect(semanticModel, root, spans, cancellationToken);
        return (root == newRoot) ? document : document.WithSyntaxRoot(newRoot);
    }

    public SyntaxNode CaseCorrect(SyntaxNode root, ImmutableArray<TextSpan> spans, CancellationToken cancellationToken)
        => CaseCorrect(semanticModel: null, root, spans, cancellationToken);

    private SyntaxNode CaseCorrect(SemanticModel? semanticModel, SyntaxNode root, ImmutableArray<TextSpan> spans, CancellationToken cancellationToken)
    {
        using (Logger.LogBlock(FunctionId.CaseCorrection_CaseCorrect, cancellationToken))
        {
            var normalizedSpanCollection = new NormalizedTextSpanCollection(spans);
            var replacements = new ConcurrentDictionary<SyntaxToken, SyntaxToken>();

            using (Logger.LogBlock(FunctionId.CaseCorrection_AddReplacements, cancellationToken))
            {
                AddReplacements(semanticModel, root, [.. normalizedSpanCollection], replacements, cancellationToken);
            }

            using (Logger.LogBlock(FunctionId.CaseCorrection_ReplaceTokens, cancellationToken))
            {
                return root.ReplaceTokens(replacements.Keys, (oldToken, _) => replacements[oldToken]);
            }
        }
    }
}