// 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 System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.DocumentationComments;
using Microsoft.CodeAnalysis.LanguageService;
using Microsoft.CodeAnalysis.Shared.Extensions;

namespace Microsoft.CodeAnalysis.InlineHints;

internal static class InlineHintHelpers
{
    public static Func<Document, CancellationToken, Task<ImmutableArray<TaggedText>>>? GetDescriptionFunction(int position, ISymbol symbol, SymbolDescriptionOptions options)
    {
        return (document, cancellationToken) => GetDescriptionAsync(document, position, symbol, options, cancellationToken);
    }

    private static async Task<ImmutableArray<TaggedText>> GetDescriptionAsync(Document document, int position, ISymbol originalSymbol, SymbolDescriptionOptions options, CancellationToken cancellationToken)
    {
        var semanticModel = await document.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);

        var symbolKey = originalSymbol.GetSymbolKey(cancellationToken);
        var symbol = symbolKey.Resolve(semanticModel.Compilation, cancellationToken: cancellationToken).Symbol;
        if (symbol != null)
        {
            var symbolDisplayService = document.GetRequiredLanguageService<ISymbolDisplayService>();

            var parts = new List<TaggedText>();

            var groups = await symbolDisplayService.ToDescriptionGroupsAsync(
                semanticModel, position, [symbol], options, cancellationToken).ConfigureAwait(false);

            parts.AddRange(groups[SymbolDescriptionGroups.MainDescription]);

            var formatter = document.GetRequiredLanguageService<IDocumentationCommentFormattingService>();
            var documentation = symbol.GetDocumentationParts(semanticModel, position, formatter, cancellationToken);

            if (documentation.Any())
            {
                parts.AddLineBreak();
                parts.AddRange(documentation);
            }

            if (groups.TryGetValue(SymbolDescriptionGroups.StructuralTypes, out var anonymousTypes))
            {
                if (!anonymousTypes.IsDefaultOrEmpty)
                {
                    parts.AddLineBreak();
                    parts.AddLineBreak();
                    parts.AddRange(anonymousTypes);
                }
            }

            return [.. parts];
        }

        return default;
    }
}