// 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.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;

namespace Microsoft.CodeAnalysis.ValueTracking;

internal sealed class ValueTrackedItem
{
    public SymbolKey SymbolKey { get; }
    public ValueTrackedItem? Parent { get; }

    public DocumentId DocumentId { get; }
    public TextSpan Span { get; }
    public SourceText SourceText { get; }
    public Glyph Glyph { get; }

    internal ValueTrackedItem(
        SymbolKey symbolKey,
        SourceText sourceText,
        TextSpan textSpan,
        DocumentId documentId,
        Glyph glyph,
        ValueTrackedItem? parent)
    {
        SymbolKey = symbolKey;
        Parent = parent;
        Glyph = glyph;
        Span = textSpan;
        SourceText = sourceText;
        DocumentId = documentId;
    }

    public override string ToString()
    {
        var subText = SourceText.GetSubText(Span);
        return subText.ToString();
    }

    public static async ValueTask<ValueTrackedItem?> TryCreateAsync(Solution solution, Location location, ISymbol symbol, ValueTrackedItem? parent = null, CancellationToken cancellationToken = default)
    {
        Contract.ThrowIfNull(location.SourceTree);

        var document = solution.GetRequiredDocument(location.SourceTree);
        var syntaxTree = await document.GetRequiredSyntaxTreeAsync(cancellationToken).ConfigureAwait(false);
        var sourceText = await syntaxTree.GetTextAsync(cancellationToken).ConfigureAwait(false);

        return new ValueTrackedItem(
            SymbolKey.Create(symbol, cancellationToken),
            sourceText,
            location.SourceSpan,
            document.Id,
            symbol.GetGlyph(),
            parent);
    }
}