// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using Microsoft.Extensions.AI;
 
namespace Microsoft.AspNetCore.Components.AI;
 
internal sealed class RichTextContentHandler : ContentBlockHandler<RichContentBlock>
{
    public override BlockMappingResult<RichContentBlock> Handle(
        BlockMappingContext context, RichContentBlock state)
    {
        RichTextContent? snapshot = null;
        foreach (var content in context.UnhandledContents)
        {
            if (content is RichTextContent richText)
            {
                snapshot = richText;
            }
        }
 
        if (snapshot is null)
        {
            return state.Id.Length > 0
                ? BlockMappingResult<RichContentBlock>.Complete()
                : BlockMappingResult<RichContentBlock>.Pass();
        }
 
        if (state.Id.Length > 0 &&
            context.Update.MessageId is { Length: > 0 } messageId &&
            !string.Equals(state.Id, messageId, StringComparison.Ordinal))
        {
            return BlockMappingResult<RichContentBlock>.Complete();
        }
 
        foreach (var content in context.UnhandledContents)
        {
            if (content is RichTextContent or TextContent)
            {
                context.MarkHandled(content);
            }
        }
 
        state.ReplaceContent(snapshot.Text, snapshot.Nodes);
 
        if (state.Id.Length == 0)
        {
            state.Id = context.Update.MessageId ?? Guid.NewGuid().ToString("N");
            return BlockMappingResult<RichContentBlock>.Emit(state, state);
        }
 
        return BlockMappingResult<RichContentBlock>.Update(state);
    }
}