using ErsatzTV.Core.Domain;
using ErsatzTV.FFmpeg.State;
using ErsatzTV.Infrastructure.Data;
using ErsatzTV.Infrastructure.Streaming.Graphics;

namespace ErsatzTV.Application.Channels;

/// <summary>
/// #732: the On Now / Next overlay is a default rather than an opt-in, so every newly created channel
/// gets the built-in element attached.
/// </summary>
/// <remarks>
/// This lives in one place because there is more than one channel-creation path and they diverged
/// once already: <c>CreateChannelHandler</c> had it and <c>CreateChannelFromLineupHandler</c> -- the
/// SPA's primary "Add Channel" flow, and the one Auto-Tune bulk-creates through -- did not. Any new
/// site that persists a <c>Channel</c> must call this. The third site, <c>DbInitializer</c>'s default
/// channel, needs no call: it runs before <c>AttachOnNowNextByDefault</c> in the same startup, so the
/// backfill covers it.
/// </remarks>
public static class ChannelGraphicsDefaults
{
    public static async Task Attach(TvContext dbContext, Channel channel, CancellationToken cancellationToken)
    {
        // HLS Direct is skipped because ErsatzTV is not transcoding there -- there is no frame
        // pipeline to draw into, and the editor disables the toggle for the same reason. Identity is
        // the element's filename, never its user-editable Name (the #67 lesson).
        if (channel.StreamingMode is StreamingMode.HttpLiveStreamingDirect)
        {
            return;
        }

        Option<int> maybeElementId =
            await GraphicsElementSeeder.GetBuiltInElementId(dbContext, cancellationToken);

        foreach (int elementId in maybeElementId)
        {
            // Add rather than assign: a future create path that carries graphics ids would otherwise
            // be silently discarded here.
            channel.ChannelGraphicsElements ??= [];
            channel.ChannelGraphicsElements.Add(new ChannelGraphicsElement { GraphicsElementId = elementId });
        }
    }
}