using AcDream.App.Rendering.Gpu.Vk;

namespace AcDream.App.Composition;

/// <summary>
/// The graphics ownership that platform acquisition publishes.
///
/// <para>Vulkan is the only backend as of Campaign V slice V11: the raw-GL
/// implementation (<c>OpenGlGameWindowGraphics</c>) and the members that only
/// existed to branch on it (<c>Backend</c>, <c>Gl</c>, <c>RequireGl</c>) were
/// deleted along with it. This class stays as the seam
/// <see cref="GameWindowPlatformAcquisition"/> and the composition phases are
/// already written against, so a future second backend would still add one
/// class of this shape rather than reopening every call site.</para>
/// </summary>
internal abstract class GameWindowGraphics : IDisposable
{
    /// <summary>The live Vulkan context.</summary>
    public virtual VulkanGraphicsContext? Vulkan => null;

    /// <summary>
    /// The backend's world-pass seam. Every remaining renderer records into the
    /// pass this publishes rather than opening its own.
    /// </summary>
    public virtual AcDream.App.Rendering.IWorldPassScope? WorldPassScope => null;

    public abstract void Dispose();
}

/// <summary>
/// Vulkan ownership: the instance, surface, device, swapchain and RHI device
/// that <see cref="VulkanGraphicsContext"/> acquired and gated.
/// </summary>
internal sealed class VulkanGameWindowGraphics : GameWindowGraphics
{
    public VulkanGameWindowGraphics(VulkanGraphicsContext context)
    {
        Context = context ?? throw new ArgumentNullException(nameof(context));
        // The sample count is fixed at device creation, and every world pipeline
        // must be created against it, so the scope is built here rather than at
        // the first frame.
        WorldPassScopeCore = new VulkanWorldPassScope(context.SampleCount);
    }

    public VulkanGraphicsContext Context { get; }

    public override VulkanGraphicsContext? Vulkan => Context;

    /// <summary>The concrete scope, for the phase that publishes the encoder on it.</summary>
    public VulkanWorldPassScope WorldPassScopeCore { get; }

    public override AcDream.App.Rendering.IWorldPassScope? WorldPassScope =>
        WorldPassScopeCore;

    public override void Dispose() => Context.Dispose();
}