mach/gpu/src/NativeInstance.zig

//! A native webgpu.h implementation of the gpu.Interface
const c = @import("c.zig").c;
const Interface = @import("Interface.zig");
const Surface = @import("Surface.zig");

const NativeInstance = @This();

/// The WGPUInstance that is wrapped by this native instance.
instance: c.WGPUInstance,

/// Wraps a native WGPUInstance to provide an implementation of the gpu.Interface.
pub fn wrap(instance: *anyopaque) NativeInstance {
    return .{ .instance = @ptrCast(c.WGPUInstance, instance) };
}

const interface_vtable = Interface.VTable{
    .reference = (struct {
        pub fn reference(ptr: *anyopaque) void {
            const native = @ptrCast(*NativeInstance, @alignCast(@alignOf(*NativeInstance), ptr));
            c.wgpuInstanceReference(native.instance);
        }
    }).reference,
    .release = (struct {
        pub fn release(ptr: *anyopaque) void {
            const native = @ptrCast(*NativeInstance, @alignCast(@alignOf(*NativeInstance), ptr));
            c.wgpuInstanceRelease(native.instance);
        }
    }).release,
};

/// Returns the gpu.Interface for interacting with this native instance.
pub fn interface(native: *NativeInstance) Interface {
    return .{
        .ptr = native,
        .vtable = &interface_vtable,
    };
    // TODO: implement Device interface

    // TODO: implement Adapter interface:
    // typedef struct WGPUAdapterImpl* WGPUAdapter;
    // // Methods of Adapter
    // WGPU_EXPORT size_t wgpuAdapterEnumerateFeatures(WGPUAdapter adapter, WGPUFeatureName * features);
    // WGPU_EXPORT bool wgpuAdapterHasFeature(WGPUAdapter adapter, WGPUFeatureName feature);
    // WGPU_EXPORT bool wgpuAdapterGetLimits(WGPUAdapter adapter, WGPUSupportedLimits * limits);
    // WGPU_EXPORT void wgpuAdapterGetProperties(WGPUAdapter adapter, WGPUAdapterProperties * properties);
}

pub fn createSurface(native: *const NativeInstance, descriptor: *const Surface.Descriptor) Surface {
    const surface = switch (descriptor.*) {
        .metal_layer => |src| blk: {
            var desc: c.WGPUSurfaceDescriptorFromMetalLayer = undefined;
            desc.chain.next = null;
            desc.chain.sType = c.WGPUSType_SurfaceDescriptorFromMetalLayer;
            desc.layer = src.layer;
            break :blk c.wgpuInstanceCreateSurface(native.instance, &c.WGPUSurfaceDescriptor{
                .nextInChain = @ptrCast(*c.WGPUChainedStruct, &desc),
                .label = if (src.label) |l| @ptrCast([*c]const u8, l) else null,
            });
        },
        .windows_hwnd => |src| blk: {
            var desc: c.WGPUSurfaceDescriptorFromWindowsHWND = undefined;
            desc.chain.next = null;
            desc.chain.sType = c.WGPUSType_SurfaceDescriptorFromWindowsHWND;
            desc.hinstance = src.hinstance;
            desc.hwnd = src.hwnd;
            break :blk c.wgpuInstanceCreateSurface(native.instance, &c.WGPUSurfaceDescriptor{
                .nextInChain = @ptrCast(*c.WGPUChainedStruct, &desc),
                .label = if (src.label) |l| @ptrCast([*c]const u8, l) else null,
            });
        },
        .windows_core_window => |src| blk: {
            var desc: c.WGPUSurfaceDescriptorFromWindowsCoreWindow = undefined;
            desc.chain.next = null;
            desc.chain.sType = c.WGPUSType_SurfaceDescriptorFromWindowsCoreWindow;
            desc.coreWindow = src.core_window;
            break :blk c.wgpuInstanceCreateSurface(native.instance, &c.WGPUSurfaceDescriptor{
                .nextInChain = @ptrCast(*c.WGPUChainedStruct, &desc),
                .label = if (src.label) |l| @ptrCast([*c]const u8, l) else null,
            });
        },
        .windows_swap_chain_panel => |src| blk: {
            var desc: c.WGPUSurfaceDescriptorFromWindowsSwapChainPanel = undefined;
            desc.chain.next = null;
            desc.chain.sType = c.WGPUSType_SurfaceDescriptorFromWindowsSwapChainPanel;
            desc.swapChainPanel = src.swap_chain_panel;
            break :blk c.wgpuInstanceCreateSurface(native.instance, &c.WGPUSurfaceDescriptor{
                .nextInChain = @ptrCast(*c.WGPUChainedStruct, &desc),
                .label = if (src.label) |l| @ptrCast([*c]const u8, l) else null,
            });
        },
        .xlib_window => |src| blk: {
            var desc: c.WGPUSurfaceDescriptorFromXlibWindow = undefined;
            desc.chain.next = null;
            desc.chain.sType = c.WGPUSType_SurfaceDescriptorFromXlibWindow;
            desc.display = src.display;
            desc.window = src.window;
            break :blk c.wgpuInstanceCreateSurface(native.instance, &c.WGPUSurfaceDescriptor{
                .nextInChain = @ptrCast(*c.WGPUChainedStruct, &desc),
                .label = if (src.label) |l| @ptrCast([*c]const u8, l) else null,
            });
        },
        .canvas_html_selector => |src| blk: {
            var desc: c.WGPUSurfaceDescriptorFromCanvasHTMLSelector = undefined;
            desc.chain.next = null;
            desc.chain.sType = c.WGPUSType_SurfaceDescriptorFromCanvasHTMLSelector;
            desc.selector = @ptrCast([*c]const u8, src.selector);
            break :blk c.wgpuInstanceCreateSurface(native.instance, &c.WGPUSurfaceDescriptor{
                .nextInChain = @ptrCast(*c.WGPUChainedStruct, &desc),
                .label = if (src.label) |l| @ptrCast([*c]const u8, l) else null,
            });
        },
    };

    return Surface{
        .ptr = surface.?,
        .vtable = &surface_vtable,
    };
}

const surface_vtable = Surface.VTable{
    .reference = (struct {
        pub fn reference(ptr: *anyopaque) void {
            c.wgpuSurfaceReference(@ptrCast(c.WGPUSurface, ptr));
        }
    }).reference,
    .release = (struct {
        pub fn release(ptr: *anyopaque) void {
            c.wgpuSurfaceRelease(@ptrCast(c.WGPUSurface, ptr));
        }
    }).release,
};

test "syntax" {
    _ = wrap;
    _ = interface;
    _ = createSurface;
}