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// Copyright (c) (2023-2024) Magic Leap, Inc. All Rights Reserved.
// Use of this file is governed by the Software License Agreement, located here: https://www.magicleap.com/software-license-agreement-ml2
// Terms and conditions applicable to third-party materials accompanying this distribution may also be found in the top-level NOTICE file appearing herein.
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using System;
using Unity.Collections;
using Unity.Collections.LowLevel.Unsafe;
using UnityEngine.XR.ARSubsystems;
using UnityEngine.XR.OpenXR.NativeTypes;

namespace MagicLeap.OpenXR.ViewConfiguration
{
    internal enum StructType : ulong
    {
        ViewConfigurationDepthRange = 1000046000,
        ViewConfigurationView = 41,
        ViewConfigurationProperties = 45,
    }

    internal struct XrViewConfigurationProperties
    {
        internal StructType Type;
        internal IntPtr Next;
        internal XrViewConfigurationType ConfigurationType;
    }

    internal struct XrViewConfigurationView
    {
        internal StructType Type;
        internal IntPtr Next;
        internal uint RecommendedImageRectWidth;
        internal uint MaxImageRectWidth;
        internal uint RecommendedImageRectHeight;
        internal uint MaxImageRectHeight;
        internal uint RecommendedSwapchainSampleCount;
        internal uint MaxSwapchainSampleCount;
    }

    internal struct XrViewConfigurationDepthRange
    {
        internal StructType Type;
        internal IntPtr Next;
        internal float RecommendedNearZ;
        internal float MinNearZ;
        internal float RecommendedFarZ;
        internal float MaxFarZ;
    }

    internal unsafe class ViewConfigNativeFunctions : NativeFunctionsBase
    {
        internal delegate* unmanaged [Cdecl] <ulong, ulong, XrViewConfigurationType, uint, out uint, XrViewConfigurationView*, XrResult> XrEnumerateViewConfigurationViews;
        internal delegate* unmanaged [Cdecl] <XrInstance, XrSystemId, XrViewConfigurationType, ref XrViewConfigurationProperties, XrResult> XrGetViewConfigurationProperties;
        protected override void LocateNativeFunctions()
        {
            XrEnumerateViewConfigurationViews = (delegate* unmanaged[Cdecl]<ulong, ulong, XrViewConfigurationType, uint, out uint, XrViewConfigurationView*, XrResult>)LocateNativeFunction("xrEnumerateViewConfigurationViews");
            XrGetViewConfigurationProperties = (delegate* unmanaged[Cdecl]<XrInstance, XrSystemId, XrViewConfigurationType, ref XrViewConfigurationProperties, XrResult>)LocateNativeFunction("xrGetViewConfigurationProperties");
        }

        internal XrResult EnumerateConfigurationViews(XrInstance instance, XrSystemId systemId, out XrViewConfigurationDepthRange depthRangeResult)
        {
            depthRangeResult = default;
            var xrResult = XrEnumerateViewConfigurationViews(instance, systemId, XrViewConfigurationType.PrimaryStereo, 0, out var viewConfigurationCount, null);
            if (!Utils.DidXrCallSucceed(xrResult, nameof(XrEnumerateViewConfigurationViews)))
            {
                return xrResult;
            }

            var viewConfigurationArray = new NativeArray<XrViewConfigurationView>((int)viewConfigurationCount, Allocator.Temp);
            var depthRange = new XrViewConfigurationDepthRange
            {
                Type = StructType.ViewConfigurationDepthRange,
            };
            NativeCopyUtility.FillArrayWithValue(viewConfigurationArray, new XrViewConfigurationView
            {
                Type = StructType.ViewConfigurationView,
                Next = new IntPtr(&depthRange),
            });
            xrResult = XrEnumerateViewConfigurationViews(instance, systemId, XrViewConfigurationType.PrimaryStereo, viewConfigurationCount, out viewConfigurationCount, (XrViewConfigurationView*)viewConfigurationArray.GetUnsafePtr());
            if (!Utils.DidXrCallSucceed(xrResult, nameof(XrEnumerateViewConfigurationViews)))
            {
                return xrResult;
            }

            depthRangeResult = depthRange;
            return XrResult.Success;
        }
        
        internal XrResult EnumerateConfigurationViews(XrInstance instance, XrSystemId systemId, out XrViewConfigurationView[] viewConfigurationViews)
        {
            viewConfigurationViews = Array.Empty<XrViewConfigurationView>();
            var xrResult = XrEnumerateViewConfigurationViews(instance, systemId, XrViewConfigurationType.PrimaryStereo, 0, out var viewCount, null);
            if (!Utils.DidXrCallSucceed(xrResult, nameof(XrEnumerateViewConfigurationViews)))
            {
                return xrResult;
            }

            var viewArray = new NativeArray<XrViewConfigurationView>((int)viewCount, Allocator.Temp);
            NativeCopyUtility.FillArrayWithValue(viewArray, new XrViewConfigurationView
            {
                Type = StructType.ViewConfigurationView,
            });
            xrResult = XrEnumerateViewConfigurationViews(instance, systemId, XrViewConfigurationType.PrimaryStereo, viewCount, out viewCount, (XrViewConfigurationView*)viewArray.GetUnsafePtr());
            if (!Utils.DidXrCallSucceed(xrResult, nameof(XrEnumerateViewConfigurationViews)))
            {
                return xrResult;
            }
            viewConfigurationViews = viewArray.ToArray();
            return xrResult;
        }

        internal XrResult GetViewConfigurationProperties(XrInstance instance, XrSystemId systemId, ref XrViewConfigurationProperties properties, XrViewConfigurationType configurationType = XrViewConfigurationType.PrimaryStereo)
        {
            var xrResult = XrGetViewConfigurationProperties(instance, systemId, configurationType, ref properties);
            Utils.DidXrCallSucceed(xrResult, nameof(XrGetViewConfigurationProperties));
            return xrResult;
        }
}
}