#if HAS_VFX_GRAPH
using System;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;

namespace UnityEditor.VFX.URP
{
    class VFXURPPlanarPrimitiveOutputSubVariantProvider : VariantProvider
    {
        private readonly VFXPrimitiveType mainVariantType;

        public VFXURPPlanarPrimitiveOutputSubVariantProvider(VFXPrimitiveType type)
        {
            this.mainVariantType = type;
        }

        public override IEnumerable<Variant> GetVariants()
        {
            foreach (var primitive in Enum.GetValues(typeof(VFXPrimitiveType)).Cast<VFXPrimitiveType>())
            {
                if (primitive == this.mainVariantType)
                    continue;

                yield return new Variant(
                    "Output Particle".AppendLabel("URP Lit", false).AppendLabel(primitive.ToString()),
                    null,
                    typeof(VFXURPLitPlanarPrimitiveOutput),
                    new[] {new KeyValuePair<string, object>("primitiveType", primitive)});
            }
        }
    }

    class VFXURPPlanarPrimitiveOutputProvider : VariantProvider
    {
        public override IEnumerable<Variant> GetVariants()
        {
            yield return new Variant(
                "Output Particle".AppendLabel("URP Lit", false).AppendLabel("Quad", false),
                VFXLibraryStringHelper.Separator("Output Basic", 2),
                typeof(VFXURPLitPlanarPrimitiveOutput),
                new[] {new KeyValuePair<string, object>("primitiveType", VFXPrimitiveType.Quad)},
                () => new VFXURPPlanarPrimitiveOutputSubVariantProvider(VFXPrimitiveType.Quad));
        }
    }

    [VFXHelpURL("Context-OutputPrimitive")]
    [VFXInfo(variantProvider = typeof(VFXURPPlanarPrimitiveOutputProvider))]
    class VFXURPLitPlanarPrimitiveOutput : VFXAbstractParticleURPLitOutput
    {
        public override string name => "Output Particle".AppendLabel("URP Lit").AppendLabel(primitiveType.ToString());
        public override string codeGeneratorTemplate { get { return RenderPipeTemplate("VFXParticleLitPlanarPrimitive"); } }
        public override VFXTaskType taskType { get { return VFXPlanarPrimitiveHelper.GetTaskType(primitiveType); } }
        public override bool supportsUV { get { return GetOrRefreshShaderGraphObject() == null; } }
        public sealed override bool implementsMotionVector { get { return true; } }

        [VFXSetting(VFXSettingAttribute.VisibleFlags.InInspector), SerializeField, Tooltip("Specifies what primitive type to use for this output. Triangle outputs have fewer vertices, octagons can be used to conform the geometry closer to the texture to avoid overdraw, and quads are a good middle ground.")]
        protected VFXPrimitiveType primitiveType = VFXPrimitiveType.Quad;

        [VFXSetting(VFXSettingAttribute.VisibleFlags.InInspector), SerializeField, Tooltip("When enabled, a Normal Bending Factor slider becomes available in the output which can be used to adjust the curvature of the normals.")]
        protected bool normalBending = false;

        public class NormalBendingProperties
        {
            [Range(0, 1), Tooltip("Controls the amount by which the normals will be bent, creating a rounder look.")]
            public float normalBendingFactor = 0.1f;
        }

        protected override IEnumerable<VFXPropertyWithValue> inputProperties
        {
            get
            {
                var properties = base.inputProperties;
                if (normalBending)
                    properties = properties.Concat(PropertiesFromType("NormalBendingProperties"));
                if (primitiveType == VFXPrimitiveType.Octagon)
                    properties = properties.Concat(PropertiesFromType(typeof(VFXPlanarPrimitiveHelper.OctagonInputProperties)));
                return properties;
            }
        }

        protected override IEnumerable<VFXNamedExpression> CollectGPUExpressions(IEnumerable<VFXNamedExpression> slotExpressions)
        {
            foreach (var exp in base.CollectGPUExpressions(slotExpressions))
                yield return exp;

            if (normalBending)
                yield return slotExpressions.First(o => o.name == nameof(NormalBendingProperties.normalBendingFactor));
            if (primitiveType == VFXPrimitiveType.Octagon)
                yield return slotExpressions.First(o => o.name == nameof(VFXPlanarPrimitiveHelper.OctagonInputProperties.cropFactor));
        }

        public override IEnumerable<string> additionalDefines
        {
            get
            {
                foreach (var d in base.additionalDefines)
                    yield return d;

                if (normalBending)
                    yield return "USE_NORMAL_BENDING";

                yield return "FORCE_NORMAL_VARYING"; // To avoid discrepancy between depth and color pass which could cause glitch with ztest

                yield return VFXPlanarPrimitiveHelper.GetShaderDefine(primitiveType);
            }
        }
    }
}
#endif