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

using UnityEngine;

namespace UnityEditor.VFX.URP
{
    [VFXHelpURL("Context-OutputPrimitive")]
    [VFXInfo(name = "Output ParticleStrip|URP Lit|Quad", category = "#3Output Strip", experimental = true)]
    class VFXURPLitQuadStripOutput : VFXAbstractParticleURPLitOutput
    {
        protected VFXURPLitQuadStripOutput() : base(true) {}  // strips

        public override string name => "Output ParticleStrip".AppendLabel("URP Lit").AppendLabel("Quad");
        public override string codeGeneratorTemplate => RenderPipeTemplate("VFXParticleLitPlanarPrimitive");
        public override VFXTaskType taskType => VFXTaskType.ParticleQuadOutput;
        public override bool supportsUV => true;

        [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;

        [VFXSetting, SerializeField, Tooltip("Specifies the way the UVs are interpolated along the strip. They can either be stretched or repeated per segment.")]
        private StripTilingMode tilingMode = StripTilingMode.Stretch;

        [VFXSetting, SerializeField, Tooltip("When enabled, uvs for the strips are swapped.")]
        protected bool swapUV = 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;
        }

        public class CustomUVInputProperties
        {
            [Tooltip("Specifies the texture coordinate value (u or v depending on swap UV being enabled) used along the strip.")]
            public float texCoord = 0.0f;
        }

        protected override IEnumerable<VFXPropertyWithValue> inputProperties
        {
            get
            {
                var properties = base.inputProperties;
                if (normalBending)
                    properties = properties.Concat(PropertiesFromType(nameof(NormalBendingProperties)));
                if (tilingMode == StripTilingMode.Custom)
                    properties = properties.Concat(PropertiesFromType(nameof(CustomUVInputProperties)));
                return properties;
            }
        }

        public override IEnumerable<VFXAttributeInfo> attributes
        {
            get
            {
                yield return new VFXAttributeInfo(VFXAttribute.Position, VFXAttributeMode.Read);
                if (colorMode != ColorMode.None)
                    yield return new VFXAttributeInfo(VFXAttribute.Color, VFXAttributeMode.Read);
                yield return new VFXAttributeInfo(VFXAttribute.Alpha, VFXAttributeMode.Read);
                yield return new VFXAttributeInfo(VFXAttribute.AxisX, VFXAttributeMode.Read);
                yield return new VFXAttributeInfo(VFXAttribute.AxisY, VFXAttributeMode.Read);
                yield return new VFXAttributeInfo(VFXAttribute.AxisZ, VFXAttributeMode.Read);
                yield return new VFXAttributeInfo(VFXAttribute.AngleX, VFXAttributeMode.Read);
                yield return new VFXAttributeInfo(VFXAttribute.AngleY, VFXAttributeMode.Read);
                yield return new VFXAttributeInfo(VFXAttribute.AngleZ, VFXAttributeMode.Read);
                yield return new VFXAttributeInfo(VFXAttribute.PivotX, VFXAttributeMode.Read);
                yield return new VFXAttributeInfo(VFXAttribute.PivotY, VFXAttributeMode.Read);
                yield return new VFXAttributeInfo(VFXAttribute.PivotZ, VFXAttributeMode.Read);
                yield return new VFXAttributeInfo(VFXAttribute.Size, VFXAttributeMode.Read);

                foreach (var attribute in flipbookAttributes)
                    yield return attribute;
            }
        }

        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 (tilingMode == StripTilingMode.Custom)
                yield return slotExpressions.First(o => o.name == nameof(CustomUVInputProperties.texCoord));
        }

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

                if (normalBending)
                    yield return "USE_NORMAL_BENDING";

                if (tilingMode == StripTilingMode.Stretch)
                    yield return "VFX_STRIPS_UV_STRECHED";
                else if (tilingMode == StripTilingMode.RepeatPerSegment)
                    yield return "VFX_STRIPS_UV_PER_SEGMENT";

                if (swapUV)
                    yield return "VFX_STRIPS_SWAP_UV";

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

                yield return VFXPlanarPrimitiveHelper.GetShaderDefine(VFXPrimitiveType.Quad);
            }
        }
    }
}
#endif