// Copyright 2016 The SwiftShader Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <Device/Vertex.hpp>
#include "SetupRoutine.hpp"

#include "Constants.hpp"
#include "Device/Primitive.hpp"
#include "Device/Polygon.hpp"
#include "Device/Renderer.hpp"
#include "Reactor/Reactor.hpp"

namespace sw
{
	extern TranscendentalPrecision logPrecision;

	SetupRoutine::SetupRoutine(const SetupProcessor::State &state) : state(state)
	{
		routine = 0;
	}

	SetupRoutine::~SetupRoutine()
	{
	}

	void SetupRoutine::generate()
	{
		Function<Int(Pointer<Byte>, Pointer<Byte>, Pointer<Byte>, Pointer<Byte>)> function;
		{
			Pointer<Byte> primitive(function.Arg<0>());
			Pointer<Byte> tri(function.Arg<1>());
			Pointer<Byte> polygon(function.Arg<2>());
			Pointer<Byte> data(function.Arg<3>());

			Pointer<Byte> constants = *Pointer<Pointer<Byte> >(data + OFFSET(DrawData,constants));

			const bool point = state.isDrawPoint;
			const bool line = state.isDrawLine;
			const bool triangle = state.isDrawTriangle;

			const int V0 = OFFSET(Triangle,v0);
			const int V1 = (triangle || line) ? OFFSET(Triangle,v1) : OFFSET(Triangle,v0);
			const int V2 = triangle ? OFFSET(Triangle,v2) : (line ? OFFSET(Triangle,v1) : OFFSET(Triangle,v0));

			Pointer<Byte> v0 = tri + V0;
			Pointer<Byte> v1 = tri + V1;
			Pointer<Byte> v2 = tri + V2;

			Array<Int> X(16);
			Array<Int> Y(16);

			X[0] = *Pointer<Int>(v0 + OFFSET(Vertex,projected.x));
			X[1] = *Pointer<Int>(v1 + OFFSET(Vertex,projected.x));
			X[2] = *Pointer<Int>(v2 + OFFSET(Vertex,projected.x));

			Y[0] = *Pointer<Int>(v0 + OFFSET(Vertex,projected.y));
			Y[1] = *Pointer<Int>(v1 + OFFSET(Vertex,projected.y));
			Y[2] = *Pointer<Int>(v2 + OFFSET(Vertex,projected.y));

			Int d = 1;     // Winding direction

			// Culling
			if(triangle)
			{
				Float x0 = Float(X[0]);
				Float x1 = Float(X[1]);
				Float x2 = Float(X[2]);

				Float y0 = Float(Y[0]);
				Float y1 = Float(Y[1]);
				Float y2 = Float(Y[2]);

				Float A = (y0 - y2) * x1 + (y2 - y1) * x0 + (y1 - y0) * x2;   // Area

				If(A == 0.0f)
				{
					Return(0);
				}

				Int w0w1w2 = *Pointer<Int>(v0 + OFFSET(Vertex, builtins.position.w)) ^
							 *Pointer<Int>(v1 + OFFSET(Vertex, builtins.position.w)) ^
							 *Pointer<Int>(v2 + OFFSET(Vertex, builtins.position.w));

				A = IfThenElse(w0w1w2 < 0, -A, A);

				Bool frontFacing = state.frontFacingCCW ? A > 0.0f : A < 0.0f;

				if(state.cullMode & VK_CULL_MODE_FRONT_BIT)
				{
					If(frontFacing) Return(0);
				}
				if(state.cullMode & VK_CULL_MODE_BACK_BIT)
				{
					If(!frontFacing) Return(0);
				}

				d = IfThenElse(A > 0.0f, d, Int(0));

				If(frontFacing)
				{
					*Pointer<Byte8>(primitive + OFFSET(Primitive,clockwiseMask)) = Byte8(0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF);
					*Pointer<Byte8>(primitive + OFFSET(Primitive,invClockwiseMask)) = Byte8(0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00);
				}
				Else
				{
					*Pointer<Byte8>(primitive + OFFSET(Primitive,clockwiseMask)) = Byte8(0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00);
					*Pointer<Byte8>(primitive + OFFSET(Primitive,invClockwiseMask)) = Byte8(0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF);
				}
			}
			else
			{
				*Pointer<Byte8>(primitive + OFFSET(Primitive,clockwiseMask)) = Byte8(0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF);
				*Pointer<Byte8>(primitive + OFFSET(Primitive,invClockwiseMask)) = Byte8(0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00);
			}

			Int n = *Pointer<Int>(polygon + OFFSET(Polygon,n));
			Int m = *Pointer<Int>(polygon + OFFSET(Polygon,i));

			If(m != 0 || Bool(!triangle))   // Clipped triangle; reproject
			{
				Pointer<Byte> V = polygon + OFFSET(Polygon,P) + m * sizeof(void*) * 16;

				Int i = 0;

				Do
				{
					Pointer<Float4> p = *Pointer<Pointer<Float4> >(V + i * sizeof(void*));
					Float4 v = *Pointer<Float4>(p, 16);

					Float w = v.w;
					Float rhw = IfThenElse(w != 0.0f, 1.0f / w, Float(1.0f));

					X[i] = RoundInt(*Pointer<Float>(data + OFFSET(DrawData,X0x16)) + v.x * rhw * *Pointer<Float>(data + OFFSET(DrawData,Wx16)));
					Y[i] = RoundInt(*Pointer<Float>(data + OFFSET(DrawData,Y0x16)) + v.y * rhw * *Pointer<Float>(data + OFFSET(DrawData,Hx16)));

					i++;
				}
				Until(i >= n)
			}

			// Vertical range
			Int yMin = Y[0];
			Int yMax = Y[0];

			Int i = 1;

			Do
			{
				yMin = Min(Y[i], yMin);
				yMax = Max(Y[i], yMax);

				i++;
			}
			Until(i >= n)

			if(state.multiSample > 1)
			{
				yMin = (yMin + 0x0A) >> 4;
				yMax = (yMax + 0x14) >> 4;
			}
			else
			{
				yMin = (yMin + 0x0F) >> 4;
				yMax = (yMax + 0x0F) >> 4;
			}

			yMin = Max(yMin, *Pointer<Int>(data + OFFSET(DrawData,scissorY0)));
			yMax = Min(yMax, *Pointer<Int>(data + OFFSET(DrawData,scissorY1)));

			// If yMin and yMax are initially negative, the scissor clamping above will typically result
			// in yMin == 0 and yMax unchanged. We bail as we don't need to rasterize this primitive, and
			// code below assumes yMin < yMax.
			If(yMin >= yMax)
			{
				Return(0);
			}

			For(Int q = 0, q < state.multiSample, q++)
			{
				Array<Int> Xq(16);
				Array<Int> Yq(16);

				Int i = 0;

				Do
				{
					Xq[i] = X[i];
					Yq[i] = Y[i];

					if(state.multiSample > 1)
					{
						Xq[i] = Xq[i] + *Pointer<Int>(constants + OFFSET(Constants,Xf) + q * sizeof(int));
						Yq[i] = Yq[i] + *Pointer<Int>(constants + OFFSET(Constants,Yf) + q * sizeof(int));
					}

					i++;
				}
				Until(i >= n)

				Pointer<Byte> leftEdge = Pointer<Byte>(primitive + OFFSET(Primitive,outline->left)) + q * sizeof(Primitive);
				Pointer<Byte> rightEdge = Pointer<Byte>(primitive + OFFSET(Primitive,outline->right)) + q * sizeof(Primitive);

				if(state.multiSample > 1)
				{
					Int xMin = *Pointer<Int>(data + OFFSET(DrawData, scissorX0));
					Int xMax = *Pointer<Int>(data + OFFSET(DrawData, scissorX1));
					Short x = Short(Clamp((X[0] + 0xF) >> 4, xMin, xMax));

					For(Int y = yMin - 1, y < yMax + 1, y++)
					{
						*Pointer<Short>(leftEdge + y * sizeof(Primitive::Span)) = x;
						*Pointer<Short>(rightEdge + y * sizeof(Primitive::Span)) = x;
					}
				}

				Xq[n] = Xq[0];
				Yq[n] = Yq[0];

				// Rasterize
				{
					Int i = 0;

					Do
					{
						edge(primitive, data, Xq[i + 1 - d], Yq[i + 1 - d], Xq[i + d], Yq[i + d], q);

						i++;
					}
					Until(i >= n)
				}

				if(state.multiSample == 1)
				{
					For(, yMin < yMax && *Pointer<Short>(leftEdge + yMin * sizeof(Primitive::Span)) == *Pointer<Short>(rightEdge + yMin * sizeof(Primitive::Span)), yMin++)
					{
						// Increments yMin
					}

					For(, yMax > yMin && *Pointer<Short>(leftEdge + (yMax - 1) * sizeof(Primitive::Span)) == *Pointer<Short>(rightEdge + (yMax - 1) * sizeof(Primitive::Span)), yMax--)
					{
						// Decrements yMax
					}

					If(yMin == yMax)
					{
						Return(0);
					}

					*Pointer<Short>(leftEdge + (yMin - 1) * sizeof(Primitive::Span)) = *Pointer<Short>(leftEdge + yMin * sizeof(Primitive::Span));
					*Pointer<Short>(rightEdge + (yMin - 1) * sizeof(Primitive::Span)) = *Pointer<Short>(leftEdge + yMin * sizeof(Primitive::Span));
					*Pointer<Short>(leftEdge + yMax * sizeof(Primitive::Span)) = *Pointer<Short>(leftEdge + (yMax - 1) * sizeof(Primitive::Span));
					*Pointer<Short>(rightEdge + yMax * sizeof(Primitive::Span)) = *Pointer<Short>(leftEdge + (yMax - 1) * sizeof(Primitive::Span));
				}
			}

			*Pointer<Int>(primitive + OFFSET(Primitive,yMin)) = yMin;
			*Pointer<Int>(primitive + OFFSET(Primitive,yMax)) = yMax;

			// Sort by minimum y
			if(triangle)
			{
				Float y0 = *Pointer<Float>(v0 + OFFSET(Vertex, builtins.position.y));
				Float y1 = *Pointer<Float>(v1 + OFFSET(Vertex, builtins.position.y));
				Float y2 = *Pointer<Float>(v2 + OFFSET(Vertex, builtins.position.y));

				Float yMin = Min(Min(y0, y1), y2);

				conditionalRotate1(yMin == y1, v0, v1, v2);
				conditionalRotate2(yMin == y2, v0, v1, v2);
			}

			// Sort by maximum w
			if(triangle)
			{
				Float w0 = *Pointer<Float>(v0 + OFFSET(Vertex, builtins.position.w));
				Float w1 = *Pointer<Float>(v1 + OFFSET(Vertex, builtins.position.w));
				Float w2 = *Pointer<Float>(v2 + OFFSET(Vertex, builtins.position.w));

				Float wMax = Max(Max(w0, w1), w2);

				conditionalRotate1(wMax == w1, v0, v1, v2);
				conditionalRotate2(wMax == w2, v0, v1, v2);
			}

			Float w0 = *Pointer<Float>(v0 + OFFSET(Vertex, builtins.position.w));
			Float w1 = *Pointer<Float>(v1 + OFFSET(Vertex, builtins.position.w));
			Float w2 = *Pointer<Float>(v2 + OFFSET(Vertex, builtins.position.w));

			Float4 w012;

			w012.x = w0;
			w012.y = w1;
			w012.z = w2;
			w012.w = 1;

			Float rhw0 = *Pointer<Float>(v0 + OFFSET(Vertex,projected.w));

			Int X0 = *Pointer<Int>(v0 + OFFSET(Vertex,projected.x));
			Int X1 = *Pointer<Int>(v1 + OFFSET(Vertex,projected.x));
			Int X2 = *Pointer<Int>(v2 + OFFSET(Vertex,projected.x));

			Int Y0 = *Pointer<Int>(v0 + OFFSET(Vertex,projected.y));
			Int Y1 = *Pointer<Int>(v1 + OFFSET(Vertex,projected.y));
			Int Y2 = *Pointer<Int>(v2 + OFFSET(Vertex,projected.y));

			if(line)
			{
				X2 = X1 + Y1 - Y0;
				Y2 = Y1 + X0 - X1;
			}

			Float dx = Float(X0) * (1.0f / 16.0f);
			Float dy = Float(Y0) * (1.0f / 16.0f);

			X1 -= X0;
			Y1 -= Y0;

			X2 -= X0;
			Y2 -= Y0;

			Float x1 = w1 * (1.0f / 16.0f) * Float(X1);
			Float y1 = w1 * (1.0f / 16.0f) * Float(Y1);

			Float x2 = w2 * (1.0f / 16.0f) * Float(X2);
			Float y2 = w2 * (1.0f / 16.0f) * Float(Y2);

			Float a = x1 * y2 - x2 * y1;

			Float4 xQuad = Float4(0, 1, 0, 1) - Float4(dx);
			Float4 yQuad = Float4(0, 0, 1, 1) - Float4(dy);

			*Pointer<Float4>(primitive + OFFSET(Primitive,xQuad), 16) = xQuad;
			*Pointer<Float4>(primitive + OFFSET(Primitive,yQuad), 16) = yQuad;

			Float4 M[3];

			M[0] = Float4(0, 0, 0, 0);
			M[1] = Float4(0, 0, 0, 0);
			M[2] = Float4(0, 0, 0, 0);

			M[0].z = rhw0;

			If(a != 0.0f)
			{
				Float A = 1.0f / a;
				Float D = A * rhw0;

				M[0].x = (y1 * w2 - y2 * w1) * D;
				M[0].y = (x2 * w1 - x1 * w2) * D;
			//	M[0].z = rhw0;
			//	M[0].w = 0;

				M[1].x = y2 * A;
				M[1].y = -x2 * A;
			//	M[1].z = 0;
			//	M[1].w = 0;

				M[2].x = -y1 * A;
				M[2].y = x1 * A;
			//	M[2].z = 0;
			//	M[2].w = 0;
			}

			if(state.interpolateW)
			{
				Float4 ABC = M[0] + M[1] + M[2];

				Float4 A = ABC.x;
				Float4 B = ABC.y;
				Float4 C = ABC.z;

				*Pointer<Float4>(primitive + OFFSET(Primitive,w.A), 16) = A;
				*Pointer<Float4>(primitive + OFFSET(Primitive,w.B), 16) = B;
				*Pointer<Float4>(primitive + OFFSET(Primitive,w.C), 16) = C;
			}

			if(state.interpolateZ)
			{
				Float z0 = *Pointer<Float>(v0 + OFFSET(Vertex,projected.z));
				Float z1 = *Pointer<Float>(v1 + OFFSET(Vertex,projected.z));
				Float z2 = *Pointer<Float>(v2 + OFFSET(Vertex,projected.z));

				z1 -= z0;
				z2 -= z0;

				Float4 A;
				Float4 B;
				Float4 C;

				if(!point)
				{
					Float x1 = Float(X1) * (1.0f / 16.0f);
					Float y1 = Float(Y1) * (1.0f / 16.0f);
					Float x2 = Float(X2) * (1.0f / 16.0f);
					Float y2 = Float(Y2) * (1.0f / 16.0f);

					Float D = *Pointer<Float>(data + OFFSET(DrawData,depthRange)) / (x1 * y2 - x2 * y1);

					Float a = (y2 * z1 - y1 * z2) * D;
					Float b = (x1 * z2 - x2 * z1) * D;

					A = Float4(a);
					B = Float4(b);
				}
				else
				{
					A = Float4(0, 0, 0, 0);
					B = Float4(0, 0, 0, 0);
				}

				*Pointer<Float4>(primitive + OFFSET(Primitive,z.A), 16) = A;
				*Pointer<Float4>(primitive + OFFSET(Primitive,z.B), 16) = B;

				Float c = z0;

				if(state.isDrawTriangle && state.slopeDepthBias)
				{
					Float bias = Max(Abs(Float(A.x)), Abs(Float(B.x)));
					bias *= *Pointer<Float>(data + OFFSET(DrawData,slopeDepthBias));

					c += bias;
				}

				C = Float4(c * *Pointer<Float>(data + OFFSET(DrawData,depthRange)) + *Pointer<Float>(data + OFFSET(DrawData,depthNear)));

				*Pointer<Float4>(primitive + OFFSET(Primitive,z.C), 16) = C;
			}

			for (int interpolant = 0; interpolant < MAX_INTERFACE_COMPONENTS; interpolant++)
			{
				// Note: `sprite` mode controls whether to replace this interpolant with the point sprite PointCoord value.
				// This was an interesting thing to support for old GL because any texture coordinate could be replaced in this way.
				// In modern GL and in Vulkan, the [gl_]PointCoord builtin variable to the fragment shader is used instead.
				if (state.gradient[interpolant].Type != SpirvShader::ATTRIBTYPE_UNUSED)
					setupGradient(primitive, tri, w012, M, v0, v1, v2,
							OFFSET(Vertex, v[interpolant]),
							OFFSET(Primitive, V[interpolant]),
							state.gradient[interpolant].Flat,
							false /* is pointcoord */,
							!state.gradient[interpolant].NoPerspective, 0);
			}

			Return(1);
		}

		routine = function("SetupRoutine");
	}

	void SetupRoutine::setupGradient(Pointer<Byte> &primitive, Pointer<Byte> &triangle, Float4 &w012, Float4 (&m)[3], Pointer<Byte> &v0, Pointer<Byte> &v1, Pointer<Byte> &v2, int attribute, int planeEquation, bool flat, bool sprite, bool perspective, int component)
	{
		Float4 i;

		if(!flat)
		{
			if(!sprite)
			{
				i.x = *Pointer<Float>(v0 + attribute);
				i.y = *Pointer<Float>(v1 + attribute);
				i.z = *Pointer<Float>(v2 + attribute);
				i.w = 0;
			}
			else
			{
				if(component == 0) i.x = 0.5f;
				if(component == 1) i.x = 0.5f;
				if(component == 2) i.x = 0.0f;
				if(component == 3) i.x = 1.0f;

				if(component == 0) i.y = 1.0f;
				if(component == 1) i.y = 0.5f;
				if(component == 2) i.y = 0.0f;
				if(component == 3) i.y = 1.0f;

				if(component == 0) i.z = 0.5f;
				if(component == 1) i.z = 1.0f;
				if(component == 2) i.z = 0.0f;
				if(component == 3) i.z = 1.0f;

				i.w = 0;
			}

			if(!perspective)
			{
				i *= w012;
			}

			Float4 A = i.xxxx * m[0];
			Float4 B = i.yyyy * m[1];
			Float4 C = i.zzzz * m[2];

			C = A + B + C;

			A = C.xxxx;
			B = C.yyyy;
			C = C.zzzz;

			*Pointer<Float4>(primitive + planeEquation + 0, 16) = A;
			*Pointer<Float4>(primitive + planeEquation + 16, 16) = B;
			*Pointer<Float4>(primitive + planeEquation + 32, 16) = C;
		}
		else
		{
			int leadingVertex = OFFSET(Triangle,v0);
			Float C = *Pointer<Float>(triangle + leadingVertex + attribute);

			*Pointer<Float4>(primitive + planeEquation + 0, 16) = Float4(0, 0, 0, 0);
			*Pointer<Float4>(primitive + planeEquation + 16, 16) = Float4(0, 0, 0, 0);
			*Pointer<Float4>(primitive + planeEquation + 32, 16) = Float4(C);
		}
	}

	void SetupRoutine::edge(Pointer<Byte> &primitive, Pointer<Byte> &data, const Int &Xa, const Int &Ya, const Int &Xb, const Int &Yb, Int &q)
	{
		If(Ya != Yb)
		{
			Bool swap = Yb < Ya;

			Int X1 = IfThenElse(swap, Xb, Xa);
			Int X2 = IfThenElse(swap, Xa, Xb);
			Int Y1 = IfThenElse(swap, Yb, Ya);
			Int Y2 = IfThenElse(swap, Ya, Yb);

			Int y1 = Max((Y1 + 0x0000000F) >> 4, *Pointer<Int>(data + OFFSET(DrawData,scissorY0)));
			Int y2 = Min((Y2 + 0x0000000F) >> 4, *Pointer<Int>(data + OFFSET(DrawData,scissorY1)));

			If(y1 < y2)
			{
				Int xMin = *Pointer<Int>(data + OFFSET(DrawData,scissorX0));
				Int xMax = *Pointer<Int>(data + OFFSET(DrawData,scissorX1));

				Pointer<Byte> leftEdge = primitive + q * sizeof(Primitive) + OFFSET(Primitive,outline->left);
				Pointer<Byte> rightEdge = primitive + q * sizeof(Primitive) + OFFSET(Primitive,outline->right);
				Pointer<Byte> edge = IfThenElse(swap, rightEdge, leftEdge);

				// Deltas
				Int DX12 = X2 - X1;
				Int DY12 = Y2 - Y1;

				Int FDX12 = DX12 << 4;
				Int FDY12 = DY12 << 4;

				Int X = DX12 * ((y1 << 4) - Y1) + (X1 & 0x0000000F) * DY12;
				Int x = (X1 >> 4) + X / FDY12;   // Edge
				Int d = X % FDY12;               // Error-term
				Int ceil = -d >> 31;             // Ceiling division: remainder <= 0
				x -= ceil;
				d -= ceil & FDY12;

				Int Q = FDX12 / FDY12;   // Edge-step
				Int R = FDX12 % FDY12;   // Error-step
				Int floor = R >> 31;     // Flooring division: remainder >= 0
				Q += floor;
				R += floor & FDY12;

				Int D = FDY12;   // Error-overflow
				Int y = y1;

				Do
				{
					*Pointer<Short>(edge + y * sizeof(Primitive::Span)) = Short(Clamp(x, xMin, xMax));

					x += Q;
					d += R;

					Int overflow = -d >> 31;

					d -= D & overflow;
					x -= overflow;

					y++;
				}
				Until(y >= y2)
			}
		}
	}

	void SetupRoutine::conditionalRotate1(Bool condition, Pointer<Byte> &v0, Pointer<Byte> &v1, Pointer<Byte> &v2)
	{
		#if 0   // Rely on LLVM optimization
			If(condition)
			{
				Pointer<Byte> vX;

				vX = v0;
				v0 = v1;
				v1 = v2;
				v2 = vX;
			}
		#else
			Pointer<Byte> vX = v0;
			v0 = IfThenElse(condition, v1, v0);
			v1 = IfThenElse(condition, v2, v1);
			v2 = IfThenElse(condition, vX, v2);
		#endif
	}

	void SetupRoutine::conditionalRotate2(Bool condition, Pointer<Byte> &v0, Pointer<Byte> &v1, Pointer<Byte> &v2)
	{
		#if 0   // Rely on LLVM optimization
			If(condition)
			{
				Pointer<Byte> vX;

				vX = v2;
				v2 = v1;
				v1 = v0;
				v0 = vX;
			}
		#else
			Pointer<Byte> vX = v2;
			v2 = IfThenElse(condition, v1, v2);
			v1 = IfThenElse(condition, v0, v1);
			v0 = IfThenElse(condition, vX, v0);
		#endif
	}

	Routine *SetupRoutine::getRoutine()
	{
		return routine;
	}
}