// Copyright (c) 2012- PPSSPP Project.

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, version 2.0 or later versions.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License 2.0 for more details.

// A copy of the GPL 2.0 should have been included with the program.
// If not, see http://www.gnu.org/licenses/

// Official git repository and contact information can be found at
// https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.


// Alpha/stencil is a convoluted mess. Some good comments are here:
// https://github.com/hrydgard/ppsspp/issues/3768


#include "StateMappingGLES.h"
#include "profiler/profiler.h"
#include "gfx/gl_debug_log.h"

#include "GPU/Math3D.h"
#include "GPU/GPUState.h"
#include "GPU/ge_constants.h"
#include "Core/System.h"
#include "Core/Config.h"
#include "Core/Reporting.h"
#include "GPU/GLES/GPU_GLES.h"
#include "ext/native/gfx/GLStateCache.h"
#include "GPU/GLES/ShaderManagerGLES.h"
#include "GPU/GLES/TextureCacheGLES.h"
#include "GPU/GLES/FramebufferManagerGLES.h"
#include "GPU/GLES/FragmentShaderGeneratorGLES.h"

static const GLushort glBlendFactorLookup[(size_t)BlendFactor::COUNT] = {
	GL_ZERO,
	GL_ONE,
	GL_SRC_COLOR,
	GL_ONE_MINUS_SRC_COLOR,
	GL_DST_COLOR,
	GL_ONE_MINUS_DST_COLOR,
	GL_SRC_ALPHA,
	GL_ONE_MINUS_SRC_ALPHA,
	GL_DST_ALPHA,
	GL_ONE_MINUS_DST_ALPHA,
	GL_CONSTANT_COLOR,
	GL_ONE_MINUS_CONSTANT_COLOR,
	GL_CONSTANT_ALPHA,
	GL_ONE_MINUS_CONSTANT_ALPHA,
#if !defined(USING_GLES2)   // TODO: Remove when we have better headers
	GL_SRC1_COLOR,
	GL_ONE_MINUS_SRC1_COLOR,
	GL_SRC1_ALPHA,
	GL_ONE_MINUS_SRC1_ALPHA,
#elif !defined(IOS)
	GL_SRC1_COLOR_EXT,
	GL_ONE_MINUS_SRC1_COLOR_EXT,
	GL_SRC1_ALPHA_EXT,
	GL_ONE_MINUS_SRC1_ALPHA_EXT,
#else
	GL_INVALID_ENUM,
	GL_INVALID_ENUM,
	GL_INVALID_ENUM,
	GL_INVALID_ENUM,
#endif
	GL_INVALID_ENUM,
};

static const GLushort glBlendEqLookup[(size_t)BlendEq::COUNT] = {
	GL_FUNC_ADD,
	GL_FUNC_SUBTRACT,
	GL_FUNC_REVERSE_SUBTRACT,
	GL_MIN,
	GL_MAX,
};

static const GLushort cullingMode[] = {
	GL_FRONT,
	GL_BACK,
};

static const GLushort compareOps[] = {
	GL_NEVER, GL_ALWAYS, GL_EQUAL, GL_NOTEQUAL, 
	GL_LESS, GL_LEQUAL, GL_GREATER, GL_GEQUAL,
};

static const GLushort stencilOps[] = {
	GL_KEEP,
	GL_ZERO,
	GL_REPLACE,
	GL_INVERT,
	GL_INCR,
	GL_DECR,
	GL_KEEP, // reserved
	GL_KEEP, // reserved
};

#if !defined(USING_GLES2)
static const GLushort logicOps[] = {
	GL_CLEAR,
	GL_AND,
	GL_AND_REVERSE,
	GL_COPY,
	GL_AND_INVERTED,
	GL_NOOP,
	GL_XOR,
	GL_OR,
	GL_NOR,
	GL_EQUIV,
	GL_INVERT,
	GL_OR_REVERSE,
	GL_COPY_INVERTED,
	GL_OR_INVERTED,
	GL_NAND,
	GL_SET,
};
#endif

inline void DrawEngineGLES::ResetShaderBlending() {
	if (fboTexBound_) {
		glActiveTexture(GL_TEXTURE1);
		glBindTexture(GL_TEXTURE_2D, 0);
		glActiveTexture(GL_TEXTURE0);
		fboTexBound_ = false;
	}
}

void DrawEngineGLES::ApplyDrawState(int prim) {
	if (gstate_c.IsDirty(DIRTY_TEXTURE_IMAGE | DIRTY_TEXTURE_PARAMS) && !gstate.isModeClear() && gstate.isTextureMapEnabled()) {
		textureCache_->SetTexture();
		gstate_c.Clean(DIRTY_TEXTURE_IMAGE | DIRTY_TEXTURE_PARAMS);
		if (gstate_c.needShaderTexClamp) {
			// We will rarely need to set this, so let's do it every time on use rather than in runloop.
			// Most of the time non-framebuffer textures will be used which can be clamped themselves.
			gstate_c.Dirty(DIRTY_TEXCLAMP);
		}
	}

	// Start profiling here to skip SetTexture which is already accounted for
	PROFILE_THIS_SCOPE("applydrawstate");

	// amask is needed for both stencil and blend state so we keep it outside for now
	bool amask = (gstate.pmska & 0xFF) < 128;
	// Let's not write to alpha if stencil isn't enabled.
	if (!gstate.isStencilTestEnabled()) {
		amask = false;
	} else {
		// If the stencil type is set to KEEP, we shouldn't write to the stencil/alpha channel.
		if (ReplaceAlphaWithStencilType() == STENCIL_VALUE_KEEP) {
			amask = false;
		}
	}

	bool useBufferedRendering = g_Config.iRenderingMode != FB_NON_BUFFERED_MODE;

	if (gstate_c.IsDirty(DIRTY_BLEND_STATE)) {
		gstate_c.Clean(DIRTY_BLEND_STATE);
		gstate_c.SetAllowShaderBlend(!g_Config.bDisableSlowFramebufEffects);

		if (gstate.isModeClear()) {
			glstate.blend.disable();
			// Color Test
			bool colorMask = gstate.isClearModeColorMask();
			bool alphaMask = gstate.isClearModeAlphaMask();
			glstate.colorMask.set(colorMask, colorMask, colorMask, alphaMask);
#ifndef USING_GLES2
			if (gstate_c.Supports(GPU_SUPPORTS_LOGIC_OP)) {
				// Logic Ops
				glstate.colorLogicOp.disable();
			}
#endif
		} else {
			// Do the large chunks of state conversion. We might be able to hide these two behind a dirty-flag each,
			// to avoid recomputing heavy stuff unnecessarily every draw call.
			GenericBlendState blendState;
			ConvertBlendState(blendState, gstate_c.allowShaderBlend);

			if (blendState.applyShaderBlending) {
				if (ApplyShaderBlending()) {
					// We may still want to do something about stencil -> alpha.
					ApplyStencilReplaceAndLogicOp(blendState.replaceAlphaWithStencil, blendState);
				} else {
					// Until next time, force it off.
					ResetShaderBlending();
					gstate_c.SetAllowShaderBlend(false);
				}
			} else if (blendState.resetShaderBlending) {
				ResetShaderBlending();
			}

			if (blendState.enabled) {
				glstate.blend.enable();
				glstate.blendEquationSeparate.set(glBlendEqLookup[(size_t)blendState.eqColor], glBlendEqLookup[(size_t)blendState.eqAlpha]);
				glstate.blendFuncSeparate.set(
					glBlendFactorLookup[(size_t)blendState.srcColor], glBlendFactorLookup[(size_t)blendState.dstColor],
					glBlendFactorLookup[(size_t)blendState.srcAlpha], glBlendFactorLookup[(size_t)blendState.dstAlpha]);
				if (blendState.dirtyShaderBlend) {
					gstate_c.Dirty(DIRTY_SHADERBLEND);
				}
				if (blendState.useBlendColor) {
					uint32_t color = blendState.blendColor;
					const float col[4] = {
						(float)((color & 0xFF) >> 0) * (1.0f / 255.0f),
						(float)((color & 0xFF00) >> 8) * (1.0f / 255.0f),
						(float)((color & 0xFF0000) >> 16) * (1.0f / 255.0f),
						(float)((color & 0xFF000000) >> 24) * (1.0f / 255.0f),
					};
					glstate.blendColor.set(col);
				}
			} else {
				glstate.blend.disable();
			}

			// PSP color/alpha mask is per bit but we can only support per byte.
			// But let's do that, at least. And let's try a threshold.
			bool rmask = (gstate.pmskc & 0xFF) < 128;
			bool gmask = ((gstate.pmskc >> 8) & 0xFF) < 128;
			bool bmask = ((gstate.pmskc >> 16) & 0xFF) < 128;

#ifndef MOBILE_DEVICE
			u8 abits = (gstate.pmska >> 0) & 0xFF;
			u8 rbits = (gstate.pmskc >> 0) & 0xFF;
			u8 gbits = (gstate.pmskc >> 8) & 0xFF;
			u8 bbits = (gstate.pmskc >> 16) & 0xFF;
			if ((rbits != 0 && rbits != 0xFF) || (gbits != 0 && gbits != 0xFF) || (bbits != 0 && bbits != 0xFF)) {
				WARN_LOG_REPORT_ONCE(rgbmask, G3D, "Unsupported RGB mask: r=%02x g=%02x b=%02x", rbits, gbits, bbits);
			}
			if (abits != 0 && abits != 0xFF) {
				// The stencil part of the mask is supported.
				WARN_LOG_REPORT_ONCE(amask, G3D, "Unsupported alpha/stencil mask: %02x", abits);
			}
#endif

			glstate.colorMask.set(rmask, gmask, bmask, amask);

#ifndef USING_GLES2
			if (gstate_c.Supports(GPU_SUPPORTS_LOGIC_OP)) {
				// TODO: Make this dynamic
				// Logic Ops
				if (gstate.isLogicOpEnabled() && gstate.getLogicOp() != GE_LOGIC_COPY) {
					glstate.colorLogicOp.enable();
					glstate.logicOp.set(logicOps[gstate.getLogicOp()]);
				} else {
					glstate.colorLogicOp.disable();
				}
			}
#endif
		}
	}

	{
		// Dither
		if (gstate.isDitherEnabled()) {
			glstate.dither.enable();
			glstate.dither.set(true);
		} else {
			glstate.dither.disable();
		}

		if (gstate.isModeClear()) {
			// Culling
			glstate.cullFace.disable();
		} else {
			// Set cull
			bool cullEnabled = !gstate.isModeThrough() && prim != GE_PRIM_RECTANGLES && gstate.isCullEnabled();
			if (cullEnabled) {
				glstate.cullFace.enable();
				glstate.cullFaceMode.set(cullingMode[gstate.getCullMode() ^ !useBufferedRendering]);
			} else {
				glstate.cullFace.disable();
			}
		}
	}

	if (gstate_c.IsDirty(DIRTY_DEPTHSTENCIL_STATE)) {
		gstate_c.Clean(DIRTY_DEPTHSTENCIL_STATE);
		bool enableStencilTest = !g_Config.bDisableStencilTest;
		if (gstate.isModeClear()) {
			// Depth Test
			glstate.depthTest.enable();
			glstate.depthFunc.set(GL_ALWAYS);
			glstate.depthWrite.set(gstate.isClearModeDepthMask() ? GL_TRUE : GL_FALSE);
			if (gstate.isClearModeDepthMask()) {
				framebufferManager_->SetDepthUpdated();
			}

			// Stencil Test
			if (gstate.isClearModeAlphaMask() && enableStencilTest) {
				glstate.stencilTest.enable();
				glstate.stencilOp.set(GL_REPLACE, GL_REPLACE, GL_REPLACE);
				// TODO: In clear mode, the stencil value is set to the alpha value of the vertex.
				// A normal clear will be 2 points, the second point has the color.
				// We should set "ref" to that value instead of 0.
				// In case of clear rectangles, we set it again once we know what the color is.
				glstate.stencilFunc.set(GL_ALWAYS, 255, 0xFF);
				glstate.stencilMask.set(0xFF);
			} else {
				glstate.stencilTest.disable();
			}
		} else {
			// Depth Test
			if (gstate.isDepthTestEnabled()) {
				glstate.depthTest.enable();
				glstate.depthFunc.set(compareOps[gstate.getDepthTestFunction()]);
				glstate.depthWrite.set(gstate.isDepthWriteEnabled() ? GL_TRUE : GL_FALSE);
				if (gstate.isDepthWriteEnabled()) {
					framebufferManager_->SetDepthUpdated();
				}
			} else {
				glstate.depthTest.disable();
			}

			GenericStencilFuncState stencilState;
			ConvertStencilFuncState(stencilState);

			// Stencil Test
			if (stencilState.enabled) {
				glstate.stencilTest.enable();
				glstate.stencilFunc.set(compareOps[stencilState.testFunc], stencilState.testRef, stencilState.testMask);
				glstate.stencilOp.set(stencilOps[stencilState.sFail], stencilOps[stencilState.zFail], stencilOps[stencilState.zPass]);
				glstate.stencilMask.set(stencilState.writeMask);
			} else {
				glstate.stencilTest.disable();
			}
		}
	}

	{
		ViewportAndScissor vpAndScissor;
		ConvertViewportAndScissor(useBufferedRendering,
			framebufferManager_->GetRenderWidth(), framebufferManager_->GetRenderHeight(),
			framebufferManager_->GetTargetBufferWidth(), framebufferManager_->GetTargetBufferHeight(),
			vpAndScissor);

		if (vpAndScissor.scissorEnable) {
			glstate.scissorTest.enable();
			if (!useBufferedRendering) {
				vpAndScissor.scissorY = PSP_CoreParameter().pixelHeight - vpAndScissor.scissorH - vpAndScissor.scissorY;
			}
			glstate.scissorRect.set(vpAndScissor.scissorX, vpAndScissor.scissorY, vpAndScissor.scissorW, vpAndScissor.scissorH);
		} else {
			glstate.scissorTest.disable();
		}

		if (!useBufferedRendering) {
			vpAndScissor.viewportY = PSP_CoreParameter().pixelHeight - vpAndScissor.viewportH - vpAndScissor.viewportY;
		}
		glstate.viewport.set(vpAndScissor.viewportX, vpAndScissor.viewportY, vpAndScissor.viewportW, vpAndScissor.viewportH);
		glstate.depthRange.set(vpAndScissor.depthRangeMin, vpAndScissor.depthRangeMax);

		if (vpAndScissor.dirtyProj) {
			gstate_c.Dirty(DIRTY_PROJMATRIX);
		}
		if (vpAndScissor.dirtyDepth) {
			gstate_c.Dirty(DIRTY_DEPTHRANGE);
		}
	}
	CHECK_GL_ERROR_IF_DEBUG();
}

void DrawEngineGLES::ApplyDrawStateLate() {
	// At this point, we know if the vertices are full alpha or not.
	// TODO: Set the nearest/linear here (since we correctly know if alpha/color tests are needed)?
	if (!gstate.isModeClear()) {
		if (fboTexNeedBind_) {
			CHECK_GL_ERROR_IF_DEBUG();
			// Note that this is positions, not UVs, that we need the copy from.
			framebufferManager_->BindFramebufferAsColorTexture(1, framebufferManager_->GetCurrentRenderVFB(), BINDFBCOLOR_MAY_COPY);
			framebufferManager_->RebindFramebuffer();
			CHECK_GL_ERROR_IF_DEBUG();

			glActiveTexture(GL_TEXTURE1);
			// If we are rendering at a higher resolution, linear is probably best for the dest color.
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
			glActiveTexture(GL_TEXTURE0);
			fboTexBound_ = true;
			fboTexNeedBind_ = false;
			CHECK_GL_ERROR_IF_DEBUG();
		}
		CHECK_GL_ERROR_IF_DEBUG();

		// Apply the texture after the FBO tex, since it might unbind the texture.
		// TODO: Could use a separate texture unit to be safer?
		textureCache_->ApplyTexture();
		CHECK_GL_ERROR_IF_DEBUG();

		// Apply last, once we know the alpha params of the texture.
		if (gstate.isAlphaTestEnabled() || gstate.isColorTestEnabled()) {
			fragmentTestCache_->BindTestTexture(GL_TEXTURE2);
		}
		CHECK_GL_ERROR_IF_DEBUG();
	}
}