// 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/.

#include <algorithm>

#include "Common/Data/Convert/ColorConv.h"
#include "Common/Profiler/Profiler.h"
#include "Common/GPU/OpenGL/GLCommon.h"
#include "Common/GPU/OpenGL/GLDebugLog.h"
#include "Common/GPU/OpenGL/GLSLProgram.h"
#include "Common/GPU/thin3d.h"
#include "Core/MemMap.h"
#include "Core/Config.h"
#include "Core/ConfigValues.h"
#include "Core/System.h"
#include "Core/Reporting.h"
#include "GPU/ge_constants.h"
#include "GPU/GPUState.h"
#include "GPU/Common/FramebufferManagerCommon.h"
#include "GPU/Common/PresentationCommon.h"
#include "GPU/Common/TextureDecoder.h"
#include "GPU/Debugger/Stepping.h"
#include "GPU/GLES/FramebufferManagerGLES.h"
#include "GPU/GLES/TextureCacheGLES.h"
#include "GPU/GLES/DrawEngineGLES.h"
#include "GPU/GLES/ShaderManagerGLES.h"

static const char tex_fs[] = R"(
#if __VERSION__ >= 130
#define varying in
#define texture2D texture
#define gl_FragColor fragColor0
out vec4 fragColor0;
#endif
#ifdef GL_ES
precision mediump float;
#endif
uniform sampler2D sampler0;
varying vec2 v_texcoord0;
void main() {
	gl_FragColor = texture2D(sampler0, v_texcoord0);
}
)";

static const char basic_vs[] = R"(
#if __VERSION__ >= 130
#define attribute in
#define varying out
#endif
attribute vec4 a_position;
attribute vec2 a_texcoord0;
varying vec2 v_texcoord0;
void main() {
  v_texcoord0 = a_texcoord0;
  gl_Position = a_position;
}
)";

void FramebufferManagerGLES::CompileDraw2DProgram() {
	if (!draw2dprogram_) {
		std::string errorString;
		static std::string vs_code, fs_code;
		vs_code = ApplyGLSLPrelude(basic_vs, GL_VERTEX_SHADER);
		fs_code = ApplyGLSLPrelude(tex_fs, GL_FRAGMENT_SHADER);
		std::vector<GLRShader *> shaders;
		shaders.push_back(render_->CreateShader(GL_VERTEX_SHADER, vs_code, "draw2d"));
		shaders.push_back(render_->CreateShader(GL_FRAGMENT_SHADER, fs_code, "draw2d"));

		std::vector<GLRProgram::UniformLocQuery> queries;
		queries.push_back({ &u_draw2d_tex, "u_tex" });
		std::vector<GLRProgram::Initializer> initializers;
		initializers.push_back({ &u_draw2d_tex, 0 });
		std::vector<GLRProgram::Semantic> semantics;
		semantics.push_back({ 0, "a_position" });
		semantics.push_back({ 1, "a_texcoord0" });
		draw2dprogram_ = render_->CreateProgram(shaders, semantics, queries, initializers, false, false);
		for (auto shader : shaders)
			render_->DeleteShader(shader);
	}
}

void FramebufferManagerGLES::Bind2DShader() {
	render_->BindProgram(draw2dprogram_);
}

FramebufferManagerGLES::FramebufferManagerGLES(Draw::DrawContext *draw, GLRenderManager *render) :
	FramebufferManagerCommon(draw),
	render_(render)
{
	needBackBufferYSwap_ = true;
	needGLESRebinds_ = true;
	presentation_->SetLanguage(draw_->GetShaderLanguageDesc().shaderLanguage);
	CreateDeviceObjects();
}

void FramebufferManagerGLES::Init() {
	FramebufferManagerCommon::Init();
	CompileDraw2DProgram();
}

void FramebufferManagerGLES::SetTextureCache(TextureCacheGLES *tc) {
	textureCache_ = tc;
}

void FramebufferManagerGLES::SetShaderManager(ShaderManagerGLES *sm) {
	shaderManager_ = sm;
}

void FramebufferManagerGLES::SetDrawEngine(DrawEngineGLES *td) {
	drawEngineGL_ = td;
	drawEngine_ = td;
}

void FramebufferManagerGLES::CreateDeviceObjects() {
	CompileDraw2DProgram();

	std::vector<GLRInputLayout::Entry> entries;
	entries.push_back({ 0, 3, GL_FLOAT, GL_FALSE, sizeof(Simple2DVertex), offsetof(Simple2DVertex, pos) });
	entries.push_back({ 1, 2, GL_FLOAT, GL_FALSE, sizeof(Simple2DVertex), offsetof(Simple2DVertex, uv) });
	simple2DInputLayout_ = render_->CreateInputLayout(entries);
}

void FramebufferManagerGLES::DestroyDeviceObjects() {
	if (simple2DInputLayout_) {
		render_->DeleteInputLayout(simple2DInputLayout_);
		simple2DInputLayout_ = nullptr;
	}

	if (draw2dprogram_) {
		render_->DeleteProgram(draw2dprogram_);
		draw2dprogram_ = nullptr;
	}

	if (stencilUploadPipeline_) {
		stencilUploadPipeline_->Release();
		stencilUploadPipeline_ = nullptr;
	}

	if (depthDownloadProgram_) {
		render_->DeleteProgram(depthDownloadProgram_);
		depthDownloadProgram_ = nullptr;
	}
}

FramebufferManagerGLES::~FramebufferManagerGLES() {
	DestroyDeviceObjects();

	delete [] convBuf_;
}

void FramebufferManagerGLES::UpdateDownloadTempBuffer(VirtualFramebuffer *nvfb) {
	_assert_msg_(nvfb->fbo, "Expecting a valid nvfb in UpdateDownloadTempBuffer");

	// Discard the previous contents of this buffer where possible.
	if (gl_extensions.GLES3) {
		draw_->BindFramebufferAsRenderTarget(nvfb->fbo, { Draw::RPAction::DONT_CARE, Draw::RPAction::DONT_CARE, Draw::RPAction::DONT_CARE }, "UpdateDownloadTempBuffer");
	} else if (gl_extensions.IsGLES) {
		draw_->BindFramebufferAsRenderTarget(nvfb->fbo, { Draw::RPAction::CLEAR, Draw::RPAction::CLEAR, Draw::RPAction::CLEAR }, "UpdateDownloadTempBuffer");
		gstate_c.Dirty(DIRTY_BLEND_STATE);
	}
}

void FramebufferManagerGLES::BlitFramebuffer(VirtualFramebuffer *dst, int dstX, int dstY, VirtualFramebuffer *src, int srcX, int srcY, int w, int h, int bpp, const char *tag) {
	if (!dst->fbo || !src->fbo || !useBufferedRendering_) {
		// This can happen if they recently switched from non-buffered.
		if (useBufferedRendering_)
			draw_->BindFramebufferAsRenderTarget(nullptr, { Draw::RPAction::KEEP, Draw::RPAction::KEEP, Draw::RPAction::KEEP }, "BlitFramebuffer");
		return;
	}

	bool useBlit = draw_->GetDeviceCaps().framebufferBlitSupported;
	bool useCopy = draw_->GetDeviceCaps().framebufferCopySupported;
	if (dst == currentRenderVfb_) {
		// If already bound, using either a blit or a copy is unlikely to be an optimization.
		useBlit = false;
		useCopy = false;
	}

	float srcXFactor = useBlit ? src->renderScaleFactor : 1.0f;
	float srcYFactor = useBlit ? src->renderScaleFactor : 1.0f;
	const int srcBpp = src->format == GE_FORMAT_8888 ? 4 : 2;
	if (srcBpp != bpp && bpp != 0) {
		srcXFactor = (srcXFactor * bpp) / srcBpp;
	}
	int srcX1 = srcX * srcXFactor;
	int srcX2 = (srcX + w) * srcXFactor;
	int srcY1 = srcY * srcYFactor;
	int srcY2 = (srcY + h) * srcYFactor;

	float dstXFactor = useBlit ? dst->renderScaleFactor : 1.0f;
	float dstYFactor = useBlit ? dst->renderScaleFactor : 1.0f;
	const int dstBpp = dst->format == GE_FORMAT_8888 ? 4 : 2;
	if (dstBpp != bpp && bpp != 0) {
		dstXFactor = (dstXFactor * bpp) / dstBpp;
	}
	int dstX1 = dstX * dstXFactor;
	int dstX2 = (dstX + w) * dstXFactor;
	int dstY1 = dstY * dstYFactor;
	int dstY2 = (dstY + h) * dstYFactor;

	if (src == dst && srcX == dstX && srcY == dstY) {
		// Let's just skip a copy where the destination is equal to the source.
		WARN_LOG_REPORT_ONCE(blitSame, G3D, "Skipped blit with equal dst and src");
		return;
	}

	if (useCopy && draw_->GetDeviceCaps().framebufferCopySupported) {
		// glBlitFramebuffer can clip, but glCopyImageSubData is more restricted.
		// In case the src goes outside, we just skip the optimization in that case.
		const bool sameSize = dstX2 - dstX1 == srcX2 - srcX1 && dstY2 - dstY1 == srcY2 - srcY1;
		const bool srcInsideBounds = srcX2 <= src->renderWidth && srcY2 <= src->renderHeight;
		const bool dstInsideBounds = dstX2 <= dst->renderWidth && dstY2 <= dst->renderHeight;
		const bool xOverlap = src == dst && srcX2 > dstX1 && srcX1 < dstX2;
		const bool yOverlap = src == dst && srcY2 > dstY1 && srcY1 < dstY2;
		if (sameSize && srcInsideBounds && dstInsideBounds && !(xOverlap && yOverlap)) {
			draw_->CopyFramebufferImage(src->fbo, 0, srcX1, srcY1, 0, dst->fbo, 0, dstX1, dstY1, 0, dstX2 - dstX1, dstY2 - dstY1, 1, Draw::FB_COLOR_BIT, tag);
			return;
		}
	}

	if (useBlit) {
		draw_->BlitFramebuffer(src->fbo, srcX1, srcY1, srcX2, srcY2, dst->fbo, dstX1, dstY1, dstX2, dstY2, Draw::FB_COLOR_BIT, Draw::FB_BLIT_NEAREST, tag);
	} else {
		// TODO: Use thin3d for this, instead of dirtying up the code here.
		draw_->BindFramebufferAsRenderTarget(dst->fbo, { Draw::RPAction::KEEP, Draw::RPAction::KEEP, Draw::RPAction::KEEP }, tag);
		draw_->BindFramebufferAsTexture(src->fbo, 0, Draw::FB_COLOR_BIT, 0);

		// Make sure our 2D drawing program is ready. Compiles only if not already compiled.
		CompileDraw2DProgram();

		render_->SetViewport({ 0, 0, (float)dst->renderWidth, (float)dst->renderHeight, 0, 1.0f });
		render_->SetStencilDisabled();
		render_->SetDepth(false, false, GL_ALWAYS);
		render_->SetNoBlendAndMask(0xF);

		// The first four coordinates are relative to the 6th and 7th arguments of DrawActiveTexture.
		// Should maybe revamp that interface.
		float srcW = src->bufferWidth;
		float srcH = src->bufferHeight;
		render_->BindProgram(draw2dprogram_);
		DrawActiveTexture(dstX1, dstY1, w * dstXFactor, h * dstYFactor, dst->bufferWidth, dst->bufferHeight, srcX1 / srcW, srcY1 / srcH, srcX2 / srcW, srcY2 / srcH, ROTATION_LOCKED_HORIZONTAL, DRAWTEX_NEAREST);
		textureCache_->ForgetLastTexture();
	}

	gstate_c.Dirty(DIRTY_VIEWPORTSCISSOR_STATE | DIRTY_BLEND_STATE | DIRTY_RASTER_STATE);
}

void FramebufferManagerGLES::EndFrame() {
}

void FramebufferManagerGLES::DeviceLost() {
	FramebufferManagerCommon::DeviceLost();
	DestroyDeviceObjects();
}

void FramebufferManagerGLES::DeviceRestore(Draw::DrawContext *draw) {
	FramebufferManagerCommon::DeviceRestore(draw);
	render_ = (GLRenderManager *)draw_->GetNativeObject(Draw::NativeObject::RENDER_MANAGER);
	CreateDeviceObjects();
}

void FramebufferManagerGLES::Resized() {
	FramebufferManagerCommon::Resized();

	render_->Resize(PSP_CoreParameter().pixelWidth, PSP_CoreParameter().pixelHeight);
}

bool FramebufferManagerGLES::GetOutputFramebuffer(GPUDebugBuffer &buffer) {
	int w, h;
	draw_->GetFramebufferDimensions(nullptr, &w, &h);
	buffer.Allocate(w, h, GPU_DBG_FORMAT_888_RGB, true);
	draw_->CopyFramebufferToMemorySync(nullptr, Draw::FB_COLOR_BIT, 0, 0, w, h, Draw::DataFormat::R8G8B8_UNORM, buffer.GetData(), w, "GetOutputFramebuffer");
	return true;
}