#include <stdio.h>
#include <vector>
#include <string>
#include <map>

#include "base/logging.h"
#include "image/zim_load.h"
#include "math/dataconv.h"
#include "math/lin/matrix4x4.h"
#include "thin3d/thin3d.h"
#include "gfx/gl_common.h"
#include "gfx_es2/gpu_features.h"
#include "gfx/gl_lost_manager.h"

namespace Draw {

static const unsigned short compToGL[] = {
	GL_NEVER,
	GL_LESS,
	GL_EQUAL,
	GL_LEQUAL,
	GL_GREATER,
	GL_NOTEQUAL,
	GL_GEQUAL,
	GL_ALWAYS
};

static const unsigned short blendEqToGL[] = {
	GL_FUNC_ADD,
	GL_FUNC_SUBTRACT,
	GL_FUNC_REVERSE_SUBTRACT,
};

static const unsigned short blendFactorToGL[] = {
	GL_ZERO,
	GL_ONE,
	GL_SRC_COLOR,
	GL_SRC_ALPHA,
	GL_ONE_MINUS_SRC_COLOR,
	GL_ONE_MINUS_SRC_ALPHA,
	GL_DST_COLOR,
	GL_DST_ALPHA,
	GL_ONE_MINUS_DST_COLOR,
	GL_ONE_MINUS_DST_ALPHA,
	GL_CONSTANT_COLOR,
};

static const unsigned short texWrapToGL[] = {
	GL_REPEAT,
	GL_CLAMP_TO_EDGE,
};

static const unsigned short texFilterToGL[] = {
	GL_NEAREST,
	GL_LINEAR,
};

static const unsigned short texMipFilterToGL[2][2] = {
	// Min nearest:
	{ GL_NEAREST_MIPMAP_NEAREST, GL_NEAREST_MIPMAP_LINEAR },
	// Min linear:
	{ GL_LINEAR_MIPMAP_NEAREST, GL_LINEAR_MIPMAP_LINEAR },
};

#ifndef USING_GLES2
static const unsigned short logicOpToGL[] = {
	GL_CLEAR,
	GL_SET,
	GL_COPY,
	GL_COPY_INVERTED,
	GL_NOOP,
	GL_INVERT,
	GL_AND,
	GL_NAND,
	GL_OR,
	GL_NOR,
	GL_XOR,
	GL_EQUIV,
	GL_AND_REVERSE,
	GL_AND_INVERTED,
	GL_OR_REVERSE,
	GL_OR_INVERTED,
};
#endif

inline GLuint PrimToGL(Primitive prim) {
	switch (prim) {
	case Primitive::POINT_LIST: return GL_POINTS;
	case Primitive::LINE_LIST: return GL_LINES;
	case Primitive::LINE_LIST_ADJ: return GL_LINES_ADJACENCY;
	case Primitive::LINE_STRIP: return GL_LINE_STRIP;
	case Primitive::LINE_STRIP_ADJ: return GL_LINE_STRIP_ADJACENCY;
	case Primitive::TRIANGLE_LIST: return GL_TRIANGLES;
	case Primitive::TRIANGLE_LIST_ADJ: return GL_TRIANGLES_ADJACENCY;
	case Primitive::TRIANGLE_STRIP: return GL_TRIANGLE_STRIP;
	case Primitive::TRIANGLE_STRIP_ADJ: return GL_TRIANGLES_ADJACENCY;
	case Primitive::TRIANGLE_FAN: return GL_TRIANGLE_FAN;
	case Primitive::PATCH_LIST: return GL_PATCHES;
	default: return GL_POINTS;
	}
}
static const unsigned short primToGL[] = {
	GL_POINTS,
	GL_LINES,
	GL_TRIANGLES,
};

static const char *glsl_fragment_prelude =
"#ifdef GL_ES\n"
"precision mediump float;\n"
"#endif\n";

class Thin3DGLBlendState : public BlendState {
public:
	bool enabled;
	GLuint eqCol, eqAlpha;
	GLuint srcCol, srcAlpha, dstCol, dstAlpha;
	bool logicEnabled;
	GLuint logicOp;
	// int maskBits;
	// uint32_t fixedColor;

	void Apply() {
		if (enabled) {
			glEnable(GL_BLEND);
			glBlendEquationSeparate(eqCol, eqAlpha);
			glBlendFuncSeparate(srcCol, dstCol, srcAlpha, dstAlpha);
		} else {
			glDisable(GL_BLEND);
		}
		glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
		// glColorMask(maskBits & 1, (maskBits >> 1) & 1, (maskBits >> 2) & 1, (maskBits >> 3) & 1);
		// glBlendColor(fixedColor);
		
#if !defined(USING_GLES2)
		if (logicEnabled) {
			glEnable(GL_COLOR_LOGIC_OP);
			glLogicOp(logicOp);
		} else {
			glDisable(GL_COLOR_LOGIC_OP);
		}
#endif
	}
};

class Thin3DGLSamplerState : public SamplerState {
public:
	GLint wrapS;
	GLint wrapT;
	GLint magFilt;
	GLint minFilt;
	GLint mipMinFilt;

	void Apply(bool hasMips, bool canWrap) {
		if (canWrap) {
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrapS);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrapT);
		} else {
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
		}

		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, magFilt);
		if (hasMips) {
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, mipMinFilt);
		} else {
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, minFilt);
		}
	}
};

class Thin3DGLDepthStencilState : public DepthStencilState {
public:
	bool depthTestEnabled;
	bool depthWriteEnabled;
	GLuint depthComp;
	// bool stencilTestEnabled; TODO

	void Apply() {
		if (depthTestEnabled) {
			glEnable(GL_DEPTH_TEST);
			glDepthFunc(depthComp);
			glDepthMask(depthWriteEnabled);
		} else {
			glDisable(GL_DEPTH_TEST);
		}
		glDisable(GL_STENCIL_TEST);
	}
};

class Thin3DGLRasterState : public RasterState {
public:
	void Apply() {
		if (!cullEnable) {
			glDisable(GL_CULL_FACE);
			return;
		}
		glEnable(GL_CULL_FACE);
		glFrontFace(frontFace);
		glCullFace(cullMode);
	}

	GLboolean cullEnable;
	GLenum cullMode;
	GLenum frontFace;
};

class Thin3DGLBuffer : public Buffer, GfxResourceHolder {
public:
	Thin3DGLBuffer(size_t size, uint32_t flags) {
		glGenBuffers(1, &buffer_);
		target_ = (flags & BufferUsageFlag::INDEXDATA) ? GL_ELEMENT_ARRAY_BUFFER : GL_ARRAY_BUFFER;
		usage_ = 0;
		if (flags & BufferUsageFlag::DYNAMIC)
			usage_ = GL_STREAM_DRAW;
		else
			usage_ = GL_STATIC_DRAW;
		knownSize_ = 0;
		register_gl_resource_holder(this);
	}
	~Thin3DGLBuffer() override {
		unregister_gl_resource_holder(this);
		glDeleteBuffers(1, &buffer_);
	}

	void SetData(const uint8_t *data, size_t size) override {
		Bind();
		glBufferData(target_, size, data, usage_);
		knownSize_ = size;
	}

	void SubData(const uint8_t *data, size_t offset, size_t size) override {
		Bind();
		if (size + offset > knownSize_) {
			// Allocate the buffer.
			glBufferData(target_, size + offset, NULL, usage_);
			knownSize_ = size + offset;
		}
		glBufferSubData(target_, offset, size, data);
	}
	void Bind() {
		glBindBuffer(target_, buffer_);
	}

	void GLLost() override {
		buffer_ = 0;
	}

	void GLRestore() override {
		ILOG("Recreating vertex buffer after gl_restore");
		knownSize_ = 0;  // Will cause a new glBufferData call. Should genBuffers again though?
		glGenBuffers(1, &buffer_);
	}

private:
	GLuint buffer_;
	GLuint target_;
	GLuint usage_;

	size_t knownSize_;
};

// Not registering this as a resource holder, instead ShaderSet is registered. It will
// invoke Compile again to recreate the shader then link them together.
class Thin3DGLShader : public Shader {
public:
	Thin3DGLShader(ShaderStage stage) : shader_(0), type_(0) {
		type_ = stage == ShaderStage::FRAGMENT ? GL_FRAGMENT_SHADER : GL_VERTEX_SHADER;
	}

	bool Compile(const char *source);
	GLuint GetShader() const {
		return shader_;
	}
	const std::string &GetSource() const { return source_; }

	void Unset() {
		shader_ = 0;
	}

	~Thin3DGLShader() {
		glDeleteShader(shader_);
	}

private:
	GLuint shader_;
	GLuint type_;
	bool ok_;
	std::string source_;  // So we can recompile in case of context loss.
};

bool Thin3DGLShader::Compile(const char *source) {
	source_ = source;
	shader_ = glCreateShader(type_);

	std::string temp;
	// Add the prelude on automatically for fragment shaders.
	if (type_ == GL_FRAGMENT_SHADER) {
		temp = std::string(glsl_fragment_prelude) + source;
		source = temp.c_str();
	}

	glShaderSource(shader_, 1, &source, nullptr);
	glCompileShader(shader_);
	GLint success = 0;
	glGetShaderiv(shader_, GL_COMPILE_STATUS, &success);
	if (!success) {
#define MAX_INFO_LOG_SIZE 2048
		GLchar infoLog[MAX_INFO_LOG_SIZE];
		GLsizei len = 0;
		glGetShaderInfoLog(shader_, MAX_INFO_LOG_SIZE, &len, infoLog);
		infoLog[len] = '\0';
		glDeleteShader(shader_);
		shader_ = 0;
		ILOG("%s Shader compile error:\n%s", type_ == GL_FRAGMENT_SHADER ? "Fragment" : "Vertex", infoLog);
	}
	ok_ = success != 0;
	return ok_;
}

class Thin3DGLVertexFormat : public Thin3DVertexFormat, GfxResourceHolder {
public:
	~Thin3DGLVertexFormat();

	void Apply(const void *base = nullptr);
	void Unapply();
	void Compile();
	void GLRestore() override;
	void GLLost() override;
	bool RequiresBuffer() override {
		return id_ != 0;
	}

	std::vector<VertexComponent> components_;
	int semanticsMask_;  // Fast way to check what semantics to enable/disable.
	int stride_;
	GLuint id_;
	bool needsEnable_;
	intptr_t lastBase_;
};

struct UniformInfo {
	int loc_;
};

// TODO: Fold BlendState into this? Seems likely to be right for DX12 etc.
// TODO: Add Uniform Buffer support.
class Thin3DGLShaderSet : public ShaderSet, GfxResourceHolder {
public:
	Thin3DGLShaderSet() {
		program_ = 0;
		register_gl_resource_holder(this);
	}
	~Thin3DGLShaderSet() {
		unregister_gl_resource_holder(this);
		vshader->Release();
		fshader->Release();
		glDeleteProgram(program_);
	}
	bool Link();

	void Apply();
	void Unapply();

	int GetUniformLoc(const char *name);

	void SetVector(const char *name, float *value, int n) override;
	void SetMatrix4x4(const char *name, const float value[16]) override;

	void GLLost() override {
		program_ = 0;
		vshader->Unset();
		fshader->Unset();
	}

	void GLRestore() override {
		vshader->Compile(vshader->GetSource().c_str());
		fshader->Compile(fshader->GetSource().c_str());
		Link();
	}

	Thin3DGLShader *vshader;
	Thin3DGLShader *fshader;

private:
	GLuint program_;
	std::map<std::string, UniformInfo> uniforms_;
};

class Thin3DGLContext : public Thin3DContext {
public:
	Thin3DGLContext();
	virtual ~Thin3DGLContext();

	DepthStencilState *CreateDepthStencilState(bool depthTestEnabled, bool depthWriteEnabled, Comparison depthCompare) override;
	BlendState *CreateBlendState(const BlendStateDesc &desc) override;
	SamplerState *CreateSamplerState(const SamplerStateDesc &desc) override;
	RasterState *CreateRasterState(const T3DRasterStateDesc &desc) override;
	Buffer *CreateBuffer(size_t size, uint32_t usageFlags) override;
	ShaderSet *CreateShaderSet(Shader *vshader, Shader *fshader) override;
	Thin3DVertexFormat *CreateVertexFormat(const std::vector<VertexComponent> &components, int stride, Shader *vshader) override;
	Texture *CreateTexture(TextureType type, DataFormat format, int width, int height, int depth, int mipLevels) override;
	Texture *CreateTexture() override;

	// Bound state objects
	void SetBlendState(BlendState *state) override {
		Thin3DGLBlendState *s = static_cast<Thin3DGLBlendState *>(state);
		s->Apply();
	}

	void SetSamplerStates(int start, int count, SamplerState **states) override {
		if (samplerStates_.size() < (size_t)(start + count)) {
			samplerStates_.resize(start + count);
		}
		for (int i = 0; i < count; ++i) {
			int index = i + start;
			Thin3DGLSamplerState *s = static_cast<Thin3DGLSamplerState *>(states[index]);

			if (samplerStates_[index]) {
				samplerStates_[index]->Release();
			}
			samplerStates_[index] = s;
			samplerStates_[index]->AddRef();

			// TODO: Ideally, get these from the texture and apply on the right stage?
			if (index == 0) {
				s->Apply(false, true);
			}
		}

	}

	// Bound state objects
	void SetDepthStencilState(DepthStencilState *state) override {
		Thin3DGLDepthStencilState *s = static_cast<Thin3DGLDepthStencilState *>(state);
		s->Apply();
	}

	void SetRasterState(RasterState *state) override {
		Thin3DGLRasterState *rs = static_cast<Thin3DGLRasterState *>(state);
		rs->Apply();
	}

	Shader *CreateShader(ShaderStage stage, const char *glsl_source, const char *hlsl_source, const char *vulkan_source) override;

	void SetScissorEnabled(bool enable) override {
		if (enable) {
			glEnable(GL_SCISSOR_TEST);
		} else {
			glDisable(GL_SCISSOR_TEST);
		}
	}

	void SetScissorRect(int left, int top, int width, int height) override {
		glScissor(left, targetHeight_ - (top + height), width, height);
	}

	void SetViewports(int count, Viewport *viewports) override {
		// TODO: Add support for multiple viewports.
		glViewport(viewports[0].TopLeftX, viewports[0].TopLeftY, viewports[0].Width, viewports[0].Height);
#if defined(USING_GLES2)
		glDepthRangef(viewports[0].MinDepth, viewports[0].MaxDepth);
#else
		glDepthRange(viewports[0].MinDepth, viewports[0].MaxDepth);
#endif
	}

	void BindTextures(int start, int count, Texture **textures) override;

	// TODO: Add more sophisticated draws.
	void Draw(Primitive prim, ShaderSet *shaderSet, Thin3DVertexFormat *format, Buffer *vdata, int vertexCount, int offset) override;
	void DrawIndexed(Primitive prim, ShaderSet *shaderSet, Thin3DVertexFormat *format, Buffer *vdata, Buffer *idata, int vertexCount, int offset) override;
	void DrawUP(Primitive prim, ShaderSet *shaderSet, Thin3DVertexFormat *format, const void *vdata, int vertexCount) override;
	void Clear(int mask, uint32_t colorval, float depthVal, int stencilVal) override;

	std::string GetInfoString(InfoField info) const override {
		// TODO: Make these actually query the right information
		switch (info) {
			case APINAME:
				if (gl_extensions.IsGLES) {
					return "OpenGL ES";
				} else {
					return "OpenGL";
				}
			case VENDORSTRING: return (const char *)glGetString(GL_VENDOR);
			case VENDOR:
				switch (gl_extensions.gpuVendor) {
				case GPU_VENDOR_AMD: return "VENDOR_AMD";
				case GPU_VENDOR_POWERVR: return "VENDOR_POWERVR";
				case GPU_VENDOR_NVIDIA: return "VENDOR_NVIDIA";
				case GPU_VENDOR_INTEL: return "VENDOR_INTEL";
				case GPU_VENDOR_ADRENO: return "VENDOR_ADRENO";
				case GPU_VENDOR_ARM: return "VENDOR_ARM";
				case GPU_VENDOR_BROADCOM: return "VENDOR_BROADCOM";
				case GPU_VENDOR_UNKNOWN:
				default:
					return "VENDOR_UNKNOWN";
				}
				break;
			case RENDERER: return (const char *)glGetString(GL_RENDERER);
			case SHADELANGVERSION: return (const char *)glGetString(GL_SHADING_LANGUAGE_VERSION);
			case APIVERSION: return (const char *)glGetString(GL_VERSION);
			default: return "?";
		}
	}

	std::vector<Thin3DGLSamplerState *> samplerStates_;
};

Thin3DGLContext::Thin3DGLContext() {
	CreatePresets();
}

Thin3DGLContext::~Thin3DGLContext() {
	for (Thin3DGLSamplerState *s : samplerStates_) {
		if (s) {
			s->Release();
		}
	}
	samplerStates_.clear();
}

Thin3DVertexFormat *Thin3DGLContext::CreateVertexFormat(const std::vector<VertexComponent> &components, int stride, Shader *vshader) {
	Thin3DGLVertexFormat *fmt = new Thin3DGLVertexFormat();
	fmt->components_ = components;
	fmt->stride_ = stride;
	fmt->Compile();
	return fmt;
}

GLuint TypeToTarget(TextureType type) {
	switch (type) {
#ifndef USING_GLES2
	case LINEAR1D: return GL_TEXTURE_1D;
#endif
	case LINEAR2D: return GL_TEXTURE_2D;
	case LINEAR3D: return GL_TEXTURE_3D;
	case CUBE: return GL_TEXTURE_CUBE_MAP;
#ifndef USING_GLES2
	case ARRAY1D: return GL_TEXTURE_1D_ARRAY;
#endif
	case ARRAY2D: return GL_TEXTURE_2D_ARRAY;
	default: return GL_NONE;
	}
}

class Thin3DGLTexture : public Texture, GfxResourceHolder {
public:
	Thin3DGLTexture() : tex_(0), target_(0) {
		generatedMips_ = false;
		canWrap_ = true;
		width_ = 0;
		height_ = 0;
		depth_ = 0;
		glGenTextures(1, &tex_);
		register_gl_resource_holder(this);
	}
	Thin3DGLTexture(TextureType type, DataFormat format, int width, int height, int depth, int mipLevels) : tex_(0), target_(TypeToTarget(type)), format_(format), mipLevels_(mipLevels) {
		generatedMips_ = false;
		canWrap_ = true;
		width_ = width;
		height_ = height;
		depth_ = depth;
		glGenTextures(1, &tex_);
		register_gl_resource_holder(this);
	}
	~Thin3DGLTexture() {
		unregister_gl_resource_holder(this);
		Destroy();
	}

	bool Create(TextureType type, DataFormat format, int width, int height, int depth, int mipLevels) override {
		generatedMips_ = false;
		canWrap_ = true;
		format_ = format;
		target_ = TypeToTarget(type);
		mipLevels_ = mipLevels;
		width_ = width;
		height_ = height;
		depth_ = depth;
		return true;
	}

	void Destroy() {
		if (tex_) {
			glDeleteTextures(1, &tex_);
			tex_ = 0;
			generatedMips_ = false;
		}
	}
	void SetImageData(int x, int y, int z, int width, int height, int depth, int level, int stride, const uint8_t *data) override;
	void AutoGenMipmaps() override;

	bool HasMips() {
		return mipLevels_ > 1 || generatedMips_;
	}
	bool CanWrap() {
		return canWrap_;
	}

	void Bind() {
		glBindTexture(target_, tex_);
	}

	void GLLost() override {
		// We can assume that the texture is gone.
		tex_ = 0;
		generatedMips_ = false;
	}

	void GLRestore() override {
		if (!filename_.empty()) {
			if (LoadFromFile(filename_.c_str())) {
				ILOG("Reloaded lost texture %s", filename_.c_str());
			} else {
				ELOG("Failed to reload lost texture %s", filename_.c_str());
				tex_ = 0;
			}
		} else {
			WLOG("Texture %p cannot be restored - has no filename", this);
			tex_ = 0;
		}
	}

	void Finalize(int zim_flags) override;

private:
	GLuint tex_;
	GLuint target_;

	DataFormat format_;
	int mipLevels_;
	bool generatedMips_;
	bool canWrap_;
};

Texture *Thin3DGLContext::CreateTexture() {
	return new Thin3DGLTexture();
}

Texture *Thin3DGLContext::CreateTexture(TextureType type, DataFormat format, int width, int height, int depth, int mipLevels) {
	return new Thin3DGLTexture(type, format, width, height, depth, mipLevels);
}

void Thin3DGLTexture::AutoGenMipmaps() {
	if (!generatedMips_) {
		Bind();
		glGenerateMipmap(target_);
		// TODO: Really, this should follow the sampler state.
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
		generatedMips_ = true;
	}
}

void Thin3DGLTexture::SetImageData(int x, int y, int z, int width, int height, int depth, int level, int stride, const uint8_t *data) {
	int internalFormat;
	int format;
	int type;
	switch (format_) {
	case DataFormat::R8A8G8B8_UNORM:
		internalFormat = GL_RGBA;
		format = GL_RGBA;
		type = GL_UNSIGNED_BYTE;
		break;
	case DataFormat::R4G4B4A4_UNORM:
		internalFormat = GL_RGBA;
		format = GL_RGBA;
		type = GL_UNSIGNED_SHORT_4_4_4_4;
		break;
	default:
		return;
	}
	if (level == 0) {
		width_ = width;
		height_ = height;
		depth_ = depth;
	}

	Bind();
	switch (target_) {
	case GL_TEXTURE_2D:
		glTexImage2D(GL_TEXTURE_2D, level, internalFormat, width_, height_, 0, format, type, data);
		break;
	default:
		ELOG("Thin3D GL: Targets other than GL_TEXTURE_2D not yet supported");
		break;
	}
}

bool isPowerOf2(int n) {
	return n == 1 || (n & (n - 1)) == 0;
}

void Thin3DGLTexture::Finalize(int zim_flags) {
	canWrap_ = (zim_flags & ZIM_CLAMP) || !isPowerOf2(width_) || !isPowerOf2(height_);
}


Thin3DGLVertexFormat::~Thin3DGLVertexFormat() {
	if (id_) {
		glDeleteVertexArrays(1, &id_);
	}
}

void Thin3DGLVertexFormat::Compile() {
	int sem = 0;
	for (int i = 0; i < (int)components_.size(); i++) {
		sem |= 1 << components_[i].semantic;
	}
	semanticsMask_ = sem;
	// TODO : Compute stride as well?

	if (gl_extensions.ARB_vertex_array_object && gl_extensions.IsCoreContext) {
		glGenVertexArrays(1, &id_);
	} else {
		id_ = 0;
	}
	needsEnable_ = true;
	lastBase_ = -1;
}

void Thin3DGLVertexFormat::GLLost() {
	id_ = 0;
}

void Thin3DGLVertexFormat::GLRestore() {
	Compile();
}

DepthStencilState *Thin3DGLContext::CreateDepthStencilState(bool depthTestEnabled, bool depthWriteEnabled, Comparison depthCompare) {
	Thin3DGLDepthStencilState *ds = new Thin3DGLDepthStencilState();
	ds->depthTestEnabled = depthTestEnabled;
	ds->depthWriteEnabled = depthWriteEnabled;
	ds->depthComp = compToGL[depthCompare];
	return ds;
}

BlendState *Thin3DGLContext::CreateBlendState(const BlendStateDesc &desc) {
	Thin3DGLBlendState *bs = new Thin3DGLBlendState();
	bs->enabled = desc.enabled;
	bs->eqCol = blendEqToGL[desc.eqCol];
	bs->srcCol = blendFactorToGL[desc.srcCol];
	bs->dstCol = blendFactorToGL[desc.dstCol];
	bs->eqAlpha = blendEqToGL[desc.eqAlpha];
	bs->srcAlpha = blendFactorToGL[desc.srcAlpha];
	bs->dstAlpha = blendFactorToGL[desc.dstAlpha];
#ifndef USING_GLES2
	bs->logicEnabled = desc.logicEnabled;
	bs->logicOp = logicOpToGL[(int)desc.logicOp];
#endif
	return bs;
}

SamplerState *Thin3DGLContext::CreateSamplerState(const SamplerStateDesc &desc) {
	Thin3DGLSamplerState *samps = new Thin3DGLSamplerState();
	samps->wrapS = texWrapToGL[(int)desc.wrapS];
	samps->wrapT = texWrapToGL[(int)desc.wrapT];
	samps->magFilt = texFilterToGL[(int)desc.magFilt];
	samps->minFilt = texFilterToGL[(int)desc.minFilt];
	samps->mipMinFilt = texMipFilterToGL[(int)desc.minFilt][(int)desc.mipFilt];
	return samps;
}

RasterState *Thin3DGLContext::CreateRasterState(const T3DRasterStateDesc &desc) {
	Thin3DGLRasterState *rs = new Thin3DGLRasterState();
	if (desc.cull == CullMode::NONE) {
		rs->cullEnable = GL_FALSE;
		return rs;
	}
	rs->cullEnable = GL_TRUE;
	switch (desc.facing) {
	case Facing::CW:
		rs->frontFace = GL_CW;
		break;
	case Facing::CCW:
		rs->frontFace = GL_CCW;
		break;
	}
	switch (desc.cull) {
	case CullMode::FRONT:
		rs->cullMode = GL_FRONT;
		break;
	case CullMode::BACK:
		rs->cullMode = GL_BACK;
		break;
	case CullMode::FRONT_AND_BACK:
		rs->cullMode = GL_FRONT_AND_BACK;
		break;
	}
	return rs;
}

Buffer *Thin3DGLContext::CreateBuffer(size_t size, uint32_t usageFlags) {
	return new Thin3DGLBuffer(size, usageFlags);
}

ShaderSet *Thin3DGLContext::CreateShaderSet(Shader *vshader, Shader *fshader) {
	if (!vshader || !fshader) {
		ELOG("ShaderSet requires both a valid vertex and a fragment shader: %p %p", vshader, fshader);
		return NULL;
	}
	Thin3DGLShaderSet *shaderSet = new Thin3DGLShaderSet();
	vshader->AddRef();
	fshader->AddRef();
	shaderSet->vshader = static_cast<Thin3DGLShader *>(vshader);
	shaderSet->fshader = static_cast<Thin3DGLShader *>(fshader);
	if (shaderSet->Link()) {
		return shaderSet;
	} else {
		delete shaderSet;
		return NULL;
	}
}

void Thin3DGLContext::BindTextures(int start, int count, Texture **textures) {
	for (int i = start; i < start + count; i++) {
		Thin3DGLTexture *glTex = static_cast<Thin3DGLTexture *>(textures[i]);
		glActiveTexture(GL_TEXTURE0 + i);
		glTex->Bind();

		if ((int)samplerStates_.size() > i && samplerStates_[i]) {
			samplerStates_[i]->Apply(glTex->HasMips(), glTex->CanWrap());
		}
	}
	glActiveTexture(GL_TEXTURE0);
}


Shader *Thin3DGLContext::CreateShader(ShaderStage stage, const char *glsl_source, const char *hlsl_source, const char *vulkan_source) {
	Thin3DGLShader *shader = new Thin3DGLShader(stage);
	if (shader->Compile(glsl_source)) {
		return shader;
	} else {
		shader->Release();
		return nullptr;
	}
}

bool Thin3DGLShaderSet::Link() {
	program_ = glCreateProgram();
	glAttachShader(program_, vshader->GetShader());
	glAttachShader(program_, fshader->GetShader());

	// Bind all the common vertex data points. Mismatching ones will be ignored.
	glBindAttribLocation(program_, SEM_POSITION, "Position");
	glBindAttribLocation(program_, SEM_COLOR0, "Color0");
	glBindAttribLocation(program_, SEM_TEXCOORD0, "TexCoord0");
	glBindAttribLocation(program_, SEM_NORMAL, "Normal");
	glBindAttribLocation(program_, SEM_TANGENT, "Tangent");
	glBindAttribLocation(program_, SEM_BINORMAL, "Binormal");
	glLinkProgram(program_);

	GLint linkStatus = GL_FALSE;
	glGetProgramiv(program_, GL_LINK_STATUS, &linkStatus);
	if (linkStatus != GL_TRUE) {
		GLint bufLength = 0;
		glGetProgramiv(program_, GL_INFO_LOG_LENGTH, &bufLength);
		if (bufLength) {
			char* buf = new char[bufLength];
			glGetProgramInfoLog(program_, bufLength, NULL, buf);
			ELOG("Could not link program:\n %s", buf);
			// We've thrown out the source at this point. Might want to do something about that.
#ifdef _WIN32
			OutputDebugStringUTF8(buf);
#endif
			delete[] buf;
		}
		return false;
	}

	// Auto-initialize samplers.
	glUseProgram(program_);
	for (int i = 0; i < 4; i++) {
		char temp[256];
		sprintf(temp, "Sampler%i", i);
		int samplerLoc = GetUniformLoc(temp);
		if (samplerLoc != -1) {
			glUniform1i(samplerLoc, i);
		}
	}

	// Here we could (using glGetAttribLocation) save a bitmask about which pieces of vertex data are used in the shader
	// and then AND it with the vertex format bitmask later...
	return true;
}

int Thin3DGLShaderSet::GetUniformLoc(const char *name) {
	auto iter = uniforms_.find(name);
	int loc = -1;
	if (iter != uniforms_.end()) {
		loc = iter->second.loc_;
	} else {
		loc = glGetUniformLocation(program_, name);
		UniformInfo info;
		info.loc_ = loc;
		uniforms_[name] = info;
	}
	return loc;
}

void Thin3DGLShaderSet::SetVector(const char *name, float *value, int n) {
	glUseProgram(program_);
	int loc = GetUniformLoc(name);
	if (loc != -1) {
		switch (n) {
		case 1: glUniform1fv(loc, 1, value); break;
		case 2: glUniform1fv(loc, 2, value); break;
		case 3: glUniform1fv(loc, 3, value); break;
		case 4: glUniform1fv(loc, 4, value); break;
		}
	}
}

void Thin3DGLShaderSet::SetMatrix4x4(const char *name, const float value[16]) {
	glUseProgram(program_);
	int loc = GetUniformLoc(name);
	if (loc != -1) {
		glUniformMatrix4fv(loc, 1, false, value);
	}
}

void Thin3DGLShaderSet::Apply() {
	glUseProgram(program_);
}

void Thin3DGLShaderSet::Unapply() {
	glUseProgram(0);
}

void Thin3DGLContext::Draw(Primitive prim, ShaderSet *shaderSet, Thin3DVertexFormat *format, Buffer *vdata, int vertexCount, int offset) {
	Thin3DGLShaderSet *ss = static_cast<Thin3DGLShaderSet *>(shaderSet);
	Thin3DGLBuffer *vbuf = static_cast<Thin3DGLBuffer *>(vdata);
	Thin3DGLVertexFormat *fmt = static_cast<Thin3DGLVertexFormat *>(format);

	vbuf->Bind();
	fmt->Apply();
	ss->Apply();

	glDrawArrays(PrimToGL(prim), offset, vertexCount);

	ss->Unapply();
	fmt->Unapply();
}

void Thin3DGLContext::DrawIndexed(Primitive prim, ShaderSet *shaderSet, Thin3DVertexFormat *format, Buffer *vdata, Buffer *idata, int vertexCount, int offset) {
	Thin3DGLShaderSet *ss = static_cast<Thin3DGLShaderSet *>(shaderSet);
	Thin3DGLBuffer *vbuf = static_cast<Thin3DGLBuffer *>(vdata);
	Thin3DGLBuffer *ibuf = static_cast<Thin3DGLBuffer *>(idata);
	Thin3DGLVertexFormat *fmt = static_cast<Thin3DGLVertexFormat *>(format);

	vbuf->Bind();
	fmt->Apply();
	ss->Apply();
	// Note: ibuf binding is stored in the VAO, so call this after binding the fmt.
	ibuf->Bind();

	glDrawElements(PrimToGL(prim), vertexCount, GL_UNSIGNED_INT, (const void *)(size_t)offset);
	
	ss->Unapply();
	fmt->Unapply();
}

void Thin3DGLContext::DrawUP(Primitive prim, ShaderSet *shaderSet, Thin3DVertexFormat *format, const void *vdata, int vertexCount) {
	Thin3DGLShaderSet *ss = static_cast<Thin3DGLShaderSet *>(shaderSet);
	Thin3DGLVertexFormat *fmt = static_cast<Thin3DGLVertexFormat *>(format);

	fmt->Apply(vdata);
	ss->Apply();

	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
	glDrawArrays(PrimToGL(prim), 0, vertexCount);

	ss->Unapply();
	fmt->Unapply();
}

void Thin3DGLContext::Clear(int mask, uint32_t colorval, float depthVal, int stencilVal) {
	float col[4];
	Uint8x4ToFloat4(col, colorval);
	GLuint glMask = 0;
	if (mask & ClearFlag::COLOR) {
		glClearColor(col[0], col[1], col[2], col[3]);
		glMask |= GL_COLOR_BUFFER_BIT;
	}
	if (mask & ClearFlag::DEPTH) {
#if defined(USING_GLES2)
		glClearDepthf(depthVal);
#else
		glClearDepth(depthVal);
#endif
		glMask |= GL_DEPTH_BUFFER_BIT;
	}
	if (mask & ClearFlag::STENCIL) {
		glClearStencil(stencilVal);
		glMask |= GL_STENCIL_BUFFER_BIT;
	}
	glClear(glMask);
}

Thin3DContext *T3DCreateGLContext() {
	return new Thin3DGLContext();
}

void Thin3DGLVertexFormat::Apply(const void *base) {
	if (id_ != 0) {
		glBindVertexArray(id_);
	}

	if (needsEnable_ || id_ == 0) {
		for (int i = 0; i < SEM_MAX; i++) {
			if (semanticsMask_ & (1 << i)) {
				glEnableVertexAttribArray(i);
			}
		}
		if (id_ != 0) {
			needsEnable_ = false;
		}
	}

	intptr_t b = (intptr_t)base;
	if (b != lastBase_) {
		for (size_t i = 0; i < components_.size(); i++) {
			switch (components_[i].type) {
			case DataFormat::FLOATx2:
				glVertexAttribPointer(components_[i].semantic, 2, GL_FLOAT, GL_FALSE, stride_, (void *)(b + (intptr_t)components_[i].offset));
				break;
			case DataFormat::FLOATx3:
				glVertexAttribPointer(components_[i].semantic, 3, GL_FLOAT, GL_FALSE, stride_, (void *)(b + (intptr_t)components_[i].offset));
				break;
			case DataFormat::FLOATx4:
				glVertexAttribPointer(components_[i].semantic, 4, GL_FLOAT, GL_FALSE, stride_, (void *)(b + (intptr_t)components_[i].offset));
				break;
			case DataFormat::UNORM8x4:
				glVertexAttribPointer(components_[i].semantic, 4, GL_UNSIGNED_BYTE, GL_TRUE, stride_, (void *)(b + (intptr_t)components_[i].offset));
				break;
			case DataFormat::UNKNOWN:
			default:
				ELOG("Thin3DGLVertexFormat: Invalid or unknown component type applied.");
				break;
			}
		}
		if (id_ != 0) {
			lastBase_ = b;
		}
	}
}

void Thin3DGLVertexFormat::Unapply() {
	if (id_ == 0) {
		for (int i = 0; i < (int)SEM_MAX; i++) {
			if (semanticsMask_ & (1 << i)) {
				glDisableVertexAttribArray(i);
			}
		}
	} else {
		glBindVertexArray(0);
	}
}

}  // namespace Draw