#include "Renderer.hpp"

#include "GameObject.hpp"

#include <RapidJsonHelper.hpp>

#include <rapidjson/document.h>
#include <cassert>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/quaternion.hpp>
#include <glm/gtx/quaternion.hpp>
#include <string_view>

using namespace std::literals;

RenderObject::RenderObject()
	: mVao{ GL_NONE } {
}

RenderObject::~RenderObject() {
	DeleteGLObjects();
}

GLuint RenderObject::GetGLVao() const {
	return mVao;
}

void RenderObject::RebuildIfNecessary() {
	if (mVao != GL_NONE) {
		return;
	}

	assert(mIndexBuf != nullptr);
	assert(mVertexFormat != nullptr);

	glGenVertexArrays(1, &mVao);
	glBindVertexArray(mVao);

	auto& vBindings = mVertexBufBinding.bindings;
	auto& shaderInfo = mMaterial->GetShader()->GetInfo();

	// Setup vertex buffers
	for (auto& elm : mVertexFormat->elements) {
		assert(elm.bindingIndex < vBindings.size());
		auto& buffer = vBindings[elm.bindingIndex];

		int index = shaderInfo.FindInputLocation(elm.semantic);
		if (index == -1) {
			continue;
		}

		glBindBuffer(GL_ARRAY_BUFFER, buffer->handle);
		glEnableVertexAttribArray(index);
		glVertexAttribPointer(
			index,
			Tags::VectorLenOf(elm.type),
			Tags::FindGLType(elm.type),
			Tags::IsNormalized(elm.type),
			mVertexFormat->vertexSize,
			(void*)(uintptr_t)elm.offset);
	}

	// Setup index buffer
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mIndexBuf->handle);

	glBindVertexArray(GL_NONE);
}

void RenderObject::SetMaterial(Material* material) {
	mMaterial.Attach(material);
	DeleteGLObjects();
}

void RenderObject::UpdateIndexBuffer(GpuIndexBuffer* indexBuffer) {
	mIndexBuf.Attach(indexBuffer);
	DeleteGLObjects();
}

void RenderObject::UpdateVertexFormat(VertexFormat* vertexFormat) {
	mVertexFormat.Attach(vertexFormat);
	DeleteGLObjects();
}

void RenderObject::UpdateVertexBufferBindings(BufferBindings** bindingsOut) {
	*bindingsOut = &mVertexBufBinding;
	DeleteGLObjects();
}

void RenderObject::SetFormat(VertexFormat* vertexFormat, Tags::IndexType indexFormat) {
	mIndexBuf.Attach(new GpuIndexBuffer());
	mIndexBuf->indexType = indexFormat;
	mIndexBuf->count = 0;

	mVertexFormat.Attach(vertexFormat);
	mVertexBufBinding.Clear();
	for (auto& element : vertexFormat->elements) {
		if (mVertexBufBinding.GetBinding(element.bindingIndex) == nullptr) {
			mVertexBufBinding.SetBinding(element.bindingIndex, new GpuVertexBuffer());
		}
	}
}

void RenderObject::DeleteGLObjects() {
	if (mVao != GL_NONE) {
		glDeleteVertexArrays(1, &mVao);
		mVao = GL_NONE;
	}
}

Renderer::Renderer()
	: binding_WireframeMaterial{ gDefaultMaterial } //
{
	mRenderOptions[RO_Shading] = true;
	mRenderOptions[RO_Wireframe] = false;
}

void Renderer::LoadBindings(const rapidjson::Value& bindings) {
	if (auto rvWireframe = rapidjson::GetProperty(bindings, "WireframeMaterial"sv)) {
		Uid uidWireframe;
		uidWireframe.Read(*rvWireframe);
		// TODO don't assume
		binding_WireframeMaterial.Attach(((IresMaterial*)IresManager::instance->FindIres(uidWireframe))->GetInstance());
	}
}

void Renderer::SaveBindings(rapidjson::Value& into, rapidjson::Document& root) const {
	if (auto ires = binding_WireframeMaterial->GetIres()) {
		into.AddMember("WireframeMaterial", ires->GetUid().Write(root), root.GetAllocator());
	}
}

void Renderer::BeginFrame(Camera& camera, float currentTime, float deltaTime) {
	assert(mInsideFrame == false);
	mInsideFrame = true;
	mFrame.camera = &camera;
	mFrame.matrixView = camera.CalcViewMatrix();
	mFrame.matrixProj = camera.CalcProjectionMatrix();
	mFrame.time = currentTime;
	mFrame.deltaTime = deltaTime;
}

void Renderer::EndFrame() {
	assert(mInsideFrame == true);
	mInsideFrame = false;
}

void Renderer::Draw(const RenderObject* objects, const GameObject* gameObject, size_t count) {
	using namespace Tags;

	assert(mInsideFrame);

	// Desired order: proj * view * (translate * rotate * scale) * vec
	//                        <----- order of application <-----   ^^^ input
	glm::mat4 objectMatrix(1.0f);
	objectMatrix = glm::translate(objectMatrix, gameObject->GetPos());
	objectMatrix *= glm::toMat4(gameObject->GetRotation());
	objectMatrix = glm::scale(objectMatrix, gameObject->GetScale());
	auto mvpMatrix = mFrame.matrixProj * mFrame.matrixView * objectMatrix;

	if (GetRenderOption(RO_Shading)) {
		// TODO shader grouping
		// TODO material grouping
		for (size_t i = 0; i < count; ++i) {
			auto& object = objects[i];
			auto indexBuffer = object.GetIndexBuffer();
			auto mat = object.GetMaterial();
			auto shader = mat->GetShader();

			glUseProgram(shader->GetProgram());

			// Material uniforms
			mat->UseUniforms();

			// Next available texture unit ID after all material textures
			int texIdx = mat->GetTextures().size();

			// Autofill uniforms
			if (shader->autofill_Transform != kInvalidLocation) {
				glUniformMatrix4fv(shader->autofill_Transform, 1, GL_FALSE, &mvpMatrix[0][0]);
			}
			if (shader->autofill_Time != kInvalidLocation) {
				glUniform1f(shader->autofill_Time, mFrame.time);
			}
			if (shader->autofill_DeltaTime != kInvalidLocation) {
				glUniform1f(shader->autofill_DeltaTime, mFrame.deltaTime);
			}
			if (shader->autofill_TextureAtlas != kInvalidLocation &&
				object.autofill_TextureAtlas != nullptr)
			{
				glActiveTexture(GL_TEXTURE0 + texIdx);
				glBindTexture(GL_TEXTURE_2D, object.autofill_TextureAtlas->GetHandle());
				glUniform1i(shader->autofill_TextureAtlas, texIdx);
				++texIdx;
			}

			glBindVertexArray(object.GetGLVao());
			glDrawElements(GL_TRIANGLES, indexBuffer->count, indexBuffer->GetIndexTypeGL(), 0);
		}
	}

	if (GetRenderOption(RO_Wireframe)) {
		auto& mat = *binding_WireframeMaterial;
		auto& shader = *mat.GetShader();
		auto& shaderInfo = shader.GetInfo();

		glUseProgram(shader.GetProgram());
		mat.UseUniforms();

		// TODO reduce calls with consecutive wireframe setting
		glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
		for (size_t i = 0; i < count; ++i) {
			auto& object = objects[i];

			auto& vBindings = object.GetVertexBufferBindings().bindings;
			auto vf = object.GetVertexFormat();

			// Setup vertex buffers
			for (auto& elm : vf->elements) {
				assert(elm.bindingIndex < vBindings.size());
				auto& buffer = vBindings[elm.bindingIndex];

				int index = shaderInfo.FindInputLocation(elm.semantic);
				if (index == -1) {
					continue;
				}

				glBindBuffer(GL_ARRAY_BUFFER, buffer->handle);
				glEnableVertexAttribArray(index);
				glVertexAttribPointer(
					index,
					Tags::VectorLenOf(elm.type),
					Tags::FindGLType(elm.type),
					Tags::IsNormalized(elm.type),
					vf->vertexSize,
					(void*)(uintptr_t)elm.offset);
			}

			// Setup index buffer
			auto indexBuffer = object.GetIndexBuffer();
			glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer->handle);

			glDrawElements(GL_TRIANGLES, indexBuffer->count, indexBuffer->GetIndexTypeGL(), 0);
		}
		glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);

		return;
	}
}

bool Renderer::GetRenderOption(RenderOption option) const {
	return mRenderOptions[option];
}

void Renderer::SetRenderOption(RenderOption option, bool flag) {
	mRenderOptions[option] = flag;
}