#include "../../HEADERS/EFFECTS/CRT_shader.h"
#include "../../HEADERS/UTILS/ShaderMaker.h"
#include <glm/gtc/type_ptr.hpp>
#include <iostream>

int CRT_Shader::CRT_HORIZONTAL_PIXELS;
int CRT_Shader::CRT_VERTICAL_PIXELS;
int CRT_Shader::CRT_WIDTH;
int CRT_Shader::CRT_HEIGHT;
int CRT_Shader::PARTICLE_COUNT;
int CRT_Shader::PARTICLE_GROUP_COUNT;
bool CRT_Shader::CRT_FLIP_Y;
SIM_PRECISION CRT_Shader::resolution;

vec3 CRT_Shader::scaleToZOne(vec3 vector) {
	return (1 / vector.z) * vector;
}

vec3 CRT_Shader::crt_emission_angle(int index) {

	int xCoord = (index % CRT_HORIZONTAL_PIXELS) - (CRT_HORIZONTAL_PIXELS / 2);
	int yCoord = (index / CRT_HORIZONTAL_PIXELS) - (CRT_VERTICAL_PIXELS / 2);

	float longCat = CRT_DEPTH;
	float shortCatX = CRT_PIXEL_LENGTH * xCoord;
	float shortCatY = CRT_PIXEL_LENGTH * yCoord;
	vec3 res = vec3(shortCatX, -shortCatY, 1.0);

	return res;
}

void CRT_Shader::createRenderShader() {
	string vertexSh = resourceRoot + "vertexShader_particles.glsl";
	string fragmentSh = resourceRoot + "fragmentShader_particles.glsl";
	render_prog = ShaderMaker::createProgram(&vertexSh[0], &fragmentSh[0]);
}

void CRT_Shader::createComputeShader() {
	GLenum ErrorCheckValue = glGetError();
	string compSh = resourceRoot + "computeShader_particles.glsl";
	GLchar* VertexShader = ShaderMaker::readShaderSource(&compSh[0]);
	//Visualizzo sulla console il CODICE VERTEX SHADER
	std::cout << VertexShader;

	//Generiamo un identificativo per il vertex shader
	GLuint computeShaderId = glCreateShader(GL_COMPUTE_SHADER);
	//Associamo all'identificativo il codice del vertex shader
	glShaderSource(computeShaderId, 1, (const char**)&VertexShader, NULL);
	//Compiliamo il Vertex SHader
	glCompileShader(computeShaderId);

	int success;
	char infoLog[512];
	glGetShaderiv(computeShaderId, GL_COMPILE_STATUS, &success);
	if (!success) {
		glGetShaderInfoLog(computeShaderId, 512, NULL, infoLog);
		std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
	}

	ErrorCheckValue = glGetError();
	std::cout << ErrorCheckValue;

	if (ErrorCheckValue != GL_NO_ERROR)
	{
		fprintf(
			stderr,
			"ERROR: Could not create the shaders: %s \n",
			gluErrorString(ErrorCheckValue)
		);

		exit(-1);
	}
	//Creiamo un identificativo di un eseguibile e gli colleghiamo i due shader compilati
	compute_prog = glCreateProgram();

	glAttachShader(compute_prog, computeShaderId);
	glLinkProgram(compute_prog);
	dt_location = glGetUniformLocation(compute_prog, "dt");
}

void CRT_Shader::buffersSetup() {
	GLuint buffers[5];
	GLuint textures[3];
	glGenBuffers(5, buffers);
	start_position_buffer = buffers[0];
	end_position_buffer = buffers[1];
	velocity_buffer = buffers[2];
	color_buffer = buffers[3];
	magnets_buffer = buffers[4];

	glBindBuffer(GL_ARRAY_BUFFER, magnets_buffer);
	glBufferData(GL_ARRAY_BUFFER, 8 * sizeof(vec4), NULL, GL_DYNAMIC_COPY);			//dynamic copy ???

	for (int i = 0; i < 8; i++) {
		attractors[i] = vec4();
	}

	glBindBuffer(GL_ARRAY_BUFFER, start_position_buffer);
	glBufferData(GL_ARRAY_BUFFER, PARTICLE_COUNT * sizeof(vec4), NULL, GL_DYNAMIC_COPY);
	//Map the position buffer
	vec4* positions = (vec4*)glMapNamedBufferRangeEXT(start_position_buffer, 0, PARTICLE_COUNT * sizeof(vec4), GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT);

	for (int i = 0; i < PARTICLE_COUNT; i++)
	{
		positions[i] = vec4(0, 0, -CRT_DEPTH, 0);
	}
	glUnmapNamedBufferEXT(start_position_buffer);

	glBindBuffer(GL_ARRAY_BUFFER, end_position_buffer);
	glBufferData(GL_ARRAY_BUFFER, PARTICLE_COUNT * sizeof(vec4), NULL, GL_DYNAMIC_COPY);
	glUnmapNamedBufferEXT(end_position_buffer);

	//initialization of the velocity buffer
	glBindBuffer(GL_ARRAY_BUFFER, velocity_buffer);
	glBufferData(GL_ARRAY_BUFFER, PARTICLE_COUNT * sizeof(vec4), NULL, GL_DYNAMIC_COPY);
	vec4* velocities = (vec4*)glMapBufferRange(GL_ARRAY_BUFFER, 0, PARTICLE_COUNT * sizeof(vec4), GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT);

	for (int i = 0; i < CRT_VERTICAL_PIXELS * CRT_HORIZONTAL_PIXELS; i++)
	{
		velocities[i] = glm::vec4(crt_emission_angle(i), 0.0);
	}
	glUnmapBuffer(GL_ARRAY_BUFFER);


	//////////////////////////////////////////////////////////
	//initialization of the color buffer
	glBindBuffer(GL_ARRAY_BUFFER, color_buffer);
	glBufferData(GL_ARRAY_BUFFER, PARTICLE_COUNT * COLOR_CHANNELS * sizeof(unsigned char), NULL, GL_DYNAMIC_COPY);


	glGenTextures(3, textures);

	velocity_tbo = textures[0];
	start_position_tbo = textures[1];
	end_position_tbo = textures[2];

	glBindTexture(GL_TEXTURE_BUFFER, velocity_tbo);
	glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA32F, velocity_buffer);

	glBindTexture(GL_TEXTURE_BUFFER, start_position_tbo);
	glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA32F, start_position_buffer);

	glBindTexture(GL_TEXTURE_BUFFER, end_position_tbo);
	glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA32F, end_position_buffer);
}

void CRT_Shader::VAOsSetup() {
	glGenVertexArrays(1, &render_vao);
	glBindVertexArray(render_vao);

	glBindBuffer(GL_ARRAY_BUFFER, end_position_buffer);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);

	glBindBuffer(GL_ARRAY_BUFFER, velocity_buffer);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);
	/////////////////////
	glBindBuffer(GL_ARRAY_BUFFER, color_buffer);
	glEnableVertexAttribArray(2);
	glVertexAttribPointer(2, 4, GL_UNSIGNED_BYTE, GL_TRUE, 4 * sizeof(unsigned char), 0);

	glBindBuffer(GL_ARRAY_BUFFER, magnets_buffer);
	glEnableVertexAttribArray(3);
	glVertexAttribPointer(3, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);
}

CRT_Shader::CRT_Shader() {

	createRenderShader();
	createComputeShader();
	float top = crt_emission_angle(0).y;
	float bottom = crt_emission_angle((PARTICLE_COUNT)-1).y;
	if (CRT_FLIP_Y) {
		float swap = top;
		top = bottom;
		bottom = swap;
	}
	orthoMat = ortho(crt_emission_angle(0).x,
		crt_emission_angle((PARTICLE_COUNT) - 1).x,
		bottom,
		top,
		-1.0f,
		1.0f);

	buffersSetup();
	VAOsSetup();

	CS_LTF = vec3(scaleToZOne(crt_emission_angle(0)).x, scaleToZOne(crt_emission_angle(0)).y, 0);
	CS_RBF = vec3(scaleToZOne(crt_emission_angle((PARTICLE_COUNT) - 1)).x, scaleToZOne(crt_emission_angle((PARTICLE_COUNT) - 1)).y, 0);
	CS_LTN = vec3(-0.1, 0.1, -1);
	CS_RBN = vec3(0.1, -0.1, -1);
}

void CRT_Shader::draw(unsigned int ONE_TICK_MS, unsigned int timePassed) {

	glBindBuffer(GL_ARRAY_BUFFER, magnets_buffer);
	vec4* attractors = (vec4*)glMapNamedBufferRangeEXT(magnets_buffer, 0, 8 * sizeof(vec4), GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT);

	for (int i = 0; i < 8; i++)
		attractors[i] = this->attractors[i];

	glUnmapNamedBufferEXT(magnets_buffer);


	//activate the compute program and bind the position
	//and velocity buffers
	glUseProgram(compute_prog);
	glBindBufferBase(GL_UNIFORM_BUFFER, 0, magnets_buffer);
	glBindImageTexture(0, velocity_tbo, 0, GL_FALSE, 0, GL_READ_ONLY, GL_RGBA32F);
	glBindImageTexture(1, start_position_tbo, 0, GL_FALSE, 0, GL_READ_ONLY, GL_RGBA32F);
	glBindImageTexture(2, end_position_tbo, 0, GL_FALSE, 0, GL_WRITE_ONLY, GL_RGBA32F);

	glUniform3f(glGetUniformLocation(compute_prog, "nearTopLeft"), CS_LTN.x, CS_LTN.y, CS_LTN.z);
	glUniform3f(glGetUniformLocation(compute_prog, "nearBottomRight"), CS_RBN.x, CS_RBN.y, CS_RBN.z);
	glUniform3f(glGetUniformLocation(compute_prog, "farTopLeft"), CS_LTF.x, CS_LTF.y, CS_LTF.z);
	glUniform3f(glGetUniformLocation(compute_prog, "farBottomRight"), CS_RBF.x, CS_RBF.y, CS_RBF.z);
	//set delta time
	glUniform1f(dt_location, 1e-2 * pow(4, (int) resolution));

	//dispatch the compute shader
	glDispatchCompute(PARTICLE_GROUP_COUNT, 1, 1);

	//ensure that writes by the compute shader have completed
	glMemoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT);

	glUseProgram(render_prog);
	glUniformMatrix4fv(glGetUniformLocation(render_prog, "mvp"), 1, GL_FALSE, value_ptr(orthoMat));

	glUniform1ui(glGetUniformLocation(render_prog, "pixelWidth"), CRT_PIXEL_SCALE * 1000 * CRT_PIXEL_LENGTH);

	glBindVertexArray(render_vao);
	glEnable(GL_BLEND);
	glBlendFunc(GL_ONE, GL_ONE);
	glPointSize(CRT_PIXEL_SCALE);
	glDrawArrays(GL_POINTS, 0, PARTICLE_COUNT);
	glDisable(GL_BLEND);
}

void CRT_Shader::setMagnet(int index, vec4 positionAndMass) {
	float vieww = scaleToZOne(crt_emission_angle((PARTICLE_COUNT) - 1)).x - scaleToZOne(crt_emission_angle(0)).x;
	float viewh = scaleToZOne(crt_emission_angle((PARTICLE_COUNT) - 1)).y - scaleToZOne(crt_emission_angle(0)).y;
	magx = vieww * (positionAndMass.x - CRT_WIDTH / 2) / ((float)CRT_WIDTH);
	magy = viewh * (positionAndMass.y - CRT_HEIGHT / 2) / ((float)CRT_HEIGHT);
	attractors[index] = vec4(magx, magy, positionAndMass.z, positionAndMass.w * pow(4, (int)-resolution));
}

/*
 DOES ANYTHING CHANGE WITH CRT_FLIP_Y ???


*/


float CRT_Shader::getLeftBound() {
	return  -CRT_WIDTH / 2;
}

float CRT_Shader::getRightBound() {
	return  CRT_WIDTH / 2;
}

float CRT_Shader::getBottomBound() {
	return -(CRT_HEIGHT / 2);
}

float CRT_Shader::getTopBound() {
	return (CRT_HEIGHT / 2);
}

void CRT_Shader::loadColorFromFramebuffer(GLuint FBO) {
	glBindFramebuffer(GL_FRAMEBUFFER, FBO);
	glBindBuffer(GL_PIXEL_PACK_BUFFER, color_buffer);
	glReadPixels(0, 0, CRT_HORIZONTAL_PIXELS, CRT_VERTICAL_PIXELS, GL_RGBA, GL_UNSIGNED_BYTE, 0);
}