#include "../../HEADERS/EFFECTS/TexMerger.h"
#include "../../HEADERS/UTILS/ShaderMaker.h"
#include <string>
#include <iostream>

#include <glm/glm.hpp>

extern "C" {
#include "../../GLES_3_1_compatibility.h"
}

TexMerger::TexMerger(GLuint texCount, unsigned int texWidth, unsigned int texHeight) {
	glGenVertexArrays(1, &quadVAO);
	glBindVertexArray(quadVAO);
	glGenBuffers(1, &vertVBO);
	glBindBuffer(GL_ARRAY_BUFFER, vertVBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(quadVerts), quadVerts, GL_STATIC_DRAW);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float)/**/, (void*)0);
	glEnableVertexAttribArray(0);
	std::string root = "C:\\Users\\BoBoBoat\\Desktop\\SCUOLA\\CGI\\GL_STUFF\\GL_STUFF\\SOURCES\\EFFECTS\\TEX_MERGER";
	std::string vertSh = root + "\\vertexShader_merger.glsl";
	std::string fragSh = root + "\\fragmentShader_merger.glsl";
	program = ShaderMaker::createProgram(&vertSh[0], &fragSh[0]);
	shaderTex1Id = glGetUniformLocation(program, "inTex1");
	shaderTex2Id = glGetUniformLocation(program, "inTex2");

	bufCount = ceil(log2((float)texCount));

	mergeBuffers = (GLuint*) malloc(bufCount * sizeof(GLuint));
	glGenFramebuffers(1, &FBO);
	glGenTextures(bufCount, mergeBuffers);
	for (unsigned int i = 0; i < bufCount; i++) {
		glActiveTexture(GL_TEXTURE0 + i);
		glBindTexture(GL_TEXTURE_2D, mergeBuffers[i]);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, texWidth, texHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);		//RGB o RGBA?
		
		usageMap.push_back(false);
	}
}

GLuint TexMerger::reserveBuffer() {
	unsigned int index = 0;
	while (index < bufCount && usageMap[index]) {
		index++;
	}
	if (index >= bufCount)
		throw "TexMerger::reserveBuffer : free buffer not found";
	return mergeBuffers[index];
}

bool TexMerger::isBuffer(GLuint number) {
	bool found = false;
	int index = -1;
	while (!found && (++index < bufCount))
		if (mergeBuffers[index] == number)
			found = true;
	return found;
}

void TexMerger::freeBuffer(GLuint number) {
	bool found = false;
	int index = -1;
	while (!found && (++index < bufCount))
		if (mergeBuffers[index] == number)
			found = true;
	if (found)
		usageMap[index] = false;
	else
		throw "TexMerger::freeBuffer : index not found";
}

/*(BUFFER è in realtà un indice)
* MERGE (START,END)
*	if (END - START) == 0
*		leggi la texture
*		ritorna texture
*	else
*		MID = (START + END) / 2
*		B1 = MERGE(START, MID)
*		B2 = MERGE(MID + 1, END )
*		scegli un BUFFER libero (bloccante)
*		somma B1, B2 nel BUFFER
*		sblocca tra B1 e B2 quelli che sono BUFFER
*		ritorna BUFFER	
*/

GLuint TexMerger::merge(std::vector<GLuint> inTextures, int startIndex, int endIndex) {
	if ((endIndex - startIndex) == 0) {
		return inTextures[startIndex];
	}
	else {
		int mid = (startIndex + endIndex) / 2;
		GLuint buf1;
		GLuint buf2;
		GLuint result;
		try{
			buf1 = merge(inTextures, startIndex, mid);
			buf2 = merge(inTextures, mid + 1, endIndex);
			result = reserveBuffer();
		}
		catch( std::string ex){
			std::cout << ex;
		}
		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, FBO);
		glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, result, 0);
		GLenum DrawBuffers[1] = { GL_COLOR_ATTACHMENT0 };
		
		
		/* commented and not available
		glDrawBuffers(1, DrawBuffers);
		*/
		
		//glClearColor(0, 0, 0, 0);
		//glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		glUseProgram(program);
		glActiveTexture(GL_TEXTURE0);
		glBindTexture(GL_TEXTURE_2D, buf1);
		glUniform1i(shaderTex1Id, 0);
		glActiveTexture(GL_TEXTURE1);
		glBindTexture(GL_TEXTURE_2D, buf2);
		glUniform1i(shaderTex2Id, 1);
		glBindVertexArray(quadVAO);
		glDrawArrays(GL_TRIANGLES, 0, 6);
		glBindVertexArray(0);
		if (isBuffer(buf1))
			freeBuffer(buf1);
		if (isBuffer(buf2))
			freeBuffer(buf2);
		return result;
	}
}