#include <fmt/format.h>
#include <fstream>

#include "rglcore.hpp"

namespace hibis::rglcore {
	RGLCore::RGLCore(std::string title, IntVec2 size, LoggerCallback callback) : Renderer(callback), mTextures() {
		mLogger(Information, "Preparing GLFW3...");
		if (!glfwInit()) {
			mLogger(Fatal, "GLFW couldn't be initialised!");
			exit(1);
		}

		mLogger(Information, "Creating GLFWwindow...");
		glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
		glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
		glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
		mWindow = glfwCreateWindow(size.x, size.y, title.c_str(), NULL, NULL);
		if (!mWindow) {
			mLogger(Fatal, "Window could not be created!");
			exit(1);
		}

		glfwMakeContextCurrent(mWindow);

		mLogger(Information, "Preparing GLEW...");
		glewExperimental = GL_FALSE;
		GLenum err = glewInit();

		if (err != GLEW_OK) {
			mLogger(Fatal, "GLEW could not be created due to GLEW err " + std::to_string(err));
			exit(err);
		}

		mLogger(Information, "Setting viewport...");
		glViewport(0, 0, size.x, size.y);

		mLogger(Information, "Finished setting up RGLCore!");
	}

	RGLCore::~RGLCore() {
		glfwDestroyWindow(mWindow);
		glfwTerminate();
	}

	// Draw
	void RGLCore::clearScreen(Color col) {
		float r = (float)(col.r) / 255, g = (float)(col.g) / 255, b = (float)(col.b) / 255, a = (float)(col.a) / 255;
		glClearColor(r, g, b, a);
		glClear(GL_COLOR_BUFFER_BIT);
	}

	void RGLCore::renderCurrent() {
		glfwSwapBuffers(mWindow);
	}

	void RGLCore::drawText(Resource* resource, std::string text, IntVec2 pos, Color color) {}
	void RGLCore::drawTexture(Texture* resource, IntRect size) {
		TODO("finish this")
		return;
		unsigned int glTextureID;
		if (mTextures.find(resource) != mTextures.end()) {
			glTextureID = mTextures[resource];
		} else {
			glGenTextures(1, &glTextureID);
			glBindTexture(GL_TEXTURE_2D, glTextureID);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

			glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, resource->mImageWidth, resource->mImageHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, resource->mData);
			glGenerateMipmap(GL_TEXTURE_2D);
		}
	}

	void RGLCore::useShader(Shader* shader, Point2D points[3]) {
		glUseProgram(shader->mShaderProgram);
		glBindVertexArray(shader->mShaderVAO);
		glDrawArrays(GL_TRIANGLES, 0, 3);
	}

	void RGLCore::stopUsingShaders() {
		glUseProgram(0);
	}

	// Pre and Post draw
	void RGLCore::preDraw() {}
	void RGLCore::postDraw() {}

	void RGLCore::update() {
		mKeepOpen = !glfwWindowShouldClose(mWindow);
		glfwPollEvents();
	}

	void RGLCore::compileShader(Shader* shader) {
		if (shader->mShaderProgram != 0) return;
		char infoLog[512];

		int success;
		unsigned int shaderIDs[2] = {0, 0};

		mLogger(Information, fmt::format("Compiling shader {}", shader->mShaderPaths[0]));

		shaderIDs[0] = glCreateShader(GL_VERTEX_SHADER);
		const std::string vertShaderStr = loadFile(shader->mShaderPaths[1]);
		const char* vertShader = vertShaderStr.c_str();
		glShaderSource(shaderIDs[0], 1, &vertShader, NULL);
		glCompileShader(shaderIDs[0]);

		glGetShaderiv(shaderIDs[0], GL_COMPILE_STATUS, &success);
		if(!success) {
			glGetShaderInfoLog(shaderIDs[0], 512, NULL, infoLog);
			printf("%s", infoLog);
			mLogger(Error, fmt::format("Couldn't compile shader '{}'! what: {}", shader->mShaderPaths[0], std::string(infoLog)));
		}

		mLogger(Information, fmt::format("Compiling shader {}", shader->mShaderPaths[1]));

		shaderIDs[1] = glCreateShader(GL_FRAGMENT_SHADER);
		const std::string fragShaderStr = loadFile(shader->mShaderPaths[1]);
		const char* fragShader = fragShaderStr.c_str();
		glShaderSource(shaderIDs[1], 1, &fragShader, NULL);
		glCompileShader(shaderIDs[1]);

		glGetShaderiv(shaderIDs[1], GL_COMPILE_STATUS, &success);
		if(!success) {
			glGetShaderInfoLog(shaderIDs[1], 512, NULL, infoLog);
			mLogger(Error, fmt::format("Couldn't compile shader '{}'! what: {}", shader->mShaderPaths[1], std::string(infoLog)));
		}

		shader->mShaderProgram = glCreateProgram();

		glAttachShader(shader->mShaderProgram, shaderIDs[0]);
		glAttachShader(shader->mShaderProgram, shaderIDs[1]);

		glLinkProgram(shader->mShaderProgram);

		glGetProgramiv(shader->mShaderProgram, GL_LINK_STATUS, &success);

		if (!success) {
			TODO("what the fuck, this isn't helpful")
			glGetShaderInfoLog(shader->mShaderProgram, 512, NULL, infoLog);
			mLogger(Error, fmt::format("Couldn't link shader! what: {}", std::string(infoLog)));
		}
		else mLogger(Information, "Linked shader.");

		glDeleteShader(shaderIDs[0]);
		glDeleteShader(shaderIDs[1]);

		GLfloat vertices[] = {
			-0.5f, -0.5f * float(sqrt(3)) / 3, 0.0f, // Lower left corner
			0.5f, -0.5f * float(sqrt(3)) / 3, 0.0f, // Lower right corner
			0.0f, 0.5f * float(sqrt(3)) * 2 / 3, 0.0f // Upper corner
		};

		glGenVertexArrays(1, &shader->mShaderVAO);
		glGenBuffers(1, &shader->mShaderVBO);

		glBindVertexArray(shader->mShaderVAO);

		glBindBuffer(GL_ARRAY_BUFFER, shader->mShaderVBO);

		glBindBuffer(GL_ARRAY_BUFFER, shader->mShaderVBO);
		glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

		glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
		glEnableVertexAttribArray(0);

		glBindBuffer(GL_ARRAY_BUFFER, 0);
		glBindVertexArray(0);

		mLogger(Information, "Cleaned up leftover shader objects.");
	}

	void RGLCore::toggleWireframe() {
		if (mIsWireframeMode) glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
		else glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
		mIsWireframeMode = !mIsWireframeMode;
	}

	void RGLCore::setWindowTitle(std::string title) {
		glfwSetWindowTitle(mWindow, title.c_str());
	}

	std::string RGLCore::loadFile(std::string path) {
		std::string text, line;
		std::ifstream textFile(path);
		if (textFile.is_open()) {
			while (getline(textFile, line)) {
				text += line + '\n';
			}
			textFile.close();
		} else {
			text = "";
			mLogger(Error, fmt::format("Couldn't load file '{}'", path));
		}

		return text;
	}
}