#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, 4);
		glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6);
		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 | GL_DEPTH_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]) {
		float vertices[] = {
			points[0].x, points[0].y, 0.0f,
			points[1].x, points[1].y, 0.0f,
			points[2].x, points[2].y, 0.0f
		};
		if (shader->mShaderVAO == 0) {
			glGenVertexArrays(1, &shader->mShaderVAO);
			glBindVertexArray(shader->mShaderVAO);
			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);
		}

		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;
		mLogger(Information, fmt::format("Compiling shader {}", shader->mShaderPaths[0]));
		glGenBuffers(1, &shader->mShaderVBO);
		glBindBuffer(GL_ARRAY_BUFFER, shader->mShaderVBO);
		shader->mShaderIDs[0] = glCreateShader(GL_VERTEX_SHADER);
		const char* vertShader = loadFile(shader->mShaderPaths[0]);
		glShaderSource(shader->mShaderIDs[0], 1, &vertShader, NULL);
		glCompileShader(shader->mShaderIDs[0]);

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

		shader->mShaderIDs[1] = glCreateShader(GL_VERTEX_SHADER);
		const char* fragShader = loadFile(shader->mShaderPaths[1]);
		glShaderSource(shader->mShaderIDs[1], 1, &fragShader, NULL);
		glCompileShader(shader->mShaderIDs[1]);

		shader->mShaderProgram = glCreateProgram();

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

		glLinkProgram(shader->mShaderProgram);

		mLogger(Information, "Linked shader.");

		glDeleteShader(shader->mShaderIDs[0]);
		glDeleteShader(shader->mShaderIDs[1]);

		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());
	}

	const char* 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));
		}

		const char* textChar = text.c_str();

		return textChar;
	}
}