#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>

#include "fbo.h"

namespace {
    GLuint CreateFramebuffer() {
        GLuint fboId = 0;
        glGenFramebuffers(1, &fboId);
        return fboId;
    }

    GLuint CreateTexture(int width, int height, GLenum format) {
        GLuint textureId = 0;
        glGenTextures(1, &textureId);
        glBindTexture(GL_TEXTURE_2D, textureId);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F, width, height, 0, format, GL_FLOAT, nullptr);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glBindTexture(GL_TEXTURE_2D, 0);
        
        if(textureId == 0) {
            std::cerr << "Texture was not created!" << std::endl;
        }

        return textureId;
    }

    GLuint CreateDepthTexture(int width, int height) {
        GLuint depthId;
        glGenRenderbuffers(1, &depthId);
        glBindRenderbuffer(GL_RENDERBUFFER, depthId);
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT32, width, height);
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthId);
        glBindRenderbuffer(GL_RENDERBUFFER, 0);

        if(depthId == 0) {
            std::cerr << "Depth Texture was not created!" << std::endl;
        }
        
        return depthId;
    }

    void AttachTextureToFramebuffer(GLuint framebufferId, GLuint textureId, GLenum attachment) {
        glFramebufferTexture2D(GL_FRAMEBUFFER, attachment, GL_TEXTURE_2D, textureId, 0);
    }

} // namespace

namespace FBO {
    Framebuffer GenerateFramebuffer(int width, int height) {
        Framebuffer fbo;
        fbo.id = CreateFramebuffer();
        
        UpdateFrameBuffer(fbo, width, height);

        return fbo;
    }

    void UpdateFrameBuffer(Framebuffer& fbo, int width, int height) {
        glBindFramebuffer(GL_FRAMEBUFFER, fbo.id);

        fbo.albedoTexture = CreateTexture(width, height, GL_RGBA);
        fbo.positionTexture = CreateTexture(width, height, GL_RGBA);
        fbo.normalTexture = CreateTexture(width, height, GL_RGBA);
        fbo.depthTexture = CreateDepthTexture(width, height);

        AttachTextureToFramebuffer(fbo.id, fbo.albedoTexture, GL_COLOR_ATTACHMENT0);
        AttachTextureToFramebuffer(fbo.id, fbo.positionTexture, GL_COLOR_ATTACHMENT1);
        AttachTextureToFramebuffer(fbo.id, fbo.normalTexture, GL_COLOR_ATTACHMENT2);

        GLenum drawBuffers[3] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2 };
        glDrawBuffers(3, drawBuffers);

        if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
            std::cerr << "Error: Framebuffer is not complete!" << std::endl;
        }

        glBindFramebuffer(GL_FRAMEBUFFER, 0);
    }

    void Bind(const Framebuffer& fbo) {
        glBindFramebuffer(GL_FRAMEBUFFER, fbo.id); 
    }

    void Unbind() {
        glBindFramebuffer(GL_FRAMEBUFFER, 0); 
    }

    void Cleanup(const Framebuffer& fbo) {
        if (fbo.albedoTexture != 0) {
            glDeleteTextures(1, &fbo.albedoTexture);
        }
        if (fbo.positionTexture != 0) {
            glDeleteTextures(1, &fbo.positionTexture);
        }
        if (fbo.normalTexture != 0) {
            glDeleteTextures(1, &fbo.normalTexture);
        }
        if (fbo.depthTexture != 0) {
            glDeleteTextures(1, &fbo.depthTexture);
        }
        if (fbo.id != 0) {
            glDeleteFramebuffers(1, &fbo.id);
        }
    }
} // namespace FBO