#include "OpenGLFramebuffer.h"
#include "Core/Log.h"

#include <glad/glad.h>

namespace Donut
{
    namespace Utils
    {
        static GLenum TextureTarget(bool multisampled)
        {
            return multisampled ? GL_TEXTURE_2D_MULTISAMPLE : GL_TEXTURE_2D;
        }

        static void BindTexture(bool multisampled, uint32_t id)
        {
            glBindTexture(TextureTarget(multisampled), id);
        }

        static void CreateTextures(bool multisampled, uint32_t* outID, uint32_t count)
        {
            glCreateTextures(TextureTarget(multisampled), count, outID);
        }

        static void AttachColorTexture(uint32_t id, int samples, GLenum internalFormat, GLenum format, uint32_t width, uint32_t height, int index)
        {
            bool multisampled = samples > 1;
            if (multisampled)
            {
                glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, samples, internalFormat, width, height, GL_FALSE);
            }
            else
            {
                glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, width, height, 0, format, GL_UNSIGNED_BYTE, nullptr);

                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
            }

            glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + index, TextureTarget(multisampled), id, 0);
        }

        static void AttachDepthTexture(uint32_t id, int samples, GLenum format, GLenum attachmentType, uint32_t width, uint32_t height)
        {
            bool multisampled = samples > 1;
            if (multisampled)
            {
                glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, samples, format, width, height, GL_FALSE);
            }
            else
            {
                glTexStorage2D(GL_TEXTURE_2D, 1, format, width, height);

                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
            }

            glFramebufferTexture2D(GL_FRAMEBUFFER, attachmentType, TextureTarget(multisampled), id, 0);
        }

        static bool IsDepthFormat(FramebufferTextureFormat format)
        {
            switch (format)
            {
                case FramebufferTextureFormat::DEPTH24STENCIL8:  return true;
            }
            return false;
        }

        static GLenum DonutFBTextureFormatToGL(FramebufferTextureFormat format)
        {
            switch (format)
            {
                case FramebufferTextureFormat::RGBA8:       return GL_RGBA8;
                case FramebufferTextureFormat::RED_INTEGER: return GL_RED_INTEGER;
            }

            return 0;
        }
    }

    OpenGLFramebuffer::OpenGLFramebuffer(const FramebufferSpecification& spec)
        : m_Specification(spec)
    {
        for (auto spec : m_Specification.Attachments.Attachments)
        {
            if (!Utils::IsDepthFormat(spec.TextureFormat))
                m_ColorAttachmentSpecifications.emplace_back(spec);
            else
                m_DepthAttachmentSpecification = spec;
        }

        Invalidate();
    }

    OpenGLFramebuffer::~OpenGLFramebuffer()
    {
        glDeleteFramebuffers(1, &m_RendererID);
        glDeleteTextures(static_cast<GLsizei>(m_ColorAttachments.size()), m_ColorAttachments.data());
        glDeleteTextures(1, &m_DepthAttachment);
    }

    void OpenGLFramebuffer::Invalidate()
    {
        if (m_RendererID)
        {
            glDeleteFramebuffers(1, &m_RendererID);
            glDeleteTextures(static_cast<GLsizei>(m_ColorAttachments.size()), m_ColorAttachments.data());
            glDeleteTextures(1, &m_DepthAttachment);

            m_ColorAttachments.clear();
            m_DepthAttachment = 0;
        }

        glCreateFramebuffers(1, &m_RendererID);
        glBindFramebuffer(GL_FRAMEBUFFER, m_RendererID);

        bool multisample = m_Specification.Samples > 1;

        if (m_ColorAttachmentSpecifications.size())
        {
            m_ColorAttachments.resize(m_ColorAttachmentSpecifications.size());
            Utils::CreateTextures(multisample, m_ColorAttachments.data(), static_cast<uint32_t>(m_ColorAttachments.size()));

            for (size_t i = 0; i < m_ColorAttachments.size(); i++)
            {
                Utils::BindTexture(multisample, m_ColorAttachments[i]);
                switch (m_ColorAttachmentSpecifications[i].TextureFormat)
                {
                    case FramebufferTextureFormat::RGBA8:
                        Utils::AttachColorTexture(m_ColorAttachments[i], m_Specification.Samples, GL_RGBA8, GL_RGBA, m_Specification.Width, m_Specification.Height, static_cast<int>(i));
                        break;
                    case FramebufferTextureFormat::RED_INTEGER:
                        Utils::AttachColorTexture(m_ColorAttachments[i], m_Specification.Samples, GL_R32I, GL_RED_INTEGER, m_Specification.Width, m_Specification.Height, static_cast<int>(i));
                        break;
                }
            }
        }

        if (m_DepthAttachmentSpecification.TextureFormat != FramebufferTextureFormat::None)
        {
            Utils::CreateTextures(multisample, &m_DepthAttachment, 1);
            Utils::BindTexture(multisample, m_DepthAttachment);
            switch (m_DepthAttachmentSpecification.TextureFormat)
            {
                case FramebufferTextureFormat::DEPTH24STENCIL8:
                    Utils::AttachDepthTexture(m_DepthAttachment, m_Specification.Samples, GL_DEPTH24_STENCIL8, GL_DEPTH_STENCIL_ATTACHMENT, m_Specification.Width, m_Specification.Height);
                    break;
            }
        }

        if (m_ColorAttachments.size() > 1)
        {
            GLenum buffers[4] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2, GL_COLOR_ATTACHMENT3 };
            glDrawBuffers(static_cast<GLsizei>(m_ColorAttachments.size()), buffers);
        }
        else if (m_ColorAttachments.empty())
            glDrawBuffer(GL_NONE);

        if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        {
            GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
            switch (status)
            {
                case GL_FRAMEBUFFER_UNDEFINED:
                    DONUT_ERROR("Framebuffer is undefined");
                    break;
                case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT:
                    DONUT_ERROR("Framebuffer has incomplete attachment");
                    break;
                case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT:
                    DONUT_ERROR("Framebuffer is missing attachment");
                    break;
                case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER:
                    DONUT_ERROR("Framebuffer has incomplete draw buffer");
                    break;
                case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER:
                    DONUT_ERROR("Framebuffer has incomplete read buffer");
                    break;
                case GL_FRAMEBUFFER_UNSUPPORTED:
                    DONUT_ERROR("Framebuffer format is unsupported");
                    break;
                case GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE:
                    DONUT_ERROR("Framebuffer has incomplete multisample");
                    break;
                case GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS:
                    DONUT_ERROR("Framebuffer has incomplete layer targets");
                    break;
                default:
                    DONUT_ERROR("Framebuffer is incomplete (unknown error: {})", status);
                    break;
            }
        }

        glBindFramebuffer(GL_FRAMEBUFFER, 0);
    }

    void OpenGLFramebuffer::Bind()
    {
        glBindFramebuffer(GL_FRAMEBUFFER, m_RendererID);
        glViewport(0, 0, m_Specification.Width, m_Specification.Height);
    }

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

    void OpenGLFramebuffer::Resize(uint32_t width, uint32_t height)
    {
        m_Specification.Width = width;
        m_Specification.Height = height;

        Invalidate();
    }

    int OpenGLFramebuffer::ReadPixel(uint32_t attachmentIndex, int x, int y)
    {
        glReadBuffer(GL_COLOR_ATTACHMENT0 + attachmentIndex);
        int pixelData;
        glReadPixels(x, y, 1, 1, GL_RED_INTEGER, GL_INT, &pixelData);
        return pixelData;
    }

    void OpenGLFramebuffer::ClearAttachment(uint32_t attachmentIndex, int value)
    {
        auto& spec = m_ColorAttachmentSpecifications[attachmentIndex];
        glClearTexImage(m_ColorAttachments[attachmentIndex], 0,
            Utils::DonutFBTextureFormatToGL(spec.TextureFormat), GL_INT, &value);
    }
};