#include "CWallpaper.h"
#include "WallpaperEngine/Render/Wallpapers/CScene.h"
#include "WallpaperEngine/Render/Wallpapers/CVideo.h"
#include "WallpaperEngine/Render/Wallpapers/CWeb.h"
#include "common.h"

#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <utility>

using namespace WallpaperEngine::Render;

CWallpaper::CWallpaper (Core::CWallpaper* wallpaperData, std::string type, CRenderContext& context,
                        CAudioContext& audioContext, const CWallpaperState::TextureUVsScaling& scalingMode) :
    CContextAware (context),
    m_wallpaperData (wallpaperData),
    m_type (std::move (type)),
    m_destFramebuffer (GL_NONE),
    m_sceneFBO (nullptr),
    m_texCoordBuffer (GL_NONE),
    m_positionBuffer (GL_NONE),
    m_shader (GL_NONE),
    g_Texture0 (GL_NONE),
    a_Position (GL_NONE),
    a_TexCoord (GL_NONE),
    m_vaoBuffer (GL_NONE),
    m_audioContext (audioContext),
    m_state (scalingMode) {
    // generate the VAO to stop opengl from complaining
    glGenVertexArrays (1, &this->m_vaoBuffer);
    glBindVertexArray (this->m_vaoBuffer);

    this->setupShaders ();

    const GLfloat texCoords [] = {0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f};

    // inverted positions so the final texture is rendered properly
    const GLfloat position [] = {-1.0f, 1.0f,  0.0f, 1.0,  1.0f, 0.0f, -1.0f, -1.0f, 0.0f,
                                 -1.0f, -1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f,  -1.0f, 0.0f};

    glGenBuffers (1, &this->m_texCoordBuffer);
    glBindBuffer (GL_ARRAY_BUFFER, this->m_texCoordBuffer);
    glBufferData (GL_ARRAY_BUFFER, sizeof (texCoords), texCoords, GL_STATIC_DRAW);

    glGenBuffers (1, &this->m_positionBuffer);
    glBindBuffer (GL_ARRAY_BUFFER, this->m_positionBuffer);
    glBufferData (GL_ARRAY_BUFFER, sizeof (position), position, GL_STATIC_DRAW);
}

CWallpaper::~CWallpaper () = default;

CContainer* CWallpaper::getContainer () const {
    return this->m_wallpaperData->getProject ().getContainer ();
}

WallpaperEngine::Core::CWallpaper* CWallpaper::getWallpaperData () const {
    return this->m_wallpaperData;
}

GLuint CWallpaper::getWallpaperFramebuffer () const {
    return this->m_sceneFBO->getFramebuffer ();
}

GLuint CWallpaper::getWallpaperTexture () const {
    return this->m_sceneFBO->getTextureID (0);
}

void CWallpaper::setupShaders () {
    // reserve shaders in OpenGL
    const GLuint vertexShaderID = glCreateShader (GL_VERTEX_SHADER);

    // give shader's source code to OpenGL to be compiled
    const char* sourcePointer = "#version 330\n"
                                "precision highp float;\n"
                                "in vec3 a_Position;\n"
                                "in vec2 a_TexCoord;\n"
                                "out vec2 v_TexCoord;\n"
                                "void main () {\n"
                                "gl_Position = vec4 (a_Position, 1.0);\n"
                                "v_TexCoord = a_TexCoord;\n"
                                "}";

    glShaderSource (vertexShaderID, 1, &sourcePointer, nullptr);
    glCompileShader (vertexShaderID);

    GLint result = GL_FALSE;
    int infoLogLength = 0;

    // ensure the vertex shader was correctly compiled
    glGetShaderiv (vertexShaderID, GL_COMPILE_STATUS, &result);
    glGetShaderiv (vertexShaderID, GL_INFO_LOG_LENGTH, &infoLogLength);

    if (infoLogLength > 0) {
        char* logBuffer = new char [infoLogLength + 1];
        // ensure logBuffer ends with a \0
        memset (logBuffer, 0, infoLogLength + 1);
        // get information about the error
        glGetShaderInfoLog (vertexShaderID, infoLogLength, nullptr, logBuffer);
        // throw an exception about the issue
        const std::string message = logBuffer;
        // free the buffer
        delete [] logBuffer;
        // throw an exception
        sLog.exception (message);
    }

    // reserve shaders in OpenGL
    const GLuint fragmentShaderID = glCreateShader (GL_FRAGMENT_SHADER);

    // give shader's source code to OpenGL to be compiled
    sourcePointer = "#version 330\n"
                    "precision highp float;\n"
                    "uniform sampler2D g_Texture0;\n"
                    "in vec2 v_TexCoord;\n"
                    "out vec4 out_FragColor;\n"
                    "void main () {\n"
                    "out_FragColor = texture (g_Texture0, v_TexCoord);\n"
                    "}";

    glShaderSource (fragmentShaderID, 1, &sourcePointer, nullptr);
    glCompileShader (fragmentShaderID);

    result = GL_FALSE;
    infoLogLength = 0;

    // ensure the vertex shader was correctly compiled
    glGetShaderiv (fragmentShaderID, GL_COMPILE_STATUS, &result);
    glGetShaderiv (fragmentShaderID, GL_INFO_LOG_LENGTH, &infoLogLength);

    if (infoLogLength > 0) {
        char* logBuffer = new char [infoLogLength + 1];
        // ensure logBuffer ends with a \0
        memset (logBuffer, 0, infoLogLength + 1);
        // get information about the error
        glGetShaderInfoLog (fragmentShaderID, infoLogLength, nullptr, logBuffer);
        // throw an exception about the issue
        const std::string message = logBuffer;
        // free the buffer
        delete [] logBuffer;
        // throw an exception
        sLog.exception (message);
    }

    // create the final program
    this->m_shader = glCreateProgram ();
    // link the shaders together
    glAttachShader (this->m_shader, vertexShaderID);
    glAttachShader (this->m_shader, fragmentShaderID);
    glLinkProgram (this->m_shader);
    // check that the shader was properly linked
    result = GL_FALSE;
    infoLogLength = 0;

    glGetProgramiv (this->m_shader, GL_LINK_STATUS, &result);
    glGetProgramiv (this->m_shader, GL_INFO_LOG_LENGTH, &infoLogLength);

    if (infoLogLength > 0) {
        char* logBuffer = new char [infoLogLength + 1];
        // ensure logBuffer ends with a \0
        memset (logBuffer, 0, infoLogLength + 1);
        // get information about the error
        glGetProgramInfoLog (this->m_shader, infoLogLength, nullptr, logBuffer);
        // throw an exception about the issue
        const std::string message = logBuffer;
        // free the buffer
        delete [] logBuffer;
        // throw an exception
        sLog.exception (message);
    }

    // after being liked shaders can be dettached and deleted
    glDetachShader (this->m_shader, vertexShaderID);
    glDetachShader (this->m_shader, fragmentShaderID);

    glDeleteShader (vertexShaderID);
    glDeleteShader (fragmentShaderID);

    // get textures
    this->g_Texture0 = glGetUniformLocation (this->m_shader, "g_Texture0");
    this->a_Position = glGetAttribLocation (this->m_shader, "a_Position");
    this->a_TexCoord = glGetAttribLocation (this->m_shader, "a_TexCoord");
}

void CWallpaper::setDestinationFramebuffer (GLuint framebuffer) {
    this->m_destFramebuffer = framebuffer;
}

void CWallpaper::updateUVs (const glm::ivec4& viewport, const bool vflip) {
    // update UVs if something has changed, otherwise use old values
    if (this->m_state.hasChanged (viewport, vflip, this->getWidth (), this->getHeight ())) {
        // Update wallpaper state
        this->m_state.updateState (viewport, vflip, this->getWidth (), this->getHeight ());
    }
}

void CWallpaper::render (glm::ivec4 viewport, bool vflip) {
    this->renderFrame (viewport);
    // Update UVs coordinates according to scaling mode of this wallpaper
    updateUVs (viewport, vflip);
    auto [ustart, uend, vstart, vend] = this->m_state.getTextureUVs ();

    const GLfloat texCoords [] = {
        ustart, vstart, uend, vstart, ustart, vend, ustart, vend, uend, vstart, uend, vend,
    };

    glViewport (viewport.x, viewport.y, viewport.z, viewport.w);

    glBindFramebuffer (GL_FRAMEBUFFER, this->m_destFramebuffer);

    glBindVertexArray (this->m_vaoBuffer);

    glDisable (GL_BLEND);
    glDisable (GL_DEPTH_TEST);
    // do not use any shader
    glUseProgram (this->m_shader);
    // activate scene texture
    glActiveTexture (GL_TEXTURE0);
    glBindTexture (GL_TEXTURE_2D, this->getWallpaperTexture ());
    // set uniforms and attribs
    glEnableVertexAttribArray (this->a_TexCoord);
    glBindBuffer (GL_ARRAY_BUFFER, this->m_texCoordBuffer);
    glBufferData (GL_ARRAY_BUFFER, sizeof (texCoords), texCoords, GL_STATIC_DRAW);
    glVertexAttribPointer (this->a_TexCoord, 2, GL_FLOAT, GL_FALSE, 0, nullptr);

    glEnableVertexAttribArray (this->a_Position);
    glBindBuffer (GL_ARRAY_BUFFER, this->m_positionBuffer);
    glVertexAttribPointer (this->a_Position, 3, GL_FLOAT, GL_FALSE, 0, nullptr);

    glUniform1i (this->g_Texture0, 0);
    // write the framebuffer as is to the screen
    glBindBuffer (GL_ARRAY_BUFFER, this->m_texCoordBuffer);
    glDrawArrays (GL_TRIANGLES, 0, 6);
}

void CWallpaper::setupFramebuffers () {
    const uint32_t width = this->getWidth ();
    const uint32_t height = this->getHeight ();
    const ITexture::TextureFlags clamp = this->getContext ().getApp ().getContext ().settings.render.window.clamp;

    // create framebuffer for the scene
    this->m_sceneFBO = this->createFBO ("_rt_FullFrameBuffer", ITexture::TextureFormat::ARGB8888, clamp, 1.0, width,
                                        height, width, height);

    this->aliasFBO ("_rt_MipMappedFrameBuffer", this->m_sceneFBO);
}

CAudioContext& CWallpaper::getAudioContext () {
    return this->m_audioContext;
}

CFBO* CWallpaper::createFBO (const std::string& name, ITexture::TextureFormat format, ITexture::TextureFlags flags,
                             float scale, uint32_t realWidth, uint32_t realHeight, uint32_t textureWidth,
                             uint32_t textureHeight) {
    CFBO* fbo = new CFBO (name, format, flags, scale, realWidth, realHeight, textureWidth, textureHeight);

    this->m_fbos.insert (std::make_pair (name, fbo));

    return fbo;
}

void CWallpaper::aliasFBO (const std::string& alias, CFBO* original) {
    this->m_fbos.insert (std::make_pair (alias, original));
}

const std::map<std::string, CFBO*>& CWallpaper::getFBOs () const {
    return this->m_fbos;
}

CFBO* CWallpaper::findFBO (const std::string& name) const {
    const auto it = this->m_fbos.find (name);

    if (it == this->m_fbos.end ())
        sLog.exception ("Cannot find FBO ", name);

    return it->second;
}

CFBO* CWallpaper::getFBO () const {
    return this->m_sceneFBO;
}

CWallpaper* CWallpaper::fromWallpaper (Core::CWallpaper* wallpaper, CRenderContext& context,
                                       CAudioContext& audioContext,
                                       const CWallpaperState::TextureUVsScaling& scalingMode) {
    if (wallpaper->is<Core::CScene> ())
        return new WallpaperEngine::Render::CScene (wallpaper->as<Core::CScene> (), context, audioContext, scalingMode);
    if (wallpaper->is<Core::CVideo> ())
        return new WallpaperEngine::Render::CVideo (wallpaper->as<Core::CVideo> (), context, audioContext, scalingMode);
    else if (wallpaper->is<Core::CWeb> ())
        return new WallpaperEngine::Render::CWeb (wallpaper->as<Core::CWeb> (), context, audioContext, scalingMode);
    else
        sLog.exception ("Unsupported wallpaper type");
}