/***

    Olive - Non-Linear Video Editor
    Copyright (C) 2019  Olive Team

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

***/

#include "renderthread.h"

#include <QApplication>
#include <QImage>
#include <QOpenGLFunctions>
#include <QDateTime>
#include <QDebug>
#ifdef OLIVE_OCIO
#include <OpenColorIO/OpenColorIO.h>
namespace OCIO = OCIO_NAMESPACE;
#endif

#include "rendering/renderfunctions.h"
#include "project/sequence.h"

RenderThread::RenderThread()
{
  front_buffer1 = 0;
  front_buffer2 = 0;
  front_texture1 = 0;
  front_texture2 = 0;
  gizmos = nullptr;
  share_ctx = nullptr;
  ctx = nullptr;
  blend_mode_program = nullptr;
  premultiply_program = nullptr;
  seq = nullptr;
  tex_width = -1;
  tex_height = -1;
  queued = false;
  texture_failed = false;
  running = true;

  surface.create();
}

RenderThread::~RenderThread() {
  surface.destroy();
}

void RenderThread::run() {
  wait_lock_.lock();

  while (running) {
    if (!queued) {
      wait_cond_.wait(&wait_lock_);
    }
    if (!running) {
      break;
    }
    queued = false;

    if (share_ctx != nullptr) {
      if (ctx != nullptr) {
        ctx->makeCurrent(&surface);

        // gen fbo
        if (front_buffer1 == 0) {
          // delete any existing framebuffers
          delete_fbo();

          // create framebuffers
          ctx->functions()->glGenFramebuffers(1, &front_buffer1);
          ctx->functions()->glGenFramebuffers(1, &front_buffer2);
          ctx->functions()->glGenFramebuffers(1, &back_buffer_1);
          ctx->functions()->glGenFramebuffers(1, &back_buffer_2);
        }

        // gen texture
        if (front_texture1 == 0 || tex_width != seq->width || tex_height != seq->height) {
          // cache texture size
          tex_width = seq->width;
          tex_height = seq->height;

          // delete any existing textures
          delete_texture();

          // create texture
          glGenTextures(1, &front_texture1);
          glGenTextures(1, &front_texture2);
          glGenTextures(1, &back_texture_1);
          glGenTextures(1, &back_texture_2);

          GLuint textures[4] = { front_texture1, front_texture2, back_texture_1, back_texture_2 };
          GLuint fbos[4] = { front_buffer1, front_buffer2, back_buffer_1, back_buffer_2 };

          for (int i=0;i<4;i++) {
            allocate_texture(textures[i], fbos[i]);
          }
        }

        if (blend_mode_program == nullptr) {
          // create shader program to make blending modes work
          delete_shader_program();

          blend_mode_program = new QOpenGLShaderProgram();
          blend_mode_program->addShaderFromSourceFile(QOpenGLShader::Vertex, ":/internalshaders/common.vert");
          blend_mode_program->addShaderFromSourceFile(QOpenGLShader::Fragment, ":/internalshaders/blending.frag");
          blend_mode_program->link();

          premultiply_program = new QOpenGLShaderProgram();
          premultiply_program->addShaderFromSourceFile(QOpenGLShader::Vertex, ":/internalshaders/common.vert");
          premultiply_program->addShaderFromSourceFile(QOpenGLShader::Fragment, ":/internalshaders/premultiply.frag");
          premultiply_program->link();
        }

        // draw frame
        paint();

        front_buffer_switcher = !front_buffer_switcher;

        emit ready();
      }
    }
  }

  delete_ctx();

  wait_lock_.unlock();
}

QMutex *RenderThread::get_texture_mutex()
{
  // return the mutex for the opposite texture being drawn to by the renderer
  return front_buffer_switcher ? &front_mutex2 : &front_mutex1;
}

const GLuint &RenderThread::get_texture()
{
  // return the opposite texture to the texture being drawn to by the renderer
  return front_buffer_switcher ? front_texture2 : front_texture1;
}

void RenderThread::allocate_texture(GLuint tex, GLuint fbo)
{
  // bind framebuffer for attaching
  ctx->functions()->glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fbo);

  // bind texture
  glBindTexture(GL_TEXTURE_2D, tex);

  // allocate storage for texture
  glTexImage2D(
        GL_TEXTURE_2D, 0, GL_RGBA, seq->width, seq->height, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr
        );

  // set texture filtering to bilinear
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  // attach texture to framebuffer
  ctx->functions()->glFramebufferTexture2D(
        GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tex, 0
        );

  // release texture
  glBindTexture(GL_TEXTURE_2D, 0);

  // release framebuffer
  ctx->functions()->glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
}

void RenderThread::set_up_ocio()
{
}

void RenderThread::paint() {
  // set up compose_sequence() parameters
  ComposeSequenceParams params;
  params.viewer = nullptr;
  params.ctx = ctx;
  params.seq = seq;
  params.video = true;
  params.texture_failed = false;
  params.gizmos = &gizmos;
  params.wait_for_mutexes = true;
  params.playback_speed = 1;
  params.blend_mode_program = blend_mode_program;
  params.premultiply_program = premultiply_program;
  params.backend_buffer1 = back_buffer_1;
  params.backend_buffer2 = back_buffer_2;
  params.backend_attachment1 = back_texture_1;
  params.backend_attachment2 = back_texture_2;
  params.main_buffer = front_buffer_switcher ? front_buffer1 : front_buffer2;
  params.main_attachment = front_buffer_switcher ? front_texture1 : front_texture2;

  QMutex& active_mutex = front_buffer_switcher ? front_mutex1 : front_mutex2;
  active_mutex.lock();

  // bind framebuffer for drawing
  ctx->functions()->glBindFramebuffer(GL_DRAW_FRAMEBUFFER, params.main_buffer);

  glLoadIdentity();

  glClearColor(0.0, 0.0, 0.0, 0.0);
  glClear(GL_COLOR_BUFFER_BIT);

  glMatrixMode(GL_MODELVIEW);

  glEnable(GL_TEXTURE_2D);
  glEnable(GL_BLEND);
  glEnable(GL_DEPTH);

  gizmos = nullptr;

  compose_sequence(params);

  // flush changes
  ctx->functions()->glFinish();

  texture_failed = params.texture_failed;

  active_mutex.unlock();

  if (!save_fn.isEmpty()) {
    if (texture_failed) {
      // texture failed, try again
      queued = true;
    } else {
      ctx->functions()->glBindFramebuffer(GL_READ_FRAMEBUFFER, params.main_buffer);
      QImage img(tex_width, tex_height, QImage::Format_RGBA8888);
      glReadPixels(0, 0, tex_width, tex_height, GL_RGBA, GL_UNSIGNED_BYTE, img.bits());
      img.save(save_fn);
      ctx->functions()->glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
      save_fn = "";
    }
  }

  if (pixel_buffer != nullptr) {

    // set main framebuffer to the current read buffer
    ctx->functions()->glBindFramebuffer(GL_READ_FRAMEBUFFER, params.main_buffer);

    // store pixels in buffer
    glReadPixels(0,
                 0,
                 pixel_buffer_linesize == 0 ? tex_width : pixel_buffer_linesize,
                 tex_height,
                 GL_RGBA,
                 GL_UNSIGNED_BYTE,
                 pixel_buffer);

    // release current read buffer
    ctx->functions()->glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);

    pixel_buffer = nullptr;
  }

  glDisable(GL_DEPTH);
  glDisable(GL_BLEND);
  glDisable(GL_TEXTURE_2D);

  // release
  ctx->functions()->glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
}

void RenderThread::start_render(QOpenGLContext *share, SequencePtr s, const QString& save, GLvoid* pixels, int pixel_linesize, int idivider) {
  Q_UNUSED(idivider);

  seq = s;

  // stall any dependent actions
  texture_failed = true;

  if (share != nullptr && (ctx == nullptr || ctx->shareContext() != share_ctx)) {
    share_ctx = share;
    delete_ctx();
    ctx = new QOpenGLContext();
    ctx->setFormat(share_ctx->format());
    ctx->setShareContext(share_ctx);
    ctx->create();
    ctx->moveToThread(this);
  }

  save_fn = save;
  pixel_buffer = pixels;
  pixel_buffer_linesize = pixel_linesize;

  queued = true;

  wait_cond_.wakeAll();
}

bool RenderThread::did_texture_fail() {
  return texture_failed;
}

void RenderThread::cancel() {
  running = false;
  wait_cond_.wakeAll();
  wait();
}

void RenderThread::delete_texture() {
  if (front_texture1 > 0) {
    GLuint tex[4] = {front_texture1, front_texture2, back_texture_1, back_texture_2};
    glDeleteTextures(3, tex);
  }
  front_texture1 = 0;
  front_texture2 = 0;
  back_texture_1 = 0;
  back_texture_2 = 0;
}

void RenderThread::delete_fbo() {
  if (front_buffer1 > 0) {
    GLuint fbos[4] = {front_buffer1, front_buffer2, back_buffer_1, back_buffer_2};
    ctx->functions()->glDeleteFramebuffers(3, fbos);
  }
  front_buffer1 = 0;
  front_buffer2 = 0;
  back_buffer_1 = 0;
  back_buffer_2 = 0;
}

void RenderThread::delete_shader_program() {
  if (blend_mode_program != nullptr) {
    delete blend_mode_program;
    delete premultiply_program;
  }
  blend_mode_program = nullptr;
  premultiply_program = nullptr;
}

void RenderThread::delete_ctx() {
  if (ctx != nullptr) {
    delete_shader_program();
    delete_texture();
    delete_fbo();
    ctx->doneCurrent();
    delete ctx;
  }
  ctx = nullptr;
}