/*
 * Copyright 2011-2013 Blender Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdio.h>
#include <stdlib.h>

#include "util/opengl.h"
#include "util/string.h"
#include "util/time.h"
#include "util/version.h"
#include "util/view.h"

#ifdef __APPLE__
#  include <GLUT/glut.h>
#else
#  include <GL/glut.h>
#endif

CCL_NAMESPACE_BEGIN

/* structs */

struct View {
  ViewInitFunc initf;
  ViewExitFunc exitf;
  ViewResizeFunc resize;
  ViewDisplayFunc display;
  ViewKeyboardFunc keyboard;
  ViewMotionFunc motion;

  bool first_display;
  bool redraw;

  int mouseX, mouseY;
  int mouseBut0, mouseBut2;

  int width, height;
} V;

/* public */

static void view_display_text(int x, int y, const char *text)
{
  const char *c;

  glRasterPos3f(x, y, 0);

  for (c = text; *c != '\0'; c++)
    glutBitmapCharacter(GLUT_BITMAP_HELVETICA_10, *c);
}

void view_display_info(const char *info)
{
  const int height = 20;

  glEnable(GL_BLEND);
  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  glColor4f(0.1f, 0.1f, 0.1f, 0.8f);
  glRectf(0.0f, V.height - height, V.width, V.height);
  glDisable(GL_BLEND);

  glColor3f(0.5f, 0.5f, 0.5f);

  view_display_text(10, 7 + V.height - height, info);

  glColor3f(1.0f, 1.0f, 1.0f);
}

void view_display_help()
{
  const int w = (int)((float)V.width / 1.15f);
  const int h = (int)((float)V.height / 1.15f);

  const int x1 = (V.width - w) / 2;
  const int x2 = x1 + w;

  const int y1 = (V.height - h) / 2;
  const int y2 = y1 + h;

  glEnable(GL_BLEND);
  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  glColor4f(0.5f, 0.5f, 0.5f, 0.8f);
  glRectf(x1, y1, x2, y2);
  glDisable(GL_BLEND);

  glColor3f(0.8f, 0.8f, 0.8f);

  string info = string("Cycles Renderer ") + CYCLES_VERSION_STRING;

  view_display_text(x1 + 20, y2 - 20, info.c_str());
  view_display_text(x1 + 20, y2 - 40, "(C) 2011-2016 Blender Foundation");
  view_display_text(x1 + 20, y2 - 80, "Controls:");
  view_display_text(x1 + 20, y2 - 100, "h:  Info/Help");
  view_display_text(x1 + 20, y2 - 120, "r:  Reset");
  view_display_text(x1 + 20, y2 - 140, "p:  Pause");
  view_display_text(x1 + 20, y2 - 160, "esc:  Cancel");
  view_display_text(x1 + 20, y2 - 180, "q:  Quit program");

  view_display_text(x1 + 20, y2 - 210, "i:  Interactive mode");
  view_display_text(x1 + 20, y2 - 230, "Left mouse:  Move camera");
  view_display_text(x1 + 20, y2 - 250, "Right mouse:  Rotate camera");
  view_display_text(x1 + 20, y2 - 270, "W/A/S/D:  Move camera");
  view_display_text(x1 + 20, y2 - 290, "0/1/2/3:  Set max bounces");

  glColor3f(1.0f, 1.0f, 1.0f);
}

static void view_display()
{
  if (V.first_display) {
    if (V.initf)
      V.initf();
    if (V.exitf)
      atexit(V.exitf);

    V.first_display = false;
  }

  glClearColor(0.05f, 0.05f, 0.05f, 0.0f);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(0, V.width, 0, V.height, -1, 1);

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();

  glRasterPos3f(0, 0, 0);

  if (V.display)
    V.display();

  glutSwapBuffers();
}

static void view_reshape(int width, int height)
{
  if (width <= 0 || height <= 0)
    return;

  V.width = width;
  V.height = height;

  glViewport(0, 0, width, height);

  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();

  if (V.resize)
    V.resize(width, height);
}

static void view_keyboard(unsigned char key, int x, int y)
{
  if (V.keyboard)
    V.keyboard(key);

  if (key == 'm')
    printf("mouse %d %d\n", x, y);
  if (key == 'q') {
    if (V.exitf)
      V.exitf();
    exit(0);
  }
}

static void view_mouse(int button, int state, int x, int y)
{
  if (button == 0) {
    if (state == GLUT_DOWN) {
      V.mouseX = x;
      V.mouseY = y;
      V.mouseBut0 = 1;
    }
    else if (state == GLUT_UP) {
      V.mouseBut0 = 0;
    }
  }
  else if (button == 2) {
    if (state == GLUT_DOWN) {
      V.mouseX = x;
      V.mouseY = y;
      V.mouseBut2 = 1;
    }
    else if (state == GLUT_UP) {
      V.mouseBut2 = 0;
    }
  }
}

static void view_motion(int x, int y)
{
  const int but = V.mouseBut0 ? 0 : 2;
  const int distX = x - V.mouseX;
  const int distY = y - V.mouseY;

  if (V.motion)
    V.motion(distX, distY, but);

  V.mouseX = x;
  V.mouseY = y;
}

static void view_idle()
{
  if (V.redraw) {
    V.redraw = false;
    glutPostRedisplay();
  }

  time_sleep(0.1);
}

void view_main_loop(const char *title,
                    int width,
                    int height,
                    ViewInitFunc initf,
                    ViewExitFunc exitf,
                    ViewResizeFunc resize,
                    ViewDisplayFunc display,
                    ViewKeyboardFunc keyboard,
                    ViewMotionFunc motion)
{
  const char *name = "app";
  char *argv = (char *)name;
  int argc = 1;

  memset(&V, 0, sizeof(V));
  V.width = width;
  V.height = height;
  V.first_display = true;
  V.redraw = false;
  V.initf = initf;
  V.exitf = exitf;
  V.resize = resize;
  V.display = display;
  V.keyboard = keyboard;
  V.motion = motion;

  glutInit(&argc, &argv);
  glutInitWindowSize(width, height);
  glutInitWindowPosition(0, 0);
  glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
  glutCreateWindow(title);

  glewInit();

  view_reshape(width, height);

  glutDisplayFunc(view_display);
  glutIdleFunc(view_idle);
  glutReshapeFunc(view_reshape);
  glutKeyboardFunc(view_keyboard);
  glutMouseFunc(view_mouse);
  glutMotionFunc(view_motion);

  glutMainLoop();
}

void view_redraw()
{
  V.redraw = true;
}

CCL_NAMESPACE_END