/*************************************************************************************
 * Copyright (c) 2016, Miguel Angel Astor Romero                                     *
 * All rights reserved.                                                              *
 *                                                                                   *
 * Redistribution and use in source and binary forms, with or without                *
 * modification, are permitted provided that the following conditions are met:       *
 *                                                                                   *
 * 1. Redistributions of source code must retain the above copyright notice, this    *
 *    list of conditions and the following disclaimer.                               *
 * 2. Redistributions in binary form must reproduce the above copyright notice,      *
 *    this list of conditions and the following disclaimer in the documentation      *
 *    and/or other materials provided with the distribution.                         *
 *                                                                                   *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND   *
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED     *
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#include <iostream>
#include <cstdlib>
#include <cmath>
#include <cassert>
#include <cstring>

#include <pnglite.h>
#include <glm/glm.hpp>
#include <libplayerc++/playerc++.h>

#include "pheromone.hpp"

#define MAP_POS(X, Y, Z) (Z[((X) * m_height) + (Y)])

namespace ias_ss {
  static const unsigned int  MAX_ITERS           = 1000;
  static const float         EVAPORATION_RATE    = 0.05f;
  const        unsigned char MAX_PHERO_INTENSITY = 250;
  const        unsigned char MIN_PHERO_INTENSITY = 0;

  static inline int sign(float f) {
    return (f < 0.0f) ? -1 : ((f > 0.0f) ? 1 : 0);
  }

  static inline int side(glm::vec3 line, glm::vec3 v) {
    return sign(glm::cross(line, v).z);
  }

  static inline float random_n(float r) {
    return (((static_cast<float>(rand() % 256) / 256.0) - 0.5f) * 2.0f ) * r;
  }

  PheromoneMap::PheromoneMap(const char * file_name) {
    load_map(file_name);
    sem_init(&map_semaphore, 0, 1);
    then = 0;
    sensor_updates = 0;
    glGenTextures(1, &handle);
    glGenTextures(1, &sensor_handle);
  }

  PheromoneMap::~PheromoneMap() {
    delete data;
    sem_destroy(&map_semaphore);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, handle);
    glDeleteTextures(1, &handle);
    glDeleteTextures(1, &sensor_handle);
  }

  void PheromoneMap::load_map(const char * file_name) {
    png_t tex;

    png_init(0, 0);
    png_open_file_read(&tex, file_name);
    data = new unsigned char[tex.width * tex.height * tex.bpp];
    sensor_data = new unsigned char[tex.width * tex.height * tex.bpp];
    png_get_data(&tex, data);

    std::cout << "Loaded map \"" << file_name << "\" :: " << tex.width << "x" << tex.height << "x" << (int)tex.bpp << std::endl;
    m_width  = tex.width;
    m_height = tex.height;
    m_bpp    = tex.bpp;
  
    png_close_file(&tex);
  }

  GLuint PheromoneMap::s_build_texture() {
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, handle);
    sem_wait(&map_semaphore); {
      glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, m_width, m_height, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, data);
    } sem_post(&map_semaphore);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, 0);
  
    return handle;
  }

  GLuint PheromoneMap::s_build_sensor_texture() {
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, sensor_handle);
    sem_wait(&map_semaphore); {
      glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, m_width, m_height, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, sensor_data);
    } sem_post(&map_semaphore);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, 0);
  
    return sensor_handle;
  }

  void PheromoneMap::s_deposit_pheromone(float x, float y, float yaw, float radius) {
    unsigned int iters = 0;
    int _x, _y;
    bool         valid = false;
    float        dist, cos_theta, r_x, r_y;
    glm::vec2    v, vp;

    v  = glm::vec2(radius * cos(yaw), radius * sin(yaw)) - glm::vec2(0.0, 0.0);
    v  = glm::normalize(v);

    do {
      do {
	do {
	  do {
	    r_x  = random_n(radius) + x;
	    r_y  = random_n(radius) + y;
	  } while((r_x <= 0.0f && r_y <= 0.0f) || (r_x >= 1.0f && r_y >= 1.0f));
	  vp        = glm::vec2(r_x, r_y) - glm::vec2(x, y);
	  dist      = glm::length(vp);
	} while(dist > radius);
	vp        = glm::normalize(vp);
	cos_theta = glm::dot(vp, v);
      } while(cos_theta > 0.0f);
      _x = m_width * r_x;
      _y = m_height - (m_height * r_y);
      _x = _x < 0 ? _x = 0 : (_x >= m_width ? m_width - 1 : _x);
      _y = _y < 0 ? _y = 0 : (_y >= m_height ? m_height - 1 : _y);
      sem_wait(&map_semaphore); {
	if (MAP_POS(_y, _x, data) <= MAX_PHERO_INTENSITY) {
	  MAP_POS(_y, _x, data) += rand() % MAX_PHERO_INTENSITY;
	  MAP_POS(_y, _x, data) = MAP_POS(_y, _x, data) > MAX_PHERO_INTENSITY ? MAX_PHERO_INTENSITY : MAP_POS(_y, _x, data);
	  valid = true;
	}
      } sem_post(&map_semaphore);
      iters++;
      if (iters > MAX_ITERS)
	break;
    } while(!valid);
  }

  void PheromoneMap::s_evaporate() {
    unsigned char p_eva;

    clock_t now = clock();
    if (static_cast<float>(now - then) / CLOCKS_PER_SEC < 0.09) {
      return;
    }
    then = now;
  
    sem_wait(&map_semaphore); {
      for (unsigned i = 0; i < m_height; i++) {
	for (unsigned j = 0; j < m_width; j++) {
	  if (MAP_POS(i, j, data) <= MAX_PHERO_INTENSITY) {
	    p_eva = MAP_POS(i, j, data) * EVAPORATION_RATE;
	    MAP_POS(i, j, data) -= p_eva;
	    MAP_POS(i, j, data) = MAP_POS(i, j, data) < 0 ? 0 : MAP_POS(i, j, data);
	  }
	}
      }
    } sem_post(&map_semaphore);
  }

  void PheromoneMap::s_sample(phero_sensor_t * sensor, float x, float y, float yaw, float radius) {
    unsigned int index;
    float        dist;
    float        cos_theta;
    float        ang;
    glm::vec2    v, vp;
  
    if (sensor == NULL)
      return;
  
    else {
    
      sensor->reset();

      // Calculate the robot's view vector.
      v  = glm::vec2(radius * cos(yaw), radius * sin(yaw)) - glm::vec2(0.0, 0.0);
      v  = glm::normalize(v);
    
      sem_wait(&map_semaphore); {
	if (sensor_updates == 0) {
	  memset(sensor_data, 0, m_width * m_height * m_bpp * sizeof(unsigned char));
	}
	sensor_updates = (sensor_updates + 1) % 4;

	// For every point in the pheromone map.
	for (unsigned i = 0; i < m_height; i++) {
	  for (unsigned j = 0; j < m_width; j++) {
	    // Calculate the vector from the robot's center to the sampling point.
	    vp        = glm::vec2(j / float(m_width), 1.0f - (i / float(m_height))) - glm::vec2(x, y);
	    // Distance from the sampling point to  the robot's center.
	    dist      = glm::length(vp);
	    vp        = glm::normalize(vp);
	    // Cosine of the angle between the robot's center and the sampling point.
	    cos_theta = glm::dot(vp, v);

	    // Check if the point is close enough to the front of the robot.
	    if (cos_theta > 0.0f && dist <= radius) {
	      cos_theta = cos_theta > 1.0f ? 1.0f : cos_theta;
	      // Get the angle between the robot's center and the sampling point.
	      ang  = PlayerCc::rtod(acos(cos_theta));

	      // Put the sample in the sampling pool.
	      index = static_cast<unsigned int>(ang / (180 / 5));
	      index = index >= NUM_PHERO_SAMPLES ? NUM_PHERO_SAMPLES - 1 : index;
	      sensor->samples[index] = MAP_POS(i, j, data);
	      sensor->sample_amnt[index] += 1;
	    
	      MAP_POS(i, j, sensor_data) = MAP_POS(i, j, data);
	      
	    } else
	      continue;
	  }
	}
      } sem_post(&map_semaphore);

      // Average the samples.
      for (unsigned int i = 0; i < NUM_PHERO_SAMPLES; i++) {
	sensor->samples[i] = (sensor->sample_amnt[i] > 0) ? (sensor->samples[i] / sensor->sample_amnt[i]) : 0.0f;
      }
    }
  }
}