<?php
/**
 * tracksegment.php
 *
 * Copyright 2018 Andy Street <andy@street.me.uk>
 *
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 *
 *
 */

namespace libgpx;

use \ArrayAccess;
use \Countable;
use \DomainException;
use \IteratorAggregate;

/**
 * A GPX trk type.
 *
 * @author Andy Street <andy@street.me.uk>
 */
class Track extends DataType
  implements Geographic, ArrayAccess, Countable, IteratorAggregate
{

  /**
   * GPS track number.
   *
   * @var int
   */
  protected $number;

  /**
   * A list of track segments.
   *
   * @var DoublyLinkedList (TrackSegment)
   *
   */
  protected $segments;

  /**
   * Fetch the track number.
   *
   * @return int|null The route number or null if not set.
   */
  public function getNumber()
  {
    return $this->number;
  }

  /**
   * Set the number of the track.
   *
   * @param int $number The route number or null to delete.
   * @return void
   * @throws DomainException If the number is < 0
   */
  public function setNumber(int $number = null)
  {
    if ($number !== null && $number < 0)
      throw new DomainException(
        sprintf('Number must be >= 0 but got "%s"', $number)
      );
    $this->number = $number;
  }

  /**
   * Count the number of track points.
   *
   * @return The number of track points contained in all the segments of this
   *         track.
   */
  public function countTrackPoints()
  {
    $count = 0;
    if ($this->segments !== null) {
      foreach ($this->segments as $segment) {
        $count += count($segment);
      }
    }
    return $count;
  }

  /**
   * Fetch an ordered list of track segments.
   *
   * @param boolean $create Create the list if it does not already exist.
   * @return TypedDoublyLinkedList|null A list of track segments.
   */
  public function getSegments(bool $create = true)
  {
    if ($create && $this->segments === null)
      $this->segments = new TypedDoublyLinkedList('libgpx\TrackSegment');
    return $this->segments;
  }

  /**
   * Fetch a bounding box that covers the feature.
   *
   * @return Bounds|null A bounding box covering the extent of the feature or
   *         null if not applicable.
   */
  public function getBounds()
  {
    $result = null;
    if ($this->segments !== null) {
      foreach ($this->segments as $segment) {
        $bounds = $segment->getBounds();
        if ($result === null) {
          $result = $bounds;
        } else {
          $result->extend($bounds);
        }
      }
    }
    return $result;
  }

  /**
   * Fetch the length of a track.
   *
   * @return float The length in meters.
   */
  public function getLength()
  {
    $length = 0;
    $segments = $this->getSegments(false);
    if ($segments !== null) {
      foreach ($segments as $segment) {
        $length += $segment->getLength();
      }
    }
    return $length;
  }

  /**
   * Check if an offset holds a value.
   *
   * @see ArrayAccess::offsetExists
   *
   * @param mixed $offset The offset to search
   * @return boolean
   */
  public function offsetExists($offset)
  {
    return $this->getSegments()->offsetExists($offset);
  }

  /**
   * Fetch a segment from this track.
   *
   * @see ArrayAccess::offsetGet
   *
   * @param mixed $offset The offset to retrieve
   * @return TrackSegment
   */
  public function offsetGet($offset)
  {
    return $this->getSegments()->offsetGet($offset);
  }

  /**
   * Set the segment at an offset.
   *
   * @see ArrayAccess::offsetSet
   *
   * @param mixed $offset Where to store the segment.
   * @param TrackSegment $value The segment to store.
   * @return void
   */
  public function offsetSet($offset, $value)
  {
    return $this->getSegments()->offsetSet($offset, $value);
  }

  /**
   * Remove a segment.
   *
   * @see ArrayAccess::offsetUnset
   *
   * @param mixed $offset Which segment to remove
   * @return void
   */
  public function offsetUnset($offset)
  {
    return $this->getSegments()->offsetUnset($offset);
  }

  /**
   * Count the number of segments in this track.
   *
   * @return int
   */
  public function count()
  {
    return ($this->segments === null ? 0 : $this->segments->count());
  }

  /**
   * Fetch an iterator for the segments contained in this track.
   *
   * @return \Iterator
   */
  public function getIterator() {
    return $this->getSegments();
  }

}