<?php
/**
 * gpxwriter.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 \DateTime;
use \DateTimeInterface;
use \DateTimeZone;
use \RuntimeException;
use \UnexpectedValueException;
use \XMLWriter;

/**
 * Write GPX files.
 *
 * @author Andy Street <andy@street.me.uk>
 */
class GPXWriter
{

  /**
   * Who to credit as the document creator in the GPX root element.
   *
   * @var string
   * @see http://www.topografix.com/GPX/1/1/#type_gpxType
   */
  protected $creator = 'libgpx';

  /**
   * The version of the GPX standard to generate.
   *
   * @var string
   */
  protected $format = '1.1';

  /**
   * Whether to indent the XML output for readability.
   *
   * @var boolean
   */
  protected $indent = true;

  /**
   * Whether to include milliseconds in timestamps.
   *
   * @var boolean
   */
  protected $milliseconds = true;

  /**
   * Fetch the name credited as the creator of the XML files.
   *
   * @return string The creator.
   */
  public function getCreator()
  {
    return $this->creator;
  }

  /**
   * Set the name to be credited as the XML document creator.
   *
   * @param string $creator The name to credit as the creator.
   * @return void
   */
  public function setCreator(string $creator)
  {
    $this->creator = $creator;
  }

  /**
   * Fetch the GPX file format that this class generates.
   *
   * @return string The GPX file format.
   */
  public function getFormat()
  {
    return $this->format;
  }

  /**
   * Set the GPX file format that this class generates.
   *
   * @param string $format Accepted values are "1.0" or "1.1".
   * @return void
   * @throws UnexpectedValueException If $format is not a known GPX version.
   */
  public function setFormat(string $format)
  {
    switch ($format) {
      case '1.0':
      case '1.1':
        $this->format = $format;
        break;
      default:
        throw new UnexpectedValueException(
          sprintf('Unknown GPX version "%s"', $format)
        );
    }
  }

  /**
   * Whether this class will indent output for readability.
   *
   * @return boolean If the output will be indented.
   */
  public function getIndent()
  {
    return $this->indent;
  }

  /**
   * Set whether to indent output for readability.
   *
   * @param boolean $indent Whether to indent.
   * @return void
   */
  public function setIndent(bool $indent)
  {
    $this->indent = $indent;
  }

  /**
   * Whether timestamps are written to include milliseconds.
   *
   * @return boolean
   */
  public function getTimestampUseMilliseconds()
  {
    return $this->milliseconds;
  }

  /**
   * Set whether to output milliseconds in timestamps.
   *
   * @param boolean $milliseconds Whether to use milliseconds.
   * @return void
   */
  public function setTimestampUseMilliseconds(bool $milliseconds)
  {
    $this->milliseconds = $milliseconds;
  }

  /**
   * Fetch an XML representation as a string.
   *
   * @param GPX $gpx The source for the XML.
   * @return string An XML representation of the GPX object.
   */
  public function fetch(GPX $gpx)
  {
    $xml = new XMLWriter();
    $xml->openMemory();
    $this->write($gpx, $xml);
    return $xml->outputMemory();
  }

  /**
   * Write XML to standard out.
   *
   * @param GPX $gpx The source for the XML.
   * @return void
   */
  public function output(GPX $gpx)
  {
    $xml = new XMLWriter();
    $xml->openURI('php://output');
    $this->write($gpx, $xml);
  }

  /**
   * Write XML to a file.
   *
   * @param GPX $gpx The source for the XML.
   * @param string $filename Where to write the XML.
   * @return void
   * @throws RuntimeException If the file cannot be written to.
   */
  public function save(GPX $gpx, string $filename)
  {
    $xml = new XMLWriter();
    if (!$xml->openURI('php://output'))
      throw RuntimeException(sprintf('Unable to write to "%s"', $filename));
    $this->write($gpx, $xml);
  }

  /**
   * Generate the XML.
   *
   * @param GPX $gpx The source for the XML.
   * @param XMLWriter $xml The instance to use to generate the XML.
   * @return void
   */
  protected function write(GPX $gpx, XMLWriter $xml)
  {
    $xml->setIndent($this->indent);
    $xml->startDocument('1.0', 'UTF-8');
    if ($this->format == '1.1') {
      $namespace = libgpx::NAMESPACE_GPX_1_1;
      $schema = libgpx::SCHEMA_GPX_1_1;
    } else {
      $namespace = libgpx::NAMESPACE_GPX_1_0;
      $schema = libgpx::SCHEMA_GPX_1_0;
    }
    $xml->startElementNs(null, 'gpx', $namespace);
    $xml->writeAttribute('version', $this->format);
    $xml->writeAttribute('creator', $this->creator);
    $xml->writeAttributeNS(
      'xsi',
      'schemaLocation',
      libgpx::NAMESPACE_XMLSCHEMA,
      $namespace . ' ' . $schema
    );
    $this->writeMetadata($gpx, $xml);
    $waypoints = $gpx->getWaypoints(false);
    if ($waypoints !== null) {
      foreach ($waypoints as $wpt) {
        $this->writePoint($wpt, 'wpt', $xml);
      }
    }
    $routes = $gpx->getRoutes(false);
    if ($routes !== null) {
      foreach ($routes as $route) {
        $this->writeRoute($route, $xml);
      }
    }
    $tracks = $gpx->getTracks(false);
    if ($tracks !== null) {
      foreach ($tracks as $track) {
        $this->writeTrack($track, $xml);
      }
    }
    $extensions = $gpx->getExtensions(false);
    if ($extensions !== null && !$extensions->isEmpty()) {
      if ($this->format == '1.1')
        $xml->startElement('extensions');
      foreach ($extensions as $extension) {
        $xml->writeRaw($extension);
      }
      if ($this->format == '1.1')
        $xml->endElement();
    }
    $xml->endElement();
    $xml->endDocument();
    $xml->flush();
  }

  /**
   * Generate XML for Metadata elements.
   *
   * @param GPX $gpx The object to source the metadata from.
   * @param XMLWriter $xml Where to write the metadata.
   * @return void
   */
  protected function writeMetadata(GPX $gpx, XMLWriter $xml)
  {
    if ($this->format == '1.1')
      $xml->startElement('metadata');
    $name = $gpx->getName();
    if (!empty($name))
      $xml->writeElement('name', $name);
    $desc = $gpx->getDesc();
    if (!empty($desc))
      $xml->writeElement('desc', $desc);
    $author = $gpx->getAuthor();
    if ($author instanceof Person)
      $this->writePerson($author, $xml);
    if ($this->format == '1.1') {
      $copyright = $gpx->getCopyright();
      if ($copyright instanceof Copyright)
        $this->writeCopyright($copyright, $xml);
    }
    $links = $gpx->getLinks(false);
    if ($links !== null) {
      foreach($links as $link) {
        $this->writeLink($link, $xml);
        if ($this->format == '1.0')
          break;
      }
    }
    $xml->writeElement('time', $this->createTimestamp(new DateTime()));
    $keywords = $gpx->getKeywords(false);
    if ($keywords !== null && !$keywords->isEmpty())
      $xml->writeElement(
        'keywords',
        implode(', ', $gpx->getKeywords()->toArray())
      );
    $bounds = $gpx->getBounds();
    if ($bounds instanceof Bounds) {
      $xml->startElement('bounds');
      $xml->writeAttribute('minlat', $bounds->getMinLat());
      $xml->writeAttribute('minlon', $bounds->getMinLon());
      $xml->writeAttribute('maxlat', $bounds->getMaxLat());
      $xml->writeAttribute('maxlon', $bounds->getMaxLon());
      $xml->endElement();
    }
    if ($this->format == '1.1') {
      $extensions = $gpx->getMetadataExtensions(false);
      if ($extensions !== null && !$extensions->isEmpty()) {
        $xml->startElement('extensions');
        foreach ($extensions as $extension) {
          $xml->writeRaw($extension);
        }
        $xml->endElement();
      }
      $xml->endElement(); // </metadata>
    }
  }

  /**
   * Generate XML for GPX Person type.
   *
   * @param Person $person The person object to source data from.
   * @param XMLWriter $xml Where to write the data.
   * @return void
   */
  protected function writePerson(Person $person, XMLWriter $xml)
  {
    if ($this->format == '1.1') {
      $xml->startElement('author');
      $name = $person->getName();
      if (!empty($name))
        $xml->writeElement('name', $name);
      $email = $person->getEmail();
      if (!empty($email)) {
        $email = explode('@', $email, 2);
        $xml->startElement('email');
        $xml->writeAttribute('id', $email[0]);
        $xml->writeAttribute('domain', $email[1]);
        $xml->endElement();
      }
      $link = $person->getLink();
      if (!empty($link))
        $this->writeLink($link, $xml);
      $xml->endElement();
    } else {
      $name = $person->getName();
      if (!empty($name))
        $xml->writeElement('author', $name);
      $email = $person->getEmail();
      if (!empty($email))
        $xml->writeElement('email', $email);
    }
  }

  /**
   * Generate XML for a GPX Link type.
   *
   * @param Link $link The link object to source data from.
   * @param XMLWriter $xml Where to write the data.
   * @return void
   */
  protected function writeLink(Link $link, XMLWriter $xml)
  {
    if ($this->format == '1.1') {
      $xml->startElement('link');
      $xml->writeAttribute('href', $link->getHref());
      $text = $link->getText();
      if (!empty($text))
        $xml->writeElement('text', $text);
      $type = $link->getType();
      if (!empty($type))
        $xml->writeElement('type', $type);
      $xml->endElement();
    } else {
      $xml->writeElement('url', $link->getHref());
      $text = $link->getText();
      if (!empty($text))
        $xml->writeElement('urlname', $text);
    }
  }

  /**
   * Generate XML for GPX Copyright type.
   *
   * @param Copyright $copyright Object to source copyright data from.
   * @param XMLWriter $xml Where to write the data.
   * @return void
   */
  protected function writeCopyright(Copyright $copyright, XMLWriter $xml)
  {
    $xml->startElement('copyright');
    $xml->writeAttribute('author', $copyright->getAuthor());
    $year = $copyright->getYear();
    if (!empty($year))
      $xml->writeElement('year', $year);
    $license = $copyright->getLicense();
    if (!empty($license))
      $xml->writeElement('license', $license);
    $xml->endElement();
  }

  /**
   * Create an ISO 8601 timestamp.
   *
   * @param DateTimeInterface $timestamp The timestamp to format.
   * @param boolean $millis Include milliseconds.
   * @return string A timestamp.
   */
  protected function createTimestamp(
    DateTimeInterface $timestamp,
    bool $millis = null
  ) {
    if ($millis === null)
      $millis = $this->milliseconds;
    if (!$timestamp->getTimezone()->getOffset($timestamp))
      $timestamp = $timestamp->setTimezone(new DateTimeZone('UTC'));
    $format = 'Y-m-d\TH:i:s' . ($millis ? '.v\Z' : '\Z');
    return $timestamp->format($format);
  }

  /**
   * Write out the common attributes for all data types.
   *
   * @param DataType $type The data type to write.
   * @param XMLWriter $xml Where to write.
   * @return void
   */
  protected function writeDataType(DataType $type, XMLWriter $xml)
  {
    $var = $type->getName();
    if ($var !== null)
      $xml->writeElement('name', $var);
    $var = $type->getComment();
    if ($var !== null)
      $xml->writeElement('cmt', $var);
    $var = $type->getDescription();
    if ($var !== null)
      $xml->writeElement('desc', $var);
    $var = $type->getSource();
    if ($var !== null)
      $xml->writeElement('src', $var);
    $var = $type->getLinks(false);
    if ($var !== null) {
      foreach($var as $link) {
        $this->writeLink($link, $xml);
        if ($this->format == '1.0')
          break;
      }
    }
    if ($this->format == '1.1' || $type instanceof Point) {
      $var = $type->getType();
      if ($var !== null)
        $xml->writeElement('type', $var);
    }
    $var = $type->getExtensions(false);
    if ($var !== null && !$var->isEmpty()) {
      if ($this->format == '1.1')
        $xml->startElement('extensions');
      foreach ($var as $extension) {
        $xml->writeRaw($extension);
      }
      if ($this->format == '1.1')
        $xml->endElement();
    }
  }

  /**
   * Generate XML for GPX wpt type.
   *
   * @param Point $point The point to write.
   * @param string $element The XML element name (e.g. <wpt>)
   * @param XMLWriter $xml Where to write the point.
   * @return void
   */
  protected function writePoint(Point $point, string $element, XMLWriter $xml)
  {
    $xml->startElement($element);
    $xml->writeAttribute('lat', $point->getLatitude());
    $xml->writeAttribute('lon', $point->getLongitude());
    $val = $point->getEle();
    if ($val !== null)
      $xml->writeElement('ele', $val);
    $val = $point->getTime();
    if ($val !== null)
      $xml->writeElement('time', $this->createTimestamp($val));
    $val = $point->getMagvar();
    if ($val !== null)
      $xml->writeElement('magvar', $val);
    $val = $point->getGeoidHeight();
    if ($val !== null)
      $xml->writeElement('geoidheight', $val);
    $var = $point->getSymbol();
    if ($var !== null)
      $xml->writeElement('sym', $var);
    $var = $point->getFix();
    if ($var !== null)
      $xml->writeElement('fix', $var);
    $var = $point->getSatellites();
    if ($var !== null)
      $xml->writeElement('sat', $var);
    $var = $point->getHdop();
    if ($var !== null)
      $xml->writeElement('hdop', $var);
    $var = $point->getVdop();
    if ($var !== null)
      $xml->writeElement('vdop', $var);
    $var = $point->getPdop();
    if ($var !== null)
      $xml->writeElement('pdop', $var);
    $var = $point->getAgeOfDGPSData();
    if ($var !== null)
      $xml->writeElement('ageofdgpsdata', $var);
    $var = $point->getDGPSId();
    if ($var !== null)
      $xml->writeElement('dgpsid', $var);
    $this->writeDataType($point, $xml);
    $xml->endElement();
  }

  /**
   * Write XML for a route element.
   *
   * @param Route $route The route to write.
   * @param XMLWriter $xml Where to write.
   * @return void
   */
  protected function writeRoute(Route $route, XMLWriter $xml)
  {
    $xml->startElement('rte');
    $var = $route->getNumber();
    if ($var !== null)
      $xml->writeElement('number', $var);
    $this->writeDataType($route, $xml);
    $var = $route->getPoints(false);
    if ($var !== null) {
      foreach ($var as $point) {
        $this->writePoint($point, 'rtept', $xml);
      }
    }
    $xml->endElement();
  }

  /**
   * Write XML for a track element.
   *
   * @param Track $track The track to write.
   * @param XMLWriter $xml Where to write.
   * @return void
   */
  protected function writeTrack(Track $track, XMLWriter $xml)
  {
    $xml->startElement('trk');
    $var = $track->getNumber();
    if ($var !== null)
      $xml->writeElement('number', $var);
    $this->writeDataType($track, $xml);
    $var = $track->getSegments(false);
    if ($var !== null) {
      foreach ($var as $segment) {
        $this->writeTrackSegment($segment, $xml);
      }
    }
    $xml->endElement();
  }

  /**
   * Write XML for a track segment element.
   *
   * @param TrackSegment $segment The segment to write.
   * @param XMLWriter $xml Where to write.
   * @return void
   */
  protected function writeTrackSegment(TrackSegment $segment, XMLWriter $xml)
  {
    $xml->startElement('trkseg');
    $var = $segment->getPoints(false);
    if ($var !== null) {
      foreach ($var as $point) {
        $this->writePoint($point, 'trkpt', $xml);
      }
    }
    if ($this->format == '1.1') {
      $var = $segment->getExtensions(false);
      if ($var !== null) {
        $xml->startElement('extensions');
        foreach ($var as $extension) {
          $xml->writeRaw($extension);
        }
        $xml->endElement();
      }
    }
    $xml->endElement();
  }

}