// This software is released into the Public Domain.
// See NOTICE.md here or copying.txt from https://github.com/openstreetmap/osmosis/blob/master/package/copying.txt for details.
package com.onthegomap.planetiler.reader.osm;

import java.util.Date;
import org.openstreetmap.osmosis.osmbinary.Osmformat;

/**
 * Manages decoding of the lower level PBF data structures.
 * <p>
 * This class is copied from Osmosis.
 *
 * @author Brett Henderson
 *         <p>
 */
public class PbfFieldDecoder {

  private static final double COORDINATE_SCALING_FACTOR = 0.000000001;
  private final String[] strings;
  private final int coordGranularity;
  private final long coordLatitudeOffset;
  private final long coordLongitudeOffset;
  private final int dateGranularity;

  /**
   * Creates a new instance.
   * <p>
   *
   * @param primitiveBlock The primitive block containing the fields to be decoded.
   */
  public PbfFieldDecoder(Osmformat.PrimitiveBlock primitiveBlock) {
    this.coordGranularity = primitiveBlock.getGranularity();
    this.coordLatitudeOffset = primitiveBlock.getLatOffset();
    this.coordLongitudeOffset = primitiveBlock.getLonOffset();
    this.dateGranularity = primitiveBlock.getDateGranularity();

    Osmformat.StringTable stringTable = primitiveBlock.getStringtable();
    strings = new String[stringTable.getSCount()];
    for (int i = 0; i < strings.length; i++) {
      strings[i] = stringTable.getS(i).toStringUtf8();
    }
  }

  /**
   * Decodes a raw latitude value into degrees.
   * <p>
   *
   * @param rawLatitude The PBF encoded value.
   * @return The latitude in degrees.
   */
  public double decodeLatitude(long rawLatitude) {
    return COORDINATE_SCALING_FACTOR * (coordLatitudeOffset + (coordGranularity * rawLatitude));
  }

  /**
   * Decodes a raw longitude value into degrees.
   * <p>
   *
   * @param rawLongitude The PBF encoded value.
   * @return The longitude in degrees.
   */
  public double decodeLongitude(long rawLongitude) {
    return COORDINATE_SCALING_FACTOR * (coordLongitudeOffset + (coordGranularity * rawLongitude));
  }

  /**
   * Decodes a raw timestamp value into a Date.
   * <p>
   *
   * @param rawTimestamp The PBF encoded timestamp.
   * @return The timestamp as a Date.
   */
  public Date decodeTimestamp(long rawTimestamp) {
    return new Date(dateGranularity * rawTimestamp);
  }

  /**
   * Decodes a raw string into a String.
   * <p>
   *
   * @param rawString The PBF encoding string.
   * @return The string as a String.
   */
  public String decodeString(int rawString) {
    return strings[rawString];
  }
}