//
//  GMSPath.h
//  Google Maps SDK for iOS
//
//  Copyright 2013 Google Inc.
//
//  Usage of this SDK is subject to the Google Maps/Google Earth APIs Terms of
//  Service: https://developers.google.com/maps/terms
//

#import <CoreLocation/CoreLocation.h>

/**
 * GMSPath encapsulates an immutable array of CLLocationCooordinate2D. All the coordinates of a
 * GMSPath must be valid. The mutable counterpart is GMSMutablePath.
 */
@interface GMSPath : NSObject <NSCopying, NSMutableCopying>

/** Convenience constructor for an empty path. */
+ (instancetype)path;

/** Initializes a newly allocated path with the contents of another GMSPath. */
- (id)initWithPath:(GMSPath *)path;

/** Get size of path. */
- (NSUInteger)count;

/** Returns kCLLocationCoordinate2DInvalid if |index| >= count. */
- (CLLocationCoordinate2D)coordinateAtIndex:(NSUInteger)index;

/**
 * Initializes a newly allocated path from |encodedPath|. This format is described at:
 * https://developers.google.com/maps/documentation/utilities/polylinealgorithm
 */
+ (instancetype)pathFromEncodedPath:(NSString *)encodedPath;

/** Returns an encoded string of the path in the format described above. */
- (NSString *)encodedPath;

/**
 * Returns a new path obtained by adding |deltaLatitude| and |deltaLongitude| to each coordinate
 * of the current path. Does not modify the current path.
 */
- (instancetype)pathOffsetByLatitude:(CLLocationDegrees)deltaLatitude
                           longitude:(CLLocationDegrees)deltaLongitude;

@end


/**
 * kGMSEquatorProjectedMeter may be useful when specifying lengths for segment in "projected" units.
 * The value of kGMSEquatorProjectedMeter, 1/(pi * EarthRadius), represents the length of one meter
 * at the equator in projected units. For example to specify a projected length that corresponds
 * to 100km at the equator use 100000 * kGMSEquatorProjectedMeter.
 * See [GMSPath segmentsForLength:kind:], [GMSPath lengthOfKind:] and kGMSLengthProjected.
 */
extern const double kGMSEquatorProjectedMeter;

/**
 * GMSLengthKind indicates the type of a length value, which can be geodesic (in meters), rhumb
 * length (in meters) and projected length (in GMSMapPoint units).
 */
typedef enum {
  /*
   * Geodesic length, in meters, along geodesic segments. May be useful, for example, to specify
   * lengths along the the trajectory of airplanes or ships.
   */
  kGMSLengthGeodesic,

  /*
   * Rhumb length, in meters, along rhumb (straight line) segments. May be useful, for example, to
   * draw a scale bar on a map. The visual size of a segment of a given length depens on the
   * latitude.
   */
  kGMSLengthRhumb,

  /*
   * Length in projected space, along rhumb segments. Projected length uses the same units as
   * GMSMapPoint - the Earth equator circumference has length 2. It is possible to specify projected
   * length in units corresponding to 1 meter at the equator by multiplying with
   * kGMSEquatorProjectedMeter, equal to 1/(pi * EarthRadius).
   *
   * Projected length may be useful, for example, to specify segments with the same visual length
   * regardless of latitude.
   */
  kGMSLengthProjected
} GMSLengthKind;


@interface GMSPath (GMSPathLength)

/**
 * Returns the fractional number of segments along the path that correspond to |length|,
 * interpreted according to |kind|. See GMSLengthKind.
 */
- (double)segmentsForLength:(CLLocationDistance)length kind:(GMSLengthKind)kind;

/**
 * Returns the length of the path, according to |kind|. See GMSLengthKind.
 */
- (CLLocationDistance)lengthOfKind:(GMSLengthKind)kind;

@end
