#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@class MGLMapView;
@class MGLAnnotationImage;
@class MGLPolygon;
@class MGLPolyline;
@class MGLShape;

/**
 The `MGLMapViewDelegate` protocol defines a set of optional methods that you
 can use to receive messages from an `MGLMapView` instance. Because many map
 operations require the `MGLMapView` class to load data asynchronously, the map
 view calls these methods to notify your application when specific operations
 complete. The map view also uses these methods to request information about
 annotations displayed on the map, such as the styles and interaction modes to
 apply to individual annotations.
 */
@protocol MGLMapViewDelegate <NSObject>

@optional

#pragma mark Responding to Map Viewpoint Changes

/**
 Tells the delegate that the viewpoint depicted by the map view is about to
 change.

 This method is called whenever the currently displayed map camera will start
 changing for any reason.

 @param mapView The map view whose viewpoint will change.
 @param animated Whether the change will cause an animated effect on the map.
 */
- (void)mapView:(MGLMapView *)mapView cameraWillChangeAnimated:(BOOL)animated;

/**
 Tells the delegate that the viewpoint depicted by the map view is changing.

 This method is called as the currently displayed map camera changes as part of
 an animation, whether due to a user gesture or due to a call to a method such
 as `-[MGLMapView setCamera:animated:]`. This method can be called before
 `-mapViewDidFinishLoadingMap:` is called.
 
 During the animation, this method may be called many times to report updates 
 to the viewpoint. Therefore, your implementation of this method should be as 
 lightweight as possible to avoid affecting performance.

 @param mapView The map view whose viewpoint is changing.
 */
- (void)mapViewCameraIsChanging:(MGLMapView *)mapView;

/**
 Tells the delegate that the viewpoint depicted by the map view has finished
 changing.

 This method is called whenever the currently displayed map camera has finished
 changing, after any calls to `-mapViewRegionIsChanging:` due to animation.
 This method can be called before `-mapViewDidFinishLoadingMap:` is 
 called.
 
 @param mapView The map view whose viewpoint has changed.
 @param animated Whether the change caused an animated effect on the map.
 */
- (void)mapView:(MGLMapView *)mapView cameraDidChangeAnimated:(BOOL)animated;

/**
 Asks the delegate whether the map view should be allowed to change from the
 existing camera to the new camera in response to a user gesture.
 
 This method is called as soon as the user gesture is recognized. It is not
 called in response to a programmatic camera change, such as by setting the
 `centerCoordinate` property or calling `-flyToCamera:completionHandler:`.
 
 This method is called many times during gesturing, so you should avoid performing 
 complex or performance-intensive tasks in your implementation.
 
 @param mapView The map view that the user is manipulating.
 @param oldCamera The camera representing the viewpoint at the moment the
    gesture is recognized. If this method returns `NO`, the map view’s camera
    continues to be this camera.
 @param newCamera The expected camera after the gesture completes. If this
    method returns `YES`, this camera becomes the map view’s camera.
 @return A Boolean value indicating whether the map view should stay at
    `oldCamera` or change to `newCamera`.
 */
- (BOOL)mapView:(MGLMapView *)mapView shouldChangeFromCamera:(MGLMapCamera *)oldCamera toCamera:(MGLMapCamera *)newCamera;

#pragma mark Loading the Map

/**
 Tells the delegate that the map view will begin to load.

 This method is called whenever the map view starts loading, including when a
 new style has been set and the map must reload.

 @param mapView The map view that is starting to load.
 */
- (void)mapViewWillStartLoadingMap:(MGLMapView *)mapView;

/**
 Tells the delegate that the map view has finished loading.

 This method is called whenever the map view finishes loading, either after the
 initial load or after a style change has forced a reload.

 @param mapView The map view that has finished loading.
 */
- (void)mapViewDidFinishLoadingMap:(MGLMapView *)mapView;

/**
 Tells the delegate that the map view was unable to load data needed for
 displaying the map.

 This method may be called for a variety of reasons, including a network
 connection failure or a failure to fetch the style from the server. You can use
 the given error message to notify the user that map data is unavailable.

 @param mapView The map view that is unable to load the data.
 @param error The reason the data could not be loaded.
 */
- (void)mapViewDidFailLoadingMap:(MGLMapView *)mapView withError:(NSError *)error;

- (void)mapViewWillStartRenderingMap:(MGLMapView *)mapView;
- (void)mapViewDidFinishRenderingMap:(MGLMapView *)mapView fullyRendered:(BOOL)fullyRendered;

/**
 Tells the delegate that the map view is about to redraw.

 This method is called any time the map view needs to redraw due to a change in
 the viewpoint or style property transition. This method may be called very
 frequently, even moreso than `-mapViewRegionIsChanging:`. Therefore, your
 implementation of this method should be as lightweight as possible to avoid
 affecting performance.

 @param mapView The map view that is about to redraw.
 */
- (void)mapViewWillStartRenderingFrame:(MGLMapView *)mapView;

/**
 Tells the delegate that the map view has just redrawn.

 This method is called any time the map view needs to redraw due to a change in
 the viewpoint or style property transition. This method may be called very
 frequently, even moreso than `-mapViewRegionIsChanging:`. Therefore, your
 implementation of this method should be as lightweight as possible to avoid
 affecting performance.

 @param mapView The map view that has just redrawn.
 */
- (void)mapViewDidFinishRenderingFrame:(MGLMapView *)mapView fullyRendered:(BOOL)fullyRendered;

/**
 Tells the delegate that the map view is entering an idle state, and no more
 drawing will be necessary until new data is loaded or there is some interaction
 with the map.
 
 - No camera transitions are in progress
 - All currently requested tiles have loaded
 - All fade/transition animations have completed
 
 @param mapView The map view that has just entered the idle state.
 */
- (void)mapViewDidBecomeIdle:(MGLMapView *)mapView;

/**
 Tells the delegate that the map has just finished loading a style.

 This method is called during the initialization of the map view and after any
 subsequent loading of a new style. This method is called between the
 `-mapViewWillStartRenderingMap:` and `-mapViewDidFinishRenderingMap:` delegate
 methods. Changes to sources or layers of the current style do not cause this
 method to be called.

 This method is the earliest opportunity to modify the layout or appearance of
 the current style before the map view is displayed to the user.

 @param mapView The map view that has just loaded a style.
 @param style The style that was loaded.
 */
- (void)mapView:(MGLMapView *)mapView didFinishLoadingStyle:(MGLStyle *)style;

- (nullable NSImage *)mapView:(MGLMapView *)mapView didFailToLoadImage:(NSString *)imageName;

#pragma mark Managing the Appearance of Annotations

/**
 Returns an annotation image object to mark the given point annotation object on
 the map.

 @param mapView The map view that requested the annotation image.
 @param annotation The object representing the annotation that is about to be
    displayed.
 @return The image object to display for the given annotation or `nil` if you
    want to display the default marker image.
 */
- (nullable MGLAnnotationImage *)mapView:(MGLMapView *)mapView imageForAnnotation:(id <MGLAnnotation>)annotation;

/**
 Returns the alpha value to use when rendering a shape annotation.

 A value of 0.0 results in a completely transparent shape. A value of 1.0, the
 default, results in a completely opaque shape.

 This method sets the opacity of an entire shape, inclusive of its stroke and
 fill. To independently set the values for stroke or fill, specify an alpha
 component in the color returned by `-mapView:strokeColorForShapeAnnotation:` or
 `-mapView:fillColorForPolygonAnnotation:`.

 @param mapView The map view rendering the shape annotation.
 @param annotation The annotation being rendered.
 @return An alpha value between 0 and 1.0.
 */
- (CGFloat)mapView:(MGLMapView *)mapView alphaForShapeAnnotation:(MGLShape *)annotation;

/**
 Returns the color to use when rendering the outline of a shape annotation.

 The default stroke color is the selected menu item color. If a pattern color is
 specified, the result is undefined.

 Opacity may be set by specifying an alpha component. The default alpha value is
 `1.0` and results in a completely opaque stroke.

 @param mapView The map view rendering the shape annotation.
 @param annotation The annotation being rendered.
 @return A color to use for the shape outline.
 */
- (NSColor *)mapView:(MGLMapView *)mapView strokeColorForShapeAnnotation:(MGLShape *)annotation;

/**
 Returns the color to use when rendering the fill of a polygon annotation.

 The default fill color is the selected menu item color. If a pattern color is
 specified, the result is undefined.

 Opacity may be set by specifying an alpha component. The default alpha value is
 `1.0` and results in a completely opaque shape.

 @param mapView The map view rendering the polygon annotation.
 @param annotation The annotation being rendered.
 @return The polygon’s interior fill color.
 */
- (NSColor *)mapView:(MGLMapView *)mapView fillColorForPolygonAnnotation:(MGLPolygon *)annotation;

/**
 Returns the line width in points to use when rendering the outline of a
 polyline annotation.

 By default, the polyline is outlined with a line 3.0 points wide.

 @param mapView The map view rendering the polygon annotation.
 @param annotation The annotation being rendered.
 @return A line width for the polyline, measured in points.
 */
- (CGFloat)mapView:(MGLMapView *)mapView lineWidthForPolylineAnnotation:(MGLPolyline *)annotation;

#pragma mark Selecting Annotations

/**
 Returns a Boolean value indicating whether the shape annotation can be selected.
 
 If the return value is `YES`, the user can select the annotation by clicking
 on it. If the delegate does not implement this method, the default value is `YES`.
 
 @param mapView The map view that has selected the annotation.
 @param annotation The object representing the shape annotation.
 @return A Boolean value indicating whether the annotation can be selected.
 */
- (BOOL)mapView:(MGLMapView *)mapView shapeAnnotationIsEnabled:(MGLShape *)annotation;

/**
 Tells the delegate that one of its annotations has been selected.

 You can use this method to track changes to the selection state of annotations.

 @param mapView The map view containing the annotation.
 @param annotation The annotation that was selected.
 */
- (void)mapView:(MGLMapView *)mapView didSelectAnnotation:(id <MGLAnnotation>)annotation;

/**
 Tells the delegate that one of its annotations has been deselected.

 You can use this method to track changes in the selection state of annotations.

 @param mapView The map view containing the annotation.
 @param annotation The annotation that was deselected.
 */
- (void)mapView:(MGLMapView *)mapView didDeselectAnnotation:(id <MGLAnnotation>)annotation;

#pragma mark Managing Callout Popovers

/**
 Returns a Boolean value indicating whether the annotation is able to display
 extra information in a callout popover.

 This method is called after an annotation is selected, before any callout is
 displayed for the annotation.

 If the return value is `YES`, a callout popover is shown when the user clicks
 on an annotation, selecting it. The default callout displays the annotation’s
 title and subtitle. You can customize the popover’s contents by implementing
 the `-mapView:calloutViewControllerForAnnotation:` method.

 If the return value is `NO`, or if this method is absent from the delegate, or
 if the annotation lacks a title, the annotation will not show a callout even
 when selected.

 @param mapView The map view that has selected the annotation.
 @param annotation The object representing the annotation.
 @return A Boolean value indicating whether the annotation should show a
    callout.
 */
- (BOOL)mapView:(MGLMapView *)mapView annotationCanShowCallout:(id <MGLAnnotation>)annotation;

/**
 Returns a view controller to manage the callout popover’s content view.

 Like any instance of `NSPopover`, an annotation callout manages its contents
 with a view controller. The annotation object is the view controller’s
 represented object. This means that you can bind controls in the view
 controller’s content view to KVO-compliant properties of the annotation object,
 such as `title` and `subtitle`.

 If each annotation should have an identical callout, you can set the
 `MGLMapView.calloutViewController` property instead.

 @param mapView The map view that is requesting a callout view controller.
 @param annotation The object representing the annotation.
 @return A view controller for the given annotation.
 */
- (nullable NSViewController *)mapView:(MGLMapView *)mapView calloutViewControllerForAnnotation:(id <MGLAnnotation>)annotation;

@end

NS_ASSUME_NONNULL_END