#import "HockeySDKFeatureConfig.h"

#if HOCKEYSDK_FEATURE_METRICS

#import "BITMetricsManager.h"
#import "BITSessionState.h"

@class BITChannel;
@class BITTelemetryContext;
@class BITSession;
@class BITPersistence;
@class BITSender;

#import "HockeySDKNullability.h"
NS_ASSUME_NONNULL_BEGIN

FOUNDATION_EXPORT NSString *const kBITApplicationWasLaunched;

@interface BITMetricsManager()

/**
 *  Create a new BITMetricsManager instance by passing the channel, the telemetry context, and persistence instance to use 
 for processing metrics. This method can be used for dependency injection.
 */
- (instancetype)initWithChannel:(BITChannel *)channel
               telemetryContext:(BITTelemetryContext *)telemetryContext
                    persistence:(BITPersistence *)persistence
                   userDefaults:(NSUserDefaults *)userDefaults;

/**
 *  The user defaults object used to store meta data.
 */
@property (nonatomic, strong, readonly) NSUserDefaults *userDefaults;

/**
 *  A channel for collecting new events before storing and sending them.
 */
@property (nonatomic, strong, readonly) BITPersistence *persistence;

/**
 *  A channel for collecting new events before storing and sending them.
 */
@property (nonatomic, strong, readonly) BITChannel *channel;

/**
 *  A telemetry context which is used to add meta info to events, before they're sent out.
 */
@property (nonatomic, strong, readonly) BITTelemetryContext *telemetryContext;

/**
 *  A concurrent queue which creates and processes telemetry items.
 */
@property (nonatomic, strong, readonly) dispatch_queue_t metricsEventQueue;

/**
 *  Sender instance to send out telemetry data.
 */
@property (nonatomic, strong) BITSender *sender;

///-----------------------------------------------------------------------------
/// @name Session Management
///-----------------------------------------------------------------------------

/**
 *  The Interval an app has to be in the background until the current session gets renewed.
 */
@property (nonatomic, assign) NSUInteger appBackgroundTimeBeforeSessionExpires;

/**
 *  Registers manager for several notifications, which influence the session state.
 */
- (void)registerObservers;

/**
 *  Unregisters manager for several notifications, which influence the session state.
 */
- (void)unregisterObservers;

/**
 *  Stores the current date before app is sent to background.
 *
 *  @see appBackgroundTimeBeforeSessionExpires
 *  @see startNewSessionIfNeeded
 */
- (void)updateDidEnterBackgroundTime;

/**
 *  Determines whether the current session needs to be renewed or not.
 *
 *  @see appBackgroundTimeBeforeSessionExpires
 *  @see updateDidEnterBackgroundTime
 */
- (void)startNewSessionIfNeeded;

/**
 *  Creates a new session, updates the session context and sends it to the channel.
 *
 *  @param sessionId the id for the new session
 */
- (void)startNewSessionWithId:(NSString *)sessionId;

/**
 *  Creates a new session and stores it to NSUserDefaults.
 *
 *  @param sessionId the id for the new session
 *  @return the newly created session
 */
- (BITSession *)createNewSessionWithId:(NSString *)sessionId;

///-----------------------------------------------------------------------------
/// @name Track telemetry data
///-----------------------------------------------------------------------------

/**
 *  Creates and enqueues a session event for the given state.
 *
 *  @param state value that determines whether the session started or ended
 */
- (void)trackSessionWithState:(BITSessionState)state;

@end

NS_ASSUME_NONNULL_END

#endif /* HOCKEYSDK_FEATURE_METRICS */