//
//  MQTTTransport.h
//  MQTTClient
//
//  Created by Christoph Krey on 06.12.15.
//  Copyright © 2015-2017 Christoph Krey. All rights reserved.
//

#import <Foundation/Foundation.h>

@protocol MQTTTransportDelegate;

/** MQTTTransport is a protocol abstracting the underlying transport level for MQTTClient
 *
 */
@protocol MQTTTransport <NSObject>

/** MQTTTransport state defines the possible state of an abstract transport
 *
 */
 typedef NS_ENUM(NSInteger, MQTTTransportState) {
     
     /** MQTTTransportCreated indicates an initialized transport */
     MQTTTransportCreated = 0,
     
     /** MQTTTransportOpening indicates a transport in the process of opening a connection */
     MQTTTransportOpening,
     
     /** MQTTTransportCreated indicates a transport opened ready for communication */
     MQTTTransportOpen,
     
     /** MQTTTransportCreated indicates a transport in the process of closing */
     MQTTTransportClosing,
     
     /** MQTTTransportCreated indicates a closed transport */
     MQTTTransportClosed
 };

/** queue The queue where the streams are scheduled. */
@property (strong, nonatomic, nonnull) dispatch_queue_t queue;

/** streamSSLLevel an NSString containing the security level for read and write streams
 * For list of possible values see:
 * https://developer.apple.com/documentation/corefoundation/cfstream/cfstream_socket_security_level_constants
 * Please also note that kCFStreamSocketSecurityLevelTLSv1_2 is not in a list
 * and cannot be used as constant, but you can use it as a string value
 * defaults to kCFStreamSocketSecurityLevelNegotiatedSSL
 */
@property (strong, nonatomic, nonnull) NSString *streamSSLLevel;

/** host an NSString containing the hostName or IP address of the host to connect to */
@property (strong, nonatomic, nonnull) NSString *host;

/** port an unsigned 32 bit integer containing the IP port number to connect to */
@property (nonatomic) UInt32 port;

/** MQTTTransportDelegate needs to be set to a class implementing th MQTTTransportDelegate protocol
 * to receive delegate messages.
 */
@property (weak, nonatomic) _Nullable id<MQTTTransportDelegate> delegate;

/** state contains the current MQTTTransportState of the transport */
@property (nonatomic) MQTTTransportState state;

/** open opens the transport and prepares it for communication
 * actual transports may require additional parameters to be set before opening
 */
- (void)open;

/** send transmits a data message
 * @param data data to be send, might be zero length
 * @result a boolean indicating if the data could be send or not
 */
- (BOOL)send:(nonnull NSData *)data;

/** close closes the transport */
- (void)close;

@end

/** MQTTTransportDelegate protocol
 * Note: the implementation of the didReceiveMessage method is mandatory, the others are optional 
 */
@protocol MQTTTransportDelegate <NSObject>

/** didReceiveMessage gets called when a message was received
 * @param mqttTransport the transport on which the message was received
 * @param message the data received which may be zero length
 */
 - (void)mqttTransport:(nonnull id<MQTTTransport>)mqttTransport didReceiveMessage:(nonnull NSData *)message;

@optional

/** mqttTransportDidOpen gets called when a transport is successfully opened
 * @param mqttTransport the transport which was successfully opened
 */
- (void)mqttTransportDidOpen:(_Nonnull id<MQTTTransport>)mqttTransport;

/** didFailWithError gets called when an error was detected on the transport
 * @param mqttTransport the transport which detected the error
 * @param error available error information, might be nil
 */
- (void)mqttTransport:(_Nonnull id<MQTTTransport>)mqttTransport didFailWithError:(nullable NSError *)error;

/** mqttTransportDidClose gets called when the transport closed
 * @param mqttTransport the transport which was closed
 */
- (void)mqttTransportDidClose:(_Nonnull id<MQTTTransport>)mqttTransport;

@end

@interface MQTTTransport : NSObject <MQTTTransport>
@end