/*

    File:       EchoConnection.m

    Contains:   Manages a single echo connection.

    Copyright:  Copyright (c) 2012 Apple Inc. All Rights Reserved.

    Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple Inc.

                ("Apple") in consideration of your agreement to the following

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                not use, install, modify or redistribute this Apple software.

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                non-exclusive license, under Apple's copyrights in this

                original Apple software (the "Apple Software"), to use,

                reproduce, modify and redistribute the Apple Software, with or

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                without modifications, you must retain this notice and the

                following text and disclaimers in all such redistributions of

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                or logos of Apple Inc. may be used to endorse or promote

                products derived from the Apple Software without specific prior

                written permission from Apple.  Except as expressly stated in

                this notice, no other rights or licenses, express or implied,

                are granted by Apple herein, including but not limited to any

                patent rights that may be infringed by your derivative works or

                by other works in which the Apple Software may be incorporated.

                The Apple Software is provided by Apple on an "AS IS" basis. 

                APPLE MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING

                WITHOUT LIMITATION THE IMPLIED WARRANTIES OF NON-INFRINGEMENT,

                MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, REGARDING

                THE APPLE SOFTWARE OR ITS USE AND OPERATION ALONE OR IN

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*/

#import "EchoConnection.h"

NSString * EchoConnectionDidCloseNotification = @"EchoConnectionDidCloseNotification";

@interface EchoConnection () <NSStreamDelegate>

@end

@implementation EchoConnection

@synthesize inputStream  = _inputStream;

@synthesize outputStream = _outputStream;

- (id)initWithInputStream:(NSInputStream *)inputStream outputStream:(NSOutputStream *)outputStream

{

    self = [super init];

    if (self != nil) {

        self->_inputStream = inputStream;

        self->_outputStream = outputStream;

    }

    return self;

}

- (BOOL)open {

    [self.inputStream  setDelegate:self];

    [self.outputStream setDelegate:self];

    [self.inputStream  scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

    [self.outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

    [self.inputStream  open];

    [self.outputStream open];

    return YES;

}

- (void)close {

    [self.inputStream  setDelegate:nil];

    [self.outputStream setDelegate:nil];

    [self.inputStream  close];

    [self.outputStream close];

    [self.inputStream  removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

    [self.outputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

    [(NSNotificationCenter *)[NSNotificationCenter defaultCenter] postNotificationName:EchoConnectionDidCloseNotification object:self];

}

- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)streamEvent {

    assert(aStream == self.inputStream || aStream == self.outputStream);

    #pragma unused(aStream)

    switch(streamEvent) {

        case NSStreamEventHasBytesAvailable: {

            uint8_t buffer[2048];

            NSInteger actuallyRead = [self.inputStream read:(uint8_t *)buffer maxLength:sizeof(buffer)];

            if (actuallyRead > 0) {

                NSInteger actuallyWritten = [self.outputStream write:buffer maxLength:(NSUInteger)actuallyRead];

                if (actuallyWritten != actuallyRead) {

                    // -write:maxLength: may return -1 to indicate an error or a non-negative 

                    // value less than maxLength to indicate a 'short write'.  In the case of an 

                    // error we just shut down the connection.  The short write case is more 

                    // interesting.  A short write means that the client has sent us data to echo but 

                    // isn't reading the data that we send back to it, thus causing its socket receive 

                    // buffer to fill up, thus causing our socket send buffer to fill up.  Again, our 

                    // response to this situation is that we simply drop the connection.

                    [self close];

                } else {

                    NSLog(@"Echoed %zd bytes.", (ssize_t) actuallyWritten);

                }

            } else {

                // A non-positive value from -read:maxLength: indicates either end of file (0) or 

                // an error (-1).  In either case we just wait for the corresponding stream event 

                // to come through.

            }

        } break;

        case NSStreamEventEndEncountered:

        case NSStreamEventErrorOccurred: {

            [self close];

        } break;

        case NSStreamEventHasSpaceAvailable:

        case NSStreamEventOpenCompleted:

        default: {

            // do nothing

        } break;

    }

}

@end