/*

    File:       RemoteCurrencyConverter.m

    Contains:   A model object that manages all networking within the client app.

    Written by: DTS

    Copyright:  Copyright (c) 2011 Apple Inc. All Rights Reserved.

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

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                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,

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                THE APPLE SOFTWARE OR ITS USE AND OPERATION ALONE OR IN

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*/

#import "RemoteCurrencyConverter.h"

#import "RemoteCurrencyClientConnection.h"

@interface RemoteCurrencyConverter () <RemoteCurrencyClientConnectionDelegate>

// read/write versions of public properties

@property (nonatomic, assign, readwrite) RemoteCurrencyConverterStatus      status;

@property (nonatomic, assign, readwrite) BOOL                               networkActive;

@property (nonatomic, assign, readwrite) BOOL                               finished;

@property (nonatomic, copy,   readwrite) NSNumber *                         result;

// private properties

@property (nonatomic, retain, readwrite) RemoteCurrencyClientConnection *   connection;

@property (nonatomic, copy,   readwrite) NSString *                         pendingCommand;

@property (nonatomic, retain, readwrite) NSTimer *                          dummyConversionTimer;

@end

@implementation RemoteCurrencyConverter

@synthesize status        = status_;

@synthesize netService    = netService_;

@synthesize networkActive = networkActive_;

@synthesize result        = result_;

@synthesize finished      = finished_;

@synthesize connection     = connection_;

@synthesize pendingCommand = pendingCommand_;

@synthesize dummyConversionTimer = dummyConversionTimer_;

- (id)initWithNetService:(NSNetService *)netService

{

    assert(netService != nil);

    self = [super init];

    if (self != nil) {

        self->status_ = kRemoteCurrencyConverterInitialised;

        self->netService_ = [netService retain];

    }

    return self;

}

- (void)dealloc

{

    // All of the following should have be cleaned up by -stopConverting 

    // (actually, either -networkStopConverting or -dummyStopConverting).

    assert(self->connection_ == nil);

    assert(self->pendingCommand_ == nil);

    assert(self->dummyConversionTimer_ == nil);

    [self->netService_ release];

    [self->result_ release];

    [super dealloc];

}

#pragma mark * Network core conversion

+ (NSString *)nextConnectionName

{

    static NSUInteger sConnectionSequenceNumber;

    NSString *  result;

    result = [NSString stringWithFormat:@"%zu", (size_t) sConnectionSequenceNumber];

    sConnectionSequenceNumber += 1;

    return result;

}

- (void)networkStartConvertingValue:(double)value fromCurrency:(NSString *)fromCurrency toCurrency:(NSString *)toCurrency

    // The network implementation of -startConvertingValue:fromCurrency:toCurrency:, for which you 

    // should see the comments in the header.

{

    #pragma unused(value)

    #pragma unused(fromCurrency)

    #pragma unused(toCurrency)

    NSString *  command;

    assert(fromCurrency != nil);

    assert(toCurrency != nil);

    // If the connection is not open, open it.

    if (self.connection == nil) {

        NSInputStream *     input;

        NSOutputStream *    output;

        assert( (self.status == kRemoteCurrencyConverterInitialised) || (self.status == kRemoteCurrencyConverterClosed) || (self.status == kRemoteCurrencyConverterFailed) );

        [self.netService getInputStream:&input outputStream:&output];

        self.connection = [[[RemoteCurrencyClientConnection alloc] initWithInputStream:input outputStream:output] autorelease];

        self.connection.clientDelegate = self;

        self.connection.name = [[self class] nextConnectionName];

        [self.connection open];

        // -[NSNetService getInputStream:outputStream:] currently returns the stream 

        // with a reference that we have to release (something that's counter to the 

        // standard Cocoa memory management rules <rdar://problem/6868813>).

        [input release];

        [output release];

        self.status = kRemoteCurrencyConverterIdle;

    }

    assert( (self.status == kRemoteCurrencyConverterIdle) || (self.status == kRemoteCurrencyConverterConverting) );

    // Form up a command based on the inputs.

    command = [NSString stringWithFormat:@"convert %@ %.2f to %@", fromCurrency, value, toCurrency];

    assert(command != nil);

    // If the connection is idle, send the command straight away.  If we're still 

    // waiting for a result, store this command in pendingCommand, replacing any 

    // previous pending command, so that it gets sent then the current command completes.

    switch (self.status) {

        case kRemoteCurrencyConverterIdle: {

            assert(self.pendingCommand == nil);

            [self.connection sendRequest:command];

            self.networkActive = YES;

            self.finished = NO;

            self.status = kRemoteCurrencyConverterConverting;

        } break;

        case kRemoteCurrencyConverterConverting: {

            self.pendingCommand = command;

        } break;

        default: {

            assert(NO);

        } break;

    }

}

- (void)networkFailedConverting

{

    if (self.connection != nil) {

        self.connection.delegate = nil;

        [self.connection close];

        self.connection = nil;

    }

    self.pendingCommand = nil;

    self.status = kRemoteCurrencyConverterFailed;

    self.networkActive = NO;

    self.finished = NO;

}

- (void)networkStopConverting

    // The network implementation of -stopConverting, for which you should see the comments in the header.

{

    if (self.connection != nil) {

        self.connection.delegate = nil;

        [self.connection close];

        self.connection = nil;

    }

    self.pendingCommand = nil;

    self.status = kRemoteCurrencyConverterClosed;

    self.networkActive = NO;

    self.finished = NO;

}

- (void)remoteCurrencyClientConnection:(RemoteCurrencyClientConnection *)connection willCloseWithError:(NSError *)error

    // Called by the network connection when the connection tears. The current implementation 

    // just shuts everything down and leaves it up to the user to trigger a retry.

{

    assert(connection == self.connection);

    #pragma unused(error)

    // error may be nil

    [self networkFailedConverting];

}

- (void)remoteCurrencyClientConnection:(RemoteCurrencyClientConnection *)connection didReceiveResponse:(NSString *)response lines:(NSArray *)lines

    // Called by the network connection when it receives a valid response from the server. 

    // This parses the response to extract the converted value and then passes that 

    // back up to the user interface.  Also, if there is a pending conversion, it kicks 

    // that off.

{

    BOOL            success;

    NSScanner *     scanner;

    double          value;

    assert(self.status == kRemoteCurrencyConverterConverting);

    assert(connection == self.connection);

    assert(response != nil);

    assert(lines != nil);

    success = NO;

    if ([response caseInsensitiveCompare:@"OK"] == NSOrderedSame) {

        if ([lines count] == 1) {

            scanner = [NSScanner scannerWithString:[lines objectAtIndex:0]];

            assert(scanner != nil);

            success = [scanner scanDouble:&value];

            if (success) {

                success = [scanner isAtEnd];

            }

        }

    }

    if (success) {

        self.result = [NSNumber numberWithDouble:value];

        // If a subsequent conversion got queued behind this one, start it. 

        // Otherwise all our conversions are done and we can set finished, 

        // which triggers a UI update.

        if (self.pendingCommand != nil) {

            NSString *  command;

            command = [[self.pendingCommand retain] autorelease];

            self.pendingCommand = nil;

            [self.connection sendCommandLine:command];

        } else {

            self.status = kRemoteCurrencyConverterIdle;

            self.networkActive = NO;

            self.finished = YES;

        }

    } else {

        [self networkFailedConverting];

    }

}

- (void)remoteCurrencyClientConnection:(RemoteCurrencyClientConnection *)connection didReceiveError:(NSString *)errorResponse

    // Called by the network connection it receives an error response from the server. 

    // The current implementation just shuts everything down and leaves it up to the user 

    // to trigger a retry.

{

    assert(connection == self.connection);

    assert(errorResponse != nil);

    [self networkFailedConverting];

}

- (void)remoteCurrencyClientConnection:(RemoteCurrencyClientConnection *)connection logWithFormat:(NSString *)format arguments:(va_list)argList

{

    NSString *  str;

    assert(connection != nil);

    assert( (self.connection == nil) || (connection == self.connection) );          // self.connection can be nil during shut down

    assert(format != nil);

    str = [[NSString alloc] initWithFormat:format arguments:argList];

    assert(str != nil);

    NSLog(@"control-%@ %@", connection.name, str);

    [str release];

}

#pragma mark * Dummy core conversion

// To make testing easier we have a dummy converter that juts converts values 

// locally, with a suitable delay.

- (void)dummyStartConvertingValue:(double)value fromCurrency:(NSString *)fromCurrency toCurrency:(NSString *)toCurrency

    // The local implementation of -startConvertingValue:fromCurrency:toCurrency:, for which you 

    // should see the comments in the header.  This uses an NSTimer to simulate the delays caused 

    // by a network operation.

{

    static NSDictionary *  sValueFromCurrencyStr;

    NSDictionary *  userInfo;

    NSNumber *      fromValueObj;

    NSNumber *      toValueObj;

    assert(fromCurrency != nil);

    assert(toCurrency != nil);

    if (sValueFromCurrencyStr == nil) {

        sValueFromCurrencyStr = [[NSDictionary alloc] initWithObjectsAndKeys:

            [NSNumber numberWithDouble:1.3246], @"USD", 

            [NSNumber numberWithDouble:1.0],    @"EUR", 

            [NSNumber numberWithDouble:0.848],  @"GBP", 

            [NSNumber numberWithDouble:110.86], @"JPY", 

            [NSNumber numberWithDouble:1.3508], @"AUD", 

            nil

        ];

        assert(sValueFromCurrencyStr != nil);

    }

    fromValueObj = [sValueFromCurrencyStr objectForKey:fromCurrency];

    assert(fromValueObj != nil);

    toValueObj = [sValueFromCurrencyStr objectForKey:toCurrency];

    assert(toValueObj != nil);

    userInfo = [NSDictionary dictionaryWithObjectsAndKeys:

        [NSNumber numberWithDouble:value / [fromValueObj doubleValue] * [toValueObj doubleValue]], @"result", 

        nil

    ];

    assert(userInfo != nil);

    self.result = nil;

    self.networkActive = YES;

    self.finished = NO;

    [self.dummyConversionTimer invalidate];

    self.dummyConversionTimer = nil;

    self.dummyConversionTimer = [NSTimer scheduledTimerWithTimeInterval:3.0 target:self selector:@selector(didFinishDummyConversionTimer:) userInfo:userInfo repeats:NO];

}

- (void)dummyStopConverting

    // The local implementation of -stopConverting, for which you should see the comments in the header.

{

    if (self.dummyConversionTimer != nil) {

        assert(self.result == nil);

        assert(self.networkActive);

        assert( ! self.finished );

        [self.dummyConversionTimer invalidate];

        self.dummyConversionTimer = nil;

        self.networkActive = NO;

        self.finished = NO;

    }

}

- (void)didFinishDummyConversionTimer:(NSTimer *)timer

    // Called when the dummy conversion timer fires, this sets up the result 

    // so that the app can see it.

{

    NSDictionary *  userInfo;

    assert(timer == self.dummyConversionTimer);

    assert(self.result == nil);

    assert(self.networkActive);

    assert( ! self.finished );

    userInfo = [[[timer userInfo] retain] autorelease];

    assert(userInfo != nil);

    [self.dummyConversionTimer invalidate];

    self.dummyConversionTimer = nil;

    self.result = [userInfo objectForKey:@"result"];

    self.networkActive = NO;

    self.finished = YES;

}

#pragma mark * Core conversion dispatch

- (void)startConvertingValue:(double)value fromCurrency:(NSString *)fromCurrency toCurrency:(NSString *)toCurrency

    // See comment in header.

{

    assert(fromCurrency != nil);

    assert(toCurrency != nil);

    // Dispatches to either the network converter or our dummy local converter.

    if ( [[NSUserDefaults standardUserDefaults] boolForKey:@"enableDummyLocalConverter"]) {

        [self dummyStartConvertingValue:value fromCurrency:fromCurrency toCurrency:toCurrency];

    } else {

        [self networkStartConvertingValue:value fromCurrency:fromCurrency toCurrency:toCurrency];

    }

}

- (void)stopConverting

    // See comment in header.

{

    // Dispatches to either the network converter or our dummy local converter.

    if ( [[NSUserDefaults standardUserDefaults] boolForKey:@"enableDummyLocalConverter"]) {

        [self dummyStopConverting];

    } else {

        [self networkStopConverting];

    }

}

@end