// exception6.cpp			By: Aiman Hanna -  ©1993-2006 Aiman Hanna

// This program illustrates more on how exceptions can be handled. As an example, the program
// shows how the catch clause may have another try/catch clause. 

// Key Points:		1) Handling exceptions



#include "exception6.h"

ProducerConsumer::ProducerConsumer()
{
	for (int i = 0; i < 10; i++)
		buff[i] = -1;

}


bool ProducerConsumer::isEmpty()
{

	if (buff[0] == -1)
		return true;

	return false;
}


bool ProducerConsumer::isFull()
{

	if (buff[9] != -1)
		return true;

	return false;
}


void ProducerConsumer::produceItem( int item )
{
	if (isFull())
		throw ProduceOnFull();		// Not "throw ProduceOnFull;"

	if ( item == -1 )
		throw ProduceInvalidValue();

	int i = 0;
	while (buff[i++] != -1);
		buff[i - 1] = item;
	
}

void ProducerConsumer::consumeItem( )
{
	if (isEmpty())
		throw ConsumeOnEmpty();		

	int i = 0, item = -1;
	while ( (i < 10) && (buff[i] != -1) ) 
		i++;
	
	item = buff[i-1];
	buff[i-1] = -1;
	

}

void ProducerConsumer::setItem(int item)
{
	produceItem( item );
}


void ProducerConsumer::displayBuffContents()
{
	cout << "\nThe buffer contents at this point are: " << endl;
	for (int i= 0; i < 10; i++)
		cout << buff[i] << "  ";
	cout << endl << endl;

}


void Excp::showExcpMessage()
{

	cerr << "An exception has occurred" << endl;
	
}


void ProducerConsumerExcp::showExcpMessage()
{
	cerr << "A producer-consumer exception has occurred" << endl;

}



void ConsumeOnEmpty::showExcpMessage()
{
	cerr << "An exception has occurred: Trying to consume from an empty buffer" << endl;
}


void ProduceOnFull::showExcpMessage()
{
	cerr << "An exception has occurred: Trying to produce to a full buffer" << endl;
}


void ProduceInvalidValue::showExcpMessage()
{
	cerr << "An exception has occurred: Trying to produce an invalid value" << endl;
}


void ProduceInvalidValue::showExcpMessage2()
{
	cout << "You will be given another chance to re-enter a correct production value. Please enter this value now: ";
}


void ProduceInvalidValue::showFailedTwiceMessage()
{
	cerr << "An exception has occurred: Production failed twice due to attempts to produce ivalid values. Will give up." << endl;
}


int main()
{
	
	ProducerConsumer pc1;
	

	try{
		pc1.consumeItem( );
	}
	catch (ConsumeOnEmpty coe)
	{
		coe.showExcpMessage();
	}

	// Try to produce more items than the buffer can hold
	// Notice what happens when the exception is thrown
	try
	{
		for (int i = 0; i < 13; i++)
		{
			if ( i == 9 )
				pc1.produceItem (-1);	// Attempt to produce an invalid value
			pc1.produceItem(i * 5);		// i*5 is just a value 
		}
	}
	catch (ProduceOnFull pof)
	{	
		pof.showExcpMessage();
	}
	catch (ProduceInvalidValue piv)
	{	
		piv.showExcpMessage();
		piv.showExcpMessage2();
		int v;
		cin >> v;
		try
		{
			pc1.produceItem (v);
			cout << "Production accepted for value " << v 
				 << ". Contents of buffer now are as follows: " << endl;
		}
		catch (ProduceInvalidValue piv)
		{
			piv.showFailedTwiceMessage();
		}
		
	}
	catch ( ... )
	{
		cerr <<"Your program has thrown an exception, but this exception does not seem to be handled.";
		cerr << " Check your code again." << endl;
	}

	pc1.displayBuffContents();

	// try to consume more items than what the buffer has
	try
	{
		for (int i = 0; i < 13; i++)
		{
			pc1.consumeItem();	

			if ((i == 7) || (i ==8) || (i ==9))		// display the contents just before the 
				pc1.displayBuffContents();	// exception should occur
					
		}
	}
	catch (ConsumeOnEmpty coe)
	{	
		coe.showExcpMessage();
	}
	catch ( ... )
	{
		cerr <<"Your program has thrown an exception, but this exception does not seem to be handled.";
		cerr << " Check your code again." << endl;
	}

	return 0;
}


// The result of running the program (see another run below)
/*
An exception has occurred: Trying to consume from an empty buffer
An exception has occurred: Trying to produce an invalid value
You will be given another chance to re-enter a correct production value. Please enter this value now: 2
Production accepted for value 2. Contents of buffer now are as follows:

The buffer contents at this point are:
0  5  10  15  20  25  30  35  40  2


The buffer contents at this point are:
0  5  -1  -1  -1  -1  -1  -1  -1  -1


The buffer contents at this point are:
0  -1  -1  -1  -1  -1  -1  -1  -1  -1


The buffer contents at this point are:
-1  -1  -1  -1  -1  -1  -1  -1  -1  -1

An exception has occurred: Trying to consume from an empty buffer

*/


// Another run of the program 
/*

An exception has occurred: Trying to consume from an empty buffer
An exception has occurred: Trying to produce an invalid value
You will be given another chance to re-enter a correct production value. Please enter this value now: -1
An exception has occurred: Production failed twice due to attempts to produce ivalid values. Will give up.

The buffer contents at this point are:
0  5  10  15  20  25  30  35  40  -1


The buffer contents at this point are:
0  -1  -1  -1  -1  -1  -1  -1  -1  -1


The buffer contents at this point are:
-1  -1  -1  -1  -1  -1  -1  -1  -1  -1

An exception has occurred: Trying to consume from an empty buffer

*/