//////////////////////////////////////////////////////////////////
//
//	email2.cpp
//
//	This program asks the user for the name of an e-mail
//	file, and then alternately:
//
//		(1) prints the numbered list of e-mail messages
//
//		(2) asks the user for a message number and
//			prints that message
//
//	until the user types 0.
//
//	REVISION HISTORY:
//		1/16/01 (Jeff Ondich) Wrote the main program,
//			OpenEmailFile, and stubs for the rest of
//			the functions.
//
//////////////////////////////////////////////////////////////////


// This program uses files, so we need fstream instead of iostream.
// Note that fstream implies iostream (so you can still use
// cin and cout).

#include	<fstream>
#include	<string>


//////////////////////////////////////////////////////
// Function prototypes.
//////////////////////////////////////////////////////

void OpenEmailFile( ifstream& inputFile, string fileName );
int GetSelection();
void PrintMessageList( ifstream& inputFile );
void PrintMessage( ifstream& inputFile, int messageNumber );


//////////////////////////////////////////////////////
// main program
//////////////////////////////////////////////////////

int main()
{
	// Get the e-mail file's name from the user.

	string fileName;
	cout << "Please type the name of your e-mail file: ";
	cin >> fileName;


	// Go around and around, printing the numbered list
	// of messages, asking the user for a message number,
	// and printing the requested message.  When the
	// user types any number less than or equal to 0, stop.

	ifstream inputFile;
	int selection = 1;

	while( selection > 0 )
	{
		// Print the message list.
		OpenEmailFile( inputFile, fileName );
		PrintMessageList( inputFile );
		inputFile.close();

		// Get the user's selection.
		selection = GetSelection();

		// Print the selected message.
		if( selection > 0 )
		{
			OpenEmailFile( inputFile, fileName );
			PrintMessage( inputFile, selection );
			inputFile.close();

			// Make it easier for the user to read the message
			// before moving on.
			cout << "Hit return when you're ready for the list again." << endl;
			cin.ignore();
			cin.ignore();
		}
	}

	return( 0 );
}


//////////////////////////////////////////////////////
// Opens an input stream corresponding to
// the file of the given name.  If the file can't
// be opened, we give the user a descriptive
// error message and quit the program.
//////////////////////////////////////////////////////

void OpenEmailFile( ifstream& inputFile, string fileName )
{
	inputFile.open( fileName.c_str() );
	if( !(inputFile.is_open()) )
	{
		cout << "An error occurred during the attempt to open "
			<< fileName << "." << endl
			<< "Perhaps the file does not exist." << endl;

		exit( 1 );
	}
}


//////////////////////////////////////////////////////
// Prompts the user for a message number and returns
// the user's response.  The prompt should explain
// that the choice 0 will quit the program.
//////////////////////////////////////////////////////

int GetSelection()
{
	// This is a "stub."  That is, it's a function
	// that compiles, but that doesn't have any
	// code in it yet so it doesn't do its job.
	// Since it compiles, however, you can test
	// the other parts of the program.

	cout << "Greetings from GetSelection()." << endl;
	return( 0 );
}


//////////////////////////////////////////////////////
// Scans through inputFile, printing a numbered
// list of the "From:" and "Subject:" lines.
// Specifically, you should print out a number
// whenever you detect a "From " line, and then
// just print every "From:" and "Subject:" line.
//
// Precondition: inputFile is open, and can thus be
// used in input statements just like cin.
//////////////////////////////////////////////////////

void PrintMessageList( ifstream& inputFile )
{
	// Another stub.
	cout << "PrintMessageList() says 'Howdy.'" << endl;
}


//////////////////////////////////////////////////////
// Scans through the inputFile, counting messages
// (that is, counting "From " lines, of which there
// is one per message).  While the message count
// is equal to messageNumber, just print out
// every line.
//
// Precondition: inputFile is open, and can thus be
// used in input statements just like cin.
//////////////////////////////////////////////////////

void PrintMessage( ifstream& inputFile, int messageNumber )
{
	cout << "PrintMessage() got called with " << messageNumber << endl;
}