/**
 * Assignment #3, Program 1
 * Program to calculate cost of a phone call
 * Author: Mark Allen Weiss
 * SSN: 000-00-0000
 * Course: COP-2210 Section 8
 * Date: October 7, 1998
 *
 * CERTIFICATION OF SOLE AUTHORSHIP
 * I certify that this work is solely my own and
 * that none if it is the work of any other person.
 * I further certify that I have not provided any
 * assistance to other students enrolled in COP-2210 that
 * would render their CERTIFICATION OF SOLE AUTHORSHIP
 * invalid. I understand that violations of this pledge
 * may result in severe sanctions.
 *
 *
 *
 * -----------------------------------
 *   (Mark Allen Weiss)       <--- Put your name here, and sign above
 */

#include <iostream.h>
#include "money.h"
#include "apstring.h"

  // Program constants
const money REGULAR_RATE        = 0.40;
const double NIGHT_DISCOUNT     = 0.50;
const double LONG_DISCOUNT      = 0.15;
const int MINUTES_IN_SHORT_CALL = 60;
const int NIGHT_START           = 1800;
const int DAY_START             = 800;   // Watch out: 0800 is wrong!
const double TAX_RATE           = 0.04;

  // Function declarations
void display_instructions( );
int get_input( apstring message );
bool is_night_call( int starting_time );
money compute_gross_cost( int starting_time, int call_length );
money compute_discounts( money gross_cost, int starting_time, int call_length );
void print_answers( money gross_cost, money net_cost );

int main( )
{
      // Inputs
    int starting_time;
    int call_length;

      // Outputs
    money gross_cost;
    money net_cost;

      // Read values
    display_instructions( );
    starting_time = get_input( "Enter starting time in 24 hour format" );
    call_length = get_input( "Enter the length of the call in minutes" );

      // Compute answers
    gross_cost = compute_gross_cost( starting_time, call_length );
    net_cost = compute_discounts( gross_cost, starting_time, call_length );

      // Print the answers
    print_answers( gross_cost, net_cost );

    return 0;
}

/**
 * Print instructions.
 */
void display_instructions( )
{
    cout << "This program will compute the cost of a phone call";
    cout << ", given two parameters:" << endl;
    cout << "\t1. The starting time" << endl;
    cout << "\t2. The call length" << endl;
    cout << "The starting time is in 24-hour format (i.e. 1800 is 6PM)."
         << endl << endl;
}

/**
 * Print answers.
 */
void print_answers( money gross_cost, money net_cost )
{
    cout << endl;
    cout << "The cost before discounts is " << gross_cost << endl;
    cout << "The cost after discounts is " << net_cost << endl;
}

/**
 * Read an input; message is used to give a prompt.
 */
int get_input( apstring message )
{
    int value_read;

    cout << message << ": ";
    cin >> value_read;

    return value_read;
}

/**
 * Compute cost of phone call before discounts.
 */
money compute_gross_cost( int starting_time, int call_length )
{
    return REGULAR_RATE * call_length;
}
    
/**
 * Compute cost of phone call after discounts.
 */
money compute_discounts( money gross_cost, int starting_time, int call_length )
{
    money net_cost = gross_cost;

    if( is_night_call( starting_time ) )
        net_cost -= NIGHT_DISCOUNT * net_cost;
    if( call_length > MINUTES_IN_SHORT_CALL )
        net_cost -= LONG_DISCOUNT * net_cost;
    net_cost += TAX_RATE * net_cost;

    return net_cost;
}

/**
 * Returns true if and only if starting_time is a night call.
 */
bool is_night_call( int starting_time )
{
    return starting_time >= NIGHT_START || starting_time < DAY_START;
}