/**
 * CS151 Fall 2007 Lab #5 solution.<BR>
 * Models a simple version of an automobile with fuel amount, fuel efficiency,
 * and mileage attributes.  Fuel measured in gallons and efficiency in
 * miles/gallon.
 * 
 * @author Scott Russell
 * @version 10/02/2007
 */
public class Automobile
{ 
    //* Constants *
    public static final String CIVIC = "Civic";
    public static final String TAURUS = "Taurus";
    public static final String PRIUS = "Prius";

    public static final double CIVIC_EFFICIENCY = 40.0;
    public static final double TAURUS_EFFICIENCY = 30.0;  
    public static final double PRIUS_EFFICIENCY = 40.0;
    public static final double PRIUS_BATTERY_EFFICIENCY = 50.0;
    //the fraction of the efficiency when driving in city or at begin and end of trip
    public static final double CITY_EFFICIENCY_MULT = 0.75;
    public static final double START_LOW_EFFIC_MILES = 5.0;
    public static final double END_LOW_EFFIC_MILES = 5.0;
    
    public static final double DEFAULT_FUEL_EFFICIENCY = 25.0;
    //in practice get current_year from a GregorianCalendar object
    public static final int CURRENT_YEAR = 2007;
    public static final int DEFAULT_YEAR = CURRENT_YEAR;
    public static final int AGE_CUTOFF = 5;
    public static final int HIGH_MILE_LIMIT =100000;
    public static final double HIGH_MILE_MULT = 0.9;
    public static final double HIGH_MILE_MULT2 = 2.0;
    public static final int MILEAGE_DIVISOR = 50000;
    public static final int LOW_MILE_LIMIT = 60000;
    public static final double LOW_MILE_MULT = 0.95;
    //Instance Fields/Variables 
    //We need not intialize theses since we will do so in constructors
    //amount of fuel in the vehicle in gallons
    private double fuelLevel;
    
    //amount of distance the car can travel per gallon of fuel
    private double fuelEfficiency;
    
    //total distance in miles the car has traveled
    private double mileage;

    //the model of the car
    private String model;

    //the year the car was manufactured
    private int year;

    //Constructors
    /**
     * Creates a new automobile with the specified efficiency.  Fuel level and 
     * mileage are initialize to 0.
     * @param efficiency number of miles/gallon of fuel the car can travel.
     */
    public Automobile(double efficiency)
    {
        //initialize the model to blank
        model = new String();
        
        //initialize the efficiency to specified value
        fuelEfficiency = efficiency;
        
        //initialize fuel level to 0
        fuelLevel = 0;

        //initialize mileage to 0
        mileage = 0;

        //initialize year to this default
        year = DEFAULT_YEAR;
    }
    
    /**
     * Creates a new automobile with the specified efficiency and fuel level.
     * Mileage is initialized to 0.
     * @param efficiency number of miles/gallon of fuel the car can travel.
     * @param fuelAmount amount of fuel in gallons.
     */
    public Automobile(double efficiency, double fuelAmount)
    {
        //initialize the model to blank
        model = new String();

        //initialize the efficiency to specified value
        fuelEfficiency = efficiency;
        
        //initialize fuel level to specified value
        fuelLevel = fuelAmount;

        //initialize mileage to 0
        mileage = 0;

        //initialize year to this default
        year = DEFAULT_YEAR;
    }       
    
    /**
     * Creates a new automobile with the specified efficiency and fuel level.
     * Mileage is initialized to 0.
     * @param model the model of the car, e.g. Taurus, Civic, etc.
     * @param amount the initial amount of fuel in gallons.
     */
    public Automobile(String theModel, double fuelAmount, double miles)
    {
        //initialize the efficiency to specified value base on the model
        model = theModel;
        setFuelEfficiency(model);
        
        //initialize fuel level 0
        fuelLevel = fuelAmount;

        //initialize mileage to specified amount
        mileage = miles;

        //initialize year to this default
        year = DEFAULT_YEAR;
    }   

    /**
     * Creates a new automobile with the specified efficiency, fuel level, and mileage.
     * @param efficiency number of miles/gallon of fuel the car can travel.
     * @param fuelAmount amount of fuel in gallons.
     * @param miles initial mileage reading in miles.
     */
    public Automobile(double efficiency, double fuelAmount, double miles)
    {
        //initialize the model to blank
        model = new String();

        //initialize the efficiency to specified value
        fuelEfficiency = efficiency;
        
        //initialize fuel level to specified value
        fuelLevel = fuelAmount;

        //initialize mileage to specified value
        mileage = miles;

        //initialize year to this default
        year = DEFAULT_YEAR;
    }

    //Methods
    /**
     * Add the specified amount of fuel to the auto's fuel level.
     * @param fuelAmount number of gallons of fuel to add.
     */
    public void addFuel(double fuelAmount)
    {
        fuelLevel = fuelLevel + fuelAmount;   
    }
    
    /**
     * Simulate driving the auto the specified number of miles.
     * @param distance number of miles to drive.
     */
    public void drive(double distance)
    {
        //calculate fuel needed to travel distance and range given fuel level
        double range = fuelLevel*fuelEfficiency;
        double fuelNeeded = distance/fuelEfficiency;
        
        //alterntatively you can test (fuelLevel >= fuelNeeded)
        if (range >= distance)
        {
            fuelLevel = fuelLevel - fuelNeeded; 
            mileage = mileage + distance;
        }
        else
        {
            fuelLevel = 0;
            mileage = mileage + range;
        }
        
        //using max and min is another way to to deal with the two possible outcomes
        /*
         * fuelLevel = Math.max(0, fuelLevel - fuelNeeded);
         * mileage = mileage + Math.min(range, distance)
         */
    }
    
   /**
     * Simulate driving  and take into account variable efficiency by Prius and other cars.
     * @param distance number of miles to drive.
     */
    public void drive2(double distance)
    {
        //compute the efficiency used for the begining and end of the trip
        double localEfficiency = fuelEfficiency * CITY_EFFICIENCY_MULT;
        if (this.model.equals(PRIUS))
            localEfficiency = PRIUS_BATTERY_EFFICIENCY;
            
        /*
         * compute fuel need for this trip
         * if trip longer than start and finish low mileage distances use localEfficiency for start
         * and end distances and regular fuel efficiency for remainder of the distance
         */
        double fuelNeeded = 0.0;
        if (distance > START_LOW_EFFIC_MILES + END_LOW_EFFIC_MILES)
            fuelNeeded = (START_LOW_EFFIC_MILES + END_LOW_EFFIC_MILES)/localEfficiency + 
                        (distance - START_LOW_EFFIC_MILES - END_LOW_EFFIC_MILES)/fuelEfficiency;
        else 
            fuelNeeded = distance * localEfficiency;

        /*
         * compute the possible range of the car based on its fuel level
         * first see if enough fuel to get from localEfficiency to regular efficiency performance
         */
        
        double range = 0.0;
        double fuelUsed = 0.0;
        
        if (fuelLevel*localEfficiency > START_LOW_EFFIC_MILES + END_LOW_EFFIC_MILES)
        {
            //account for start and end of trip
            range = START_LOW_EFFIC_MILES + END_LOW_EFFIC_MILES;
            fuelUsed = range/localEfficiency;
            
            //account for middle of the trip
            range = range + (fuelLevel - fuelUsed) * fuelEfficiency;
        }
        else if (fuelLevel*localEfficiency > START_LOW_EFFIC_MILES)
        {
            //compute range assuming first localEfficiency then at regular efficiency until fuel gone
            //account for start of trip 
            range = START_LOW_EFFIC_MILES;
            fuelUsed = range/localEfficiency;
            
            //account for middle of the trip
            range = range + (fuelLevel - fuelUsed) * fuelEfficiency;
        }
        else
        {
            range = fuelLevel*localEfficiency;
        }
        
        //now update fuelLevel and mileage as before using computed range and fuelNeeded
        //alterntatively you can test (fuelLevel >= fuelNeeded)
        if (range >= distance)
        {
            fuelLevel = fuelLevel - fuelNeeded; 
            mileage = mileage + distance;
        }
        else
        {
            fuelLevel = 0;
            mileage = mileage + range;
        }
    }

    //get and set Methods
    /**
     * Sets the fuel amount to the specified value.
     * @param fuelAmount amount of fuel in gallons.
     */
    public void setFuelLevel(double fuelAmount)
    {
        fuelLevel = fuelAmount;
    }

    /**
     * Gets the current fuel level.
     * @return current fuel level in gallons.
     */
    public double getFuelLevel()
    {
        return fuelLevel;
    }

    /**
     * Sets the fuel efficiency to the specified value.
     * @param efficiency fuel efficiency in miles/gallon.
     */
    public void setFuelEfficiency(double efficiency)
    {
        fuelEfficiency = efficiency;
    }

    /**
     * Sets the fuel efficiency based on the specified auto model
     * (not the model of this auto).
     * @param model the name of the model which this auto should have the same efficiency as.
     */
    public void setFuelEfficiency(String theModel)
    {
        //See Automobile2 for a slightly more elegant and easier to maintain solution
        double efficiency = DEFAULT_FUEL_EFFICIENCY;
        
        //set local variable for efficiency depending on model and if no match use default value
        if (theModel.equals(CIVIC))
            efficiency = CIVIC_EFFICIENCY;
        else if (theModel.equals(TAURUS))
            efficiency = TAURUS_EFFICIENCY;
        else if (theModel.equals(PRIUS))
            efficiency = PRIUS_EFFICIENCY;
        else 
            efficiency = DEFAULT_FUEL_EFFICIENCY;

        //now set this automobile's efficiency once which makes the above easier to read
        //and reduces the chance of making an error when assigning the value.
        this.setFuelEfficiency(efficiency);
    }

    /**
     * Computes and sets the fuel efficiency based on the vehicle's model, year, and mileage.
     */
    public void computeFuelEfficiency()
    {
        //set the efficiency as if a new car of this model
        setFuelEfficiency(this.model);
        
        final int carAge = CURRENT_YEAR - this.year;
        double efficiency = this.fuelEfficiency;

        if (carAge >= AGE_CUTOFF && this.mileage >= HIGH_MILE_LIMIT)
        {
            efficiency = HIGH_MILE_MULT * efficiency - HIGH_MILE_MULT2 * Math.floor(mileage/MILEAGE_DIVISOR);
        }
        else if (carAge >= AGE_CUTOFF || this.mileage >= LOW_MILE_LIMIT)
        {
            efficiency = LOW_MILE_MULT * efficiency;
        }
        //otherwise the efficiency is like that of a new car which we already set
        
        //now set this automobile's efficiency once 
        fuelEfficiency = efficiency;
    }

    
    /**
     * Gets the current fuel efficiency.
     * @return current fuel efficiency in miles/gallons.
     */
    public double getFuelEfficiency()
    {
        return fuelEfficiency;
    }

    /**
     * Sets the mileage to the specified value.
     * @param miles mileage value.
     */
    public void setMileage(double miles)
    {
        mileage = miles;
    }

    /**
     * Gets the current fuel efficiency.
     * @return current fuel efficiency in miles/gallons.
     */
    public double getMileage()
    {
        return mileage;
    }

    /**
     * Sets the manufacture year of the vehicle to the specified year.
     * @param year the year the vehicle was made.
     */
    public void setYear(int theYear)
    {
        year = theYear;
    }

}