import java.util.*;
import java.io.*;

public class Scheduler {
    //Address of File name relative to code. Replace with request for filename?
    String fileName = "datafiles/datafile1.txt";
    
    LinkedList<Process> processList = new LinkedList<Process>();
    LinkedList<Integer> randomNum = new LinkedList<>();
    int randomNumConsumed = -1; //Counter to track which "random numbers" have been used thus far.

    //Initialise Dispatcher time variable
    int disp;

    /**
     * Main. Runs the program
     */
    public static void main(String[] args){
        Scheduler system = new Scheduler();
        system.run();
    }

    /**
     * Run. Most of the program starts from here.
     */
    public void run()
    {
        readFile(fileName); //Read the file
        
        //Test Print
        System.out.println("DISP: " + disp + "\n");

        System.out.println("Begin Process List:");
        
        for (int i = 0; i < processList.size() ; i++)
        {
            System.out.println("ID: " + processList.get(i).getId());
            System.out.println("Arrive: " + processList.get(i).getArrive());
            System.out.println("ExecSize: " + processList.get(i).getExecSize());
            System.out.println("Tickets: " + processList.get(i).getTickets());  
            System.out.println();      
        }
        System.out.println("End Process List.\n");

        System.out.println("Begin Random:");
        for (int i = 0; i < randomNum.size(); i++)
        {
            System.out.println(randomNum.get(i));
        }
        System.out.println("End Random.");

        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();
        algorithmLTR();        
    }

/**
     * readFile. Reads the file given, creating processes as needed to save details.
     * @param fileNameInput address of the file to be read in.
     */
    public void readFile(String fileNameInput)
    {
        Scanner fileReader; //Scanner to read the file.
        File dataSet = new File(fileNameInput);
        
        
        //Try and open file. If it works, procede.
        try {
            fileReader = new Scanner(dataSet);
            System.out.println("File Opened.");

            //Progress through each line in the text file
            while(fileReader.hasNextLine()){
                String line = fileReader.nextLine();
                
                //If the line has "EOF" written, stop reading lines.
                if(line.equals("EOF"))
                {
                    System.out.println("End of File Reached");
                    break;
                }

                else if(line.startsWith("DISP"))
                {
                    disp =Integer.parseInt(line.substring(6));
                }
                
                //If the Line starts with "ID:", create a new process
                else if(line.startsWith("ID:"))
                {
                    //Create new proccess
                    Process temp = new Process();


                    temp.setId(line.substring(4));   //Set the id of the proccess to whatever remains of the line after the "ID: "

                    //As we've read in the ID, we shall assume the following lines (until "END") are all part of the process definition.
                    while(fileReader.hasNextLine())
                    {
                        line = fileReader.nextLine();

                        if(line.equals("END"))
                        {
                            break;
                        }
                        
                        else if(line.startsWith("Arrive:"))
                        {   
                            temp.setArrive(Integer.parseInt(line.substring(8))); 
                        }

                        else if(line.startsWith("ExecSize:"))
                        {   
                            
                            temp.setSize(Integer.parseInt(line.substring(10))); 
                        }                        
                        
                        else if(line.startsWith("Tickets:"))
                        {   
                            temp.setTickets(Integer.parseInt(line.substring(9))); 
                        }    

                        else 
                        {
                            //Delete process?
                        }
                    }

                    processList.add(temp);
                }
                
                //If we read the line "BEGINRANDOM", we've started the random numbers section. Until the "ENDRANDOM" line,
                //we'll just keep reading in each number (and it is assumed each line is a single number) and adding it 
                //to the random number array.
                else if(line.equals("BEGINRANDOM"))
                {
                    while(fileReader.hasNextLine())
                    {
                        line = fileReader.nextLine();

                        if(line.equals("ENDRANDOM"))
                        {
                            break;
                        }
                        else
                        {
                            randomNum.add(Integer.parseInt(line));
                        }
                    }
                }
            }
            fileReader.close();
        } 
        
        //If the file isn't found, throw a hissy fit.
        catch (FileNotFoundException e) {
            System.out.println("File not found.");
            //e.printStackTrace();  //Optional, shows more data.
        }
    }    

    public void algorithmFCFS()
    {

    }

    public void algorithmSRT()
    {

    }

    public void algorithmFBV()
    {

    }    

    public void algorithmLTR()
    {
        // counter: used to track if we’ve found the winner yet
        int counter = 0; 
        int totalTickets = 0;
        int winner = -1;
        
        //count the total number of tickets in play
        for (int i = 0; i < processList.size() ; i++)
        {
           totalTickets += processList.get(i).getTickets();  
        }

        // winner: use some call to a random number generator to
        // get a value, between 0 and the total # of tickets 
        int winnerValue = returnRandomNum(totalTickets); 

        for (int i = 0; i < processList.size(); i++)
        {
            counter = processList.get(i).getTickets();

            if(counter > winnerValue)
            {
                winner = i;
                break;
            }
        }

        if(winner == -1)
        {
            System.out.println("No winner");
        }
        else
        {
            System.out.println("Winner: " + processList.get(winner).getId());
        }
        
        // current: use this to walk through the list of jobs
        
        //node_t *current = head; 
        /*
        while (current) 
        { 
            counter = counter + current->tickets; 
            if (counter > winner)
            {
                break; // found the winner 
            }

        current = current->next; 
        // 'current' is the winner: schedule it...
        }
        */
    }    

    public int returnRandomNum(int totalTickets)
    {
        int randomValue = 0;
        

        //Loop back to begining. Probably could remove each consumed random number from the linked list.... but I don't want to right now.
        if((randomNumConsumed+1) >= randomNum.size())
        {
            randomNumConsumed = 0;
        }
        else 
        {
            randomNumConsumed += 1;
        }

        randomValue = randomNum.get(randomNumConsumed) % totalTickets;
        
        return randomValue;
    }

}