using System;
using System.Collections.Generic;
using System.Threading;
using System.Text;
using System.Diagnostics;

namespace Lab4
{
    // First-Come, First-Serverd
    class FCFS
    {
        private List<Process> procs = new List<Process>();  // list of processes
        private List<Int32> queue = new List<Int32>();  // list for current amount of idling processes
        Thread serve;   // thread for emulating serve
        bool isServing = false, isEnd = false;  // some flags
        Int32 totalIdlingProcs = 0;    // indocate total idling procs
        Stopwatch[] idleSW; // array of stopwatches for each process
        Process current;

        public FCFS(Int32 totalProcs)
        {
            idleSW = new Stopwatch[totalProcs]; // init

            for (Int32 i = 0; i < totalProcs; i++)
                idleSW[i] = new Stopwatch();
        }

        public void AddProcess(Process proc)    // add new process to queue
        {
            Console.WriteLine("FCFS: add proc with id " + proc.PID.ToString());
            procs.Add(proc);    // to list

            if (!isServing) // processes not serving, there were no processes
            {
                isServing = true;   // serving flag
                serve = new Thread(this.ServeProcess);
                serve.Start();      // start new serving thread
            }
            else
            {
                queue.Add(procs.Count); // was added new process, store total queued processes

                totalIdlingProcs++;    // inc number of idling procs
                idleSW[proc.PID].Start();   // start SW by procs PID
            }
        }

        public void CheckQueue() // check processes queue
        {
            if (procs.Count > 0)    // there is some procs in queue 
            {
                serve = new Thread(this.ServeProcess);  // start another thread to serve
                serve.Start();
            }
            else
            {
                isServing = false;  // no procs, stop serving

                if (isEnd)  // it's end of emulation, show info
                    Console.WriteLine("FCFS: emulation end, press any key to view results.");
            }
        }

        void ServeProcess() // serve process
        {
            idleSW[procs[0].PID].Stop(); // stop idling proc SW
            current = procs[0];
            procs.RemoveAt(0);  // remove first proc cause it's serving
            //Console.WriteLine("FCFS: remove proc with id " + current.PID.ToString());
            Console.WriteLine("FCFS: start serving proc with id " + current.PID.ToString());
            Thread.Sleep(current.executionTime * 100); // emulate serving
            Console.WriteLine("FCFS: served proc with id " + current.PID.ToString());
            CheckQueue();
            //RemoveProcess();    // remove process
        }

        public void EndEmulation()
        {
            isEnd = true;
        }

        public Int32 maxQueue   // get max queue count
        {
            get {
                Int32 res = 0;

                foreach(Int32 i in queue)
                    if(i > res)
                        res = i;
                
                return res;
            }
        }

        public Double avgIdleTime   // get average idle time
        {
            get {
                Int64 res = 0;

                for (Int32 i = 0; i < idleSW.Length; i++)   // sum all
                    res += idleSW[i].ElapsedMilliseconds;

                return 1.0 * res / totalIdlingProcs / 100;   // divide by number of total idling procs
            }
        }
    }
}