#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <cmath>
#include <set>

#include "Events.h"
#include "Simulations.h"

// Author:  Douglas Wilhelm Harder
// Copyright (c) 2012 by Douglas Wilhelm Harder.  All rights reserved.

/* We will assume that requests arrive via a Poisson process with
 * a mean of lambda.  Therefore, the inter-arrival periods are
 * exponentially distributed with mean 1/lambda.
 *
 * Therefore, we assume an event occurs at time t = 0 and we will
 * proceed by finding random variables that come from the
 * exponential distribution.
 *
 * The probability density function (pdf) of the exponential distribution
 * with mean 1/lambda is given by lambda*exp(-lambda*t)*u(t) where u(t) is
 * the unit step function.
 *
 * The cumulative distribution function is given by (1 - exp(-lambda*t))*u(t)
 * which grows from 0 to 1 with 0 <= t < Inf.
 *
 * The inverse is t = -ln(1 - X)/lambda. 
 *
 * Tracks per disk       36 000 tracks
 * Rotational latency         2 ms 
 * Average seek time          8 ms
 * Read time                  2.5 ms
 * Head speed                 2 tracks/us
 */

int const TRACKS_PER_DISK = 36000;
int const ROTATIONAL_LATENCY = 2000;  // 2 ms or 2,000 us
int const READ_TIME = 2500;           // 2500 us
int const HEAD_SPEED = 2;             // 2 tracks/us

int main() {
	srand48( std::time(0) );

	int const N = 1000;
	double const mean_arrivals = 0.0002;   // One arrival per 5000 us or 10 ms
	Event event_list[N];

	std::cout << "Uniform Distribution of Requests" << std::endl;

	generate_uniform_events( event_list, N, mean_arrivals, TRACKS_PER_DISK );

	std::cout << "First come, first serve" << std::endl;
	simulate_fcfs( event_list, N, ROTATIONAL_LATENCY + READ_TIME, HEAD_SPEED );
	// print( event_list, N );
	analyze( event_list, N );
	std::cout << std::endl;

	std::cout << "Shortest service time first" << std::endl;
	simulate_sstf( event_list, N, ROTATIONAL_LATENCY + READ_TIME, HEAD_SPEED );
	// print( event_list, N );
	analyze( event_list, N );
	std::cout << std::endl;

	std::cout << "LOOK" << std::endl;
	simulate_look( event_list, N, ROTATIONAL_LATENCY + READ_TIME, HEAD_SPEED );
	// print( event_list, N );
	analyze( event_list, N );
	std::cout << std::endl;

	std::cout << "C-LOOK" << std::endl;
	simulate_c_look( event_list, N, ROTATIONAL_LATENCY + READ_TIME, HEAD_SPEED );
	// print( event_list, N );
	analyze( event_list, N );
	std::cout << std::endl;

	std::cout << "F-LOOK" << std::endl;
	simulate_f_look( event_list, N, ROTATIONAL_LATENCY + READ_TIME, HEAD_SPEED );
	// print( event_list, N );
	analyze( event_list, N );
	std::cout << std::endl;

	std::cout << std::endl << "Uniform Distribution of Requests with Probability 0.2 with Others Targetted" << std::endl;

	generate_uniform_and_targetted_events( event_list, N, mean_arrivals, TRACKS_PER_DISK, 0.2, 40 );

	std::cout << "First come, first serve" << std::endl;
	simulate_fcfs( event_list, N, ROTATIONAL_LATENCY + READ_TIME, HEAD_SPEED );
	// print( event_list, N );
	analyze( event_list, N );
	std::cout << std::endl;

	std::cout << "Shortest service time first" << std::endl;
	simulate_sstf( event_list, N, ROTATIONAL_LATENCY + READ_TIME, HEAD_SPEED );
	// print( event_list, N );
	analyze( event_list, N );
	std::cout << std::endl;

	std::cout << "LOOK" << std::endl;
	simulate_look( event_list, N, ROTATIONAL_LATENCY + READ_TIME, HEAD_SPEED );
	// print( event_list, N );
	analyze( event_list, N );
	std::cout << std::endl;

	std::cout << "C-LOOK" << std::endl;
	simulate_c_look( event_list, N, ROTATIONAL_LATENCY + READ_TIME, HEAD_SPEED );
	// print( event_list, N );
	analyze( event_list, N );
	std::cout << std::endl;

	std::cout << "F-LOOK" << std::endl;
	simulate_f_look( event_list, N, ROTATIONAL_LATENCY + READ_TIME, HEAD_SPEED );
	// print( event_list, N );
	analyze( event_list, N );
	std::cout << std::endl;

	return 0;
}