import std.array;
import std.math;
import std.random;
import std.stdio;
import dregs.algorithms.avg;
import dregs.algorithms.yzlm;

void main()
{
	Rating[] ratings;
	double[] reputationObject, reputationUser;
	double[] objectQuality, userError;
	Mt19937 rng;
	auto aa = new AvgArithmetic;
	auto yzlm = new Yzlm(0.8,1e-12,1e-36);
	
	rng.seed(1001);
	
	reputationObject.length = 1000;
	reputationUser.length = 1000;
	
	objectQuality.length = reputationObject.length;
	userError.length = reputationUser.length;
	
	ratings.reserve(reputationObject.length * reputationUser.length);
	
	foreach(uint i;0..100) {	
		foreach(ref double Q; objectQuality)
			Q = uniform(0.0L, 10.0L, rng);
	
		foreach(ref double sigma2; userError)
			sigma2 = uniform(0.0L, 1.0L, rng);
		
		ratings.length = 0;
		assumeSafeAppend(ratings);
		
		auto ratingsAppend = appender(&ratings);
		
		foreach(uint object, double Q; objectQuality) {
			foreach(uint user, double sigma2; userError) {	
				double v = uniform( (Q-sigma2), (Q+sigma2), rng );
				Rating r = { user, object, v };
				ratingsAppend.put(r);
			}
		}
		
		writefln("We now have %u ratings.",ratings.length);
	
		aa(ratings,reputationUser,reputationObject);
		yzlm(ratings,reputationUser,reputationObject);

		double deltaQ = 0;
		foreach(uint object, double r; reputationObject)
			deltaQ += pow( (r-objectQuality[object]), 2);
		deltaQ = sqrt(deltaQ/reputationObject.length);
		writefln("[%u] Error in quality estimate: %g",i,deltaQ);
	}
}