package bitcoinattackmodel;

/**
 *
 * @author Kooooooj
 */
public class BitcoinAttackModel {

    public static void main(String[] args) {
        int honestBlocks = 0, attackBlocks = 0;//counts profit of honest and attack
        int currentHonestChain = 0, currentAttackChain = 0;//number of blocks not yet accepted
        double attackPercent = .3333, honestPercent = 1-attackPercent;//relative percentages of the network
        double raceOdds = .0;//odds that an honest miner builds off of the attacker's block.  Typical range 0 to .5.  Can be as high as 1. 
        double oddsPerStep = 0.00001;//small number to discourage simultaneous mining of blocks by attacker and honest.  Will run faster with larger values but could be less accurate
        long maxSteps = 1000000000L;//exit condition.  Program will exit eariler with smaller values but will use a smaller data set
        long currentStep = 0;//counter
        while(currentStep < maxSteps)
        {
            currentStep++;
            if(Math.random() < oddsPerStep * attackPercent) {//attackers found a block
                if(currentAttackChain>0 && currentAttackChain == currentHonestChain){
                    //attackers found the block.  They *always* build off of the attack chain
                    attackBlocks+=currentAttackChain + 1;//they get the old chain plus the added block
                    currentAttackChain = 0;
                    currentHonestChain = 0;
                }
                else{
                    currentAttackChain++;//only get to start a new chain if we didn't just resolve a race
                }
               // System.out.println("Attack found a block. Current Attack Chain of " + currentAttackChain + " blocks.");
            }
            if(Math.random() < oddsPerStep * honestPercent) {//honest found a block
                if(currentAttackChain>0 && currentAttackChain==currentHonestChain){//there's a race condition in place
                    System.out.println("Race!!");
                    if(Math.random() < raceOdds){//honest miners mined on top of the attack chain
                        attackBlocks+=currentAttackChain;//accept the attack block
                    }
                    else{//honest miners mined on top of the honest chain; attackers lost the race
                        honestBlocks += currentHonestChain;
                    }
                    currentAttackChain = 0;
                    currentHonestChain = 0;
                }
                currentHonestChain++;//race (if any) has been resolved.  Note the new block
                System.out.println("Honest found a block.  Current Honest Chain of " + currentHonestChain + " blocks\t\tCurrent Stats: " + attackBlocks + " : " + honestBlocks + ", " + attackBlocks/((double)honestBlocks+attackBlocks));
            }
            
            if(currentHonestChain>0 && currentAttackChain ==0){
                honestBlocks+=currentHonestChain;
                currentHonestChain = 0;
                currentAttackChain = 0;
              //  System.out.println("Honest block accepted.  " + honestBlocks + " honest blocks found");
            }   
            
            if(currentAttackChain > 1 && currentAttackChain - currentHonestChain == 1){
                attackBlocks += currentAttackChain;
            //    System.out.println("Attacker orphaned " + currentHonestChain + " blocks");
                currentAttackChain = 0;
                currentHonestChain = 0;
            }
        }
        
        System.out.println("Attacker mined " + attackBlocks + " blocks while honest mined " + honestBlocks);
        System.out.println("Attacker's percentage is " + ((double)attackBlocks/(attackBlocks + honestBlocks)) + " while expected was " + attackPercent);
    }
}