class MultiplicationProblem {

constructor(first, second) {

this.first = first;

this.second = second;

}

get display() {

return this.displayProblem() + " = " + this.answer() + " choices " + this.choices().toString();

}

get allChoices() {

return this.choices();

}

displayProblem() {

return this.first + " x " + this.second;

}

answer() {

return this.first * this.second;

}

choices() {

const answ = this.answer();

var choices = new Set();

choices.add(answ);

choices.add(answ + 10);

choices.add(answ + 1);

choices.add(answ + RandomUtils.getRandomInt(1,10));

//Ensure we have 6 choices

var choicesRange = (answ > 100) ? answ : 100;

while(choices.size < 6) {

choices.add(RandomUtils.getRandomInt(1,choicesRange));

}

return Array.from(choices);

}

static generateProblems(range) {

var problems = new Array();

if(range && range.start >= 0 && range.end >= range.start) {

for(var i = range.start; i<range.end+1; i++) {

for(var j = range.start; j<range.end+1; j++) {

problems.push(new MultiplicationProblem(i,j));

}

}

}

return problems;

}

}