module.exports = makeSets

function makeSets ({ ranges, setSize }) {

const sets = []

for (var i = 0; i < ranges.length; i++) fillTheSet(ranges[i], sets, setSize)

formatSets(sets)

// if (sets[0] === setSize) formatSets(sets)

return sets

}

var counter = 0

function fillTheSet (range, sets, setSize) {

const [min, max] = range // [7,23]

for (var i = min; i < max + 1; i++) {

if (!sets[counter]) sets[counter] = []

if (sets[counter].length < setSize) { sets[counter].push(i) }

if (sets[counter].length === setSize) counter++

}

}

function formatSets (sets) {

var prev

for (var i = 0; i < sets.length; i++) { // [[0,1,2,3,4,5,6,7,8,9],[10,11,12,13,14,15,16,17,18,19],[20,21,22,23,24,25,28,29,30,31],[32,33,34,35,36,37,39,40,42,43],[72,73,74,75,76,77,78,79,80,81],[82,83,84,85,86,87,88,89,90,91],[92,93,94,95,96,97,98,99,100]]

const set = sets[i]

var count = 0

sets[i] = []

for (var j = 0; j < set.length; j++) { // [0,1,2,3,4,5,6,7,8,9]

const current = set[j]

if (!sets[i][count]) sets[i][count] = [current, undefined]

// current is last el & current - prev > 1

if (j === set.length-1 && current - prev !== 1 && prev !== undefined) {

sets[i][count][1] = prev

count++

sets[i][count] = [current, current]

}

// current - prev > 1

else if (current - prev !== 1 && prev !== undefined && j !== 0) {

sets[i][count][1] = prev

count++

sets[i][count] = [current, undefined]

}

// current is last el & current - prev = 1

else if (j === set.length-1 && current - prev === 1) {

sets[i][count][1] = current

}

prev = current

}

}

}