const TOPIC = "topic"
const CATEGORY = "category"

const typeName = levels => (levels >= 3 ? TOPIC : CATEGORY)

const createNode = ({ perLevel, levels, remainingLevels }) => {
  if (remainingLevels === 0) return { type: TOPIC, children: [] }

  return {
    type: typeName(levels - remainingLevels),
    children: new Array(perLevel).fill(createNode({ perLevel, levels, remainingLevels: remainingLevels - 1 })),
  }
}

const createHierarchy = ({ perLevel, levels }) => {
  return new Array(perLevel).fill(createNode({ perLevel, levels, remainingLevels: levels - 1 }))
}

module.exports = { createHierarchy }