pagination.js

import * as R from 'ramda'

export const between = (num: number, min: number, max: number) =>
  R.max(min, R.min(num, max))

export const paginate = (
  records: number,
  limit: number = 10,
  current: number = 1,
  delta: number = 1,
  fixed: number = 1
) => {
  const total = Math.ceil(R.max(1, records / limit))
  const page = between(current, 1, total)

  const min = 1 + fixed
  const max = total - fixed

  const maxLeft = R.min(max - delta * 2 - 1, max)
  const minRight = R.min(min + delta * 2 + 1, max)

  const left = between(page - delta, min, maxLeft)
  const right = between(page + delta, minRight, max)

  const missLeft = left - fixed
  const missRight = total - fixed - right + 1

  const prev = missLeft > 2
  const next = missRight > 2

  const start = R.range(1, between(fixed + 1, 1, total + 1))
  const middle = R.range(
    missLeft === 2 ? left - 1 : left,
    missRight === 2 ? right + 2 : right + 1
  )
  const end = R.range(between(total - fixed + 1, 2, total + 1), total + 1)

  const from = between(limit * page - limit + 1, 1, records)
  const to = between(limit * page, 1, records)

  return { total, current: page, start, end, prev, next, middle, from, to }
}