pagination.go

pagination.go

package pagination

import "fmt"

type Pair struct {
	StartIndex int64
	EndIndex   int64
}

func newPair(l, r int64) Pair {
	return Pair{
		StartIndex: l,
		EndIndex:   r,
	}
}

func newPairSlice(pairs ...Pair) []Pair {
	return pairs
}

// Pages get pagination index list
func Pages(total int64, pageSize int64, startIndex int64) []Pair {
	// check total
	if total <= 0 {
		return nil
	}

	// check pageSize
	if pageSize <= 0 {
		panic(fmt.Sprintf("invalid parameter value: pageSize = %v", pageSize))
	}

	// end
	if total <= pageSize {
		return newPairSlice(newPair(startIndex, startIndex+total-1))
	}

	// head + tail
	return append(
		newPairSlice(newPair(startIndex, startIndex+pageSize-1)),
		// recursive to get tail
		Pages(total-pageSize, pageSize, startIndex+pageSize)...)
}