package store

import (
	"strconv"
	"strings"
)

// ParsePrefixPageCursor decodes opaque cursors for revision prefix pagination.
func ParsePrefixPageCursor(cursor string) (afterID *int64, offset int, useOffset bool) {
	cursor = strings.TrimSpace(cursor)
	if cursor == "" {
		return nil, 0, false
	}
	if strings.HasPrefix(cursor, "o:") {
		n, err := strconv.Atoi(strings.TrimPrefix(cursor, "o:"))
		if err != nil || n < 0 {
			return nil, 0, false
		}
		return nil, n, true
	}
	if n, err := strconv.ParseInt(cursor, 10, 64); err == nil && n >= 0 {
		return &n, 0, false
	}
	return nil, 0, false
}

// FormatPrefixPageCursor encodes the keyset cursor (last row id or slice index).
func FormatPrefixPageCursor(lastID int64) string {
	return strconv.FormatInt(lastID, 10)
}