package cuckoo

// DefaultCapacity is the initial capacity of a [Table]. It is inspired from
// Java's [HashMap] implementation, which also uses 16.
//
// [HashMap]: https://docs.oracle.com/javase/8/docs/api/java/util/HashMap.html#HashMap--
const DefaultCapacity uint64 = 16

// DefaultGrowthFactor is the standard resize multiplier for a [Table]. Most
// hash table implementations use 2.
const DefaultGrowthFactor uint64 = 2

// DefaultMinimumLoad is the default lowest acceptable occupancy of a [Table].
// The value of 5% is taken from [libcuckoo].
//
// [libcuckoo]: https://github.com/efficient/libcuckoo/blob/656714705a055df2b7a605eb3c71586d9da1e119/libcuckoo/cuckoohash_config.hh#L21
const DefaultMinimumLoad float64 = 0.05

type settings struct {
	growthFactor  uint64
	minLoadFactor float64
	bucketSize    uint64
}

// An Option modifies the settings of a [Table]. It is used in its constructors
// like [NewTable], for example.
type Option func(*settings)

// Capacity modifies the starting capacity of each bucket of the [Table]. The
// value must be greater than 0.
func Capacity(value int) Option {
	return func(s *settings) { s.bucketSize = uint64(value) }
}

// MinimumLoad modifies the [DefaultMinimumLoad] of the [Table]. The value must
// be between 0.00 and 1.00.
func MinimumLoad(value float64) Option {
	return func(s *settings) { s.minLoadFactor = value }
}

// GrowthFactor controls how much the capacity of the [Table] multiplies when
// it must resize. The value must be greater than 1.
func GrowthFactor(value int) Option {
	return func(s *settings) { s.growthFactor = uint64(value) }
}