package ptr

// scb: scalar base / common stuff

type scb[V any] struct {
	started bool
}

func (p *scb[V]) Size() int {
	return 1
}

func (p *scb[V]) Started() bool {
	return p.started
}

func (p *scb[V]) Append(v V) Ptr[V] {
	p.started = true
	return p.Set(v)
}

func (p *scb[V]) Insert(v V, pos int) Ptr[V] {
	return p.Append(v)
}

func (p *scb[V]) Next() Ptr[V] {
	if p.started {
		return nil
	}
	p.started = true
	return p
}

func (p *scb[V]) Value() V {
	var v V
	return v
}

func (p *scb[V]) Set(v V) Ptr[V] {
	return p
}

func (p *scb[V]) Seek(i int) Ptr[V] {
	p.started = true
	return p
}

func (p *scb[V]) Reset() Ptr[V] {
	p.started = false
	return p
}

func (p *scb[V]) Clone() Ptr[V] {
	return &scb[V]{p.started}
}

func (p *scb[V]) New() Ptr[V] {
	return New[V](p)
}

func (p *scb[V]) Copy() Ptr[V] {
	return Copy[V](p, &scb[V]{false})
}

// scalar implementation using a value pointer

func NewScalar[V any]() Ptr[V] {
	var v V
	return NewVP(&v)
}

func NewVP[V any](vp *V) Ptr[V] {
	get := func() V {
		return *vp
	}
	set := func(v V) {
		*vp = v
	}
	return NewAcc(get, set)
}

// scalar implementation using accessor functions

type acc[V any] struct {
	*scb[V]
	getter func() V
	setter func(v V)
}

func NewAcc[V any](g func() V, s func(v V)) *acc[V] {
	return &acc[V]{
		getter: g,
		setter: s,
		scb:    &scb[V]{false},
	}
}

func (p *acc[V]) Append(v V) Ptr[V] {
	p.started = true
	return p.Set(v)
}

func (p *acc[V]) Insert(v V, pos int) Ptr[V] {
	return p.Append(v)
}

func (p *acc[V]) Value() V {
	return p.getter()
}

func (p *acc[V]) Set(v V) Ptr[V] {
	p.setter(v)
	return p
}

func (p *acc[V]) Clone() Ptr[V] {
	return &acc[V]{
		getter: p.getter,
		setter: p.setter,
		scb:    &scb[V]{p.started},
	}
}

func (p *acc[V]) New() Ptr[V] {
	return New[V](p)
}

func (p *acc[V]) Copy() Ptr[V] {
	return Copy[V](p, NewScalar[V]())
}