package unsafe

import "unsafe"

type iter struct {
	key         unsafe.Pointer
	elem        unsafe.Pointer
	t           unsafe.Pointer
	h           unsafe.Pointer
	buckets     unsafe.Pointer
	bptr        unsafe.Pointer
	overflow    unsafe.Pointer
	oldoverflow unsafe.Pointer
	startBucket uintptr
	offset      uint8
	wrapped     bool
	B           uint8
	i           uint8
	bucket      uintptr
	checkBucket uintptr
}

type Iter[K comparable, V any] iter

//go:linkname mapiterinit runtime.mapiterinit
func mapiterinit(t unsafe.Pointer, h unsafe.Pointer, it *iter)

//go:linkname mapiternext runtime.mapiternext
func mapiternext(it *iter)

func NewIter[K comparable, V any](m map[K]V) *Iter[K, V] {
	mi := any(m)
	hi := new(iter)
	mapiterinit(*(*unsafe.Pointer)(unsafe.Pointer(&mi)), *(*unsafe.Pointer)(unsafe.Pointer(&m)), hi)
	return (*Iter[K, V])(hi)
}

func (i *Iter[K, V]) Next() {
	mapiternext((*iter)(i))
}

func (i *Iter[K, V]) Has() bool {
	return i.key != nil
}

func (i *Iter[K, V]) Key() K {
	return *(*K)(i.key)
}

func (i *Iter[K, V]) Value() V {
	return *(*V)(i.elem)
}