package pointer

import (
	"runtime"
	"unsafe"

	"git.brut.systems/judah/xx/mem"
)

type Pinned[T any] struct {
	base   unsafe.Pointer
	pinner runtime.Pinner
}

func Pin[T any](ptr *T) (r Pinned[T]) {
	r.pinner.Pin(ptr)
	r.base = unsafe.Pointer(ptr)
	return
}

func Cast[TOut, TIn any](p Pinned[TIn]) Pinned[TOut] {
	return Pinned[TOut]{
		base:   unsafe.Pointer(p.base),
		pinner: p.pinner,
	}
}

func (p Pinned[T]) Unpin() {
	p.pinner.Unpin()
	p.base = nil
}

func (p Pinned[T]) Pointer() unsafe.Pointer {
	return p.base
}

func (p Pinned[T]) Address() uintptr {
	return uintptr(p.base)
}

func (p Pinned[T]) Nil() bool {
	return p.base == nil
}

func (p Pinned[T]) Add(amount uintptr) Pinned[T] {
	return Pinned[T]{
		base:   unsafe.Pointer(uintptr(p.base) + amount),
		pinner: p.pinner,
	}
}

func (p Pinned[T]) Sub(amount uintptr) Pinned[T] {
	return Pinned[T]{
		base:   unsafe.Pointer(uintptr(p.base) - amount),
		pinner: p.pinner,
	}
}

func (p Pinned[T]) Aligned() bool {
	return mem.Aligned(uintptr(p.base), mem.Alignof[T]())
}

func (p Pinned[T]) AlignForward() Pinned[T] {
	return Pinned[T]{
		base:   unsafe.Pointer(mem.AlignForward(uintptr(p.base), mem.Alignof[T]())),
		pinner: p.pinner,
	}
}

func (p Pinned[T]) AlignBackward() Pinned[T] {
	return Pinned[T]{
		base:   unsafe.Pointer(mem.AlignBackward(uintptr(p.base), mem.Alignof[T]())),
		pinner: p.pinner,
	}
}

func (p Pinned[T]) Load() T {
	return *(*T)(p.base)
}

func (p Pinned[T]) Store(value T) {
	*(*T)(p.base) = value
}

func (p Pinned[T]) Nth(index int) T {
	return p.Add(uintptr(index) * mem.Sizeof[T]()).Load()
}