package slices

import (
	"reflect"

	errors "golang.org/x/xerrors"
)

type PtrSlice struct {
	slice   reflect.Value
	current interface{}
	t       reflect.Type
	idx     int
	length  int
}

func NewPtrSlice(s interface{}) (*PtrSlice, error) {
	ps := &PtrSlice{}
	ps.t = reflect.TypeOf(s)
	if ps.t.Kind() != reflect.Slice {
		return nil, errors.New("Attempted to create a PtrSlice from non-Slice")
	}
	ps.slice = reflect.ValueOf(s)
	ps.length = ps.slice.Len()
	ps.idx = 0
	ps.current = ps.slice.Index(ps.idx).Interface()
	return ps, nil
}

func MustPtrSlice(s interface{}) *PtrSlice {
	ps, err := NewPtrSlice(s)
	if err != nil {
		panic(err)
	}
	return ps
}

func (ps *PtrSlice) Val() interface{} {
	return ps.current
}

func (ps *PtrSlice) Next() {
	if ps.idx < ps.length-1 {
		ps.idx++
		ps.current = ps.slice.Index(ps.idx).Interface()
	} else if ps.idx == ps.length-1 {
		ps.idx++
		ps.current = nil
	}
}

func (ps *PtrSlice) Len() int {
	return ps.length
}

func (ps *PtrSlice) Offset(offset int) interface{} {
	return ps.slice.Index(ps.idx + offset).Interface()
}

func (ps *PtrSlice) Get(idx int) interface{} {
	return ps.slice.Index(idx).Interface()
}