package util

import "unsafe"

type eface struct {
	v   int64
	ptr unsafe.Pointer
}

const (
	DefaultBool    bool    = false
	DefaultString  string  = ""
	DefaultInt     int     = 0
	DefaultInt32   int32   = 0
	DefaultInt64   int64   = 0
	DefaultFloat32 float32 = 0
	DefaultFloat64 float64 = 0
)

func DerefBool(p *bool) bool {
	if p != nil {
		return *p
	}
	return DefaultBool
}

func DerefString(p *string) string {
	if p != nil {
		return *p
	}
	return DefaultString
}

func DerefInt(p *int) int {
	if p != nil {
		return *p
	}
	return DefaultInt
}

func DerefInt32(p *int32) int32 {
	if p != nil {
		return *p
	}
	return DefaultInt32
}

func DerefInt64(p *int64) int64 {
	if p != nil {
		return *p
	}
	return DefaultInt64
}

func DerefFloat32(p *float32) float32 {
	if p != nil {
		return *p
	}
	return DefaultFloat32
}

func DerefFloat64(p *float64) float64 {
	if p != nil {
		return *p
	}
	return DefaultFloat64
}

func Int64Slice(v []int64) *[]int64 {
	return &v
}

func DerefInt64Slice(p *[]int64) []int64 {
	if p != nil {
		return *p
	}
	return make([]int64, 0)
}

func DerefStringSlice(p *[]string) []string {
	if p != nil {
		return *p
	}
	return make([]string, 0)
}

// 判断转为any的指针是否为空指针
func IsElemNil(elem any) bool {
	efaceptr := (*eface)(unsafe.Pointer(&elem))
	if efaceptr == nil || uintptr(efaceptr.ptr) == 0x0 {
		return true
	}
	return false
}

// 判断转为any的切片是否为空切片
func IsSliceNil(elem any) bool {
	efaceptr := (*eface)(unsafe.Pointer(&elem))
	if efaceptr == nil || uintptr(efaceptr.ptr) == 0x0 {
		return true
	}

	var sliceInfo = *(*[3]int)(efaceptr.ptr)

	return sliceInfo[1] == 0
}