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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
use std::fmt::Debug;use std::ops::Deref;use std::ops::DerefMut;
use super::transl8::FromV8;use super::transl8::ToV8;use super::v8slice::V8Slice;use crate::magic::transl8::impl_magic;
// An asymmetric wrapper around V8Slice,// allowing us to use a single type for familiaritypub enum ZeroCopyBuf {  FromV8(V8Slice),  ToV8(Option<Box<[u8]>>),  // Variant of the ZeroCopyBuf than is never exposed to the JS.  // Generally used to pass Vec<u8> backed buffers to resource methods.  Temp(Vec<u8>),}
impl_magic!(ZeroCopyBuf);
impl Debug for ZeroCopyBuf {  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {    f.debug_list().entries(self.as_ref().iter()).finish()  }}
impl ZeroCopyBuf {  pub fn empty() -> Self {    ZeroCopyBuf::ToV8(Some(vec![0_u8; 0].into_boxed_slice()))  }
  pub fn new_temp(vec: Vec<u8>) -> Self {    ZeroCopyBuf::Temp(vec)  }
  // TODO(@littledivy): Temporary, this needs a refactor.  pub fn to_temp(self) -> Vec<u8> {    match self {      ZeroCopyBuf::Temp(vec) => vec,      _ => unreachable!(),    }  }}
impl Clone for ZeroCopyBuf {  fn clone(&self) -> Self {    match self {      Self::FromV8(zbuf) => Self::FromV8(zbuf.clone()),      Self::Temp(vec) => Self::Temp(vec.clone()),      Self::ToV8(_) => panic!("Don't Clone a ZeroCopyBuf sent to v8"),    }  }}
impl AsRef<[u8]> for ZeroCopyBuf {  fn as_ref(&self) -> &[u8] {    self  }}
impl AsMut<[u8]> for ZeroCopyBuf {  fn as_mut(&mut self) -> &mut [u8] {    &mut *self  }}
impl Deref for ZeroCopyBuf {  type Target = [u8];  fn deref(&self) -> &[u8] {    match self {      Self::FromV8(buf) => buf,      Self::Temp(vec) => vec,      Self::ToV8(_) => panic!("Don't Deref a ZeroCopyBuf sent to v8"),    }  }}
impl DerefMut for ZeroCopyBuf {  fn deref_mut(&mut self) -> &mut [u8] {    match self {      Self::FromV8(buf) => &mut *buf,      Self::Temp(vec) => &mut *vec,      Self::ToV8(_) => panic!("Don't Deref a ZeroCopyBuf sent to v8"),    }  }}
impl From<Box<[u8]>> for ZeroCopyBuf {  fn from(buf: Box<[u8]>) -> Self {    ZeroCopyBuf::ToV8(Some(buf))  }}
impl From<Vec<u8>> for ZeroCopyBuf {  fn from(vec: Vec<u8>) -> Self {    vec.into_boxed_slice().into()  }}
impl ToV8 for ZeroCopyBuf {  fn to_v8<'a>(    &mut self,    scope: &mut v8::HandleScope<'a>,  ) -> Result<v8::Local<'a, v8::Value>, crate::Error> {    let buf: Box<[u8]> = match self {      Self::FromV8(buf) => {        let value: &[u8] = buf;        value.into()      }      Self::Temp(_) => unreachable!(),      Self::ToV8(ref mut x) => x.take().expect("ZeroCopyBuf was empty"),    };
    if buf.is_empty() {      let ab = v8::ArrayBuffer::new(scope, 0);      return Ok(        v8::Uint8Array::new(scope, ab, 0, 0)          .expect("Failed to create Uint8Array")          .into(),      );    }    let buf_len = buf.len();    let backing_store =      v8::ArrayBuffer::new_backing_store_from_boxed_slice(buf);    let backing_store_shared = backing_store.make_shared();    let ab = v8::ArrayBuffer::with_backing_store(scope, &backing_store_shared);    Ok(      v8::Uint8Array::new(scope, ab, 0, buf_len)        .expect("Failed to create Uint8Array")        .into(),    )  }}
impl FromV8 for ZeroCopyBuf {  fn from_v8(    scope: &mut v8::HandleScope,    value: v8::Local<v8::Value>,  ) -> Result<Self, crate::Error> {    Ok(Self::FromV8(V8Slice::from_v8(scope, value)?))  }}
impl From<ZeroCopyBuf> for bytes::Bytes {  fn from(zbuf: ZeroCopyBuf) -> bytes::Bytes {    match zbuf {      ZeroCopyBuf::FromV8(v) => v.into(),      ZeroCopyBuf::ToV8(mut v) => {        v.take().expect("ZeroCopyBuf was empty").into()      }      ZeroCopyBuf::Temp(v) => v.into(),    }  }}