// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.

use deno_core::error::resource_unavailable;
use deno_core::error::AnyError;
use deno_core::op;
use deno_core::AsyncMutFuture;
use deno_core::AsyncRefCell;
use deno_core::AsyncResult;
use deno_core::CancelHandle;
use deno_core::CancelTryFuture;
use deno_core::Extension;
use deno_core::OpState;
use deno_core::RcRef;
use deno_core::Resource;
use deno_core::ResourceId;
use deno_core::ZeroCopyBuf;
use once_cell::sync::Lazy;
use std::borrow::Cow;
use std::cell::RefCell;
use std::fs::File as StdFile;
use std::io::ErrorKind;
use std::io::Read;
use std::io::Write;
use std::rc::Rc;
use tokio::io::AsyncRead;
use tokio::io::AsyncReadExt;
use tokio::io::AsyncWrite;
use tokio::io::AsyncWriteExt;
use tokio::process;

#[cfg(unix)]
use std::os::unix::io::FromRawFd;

#[cfg(windows)]
use {
  std::os::windows::io::FromRawHandle,
  winapi::um::{processenv::GetStdHandle, winbase},
};

// Store the stdio fd/handles in global statics in order to keep them
// alive for the duration of the application since the last handle/fd
// being dropped will close the corresponding pipe.
#[cfg(unix)]
static STDIN_HANDLE: Lazy<StdFile> = Lazy::new(|| {
  // SAFETY: corresponds to OS stdin
  unsafe { StdFile::from_raw_fd(0) }
});
#[cfg(unix)]
static STDOUT_HANDLE: Lazy<StdFile> = Lazy::new(|| {
  // SAFETY: corresponds to OS stdout
  unsafe { StdFile::from_raw_fd(1) }
});
#[cfg(unix)]
static STDERR_HANDLE: Lazy<StdFile> = Lazy::new(|| {
  // SAFETY: corresponds to OS stderr
  unsafe { StdFile::from_raw_fd(2) }
});

#[cfg(windows)]
static STDIN_HANDLE: Lazy<StdFile> = Lazy::new(|| {
  // SAFETY: corresponds to OS stdin
  unsafe { StdFile::from_raw_handle(GetStdHandle(winbase::STD_INPUT_HANDLE)) }
});
#[cfg(windows)]
static STDOUT_HANDLE: Lazy<StdFile> = Lazy::new(|| {
  // SAFETY: corresponds to OS stdout
  unsafe { StdFile::from_raw_handle(GetStdHandle(winbase::STD_OUTPUT_HANDLE)) }
});
#[cfg(windows)]
static STDERR_HANDLE: Lazy<StdFile> = Lazy::new(|| {
  // SAFETY: corresponds to OS stderr
  unsafe { StdFile::from_raw_handle(GetStdHandle(winbase::STD_ERROR_HANDLE)) }
});

pub fn init() -> Extension {
  Extension::builder()
    .ops(vec![op_read_sync::decl(), op_write_sync::decl()])
    .build()
}

pub enum StdioPipe {
  Inherit,
  File(StdFile),
}

impl Default for StdioPipe {
  fn default() -> Self {
    Self::Inherit
  }
}

impl Clone for StdioPipe {
  fn clone(&self) -> Self {
    match self {
      StdioPipe::Inherit => StdioPipe::Inherit,
      StdioPipe::File(pipe) => StdioPipe::File(pipe.try_clone().unwrap()),
    }
  }
}

/// Specify how stdin, stdout, and stderr are piped.
/// By default, inherits from the process.
#[derive(Clone, Default)]
pub struct Stdio {
  pub stdin: StdioPipe,
  pub stdout: StdioPipe,
  pub stderr: StdioPipe,
}

pub fn init_stdio(stdio: Stdio) -> Extension {
  // todo(dsheret): don't do this? Taking out the writers was necessary to prevent invalid handle panics
  let stdio = Rc::new(RefCell::new(Some(stdio)));

  Extension::builder()
    .middleware(|op| match op.name {
      "op_print" => op_print::decl(),
      _ => op,
    })
    .state(move |state| {
      let stdio = stdio
        .borrow_mut()
        .take()
        .expect("Extension only supports being used once.");
      let t = &mut state.resource_table;
      t.add(StdFileResource::stdio(
        match stdio.stdin {
          StdioPipe::Inherit => {
            StdFileResourceInner::Stdin(STDIN_HANDLE.try_clone().unwrap())
          }
          StdioPipe::File(pipe) => StdFileResourceInner::file(pipe),
        },
        "stdin",
      ));
      t.add(StdFileResource::stdio(
        match stdio.stdout {
          StdioPipe::Inherit => {
            StdFileResourceInner::Stdout(STDOUT_HANDLE.try_clone().unwrap())
          }
          StdioPipe::File(pipe) => StdFileResourceInner::file(pipe),
        },
        "stdout",
      ));
      t.add(StdFileResource::stdio(
        match stdio.stderr {
          StdioPipe::Inherit => {
            StdFileResourceInner::Stderr(STDERR_HANDLE.try_clone().unwrap())
          }
          StdioPipe::File(pipe) => StdFileResourceInner::file(pipe),
        },
        "stderr",
      ));
      Ok(())
    })
    .build()
}

#[cfg(unix)]
use nix::sys::termios;

#[derive(Default)]
pub struct TtyMetadata {
  #[cfg(unix)]
  pub mode: Option<termios::Termios>,
}

#[derive(Default)]
pub struct FileMetadata {
  pub tty: TtyMetadata,
}

#[derive(Debug)]
pub struct WriteOnlyResource<S> {
  stream: AsyncRefCell<S>,
}

impl<S: 'static> From<S> for WriteOnlyResource<S> {
  fn from(stream: S) -> Self {
    Self {
      stream: stream.into(),
    }
  }
}

impl<S> WriteOnlyResource<S>
where
  S: AsyncWrite + Unpin + 'static,
{
  pub fn borrow_mut(self: &Rc<Self>) -> AsyncMutFuture<S> {
    RcRef::map(self, |r| &r.stream).borrow_mut()
  }

  async fn write(self: Rc<Self>, buf: ZeroCopyBuf) -> Result<usize, AnyError> {
    let mut stream = self.borrow_mut().await;
    let nwritten = stream.write(&buf).await?;
    Ok(nwritten)
  }

  async fn shutdown(self: Rc<Self>) -> Result<(), AnyError> {
    let mut stream = self.borrow_mut().await;
    stream.shutdown().await?;
    Ok(())
  }

  pub fn into_inner(self) -> S {
    self.stream.into_inner()
  }
}

#[derive(Debug)]
pub struct ReadOnlyResource<S> {
  stream: AsyncRefCell<S>,
  cancel_handle: CancelHandle,
}

impl<S: 'static> From<S> for ReadOnlyResource<S> {
  fn from(stream: S) -> Self {
    Self {
      stream: stream.into(),
      cancel_handle: Default::default(),
    }
  }
}

impl<S> ReadOnlyResource<S>
where
  S: AsyncRead + Unpin + 'static,
{
  pub fn borrow_mut(self: &Rc<Self>) -> AsyncMutFuture<S> {
    RcRef::map(self, |r| &r.stream).borrow_mut()
  }

  pub fn cancel_handle(self: &Rc<Self>) -> RcRef<CancelHandle> {
    RcRef::map(self, |r| &r.cancel_handle)
  }

  pub fn cancel_read_ops(&self) {
    self.cancel_handle.cancel()
  }

  async fn read(
    self: Rc<Self>,
    mut buf: ZeroCopyBuf,
  ) -> Result<(usize, ZeroCopyBuf), AnyError> {
    let mut rd = self.borrow_mut().await;
    let nread = rd
      .read(&mut buf)
      .try_or_cancel(self.cancel_handle())
      .await?;
    Ok((nread, buf))
  }

  pub fn into_inner(self) -> S {
    self.stream.into_inner()
  }
}

pub type ChildStdinResource = WriteOnlyResource<process::ChildStdin>;

impl Resource for ChildStdinResource {
  fn name(&self) -> Cow<str> {
    "childStdin".into()
  }

  fn write(self: Rc<Self>, buf: ZeroCopyBuf) -> AsyncResult<usize> {
    Box::pin(self.write(buf))
  }

  fn shutdown(self: Rc<Self>) -> AsyncResult<()> {
    Box::pin(self.shutdown())
  }
}

pub type ChildStdoutResource = ReadOnlyResource<process::ChildStdout>;

impl Resource for ChildStdoutResource {
  fn name(&self) -> Cow<str> {
    "childStdout".into()
  }

  fn read_return(
    self: Rc<Self>,
    buf: ZeroCopyBuf,
  ) -> AsyncResult<(usize, ZeroCopyBuf)> {
    Box::pin(self.read(buf))
  }

  fn close(self: Rc<Self>) {
    self.cancel_read_ops();
  }
}

pub type ChildStderrResource = ReadOnlyResource<process::ChildStderr>;

impl Resource for ChildStderrResource {
  fn name(&self) -> Cow<str> {
    "childStderr".into()
  }

  fn read_return(
    self: Rc<Self>,
    buf: ZeroCopyBuf,
  ) -> AsyncResult<(usize, ZeroCopyBuf)> {
    Box::pin(self.read(buf))
  }

  fn close(self: Rc<Self>) {
    self.cancel_read_ops();
  }
}

enum StdFileResourceInner {
  File(StdFile),
  Stdin(StdFile),
  // For stdout and stderr, we sometimes instead use std::io::stdout() directly,
  // because we get some Windows specific functionality for free by using Rust
  // std's wrappers. So we take a bit of a complexity hit in order to not
  // have to duplicate the functionality in Rust's std/src/sys/windows/stdio.rs
  Stdout(StdFile),
  Stderr(StdFile),
}

impl StdFileResourceInner {
  pub fn file(fs_file: StdFile) -> Self {
    StdFileResourceInner::File(fs_file)
  }

  pub fn with_file<R>(&mut self, f: impl FnOnce(&mut StdFile) -> R) -> R {
    match self {
      Self::File(file)
      | Self::Stdin(file)
      | Self::Stdout(file)
      | Self::Stderr(file) => f(file),
    }
  }

  pub fn write_and_maybe_flush(
    &mut self,
    buf: &[u8],
  ) -> Result<usize, AnyError> {
    // Rust will line buffer and we don't want that behavior
    // (see https://github.com/denoland/deno/issues/948), so flush stdout and stderr.
    // Although an alternative solution could be to bypass Rust's std by
    // using the raw fds/handles, it will cause encoding issues on Windows
    // that we get solved for free by using Rust's stdio wrappers (see
    // std/src/sys/windows/stdio.rs in Rust's source code).
    match self {
      Self::File(file) => Ok(file.write(buf)?),
      Self::Stdin(_) => {
        Err(Into::<std::io::Error>::into(ErrorKind::Unsupported).into())
      }
      Self::Stdout(_) => {
        // bypass the file and use std::io::stdout()
        let mut stdout = std::io::stdout().lock();
        let nwritten = stdout.write(buf)?;
        stdout.flush()?;
        Ok(nwritten)
      }
      Self::Stderr(_) => {
        // bypass the file and use std::io::stderr()
        let mut stderr = std::io::stderr().lock();
        let nwritten = stderr.write(buf)?;
        stderr.flush()?;
        Ok(nwritten)
      }
    }
  }

  pub fn write_all_and_maybe_flush(
    &mut self,
    buf: &[u8],
  ) -> Result<(), AnyError> {
    // this method exists instead of using a `Write` implementation
    // so that we can acquire the locks once and do both actions
    match self {
      Self::File(file) => Ok(file.write_all(buf)?),
      Self::Stdin(_) => {
        Err(Into::<std::io::Error>::into(ErrorKind::Unsupported).into())
      }
      Self::Stdout(_) => {
        // bypass the file and use std::io::stdout()
        let mut stdout = std::io::stdout().lock();
        stdout.write_all(buf)?;
        stdout.flush()?;
        Ok(())
      }
      Self::Stderr(_) => {
        // bypass the file and use std::io::stderr()
        let mut stderr = std::io::stderr().lock();
        stderr.write_all(buf)?;
        stderr.flush()?;
        Ok(())
      }
    }
  }
}

impl Read for StdFileResourceInner {
  fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
    match self {
      Self::File(file) | Self::Stdin(file) => file.read(buf),
      Self::Stdout(_) | Self::Stderr(_) => Err(ErrorKind::Unsupported.into()),
    }
  }
}

pub struct StdFileResource {
  name: String,
  cell: AsyncRefCell<Option<(StdFileResourceInner, FileMetadata)>>,
}

impl StdFileResource {
  fn stdio(inner: StdFileResourceInner, name: &str) -> Self {
    Self {
      cell: AsyncRefCell::new(Some((inner, Default::default()))),
      name: name.to_string(),
    }
  }

  pub fn fs_file(fs_file: StdFile) -> Self {
    Self {
      cell: AsyncRefCell::new(Some((
        StdFileResourceInner::file(fs_file),
        Default::default(),
      ))),
      name: "fsFile".to_string(),
    }
  }

  fn with_inner_and_metadata<TResult>(
    self: Rc<Self>,
    action: impl FnOnce(
      &mut StdFileResourceInner,
      &mut FileMetadata,
    ) -> Result<TResult, AnyError>,
  ) -> Result<TResult, AnyError> {
    match RcRef::map(&self, |r| &r.cell).try_borrow_mut() {
      Some(mut cell) => {
        let mut file = cell.take().unwrap();
        let result = action(&mut file.0, &mut file.1);
        cell.replace(file);
        result
      }
      None => Err(resource_unavailable()),
    }
  }

  async fn with_inner_blocking_task<F, R: Send + 'static>(
    self: Rc<Self>,
    action: F,
  ) -> R
  where
    F: FnOnce(&mut StdFileResourceInner) -> R + Send + 'static,
  {
    // we take the value out of the cell, use it on a blocking task,
    // then put it back into the cell when we're done
    let mut cell = RcRef::map(&self, |r| &r.cell).borrow_mut().await;
    let mut file = cell.take().unwrap();
    let (file, result) = tokio::task::spawn_blocking(move || {
      let result = action(&mut file.0);
      (file, result)
    })
    .await
    .unwrap();
    cell.replace(file);
    result
  }

  async fn read(
    self: Rc<Self>,
    mut buf: ZeroCopyBuf,
  ) -> Result<(usize, ZeroCopyBuf), AnyError> {
    self
      .with_inner_blocking_task(
        move |inner| -> Result<(usize, ZeroCopyBuf), AnyError> {
          Ok((inner.read(&mut buf)?, buf))
        },
      )
      .await
  }

  async fn write(self: Rc<Self>, buf: ZeroCopyBuf) -> Result<usize, AnyError> {
    self
      .with_inner_blocking_task(move |inner| inner.write_and_maybe_flush(&buf))
      .await
  }

  fn with_resource<F, R>(
    state: &mut OpState,
    rid: ResourceId,
    f: F,
  ) -> Result<R, AnyError>
  where
    F: FnOnce(Rc<StdFileResource>) -> Result<R, AnyError>,
  {
    let resource = state.resource_table.get::<StdFileResource>(rid)?;
    f(resource)
  }

  pub fn with_file<F, R>(
    state: &mut OpState,
    rid: ResourceId,
    f: F,
  ) -> Result<R, AnyError>
  where
    F: FnOnce(&mut StdFile) -> Result<R, AnyError>,
  {
    Self::with_resource(state, rid, move |resource| {
      resource.with_inner_and_metadata(move |inner, _| inner.with_file(f))
    })
  }

  pub fn with_file_and_metadata<F, R>(
    state: &mut OpState,
    rid: ResourceId,
    f: F,
  ) -> Result<R, AnyError>
  where
    F: FnOnce(&mut StdFile, &mut FileMetadata) -> Result<R, AnyError>,
  {
    Self::with_resource(state, rid, move |resource| {
      resource.with_inner_and_metadata(move |inner, metadata| {
        inner.with_file(move |file| f(file, metadata))
      })
    })
  }

  pub async fn with_file_blocking_task<F, R: Send + 'static>(
    state: Rc<RefCell<OpState>>,
    rid: ResourceId,
    f: F,
  ) -> Result<R, AnyError>
  where
    F: (FnOnce(&mut StdFile) -> Result<R, AnyError>) + Send + 'static,
  {
    let resource = state
      .borrow_mut()
      .resource_table
      .get::<StdFileResource>(rid)?;

    resource
      .with_inner_blocking_task(move |inner| inner.with_file(f))
      .await
  }

  pub fn clone_file(
    state: &mut OpState,
    rid: ResourceId,
  ) -> Result<StdFile, AnyError> {
    Self::with_file(state, rid, move |std_file| {
      std_file.try_clone().map_err(AnyError::from)
    })
  }

  pub fn as_stdio(
    state: &mut OpState,
    rid: u32,
  ) -> Result<std::process::Stdio, AnyError> {
    Self::with_resource(state, rid, |resource| {
      resource.with_inner_and_metadata(|inner, _| match inner {
        StdFileResourceInner::File(file) => {
          let file = file.try_clone()?;
          Ok(file.into())
        }
        _ => Ok(std::process::Stdio::inherit()),
      })
    })
  }
}

impl Resource for StdFileResource {
  fn name(&self) -> Cow<str> {
    self.name.as_str().into()
  }

  fn read_return(
    self: Rc<Self>,
    buf: ZeroCopyBuf,
  ) -> AsyncResult<(usize, ZeroCopyBuf)> {
    Box::pin(self.read(buf))
  }

  fn write(self: Rc<Self>, buf: ZeroCopyBuf) -> AsyncResult<usize> {
    Box::pin(self.write(buf))
  }

  #[cfg(unix)]
  fn backing_fd(self: Rc<Self>) -> Option<std::os::unix::prelude::RawFd> {
    use std::os::unix::io::AsRawFd;
    self
      .with_inner_and_metadata(move |std_file, _| {
        Ok(std_file.with_file(|f| f.as_raw_fd()))
      })
      .ok()
  }
}

// override op_print to use the stdout and stderr in the resource table
#[op]
pub fn op_print(
  state: &mut OpState,
  msg: String,
  is_err: bool,
) -> Result<(), AnyError> {
  let rid = if is_err { 2 } else { 1 };
  StdFileResource::with_resource(state, rid, move |resource| {
    resource.with_inner_and_metadata(|inner, _| {
      inner.write_all_and_maybe_flush(msg.as_bytes())?;
      Ok(())
    })
  })
}

#[op]
fn op_read_sync(
  state: &mut OpState,
  rid: ResourceId,
  mut buf: ZeroCopyBuf,
) -> Result<u32, AnyError> {
  StdFileResource::with_resource(state, rid, move |resource| {
    resource.with_inner_and_metadata(|inner, _| {
      inner
        .read(&mut buf)
        .map(|n: usize| n as u32)
        .map_err(AnyError::from)
    })
  })
}

#[op]
fn op_write_sync(
  state: &mut OpState,
  rid: ResourceId,
  buf: ZeroCopyBuf,
) -> Result<u32, AnyError> {
  StdFileResource::with_resource(state, rid, move |resource| {
    resource.with_inner_and_metadata(|inner, _| {
      inner
        .write_and_maybe_flush(&buf)
        .map(|nwritten: usize| nwritten as u32)
        .map_err(AnyError::from)
    })
  })
}