// 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))
    }
}

// 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)
        })
    })
}