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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
use crate::permissions::Permissions;use deno_core::error::AnyError;use deno_core::parking_lot::Mutex;use deno_core::AsyncRefCell;use deno_core::CancelFuture;use deno_core::CancelHandle;use deno_core::OpState;use deno_core::RcRef;use deno_core::Resource;use deno_core::ResourceId;
use deno_core::op;
use deno_core::Extension;use notify::event::Event as NotifyEvent;use notify::Error as NotifyError;use notify::EventKind;use notify::RecommendedWatcher;use notify::RecursiveMode;use notify::Watcher;use serde::Deserialize;use serde::Serialize;use std::borrow::Cow;use std::cell::RefCell;use std::convert::From;use std::path::PathBuf;use std::rc::Rc;use tokio::sync::mpsc;
pub fn init() -> Extension {  Extension::builder()    .ops(vec![op_fs_events_open::decl(), op_fs_events_poll::decl()])    .build()}
struct FsEventsResource {  #[allow(unused)]  watcher: RecommendedWatcher,  receiver: AsyncRefCell<mpsc::Receiver<Result<FsEvent, AnyError>>>,  cancel: CancelHandle,}
impl Resource for FsEventsResource {  fn name(&self) -> Cow<str> {    "fsEvents".into()  }
  fn close(self: Rc<Self>) {    self.cancel.cancel();  }}
/// Represents a file system event.////// We do not use the event directly from the notify crate. We flatten/// the structure into this simpler structure. We want to only make it more/// complex as needed.////// Feel free to expand this struct as long as you can add tests to demonstrate/// the complexity.#[derive(Serialize, Debug)]struct FsEvent {  kind: &'static str,  paths: Vec<PathBuf>,  flag: Option<&'static str>,}
impl From<NotifyEvent> for FsEvent {  fn from(e: NotifyEvent) -> Self {    let kind = match e.kind {      EventKind::Any => "any",      EventKind::Access(_) => "access",      EventKind::Create(_) => "create",      EventKind::Modify(_) => "modify",      EventKind::Remove(_) => "remove",      EventKind::Other => "other",    };    let flag = e.flag().map(|f| match f {      notify::event::Flag::Rescan => "rescan",    });    FsEvent {      kind,      paths: e.paths,      flag,    }  }}
#[derive(Deserialize)]pub struct OpenArgs {  recursive: bool,  paths: Vec<String>,}
#[op]fn op_fs_events_open(  state: &mut OpState,  args: OpenArgs,) -> Result<ResourceId, AnyError> {  let (sender, receiver) = mpsc::channel::<Result<FsEvent, AnyError>>(16);  let sender = Mutex::new(sender);  let mut watcher: RecommendedWatcher = Watcher::new(    move |res: Result<NotifyEvent, NotifyError>| {      let res2 = res.map(FsEvent::from).map_err(AnyError::from);      let sender = sender.lock();      // Ignore result, if send failed it means that watcher was already closed,      // but not all messages have been flushed.      let _ = sender.try_send(res2);    },    Default::default(),  )?;  let recursive_mode = if args.recursive {    RecursiveMode::Recursive  } else {    RecursiveMode::NonRecursive  };  for path in &args.paths {    let path = PathBuf::from(path);    state      .borrow_mut::<Permissions>()      .read      .check(&path, Some("Deno.watchFs()"))?;    watcher.watch(&path, recursive_mode)?;  }  let resource = FsEventsResource {    watcher,    receiver: AsyncRefCell::new(receiver),    cancel: Default::default(),  };  let rid = state.resource_table.add(resource);  Ok(rid)}
#[op]async fn op_fs_events_poll(  state: Rc<RefCell<OpState>>,  rid: ResourceId,) -> Result<Option<FsEvent>, AnyError> {  let resource = state.borrow().resource_table.get::<FsEventsResource>(rid)?;  let mut receiver = RcRef::map(&resource, |r| &r.receiver).borrow_mut().await;  let cancel = RcRef::map(resource, |r| &r.cancel);  let maybe_result = receiver.recv().or_cancel(cancel).await?;  match maybe_result {    Some(Ok(value)) => Ok(Some(value)),    Some(Err(err)) => Err(err),    None => Ok(None),  }}