// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
use crate::errors::*;
use crate::flags::DenoFlags;
use crate::isolate::{DenoBehavior, Isolate};
use crate::isolate_state::IsolateState;
use crate::isolate_state::IsolateStateContainer;
use crate::isolate_state::WorkerChannels;
use crate::ops;
use crate::resources;
use crate::startup_data;
use deno::deno_buf;
use deno::Behavior;
use deno::Buf;
use deno::JSError;
use deno::Op;
use deno::StartupData;
use futures::sync::mpsc;
use futures::Future;
use futures::Poll;
use std::sync::Arc;

pub struct UserWorkerBehavior {
  pub state: Arc<IsolateState>,
}

impl UserWorkerBehavior {
  pub fn new(flags: DenoFlags, argv_rest: Vec<String>) -> Self {
    Self {
      state: Arc::new(IsolateState::new(flags, argv_rest, None, true)),
    }
  }
}

impl IsolateStateContainer for UserWorkerBehavior {
  fn state(&self) -> Arc<IsolateState> {
    self.state.clone()
  }
}

impl IsolateStateContainer for &UserWorkerBehavior {
  fn state(&self) -> Arc<IsolateState> {
    self.state.clone()
  }
}

impl Behavior for UserWorkerBehavior {
  fn startup_data(&mut self) -> Option<StartupData> {
    Some(startup_data::deno_isolate_init())
  }

  fn dispatch(
    &mut self,
    control: &[u8],
    zero_copy: deno_buf,
  ) -> (bool, Box<Op>) {
    ops::dispatch_all(self, control, zero_copy, ops::op_selector_worker)
  }
}

impl WorkerBehavior for UserWorkerBehavior {
  fn set_internal_channels(&mut self, worker_channels: WorkerChannels) {
    self.state = Arc::new(IsolateState::new(
      self.state.flags.clone(),
      self.state.argv.clone(),
      Some(worker_channels),
      true,
    ));
  }
}

/// Behavior trait specific to workers
pub trait WorkerBehavior: DenoBehavior {
  /// Used to setup internal channels at worker creation.
  /// This is intended to be temporary fix.
  /// TODO(afinch7) come up with a better solution to set worker channels
  fn set_internal_channels(&mut self, worker_channels: WorkerChannels);
}

/// Rust interface for WebWorkers.
pub struct Worker<B: WorkerBehavior> {
  isolate: Isolate<B>,
  pub resource: resources::Resource,
}

impl<B: WorkerBehavior> Worker<B> {
  pub fn new(mut behavior: B) -> Self {
    let (worker_in_tx, worker_in_rx) = mpsc::channel::<Buf>(1);
    let (worker_out_tx, worker_out_rx) = mpsc::channel::<Buf>(1);

    let internal_channels = (worker_out_tx, worker_in_rx);
    let external_channels = (worker_in_tx, worker_out_rx);

    behavior.set_internal_channels(internal_channels);

    let isolate = Isolate::new(behavior);

    Worker {
      isolate,
      resource: resources::add_worker(external_channels),
    }
  }

  pub fn execute(&mut self, js_source: &str) -> Result<(), JSError> {
    self.isolate.execute(js_source)
  }

  pub fn execute_mod(
    &mut self,
    js_filename: &str,
    is_prefetch: bool,
  ) -> Result<(), RustOrJsError> {
    self.isolate.execute_mod(js_filename, is_prefetch)
  }
}

impl<B: WorkerBehavior> Future for Worker<B> {
  type Item = ();
  type Error = JSError;

  fn poll(&mut self) -> Poll<(), JSError> {
    self.isolate.poll()
  }
}

/// Method and data used to initalize a worker
pub enum WorkerInit {
  Script(String),
  Module(String),
}

pub fn spawn<B: WorkerBehavior + 'static>(
  behavior: B,
  worker_debug_name: &str,
  init: WorkerInit,
) -> Result<Worker<B>, RustOrJsError> {
  let state = behavior.state().clone();
  let mut worker = Worker::new(behavior);

  worker
    .execute(&format!("denoMain('{}')", worker_debug_name))
    .expect("worker workerInit failed");

  worker
    .execute("workerMain()")
    .expect("worker workerMain failed");

  let init_result = match init {
    WorkerInit::Script(script) => match worker.execute(&script) {
      Ok(_) => Ok(()),
      Err(e) => Err(RustOrJsError::Js(e)),
    },
    WorkerInit::Module(specifier) => {
      let should_prefetch = state.flags.prefetch || state.flags.info;
      match state.dir.resolve_module_url(&specifier, ".") {
        Err(err) => Err(RustOrJsError::Rust(DenoError::from(err))),
        Ok(module_url) => {
          worker.execute_mod(&module_url.to_string(), should_prefetch)
        }
      }
    }
  };

  match init_result {
    Ok(_) => Ok(worker),
    Err(err) => Err(err),
  }
}

#[cfg(test)]
mod tests {
  use super::*;
  use crate::compiler::CompilerBehavior;
  use crate::isolate_state::IsolateState;
  use crate::js_errors::JSErrorColor;
  use crate::tokio_util;
  use futures::future::lazy;
  use std::thread;

  #[test]
  fn test_spawn() {
    tokio_util::init(|| {
      let worker_result = spawn(
        CompilerBehavior::new(
          IsolateState::mock().flags.clone(),
          IsolateState::mock().argv.clone(),
        ),
        "TEST",
        WorkerInit::Script(
          r#"
        onmessage = function(e) {
          console.log("msg from main script", e.data);
          if (e.data == "exit") {
            close();
            return;
          } else {
            console.assert(e.data === "hi");
          }
          postMessage([1, 2, 3]);
          console.log("after postMessage");
        }
        "#.into(),
        ),
      );
      assert!(worker_result.is_ok());
      let worker = worker_result.unwrap();
      let resource = worker.resource.clone();
      let resource_ = resource.clone();

      tokio::spawn(lazy(move || {
        worker.then(move |r| -> Result<(), ()> {
          resource_.close();
          debug!("workers.rs after resource close");
          if let Err(err) = r {
            panic!("{}", JSErrorColor(&err).to_string());
          }
          Ok(())
        })
      }));

      let msg = json!("hi").to_string().into_boxed_str().into_boxed_bytes();

      let r = resources::post_message_to_worker(resource.rid, msg).wait();
      assert!(r.is_ok());

      let maybe_msg = resources::get_message_from_worker(resource.rid)
        .wait()
        .unwrap();
      assert!(maybe_msg.is_some());
      // Check if message received is [1, 2, 3] in json
      assert_eq!(*maybe_msg.unwrap(), *b"[1,2,3]");

      let msg = json!("exit")
        .to_string()
        .into_boxed_str()
        .into_boxed_bytes();
      let r = resources::post_message_to_worker(resource.rid, msg).wait();
      assert!(r.is_ok());
    })
  }

  #[test]
  fn removed_from_resource_table_on_close() {
    tokio_util::init(|| {
      let worker_result = spawn(
        CompilerBehavior::new(
          IsolateState::mock().flags.clone(),
          IsolateState::mock().argv.clone(),
        ),
        "TEST",
        WorkerInit::Script("onmessage = () => close();".into()),
      );
      assert!(worker_result.is_ok());
      let worker = worker_result.unwrap();
      let resource = worker.resource.clone();
      let resource_ = resource.clone();

      tokio::spawn(lazy(move || {
        worker.then(move |r| -> Result<(), ()> {
          resource_.close();
          debug!("workers.rs after resource close");
          if let Err(err) = r {
            panic!("{}", JSErrorColor(&err).to_string());
          }
          Ok(())
        })
      }));

      assert_eq!(
        resources::get_type(resource.rid),
        Some("worker".to_string())
      );

      let msg = json!("hi").to_string().into_boxed_str().into_boxed_bytes();
      let r = resources::post_message_to_worker(resource.rid, msg).wait();
      assert!(r.is_ok());
      println!("rid {:?}", resource.rid);

      // TODO Need a way to get a future for when a resource closes.
      // For now, just sleep for a bit.
      // resource.close();
      thread::sleep(std::time::Duration::from_millis(1000));
      assert_eq!(resources::get_type(resource.rid), None);
    })
  }
}