/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use dom::bindings::cell::DomRefCell;
use dom::bindings::codegen::Bindings::BlobBinding::BlobMethods;
use dom::bindings::codegen::Bindings::WebSocketBinding;
use dom::bindings::codegen::Bindings::WebSocketBinding::{BinaryType, WebSocketMethods};
use dom::bindings::codegen::UnionTypes::StringOrStringSequence;
use dom::bindings::conversions::ToJSValConvertible;
use dom::bindings::error::{Error, ErrorResult, Fallible};
use dom::bindings::inheritance::Castable;
use dom::bindings::refcounted::Trusted;
use dom::bindings::reflector::{DomObject, reflect_dom_object};
use dom::bindings::root::DomRoot;
use dom::bindings::str::{DOMString, USVString, is_token};
use dom::blob::{Blob, BlobImpl};
use dom::closeevent::CloseEvent;
use dom::event::{Event, EventBubbles, EventCancelable};
use dom::eventtarget::EventTarget;
use dom::globalscope::GlobalScope;
use dom::messageevent::MessageEvent;
use dom_struct::dom_struct;
use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
use js::jsapi::{JSAutoCompartment, JSObject};
use js::jsval::UndefinedValue;
use js::typedarray::{ArrayBuffer, CreateWith};
use net_traits::{CoreResourceMsg, FetchChannels};
use net_traits::{WebSocketDomAction, WebSocketNetworkEvent};
use net_traits::MessageData;
use net_traits::request::{RequestInit, RequestMode};
use script_runtime::CommonScriptMsg;
use script_runtime::ScriptThreadEventCategory::WebSocketEvent;
use servo_url::ServoUrl;
use std::borrow::ToOwned;
use std::cell::Cell;
use std::ptr;
use std::thread;
use task::{TaskOnce, TaskCanceller};
use task_source::TaskSource;
use task_source::networking::NetworkingTaskSource;

#[derive(Clone, Copy, Debug, JSTraceable, MallocSizeOf, PartialEq)]
enum WebSocketRequestState {
    Connecting = 0,
    Open = 1,
    Closing = 2,
    Closed = 3,
}

// Close codes defined in https://tools.ietf.org/html/rfc6455#section-7.4.1
// Names are from https://github.com/mozilla/gecko-dev/blob/master/netwerk/protocol/websocket/nsIWebSocketChannel.idl
#[allow(dead_code)]
mod close_code {
    pub const NORMAL: u16 = 1000;
    pub const GOING_AWAY: u16 = 1001;
    pub const PROTOCOL_ERROR: u16 = 1002;
    pub const UNSUPPORTED_DATATYPE: u16 = 1003;
    pub const NO_STATUS: u16 = 1005;
    pub const ABNORMAL: u16 = 1006;
    pub const INVALID_PAYLOAD: u16 = 1007;
    pub const POLICY_VIOLATION: u16 = 1008;
    pub const TOO_LARGE: u16 = 1009;
    pub const EXTENSION_MISSING: u16 = 1010;
    pub const INTERNAL_ERROR: u16 = 1011;
    pub const TLS_FAILED: u16 = 1015;
}

pub fn close_the_websocket_connection(
    address: Trusted<WebSocket>,
    task_source: &NetworkingTaskSource,
    canceller: &TaskCanceller,
    code: Option<u16>,
    reason: String,
) {
    let close_task = CloseTask {
        address: address,
        failed: false,
        code: code,
        reason: Some(reason),
    };
    task_source.queue_with_canceller(close_task, &canceller).unwrap();
}

pub fn fail_the_websocket_connection(
    address: Trusted<WebSocket>,
    task_source: &NetworkingTaskSource,
    canceller: &TaskCanceller,
) {
    let close_task = CloseTask {
        address: address,
        failed: true,
        code: Some(close_code::ABNORMAL),
        reason: None,
    };
    task_source.queue_with_canceller(close_task, &canceller).unwrap();
}

#[dom_struct]
pub struct WebSocket {
    eventtarget: EventTarget,
    url: ServoUrl,
    ready_state: Cell<WebSocketRequestState>,
    buffered_amount: Cell<u64>,
    clearing_buffer: Cell<bool>, //Flag to tell if there is a running thread to clear buffered_amount
    #[ignore_malloc_size_of = "Defined in std"]
    sender: DomRefCell<Option<IpcSender<WebSocketDomAction>>>,
    binary_type: Cell<BinaryType>,
    protocol: DomRefCell<String>, //Subprotocol selected by server
}

impl WebSocket {
    fn new_inherited(url: ServoUrl) -> WebSocket {
        WebSocket {
            eventtarget: EventTarget::new_inherited(),
            url: url,
            ready_state: Cell::new(WebSocketRequestState::Connecting),
            buffered_amount: Cell::new(0),
            clearing_buffer: Cell::new(false),
            sender: DomRefCell::new(None),
            binary_type: Cell::new(BinaryType::Blob),
            protocol: DomRefCell::new("".to_owned()),
        }
    }

    fn new(global: &GlobalScope, url: ServoUrl) -> DomRoot<WebSocket> {
        reflect_dom_object(Box::new(WebSocket::new_inherited(url)),
                           global, WebSocketBinding::Wrap)
    }

    /// <https://html.spec.whatwg.org/multipage/#dom-websocket>
    pub fn Constructor(global: &GlobalScope,
                       url: DOMString,
                       protocols: Option<StringOrStringSequence>)
                       -> Fallible<DomRoot<WebSocket>> {
        // Steps 1-2.
        let url_record = ServoUrl::parse(&url).or(Err(Error::Syntax))?;

        // Step 3.
        match url_record.scheme() {
            "ws" | "wss" => {},
            _ => return Err(Error::Syntax),
        }

        // Step 4.
        if url_record.fragment().is_some() {
            return Err(Error::Syntax);
        }

        // Step 5.
        let protocols = protocols.map_or(vec![], |p| {
            match p {
                StringOrStringSequence::String(string) => vec![string.into()],
                StringOrStringSequence::StringSequence(seq) => {
                    seq.into_iter().map(String::from).collect()
                },
            }
        });

        // Step 6.
        for (i, protocol) in protocols.iter().enumerate() {
            // https://tools.ietf.org/html/rfc6455#section-4.1
            // Handshake requirements, step 10

            if protocols[i + 1..].iter().any(|p| p.eq_ignore_ascii_case(protocol)) {
                return Err(Error::Syntax);
            }

            // https://tools.ietf.org/html/rfc6455#section-4.1
            if !is_token(protocol.as_bytes()) {
                return Err(Error::Syntax);
            }
        }

        let ws = WebSocket::new(global, url_record.clone());
        let address = Trusted::new(&*ws);

        // Create the interface for communication with the resource thread
        let (dom_action_sender, resource_action_receiver):
                (IpcSender<WebSocketDomAction>,
                IpcReceiver<WebSocketDomAction>) = ipc::channel().unwrap();
        let (resource_event_sender, dom_event_receiver):
                (IpcSender<WebSocketNetworkEvent>,
                IpcReceiver<WebSocketNetworkEvent>) = ipc::channel().unwrap();

        // Step 8.
        let request = RequestInit {
            url: url_record,
            origin: global.origin().immutable().clone(),
            mode: RequestMode::WebSocket { protocols },
            ..RequestInit::default()
        };
        let channels = FetchChannels::WebSocket {
            event_sender: resource_event_sender,
            action_receiver: resource_action_receiver,
        };
        let _ = global.core_resource_thread().send(CoreResourceMsg::Fetch(request, channels));

        *ws.sender.borrow_mut() = Some(dom_action_sender);

        let task_source = global.networking_task_source();
        let canceller = global.task_canceller();
        thread::spawn(move || {
            while let Ok(event) = dom_event_receiver.recv() {
                match event {
                    WebSocketNetworkEvent::ConnectionEstablished { protocol_in_use } => {
                        let open_thread = ConnectionEstablishedTask {
                            address: address.clone(),
                            protocol_in_use,
                        };
                        task_source.queue_with_canceller(open_thread, &canceller).unwrap();
                    },
                    WebSocketNetworkEvent::MessageReceived(message) => {
                        let message_thread = MessageReceivedTask {
                            address: address.clone(),
                            message: message,
                        };
                        task_source.queue_with_canceller(message_thread, &canceller).unwrap();
                    },
                    WebSocketNetworkEvent::Fail => {
                        fail_the_websocket_connection(address.clone(),
                            &task_source, &canceller);
                    },
                    WebSocketNetworkEvent::Close(code, reason) => {
                        close_the_websocket_connection(address.clone(),
                            &task_source, &canceller, code, reason);
                    },
                }
            }
        });

        // Step 7.
        Ok(ws)
    }

    // https://html.spec.whatwg.org/multipage/#dom-websocket-send
    fn send_impl(&self, data_byte_len: u64) -> Fallible<bool> {
        let return_after_buffer = match self.ready_state.get() {
            WebSocketRequestState::Connecting => {
                return Err(Error::InvalidState);
            },
            WebSocketRequestState::Open => false,
            WebSocketRequestState::Closing | WebSocketRequestState::Closed => true,
        };

        let address = Trusted::new(self);

        match data_byte_len.checked_add(self.buffered_amount.get()) {
            None => panic!(),
            Some(new_amount) => self.buffered_amount.set(new_amount)
        };

        if return_after_buffer {
            return Ok(false);
        }

        if !self.clearing_buffer.get() && self.ready_state.get() == WebSocketRequestState::Open {
            self.clearing_buffer.set(true);

            let task = Box::new(BufferedAmountTask {
                address: address,
            });

            let pipeline_id = self.global().pipeline_id();
            self.global()
                .script_chan()
                .send(CommonScriptMsg::Task(WebSocketEvent, task, Some(pipeline_id)))
                .unwrap();
        }

        Ok(true)
    }
}

impl WebSocketMethods for WebSocket {
    // https://html.spec.whatwg.org/multipage/#handler-websocket-onopen
    event_handler!(open, GetOnopen, SetOnopen);

    // https://html.spec.whatwg.org/multipage/#handler-websocket-onclose
    event_handler!(close, GetOnclose, SetOnclose);

    // https://html.spec.whatwg.org/multipage/#handler-websocket-onerror
    event_handler!(error, GetOnerror, SetOnerror);

    // https://html.spec.whatwg.org/multipage/#handler-websocket-onmessage
    event_handler!(message, GetOnmessage, SetOnmessage);

    // https://html.spec.whatwg.org/multipage/#dom-websocket-url
    fn Url(&self) -> DOMString {
        DOMString::from(self.url.as_str())
    }

    // https://html.spec.whatwg.org/multipage/#dom-websocket-readystate
    fn ReadyState(&self) -> u16 {
        self.ready_state.get() as u16
    }

    // https://html.spec.whatwg.org/multipage/#dom-websocket-bufferedamount
    fn BufferedAmount(&self) -> u64 {
        self.buffered_amount.get()
    }

    // https://html.spec.whatwg.org/multipage/#dom-websocket-binarytype
    fn BinaryType(&self) -> BinaryType {
        self.binary_type.get()
    }

    // https://html.spec.whatwg.org/multipage/#dom-websocket-binarytype
    fn SetBinaryType(&self, btype: BinaryType) {
        self.binary_type.set(btype)
    }

    // https://html.spec.whatwg.org/multipage/#dom-websocket-protocol
    fn Protocol(&self) -> DOMString {
         DOMString::from(self.protocol.borrow().clone())
    }

    // https://html.spec.whatwg.org/multipage/#dom-websocket-send
    fn Send(&self, data: USVString) -> ErrorResult {
        let data_byte_len = data.0.as_bytes().len() as u64;
        let send_data = self.send_impl(data_byte_len)?;

        if send_data {
            let mut other_sender = self.sender.borrow_mut();
            let my_sender = other_sender.as_mut().unwrap();
            let _ = my_sender.send(WebSocketDomAction::SendMessage(MessageData::Text(data.0)));
        }

        Ok(())
    }

    // https://html.spec.whatwg.org/multipage/#dom-websocket-send
    fn Send_(&self, blob: &Blob) -> ErrorResult {
        /* As per https://html.spec.whatwg.org/multipage/#websocket
           the buffered amount needs to be clamped to u32, even though Blob.Size() is u64
           If the buffer limit is reached in the first place, there are likely other major problems
        */
        let data_byte_len = blob.Size();
        let send_data = self.send_impl(data_byte_len)?;

        if send_data {
            let mut other_sender = self.sender.borrow_mut();
            let my_sender = other_sender.as_mut().unwrap();
            let bytes = blob.get_bytes().unwrap_or(vec![]);
            let _ = my_sender.send(WebSocketDomAction::SendMessage(MessageData::Binary(bytes)));
        }

        Ok(())
    }

    // https://html.spec.whatwg.org/multipage/#dom-websocket-close
    fn Close(&self, code: Option<u16>, reason: Option<USVString>) -> ErrorResult {
        if let Some(code) = code {
            //Fail if the supplied code isn't normal and isn't reserved for libraries, frameworks, and applications
            if code != close_code::NORMAL && (code < 3000 || code > 4999) {
                return Err(Error::InvalidAccess);
            }
        }
        if let Some(ref reason) = reason {
            if reason.0.as_bytes().len() > 123 { //reason cannot be larger than 123 bytes
                return Err(Error::Syntax);
            }
        }

        match self.ready_state.get() {
            WebSocketRequestState::Closing | WebSocketRequestState::Closed  => {} //Do nothing
            WebSocketRequestState::Connecting => { //Connection is not yet established
                /*By setting the state to closing, the open function
                  will abort connecting the websocket*/
                self.ready_state.set(WebSocketRequestState::Closing);

                let address = Trusted::new(self);
                let task_source = self.global().networking_task_source();
                fail_the_websocket_connection(address, &task_source, &self.global().task_canceller());
            }
            WebSocketRequestState::Open => {
                self.ready_state.set(WebSocketRequestState::Closing);

                // Kick off _Start the WebSocket Closing Handshake_
                // https://tools.ietf.org/html/rfc6455#section-7.1.2
                let reason = reason.map(|reason| reason.0);
                let mut other_sender = self.sender.borrow_mut();
                let my_sender = other_sender.as_mut().unwrap();
                let _ = my_sender.send(WebSocketDomAction::Close(code, reason));
            }
        }
        Ok(()) //Return Ok
    }
}


/// Task queued when *the WebSocket connection is established*.
/// <https://html.spec.whatwg.org/multipage/#feedback-from-the-protocol:concept-websocket-established>
struct ConnectionEstablishedTask {
    address: Trusted<WebSocket>,
    protocol_in_use: Option<String>,
}

impl TaskOnce for ConnectionEstablishedTask {
    /// <https://html.spec.whatwg.org/multipage/#feedback-from-the-protocol:concept-websocket-established>
    fn run_once(self) {
        let ws = self.address.root();

        // Step 1.
        ws.ready_state.set(WebSocketRequestState::Open);

        // Step 2: Extensions.
        // TODO: Set extensions to extensions in use.

        // Step 3.
        if let Some(protocol_name) = self.protocol_in_use {
            *ws.protocol.borrow_mut() = protocol_name;
        };

        // Step 4.
        ws.upcast().fire_event(atom!("open"));
    }
}

struct BufferedAmountTask {
    address: Trusted<WebSocket>,
}

impl TaskOnce for BufferedAmountTask {
    // See https://html.spec.whatwg.org/multipage/#dom-websocket-bufferedamount
    //
    // To be compliant with standards, we need to reset bufferedAmount only when the event loop
    // reaches step 1.  In our implementation, the bytes will already have been sent on a background
    // thread.
    fn run_once(self) {
        let ws = self.address.root();

        ws.buffered_amount.set(0);
        ws.clearing_buffer.set(false);
    }
}

struct CloseTask {
    address: Trusted<WebSocket>,
    failed: bool,
    code: Option<u16>,
    reason: Option<String>,
}

impl TaskOnce for CloseTask {
    fn run_once(self) {
        let ws = self.address.root();

        if ws.ready_state.get() == WebSocketRequestState::Closed {
            // Do nothing if already closed.
            return;
        }

        // Perform _the WebSocket connection is closed_ steps.
        // https://html.spec.whatwg.org/multipage/#closeWebSocket

        // Step 1.
        ws.ready_state.set(WebSocketRequestState::Closed);

        // Step 2.
        if self.failed {
            ws.upcast().fire_event(atom!("error"));
        }

        // Step 3.
        let clean_close = !self.failed;
        let code = self.code.unwrap_or(close_code::NO_STATUS);
        let reason = DOMString::from(self.reason.unwrap_or("".to_owned()));
        let close_event = CloseEvent::new(&ws.global(),
                                          atom!("close"),
                                          EventBubbles::DoesNotBubble,
                                          EventCancelable::NotCancelable,
                                          clean_close,
                                          code,
                                          reason);
        close_event.upcast::<Event>().fire(ws.upcast());
    }
}

struct MessageReceivedTask {
    address: Trusted<WebSocket>,
    message: MessageData,
}

impl TaskOnce for MessageReceivedTask {
    #[allow(unsafe_code)]
    fn run_once(self) {
        let ws = self.address.root();
        debug!("MessageReceivedTask::handler({:p}): readyState={:?}", &*ws,
               ws.ready_state.get());

        // Step 1.
        if ws.ready_state.get() != WebSocketRequestState::Open {
            return;
        }

        // Step 2-5.
        let global = ws.global();
        // global.get_cx() returns a valid `JSContext` pointer, so this is safe.
        unsafe {
            let cx = global.get_cx();
            let _ac = JSAutoCompartment::new(cx, ws.reflector().get_jsobject().get());
            rooted!(in(cx) let mut message = UndefinedValue());
            match self.message {
                MessageData::Text(text) => text.to_jsval(cx, message.handle_mut()),
                MessageData::Binary(data) => {
                    match ws.binary_type.get() {
                        BinaryType::Blob => {
                            let blob = Blob::new(&global, BlobImpl::new_from_bytes(data), "".to_owned());
                            blob.to_jsval(cx, message.handle_mut());
                        }
                        BinaryType::Arraybuffer => {
                            rooted!(in(cx) let mut array_buffer = ptr::null_mut::<JSObject>());
                            assert!(ArrayBuffer::create(cx,
                                                        CreateWith::Slice(&data),
                                                        array_buffer.handle_mut())
                                    .is_ok());

                            (*array_buffer).to_jsval(cx, message.handle_mut());
                        }

                    }
                },
            }
            MessageEvent::dispatch_jsval(ws.upcast(), &global, message.handle());
        }
    }
}