/* 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 devtools;
use devtools_traits::DevtoolScriptControlMsg;
use dom::abstractworker::WorkerScriptMsg;
use dom::bindings::codegen::Bindings::ServiceWorkerGlobalScopeBinding;
use dom::bindings::codegen::Bindings::ServiceWorkerGlobalScopeBinding::ServiceWorkerGlobalScopeMethods;
use dom::bindings::inheritance::Castable;
use dom::bindings::reflector::DomObject;
use dom::bindings::root::{DomRoot, RootCollection, ThreadLocalStackRoots};
use dom::bindings::str::DOMString;
use dom::event::Event;
use dom::eventtarget::EventTarget;
use dom::extendableevent::ExtendableEvent;
use dom::extendablemessageevent::ExtendableMessageEvent;
use dom::globalscope::GlobalScope;
use dom::workerglobalscope::WorkerGlobalScope;
use dom_struct::dom_struct;
use ipc_channel::ipc::{self, IpcSender, IpcReceiver};
use ipc_channel::router::ROUTER;
use js::jsapi::{JS_SetInterruptCallback, JSAutoCompartment, JSContext};
use js::jsval::UndefinedValue;
use js::rust::Runtime;
use net_traits::{load_whole_resource, IpcSend, CustomResponseMediator};
use net_traits::request::{CredentialsMode, Destination, RequestInit, Type as RequestType};
use script_runtime::{CommonScriptMsg, ScriptChan, new_rt_and_cx};
use script_traits::{TimerEvent, WorkerGlobalScopeInit, ScopeThings, ServiceWorkerMsg, WorkerScriptLoadOrigin};
use servo_config::prefs::PREFS;
use servo_rand::random;
use servo_url::ServoUrl;
use std::sync::mpsc::{Receiver, RecvError, Select, Sender, channel};
use std::thread;
use std::time::Duration;
use style::thread_state::{self, IN_WORKER, SCRIPT};

/// Messages used to control service worker event loop
pub enum ServiceWorkerScriptMsg {
    /// Message common to all workers
    CommonWorker(WorkerScriptMsg),
    // Message to request a custom response by the service worker
    Response(CustomResponseMediator)
}

pub enum MixedMessage {
    FromServiceWorker(ServiceWorkerScriptMsg),
    FromDevtools(DevtoolScriptControlMsg),
    FromTimeoutThread(())
}

#[derive(Clone, JSTraceable)]
pub struct ServiceWorkerChan {
    pub sender: Sender<ServiceWorkerScriptMsg>
}

impl ScriptChan for ServiceWorkerChan {
    fn send(&self, msg: CommonScriptMsg) -> Result<(), ()> {
        self.sender
            .send(ServiceWorkerScriptMsg::CommonWorker(WorkerScriptMsg::Common(msg)))
            .map_err(|_| ())
    }

    fn clone(&self) -> Box<ScriptChan + Send> {
        Box::new(ServiceWorkerChan {
            sender: self.sender.clone(),
        })
    }
}

#[dom_struct]
pub struct ServiceWorkerGlobalScope {
    workerglobalscope: WorkerGlobalScope,
    #[ignore_heap_size_of = "Defined in std"]
    receiver: Receiver<ServiceWorkerScriptMsg>,
    #[ignore_heap_size_of = "Defined in std"]
    own_sender: Sender<ServiceWorkerScriptMsg>,
    #[ignore_heap_size_of = "Defined in std"]
    timer_event_port: Receiver<()>,
    #[ignore_heap_size_of = "Defined in std"]
    swmanager_sender: IpcSender<ServiceWorkerMsg>,
    scope_url: ServoUrl,
}

impl ServiceWorkerGlobalScope {
    fn new_inherited(init: WorkerGlobalScopeInit,
                     worker_url: ServoUrl,
                     from_devtools_receiver: Receiver<DevtoolScriptControlMsg>,
                     runtime: Runtime,
                     own_sender: Sender<ServiceWorkerScriptMsg>,
                     receiver: Receiver<ServiceWorkerScriptMsg>,
                     timer_event_chan: IpcSender<TimerEvent>,
                     timer_event_port: Receiver<()>,
                     swmanager_sender: IpcSender<ServiceWorkerMsg>,
                     scope_url: ServoUrl)
                     -> ServiceWorkerGlobalScope {
        ServiceWorkerGlobalScope {
            workerglobalscope: WorkerGlobalScope::new_inherited(init,
                                                                worker_url,
                                                                runtime,
                                                                from_devtools_receiver,
                                                                timer_event_chan,
                                                                None),
            receiver: receiver,
            timer_event_port: timer_event_port,
            own_sender: own_sender,
            swmanager_sender: swmanager_sender,
            scope_url: scope_url
        }
    }

    #[allow(unsafe_code)]
    pub fn new(init: WorkerGlobalScopeInit,
               worker_url: ServoUrl,
               from_devtools_receiver: Receiver<DevtoolScriptControlMsg>,
               runtime: Runtime,
               own_sender: Sender<ServiceWorkerScriptMsg>,
               receiver: Receiver<ServiceWorkerScriptMsg>,
               timer_event_chan: IpcSender<TimerEvent>,
               timer_event_port: Receiver<()>,
               swmanager_sender: IpcSender<ServiceWorkerMsg>,
               scope_url: ServoUrl)
               -> DomRoot<ServiceWorkerGlobalScope> {
        let cx = runtime.cx();
        let scope = Box::new(ServiceWorkerGlobalScope::new_inherited(
            init,
            worker_url,
            from_devtools_receiver,
            runtime,
            own_sender,
            receiver,
            timer_event_chan,
            timer_event_port,
            swmanager_sender,
            scope_url
        ));
        unsafe {
            ServiceWorkerGlobalScopeBinding::Wrap(cx, scope)
        }
    }

    #[allow(unsafe_code)]
    pub fn run_serviceworker_scope(scope_things: ScopeThings,
                            own_sender: Sender<ServiceWorkerScriptMsg>,
                            receiver: Receiver<ServiceWorkerScriptMsg>,
                            devtools_receiver: IpcReceiver<DevtoolScriptControlMsg>,
                            swmanager_sender: IpcSender<ServiceWorkerMsg>,
                            scope_url: ServoUrl) {
        let ScopeThings { script_url,
                          init,
                          worker_load_origin,
                          .. } = scope_things;

        let serialized_worker_url = script_url.to_string();
        let origin = GlobalScope::current().expect("No current global object").origin().immutable().clone();
        thread::Builder::new().name(format!("ServiceWorker for {}", serialized_worker_url)).spawn(move || {
            thread_state::initialize(SCRIPT | IN_WORKER);
            let roots = RootCollection::new();
            let _stack_roots = ThreadLocalStackRoots::new(&roots);

            let WorkerScriptLoadOrigin { referrer_url, referrer_policy, pipeline_id } = worker_load_origin;

            let request = RequestInit {
                url: script_url.clone(),
                type_: RequestType::Script,
                destination: Destination::ServiceWorker,
                credentials_mode: CredentialsMode::Include,
                use_url_credentials: true,
                pipeline_id: pipeline_id,
                referrer_url: referrer_url,
                referrer_policy: referrer_policy,
                origin,
                .. RequestInit::default()
            };

            let (url, source) = match load_whole_resource(request,
                                                          &init.resource_threads.sender()) {
                Err(_) => {
                    println!("error loading script {}", serialized_worker_url);
                    return;
                }
                Ok((metadata, bytes)) => {
                    (metadata.final_url, String::from_utf8(bytes).unwrap())
                }
            };

            let runtime = unsafe { new_rt_and_cx() };

            let (devtools_mpsc_chan, devtools_mpsc_port) = channel();
            ROUTER.route_ipc_receiver_to_mpsc_sender(devtools_receiver, devtools_mpsc_chan);
            // TODO XXXcreativcoder use this timer_ipc_port, when we have a service worker instance here
            let (timer_ipc_chan, _timer_ipc_port) = ipc::channel().unwrap();
            let (timer_chan, timer_port) = channel();
            let global = ServiceWorkerGlobalScope::new(
                init, url, devtools_mpsc_port, runtime,
                own_sender, receiver,
                timer_ipc_chan, timer_port, swmanager_sender, scope_url);
            let scope = global.upcast::<WorkerGlobalScope>();

            unsafe {
                // Handle interrupt requests
                JS_SetInterruptCallback(scope.runtime(), Some(interrupt_callback));
            }

            scope.execute_script(DOMString::from(source));
            // Service workers are time limited
            thread::Builder::new().name("SWTimeoutThread".to_owned()).spawn(move || {
                let sw_lifetime_timeout = PREFS.get("dom.serviceworker.timeout_seconds").as_u64().unwrap();
                thread::sleep(Duration::new(sw_lifetime_timeout, 0));
                let _ = timer_chan.send(());
            }).expect("Thread spawning failed");

            global.dispatch_activate();
            let reporter_name = format!("service-worker-reporter-{}", random::<u64>());
            scope.upcast::<GlobalScope>().mem_profiler_chan().run_with_memory_reporting(|| {
                // https://html.spec.whatwg.org/multipage/#event-loop-processing-model
                // Step 1
                while let Ok(event) = global.receive_event() {
                    // Step 3
                    if !global.handle_event(event) {
                        break;
                    }
                    // Step 6
                    global.upcast::<GlobalScope>().perform_a_microtask_checkpoint();
                }
            }, reporter_name, scope.script_chan(), CommonScriptMsg::CollectReports);
        }).expect("Thread spawning failed");
    }

    fn handle_event(&self, event: MixedMessage) -> bool {
        match event {
            MixedMessage::FromDevtools(msg) => {
                match msg {
                    DevtoolScriptControlMsg::EvaluateJS(_pipe_id, string, sender) =>
                        devtools::handle_evaluate_js(self.upcast(), string, sender),
                    DevtoolScriptControlMsg::GetCachedMessages(pipe_id, message_types, sender) =>
                        devtools::handle_get_cached_messages(pipe_id, message_types, sender),
                    DevtoolScriptControlMsg::WantsLiveNotifications(_pipe_id, bool_val) =>
                        devtools::handle_wants_live_notifications(self.upcast(), bool_val),
                    _ => debug!("got an unusable devtools control message inside the worker!"),
                }
                true
            }
            MixedMessage::FromServiceWorker(msg) => {
                self.handle_script_event(msg);
                true
            }
            MixedMessage::FromTimeoutThread(_) => {
                let _ = self.swmanager_sender.send(ServiceWorkerMsg::Timeout(self.scope_url.clone()));
                false
            }
        }
    }

    fn handle_script_event(&self, msg: ServiceWorkerScriptMsg) {
        use self::ServiceWorkerScriptMsg::*;

        match msg {
            CommonWorker(WorkerScriptMsg::DOMMessage(data)) => {
                let scope = self.upcast::<WorkerGlobalScope>();
                let target = self.upcast();
                let _ac = JSAutoCompartment::new(scope.get_cx(), scope.reflector().get_jsobject().get());
                rooted!(in(scope.get_cx()) let mut message = UndefinedValue());
                data.read(scope.upcast(), message.handle_mut());
                ExtendableMessageEvent::dispatch_jsval(target, scope.upcast(), message.handle());
            },
            CommonWorker(WorkerScriptMsg::Common(msg)) => {
                self.upcast::<WorkerGlobalScope>().process_event(msg);
            },
            Response(mediator) => {
                // TODO XXXcreativcoder This will eventually use a FetchEvent interface to fire event
                // when we have the Request and Response dom api's implemented
                // https://slightlyoff.github.io/ServiceWorker/spec/service_worker_1/index.html#fetch-event-section
                self.upcast::<EventTarget>().fire_event(atom!("fetch"));
                let _ = mediator.response_chan.send(None);
            }
        }
    }

    #[allow(unsafe_code)]
    fn receive_event(&self) -> Result<MixedMessage, RecvError> {
        let scope = self.upcast::<WorkerGlobalScope>();
        let worker_port = &self.receiver;
        let devtools_port = scope.from_devtools_receiver();
        let timer_event_port = &self.timer_event_port;

        let sel = Select::new();
        let mut worker_handle = sel.handle(worker_port);
        let mut devtools_handle = sel.handle(devtools_port);
        let mut timer_port_handle = sel.handle(timer_event_port);
        unsafe {
            worker_handle.add();
            if scope.from_devtools_sender().is_some() {
                devtools_handle.add();
            }
            timer_port_handle.add();
        }

        let ret = sel.wait();
        if ret == worker_handle.id() {
            Ok(MixedMessage::FromServiceWorker(worker_port.recv()?))
        }else if ret == devtools_handle.id() {
            Ok(MixedMessage::FromDevtools(devtools_port.recv()?))
        } else if ret == timer_port_handle.id() {
            Ok(MixedMessage::FromTimeoutThread(timer_event_port.recv()?))
        } else {
            panic!("unexpected select result!")
        }
    }

    pub fn script_chan(&self) -> Box<ScriptChan + Send> {
        Box::new(ServiceWorkerChan {
            sender: self.own_sender.clone()
        })
    }

    fn dispatch_activate(&self) {
        let event = ExtendableEvent::new(self, atom!("activate"), false, false);
        let event = (&*event).upcast::<Event>();
        self.upcast::<EventTarget>().dispatch_event(event);
    }
}

#[allow(unsafe_code)]
unsafe extern "C" fn interrupt_callback(cx: *mut JSContext) -> bool {
    let worker =
        DomRoot::downcast::<WorkerGlobalScope>(GlobalScope::from_context(cx))
            .expect("global is not a worker scope");
    assert!(worker.is::<ServiceWorkerGlobalScope>());

    // A false response causes the script to terminate
    !worker.is_closing()
}

impl ServiceWorkerGlobalScopeMethods for ServiceWorkerGlobalScope {
    // https://w3c.github.io/ServiceWorker/#service-worker-global-scope-onmessage-attribute
    event_handler!(message, GetOnmessage, SetOnmessage);
}