/* 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 https://mozilla.org/MPL/2.0/. */

use crate::dom::bindings::cell::DomRefCell;
use crate::dom::bindings::codegen::Bindings::RTCIceCandidateBinding::RTCIceCandidateInit;
use crate::dom::bindings::codegen::Bindings::RTCPeerConnectionBinding;
use crate::dom::bindings::codegen::Bindings::RTCPeerConnectionBinding::RTCPeerConnectionMethods;
use crate::dom::bindings::codegen::Bindings::RTCPeerConnectionBinding::{
    RTCAnswerOptions, RTCBundlePolicy, RTCConfiguration, RTCOfferOptions,
};
use crate::dom::bindings::codegen::Bindings::RTCSessionDescriptionBinding::{
    RTCSdpType, RTCSessionDescriptionInit,
};
use crate::dom::bindings::codegen::UnionTypes::StringOrStringSequence;
use crate::dom::bindings::error::Error;
use crate::dom::bindings::error::Fallible;
use crate::dom::bindings::inheritance::Castable;
use crate::dom::bindings::refcounted::{Trusted, TrustedPromise};
use crate::dom::bindings::reflector::reflect_dom_object;
use crate::dom::bindings::reflector::DomObject;
use crate::dom::bindings::root::{DomRoot, MutNullableDom};
use crate::dom::event::{Event, EventBubbles, EventCancelable};
use crate::dom::eventtarget::EventTarget;
use crate::dom::globalscope::GlobalScope;
use crate::dom::mediastream::MediaStream;
use crate::dom::promise::Promise;
use crate::dom::rtcicecandidate::RTCIceCandidate;
use crate::dom::rtcpeerconnectioniceevent::RTCPeerConnectionIceEvent;
use crate::dom::rtcsessiondescription::RTCSessionDescription;
use crate::dom::window::Window;
use crate::task::TaskCanceller;
use crate::task_source::networking::NetworkingTaskSource;
use crate::task_source::TaskSource;
use dom_struct::dom_struct;

use servo_media::streams::MediaStream as BackendMediaStream;
use servo_media::webrtc::{
    BundlePolicy, IceCandidate, SdpType, SessionDescription, WebRtcController, WebRtcSignaller,
};
use servo_media::ServoMedia;

use std::cell::Cell;
use std::rc::Rc;

#[dom_struct]
pub struct RTCPeerConnection {
    eventtarget: EventTarget,
    #[ignore_malloc_size_of = "defined in servo-media"]
    controller: DomRefCell<Option<WebRtcController>>,
    closed: Cell<bool>,
    /// Helps track state changes between the time createOffer/createAnswer
    /// is called and resolved
    offer_answer_generation: Cell<u32>,
    #[ignore_malloc_size_of = "promises are hard"]
    offer_promises: DomRefCell<Vec<Rc<Promise>>>,
    #[ignore_malloc_size_of = "promises are hard"]
    answer_promises: DomRefCell<Vec<Rc<Promise>>>,
    local_description: MutNullableDom<RTCSessionDescription>,
    remote_description: MutNullableDom<RTCSessionDescription>,
}

struct RTCSignaller {
    trusted: Trusted<RTCPeerConnection>,
    task_source: NetworkingTaskSource,
    canceller: TaskCanceller,
}

impl WebRtcSignaller for RTCSignaller {
    fn on_ice_candidate(&self, _: &WebRtcController, candidate: IceCandidate) {
        let this = self.trusted.clone();
        let _ = self.task_source.queue_with_canceller(
            task!(on_ice_candidate: move || {
                let this = this.root();
                this.on_ice_candidate(candidate);
            }),
            &self.canceller,
        );
    }

    fn on_negotiation_needed(&self, _: &WebRtcController) {
        let this = self.trusted.clone();
        let _ = self.task_source.queue_with_canceller(
            task!(on_negotiation_needed: move || {
                let this = this.root();
                this.on_negotiation_needed();
            }),
            &self.canceller,
        );
    }

    fn on_add_stream(&self, _: Box<BackendMediaStream>) {}

    fn close(&self) {
        // do nothing
    }
}

impl RTCPeerConnection {
    pub fn new_inherited() -> RTCPeerConnection {
        RTCPeerConnection {
            eventtarget: EventTarget::new_inherited(),
            controller: DomRefCell::new(None),
            closed: Cell::new(false),
            offer_answer_generation: Cell::new(0),
            offer_promises: DomRefCell::new(vec![]),
            answer_promises: DomRefCell::new(vec![]),
            local_description: Default::default(),
            remote_description: Default::default(),
        }
    }

    pub fn new(global: &GlobalScope, config: &RTCConfiguration) -> DomRoot<RTCPeerConnection> {
        let this = reflect_dom_object(
            Box::new(RTCPeerConnection::new_inherited()),
            global,
            RTCPeerConnectionBinding::Wrap,
        );
        let signaller = this.make_signaller();
        *this.controller.borrow_mut() = Some(ServoMedia::get().unwrap().create_webrtc(signaller));
        if let Some(ref servers) = config.iceServers {
            if let Some(ref server) = servers.get(0) {
                let server = match server.urls {
                    StringOrStringSequence::String(ref s) => Some(s.clone()),
                    StringOrStringSequence::StringSequence(ref s) => s.get(0).cloned(),
                };
                if let Some(server) = server {
                    let policy = match config.bundlePolicy {
                        RTCBundlePolicy::Balanced => BundlePolicy::Balanced,
                        RTCBundlePolicy::Max_compat => BundlePolicy::MaxCompat,
                        RTCBundlePolicy::Max_bundle => BundlePolicy::MaxBundle,
                    };
                    this.controller
                        .borrow()
                        .as_ref()
                        .unwrap()
                        .configure(server.to_string(), policy);
                }
            }
        }
        this
    }

    pub fn Constructor(
        window: &Window,
        config: &RTCConfiguration,
    ) -> Fallible<DomRoot<RTCPeerConnection>> {
        Ok(RTCPeerConnection::new(&window.global(), config))
    }

    fn make_signaller(&self) -> Box<WebRtcSignaller> {
        let trusted = Trusted::new(self);
        let (task_source, canceller) = self
            .global()
            .as_window()
            .task_manager()
            .networking_task_source_with_canceller();
        Box::new(RTCSignaller {
            trusted,
            task_source,
            canceller,
        })
    }

    fn on_ice_candidate(&self, candidate: IceCandidate) {
        if self.closed.get() {
            return;
        }
        let candidate = RTCIceCandidate::new(
            &self.global(),
            candidate.candidate.into(),
            None,
            Some(candidate.sdp_mline_index as u16),
            None,
        );
        let event = RTCPeerConnectionIceEvent::new(
            &self.global(),
            atom!("icecandidate"),
            Some(&candidate),
            None,
            true,
        );
        event.upcast::<Event>().fire(self.upcast());
    }

    fn on_negotiation_needed(&self) {
        if self.closed.get() {
            return;
        }
        let event = Event::new(
            &self.global(),
            atom!("negotiationneeded"),
            EventBubbles::DoesNotBubble,
            EventCancelable::NotCancelable,
        );
        event.upcast::<Event>().fire(self.upcast());
    }

    fn create_offer(&self) {
        let generation = self.offer_answer_generation.get();
        let (task_source, canceller) = self
            .global()
            .as_window()
            .task_manager()
            .networking_task_source_with_canceller();
        let this = Trusted::new(self);
        self.controller.borrow_mut().as_ref().unwrap().create_offer(
            (move |desc: SessionDescription| {
                let _ = task_source.queue_with_canceller(
                    task!(offer_created: move || {
                        let this = this.root();
                        if this.offer_answer_generation.get() != generation {
                            // the state has changed since we last created the offer,
                            // create a fresh one
                            this.create_offer();
                        } else {
                            let init: RTCSessionDescriptionInit = desc.into();
                            for promise in this.offer_promises.borrow_mut().drain(..) {
                                promise.resolve_native(&init);
                            }
                        }
                    }),
                    &canceller,
                );
            })
            .into(),
        );
    }

    fn create_answer(&self) {
        let generation = self.offer_answer_generation.get();
        let (task_source, canceller) = self
            .global()
            .as_window()
            .task_manager()
            .networking_task_source_with_canceller();
        let this = Trusted::new(self);
        self.controller
            .borrow_mut()
            .as_ref()
            .unwrap()
            .create_answer(
                (move |desc: SessionDescription| {
                    let _ = task_source.queue_with_canceller(
                        task!(answer_created: move || {
                            let this = this.root();
                            if this.offer_answer_generation.get() != generation {
                                // the state has changed since we last created the offer,
                                // create a fresh one
                                this.create_answer();
                            } else {
                                let init: RTCSessionDescriptionInit = desc.into();
                                for promise in this.answer_promises.borrow_mut().drain(..) {
                                    promise.resolve_native(&init);
                                }
                            }
                        }),
                        &canceller,
                    );
                })
                .into(),
            );
    }
}

impl RTCPeerConnectionMethods for RTCPeerConnection {
    /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-icecandidate
    event_handler!(icecandidate, GetOnicecandidate, SetOnicecandidate);

    /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-onnegotiationneeded
    event_handler!(
        negotiationneeded,
        GetOnnegotiationneeded,
        SetOnnegotiationneeded
    );

    /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-addicecandidate
    fn AddIceCandidate(&self, candidate: &RTCIceCandidateInit) -> Rc<Promise> {
        let p = Promise::new(&self.global());
        if candidate.sdpMid.is_none() && candidate.sdpMLineIndex.is_none() {
            p.reject_error(Error::Type(format!(
                "one of sdpMid and sdpMLineIndex must be set"
            )));
            return p;
        }

        // XXXManishearth add support for sdpMid
        if candidate.sdpMLineIndex.is_none() {
            p.reject_error(Error::Type(format!(
                "servo only supports sdpMLineIndex right now"
            )));
            return p;
        }

        // XXXManishearth this should be enqueued
        // https://w3c.github.io/webrtc-pc/#enqueue-an-operation

        self.controller
            .borrow_mut()
            .as_ref()
            .unwrap()
            .add_ice_candidate(IceCandidate {
                sdp_mline_index: candidate.sdpMLineIndex.unwrap() as u32,
                candidate: candidate.candidate.to_string(),
            });

        // XXXManishearth add_ice_candidate should have a callback
        p.resolve_native(&());
        p
    }

    /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-createoffer
    fn CreateOffer(&self, _options: &RTCOfferOptions) -> Rc<Promise> {
        let p = Promise::new(&self.global());
        if self.closed.get() {
            p.reject_error(Error::InvalidState);
            return p;
        }
        self.offer_promises.borrow_mut().push(p.clone());
        self.create_offer();
        p
    }

    /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-createoffer
    fn CreateAnswer(&self, _options: &RTCAnswerOptions) -> Rc<Promise> {
        let p = Promise::new(&self.global());
        if self.closed.get() {
            p.reject_error(Error::InvalidState);
            return p;
        }
        self.answer_promises.borrow_mut().push(p.clone());
        self.create_answer();
        p
    }

    /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-localdescription
    fn GetLocalDescription(&self) -> Option<DomRoot<RTCSessionDescription>> {
        self.local_description.get()
    }

    /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-remotedescription
    fn GetRemoteDescription(&self) -> Option<DomRoot<RTCSessionDescription>> {
        self.remote_description.get()
    }

    /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-setlocaldescription
    fn SetLocalDescription(&self, desc: &RTCSessionDescriptionInit) -> Rc<Promise> {
        // XXXManishearth validate the current state
        let p = Promise::new(&self.global());
        let this = Trusted::new(self);
        let desc: SessionDescription = desc.into();
        let trusted_promise = TrustedPromise::new(p.clone());
        let (task_source, canceller) = self
            .global()
            .as_window()
            .task_manager()
            .networking_task_source_with_canceller();
        self.controller
            .borrow_mut()
            .as_ref()
            .unwrap()
            .set_local_description(desc.clone(), (move || {
                    let _ = task_source.queue_with_canceller(
                        task!(local_description_set: move || {
                            // XXXManishearth spec actually asks for an intricate
                            // dance between pending/current local/remote descriptions
                            let this = this.root();
                            let desc = desc.into();
                            let desc = RTCSessionDescription::Constructor(&this.global().as_window(), &desc).unwrap();
                            this.local_description.set(Some(&desc));
                            trusted_promise.root().resolve_native(&())
                        }),
                        &canceller,
                    );
            }).into());
        p
    }

    /// https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection-setremotedescription
    fn SetRemoteDescription(&self, desc: &RTCSessionDescriptionInit) -> Rc<Promise> {
        // XXXManishearth validate the current state
        let p = Promise::new(&self.global());
        let this = Trusted::new(self);
        let desc: SessionDescription = desc.into();
        let trusted_promise = TrustedPromise::new(p.clone());
        let (task_source, canceller) = self
            .global()
            .as_window()
            .task_manager()
            .networking_task_source_with_canceller();
        self.controller
            .borrow_mut()
            .as_ref()
            .unwrap()
            .set_remote_description(desc.clone(), (move || {
                    let _ = task_source.queue_with_canceller(
                        task!(remote_description_set: move || {
                            // XXXManishearth spec actually asks for an intricate
                            // dance between pending/current local/remote descriptions
                            let this = this.root();
                            let desc = desc.into();
                            let desc = RTCSessionDescription::Constructor(&this.global().as_window(), &desc).unwrap();
                            this.remote_description.set(Some(&desc));
                            trusted_promise.root().resolve_native(&())
                        }),
                        &canceller,
                    );
            }).into());
        p
    }

    // https://w3c.github.io/webrtc-pc/#legacy-interface-extensions
    fn AddStream(&self, stream: &MediaStream) {
        let mut tracks = stream.get_tracks();

        for track in tracks.drain(..) {
            self.controller.borrow().as_ref().unwrap().add_stream(track);
        }
    }
}

impl From<SessionDescription> for RTCSessionDescriptionInit {
    fn from(desc: SessionDescription) -> Self {
        let type_ = match desc.type_ {
            SdpType::Answer => RTCSdpType::Answer,
            SdpType::Offer => RTCSdpType::Offer,
            SdpType::Pranswer => RTCSdpType::Pranswer,
            SdpType::Rollback => RTCSdpType::Rollback,
        };
        RTCSessionDescriptionInit {
            type_,
            sdp: desc.sdp.into(),
        }
    }
}

impl<'a> From<&'a RTCSessionDescriptionInit> for SessionDescription {
    fn from(desc: &'a RTCSessionDescriptionInit) -> Self {
        let type_ = match desc.type_ {
            RTCSdpType::Answer => SdpType::Answer,
            RTCSdpType::Offer => SdpType::Offer,
            RTCSdpType::Pranswer => SdpType::Pranswer,
            RTCSdpType::Rollback => SdpType::Rollback,
        };
        SessionDescription {
            type_,
            sdp: desc.sdp.to_string(),
        }
    }
}