/* 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::conversions::{ToJSValConvertible, root_from_handleobject};
use dom::bindings::inheritance::Castable;
use dom::bindings::js::{JS, MutNullableHeap, Root, RootedReference};
use dom::bindings::proxyhandler::{fill_property_descriptor, get_property_descriptor};
use dom::bindings::reflector::{Reflectable, MutReflectable, Reflector};
use dom::bindings::trace::JSTraceable;
use dom::bindings::utils::WindowProxyHandler;
use dom::bindings::utils::get_array_index_from_id;
use dom::document::Document;
use dom::element::Element;
use dom::globalscope::GlobalScope;
use dom::window::Window;
use js::JSCLASS_IS_GLOBAL;
use js::glue::{CreateWrapperProxyHandler, ProxyTraps, NewWindowProxy};
use js::glue::{GetProxyPrivate, SetProxyExtra, GetProxyExtra};
use js::jsapi::{Handle, HandleId, HandleObject, HandleValue};
use js::jsapi::{JSAutoCompartment, JSContext, JSErrNum, JSFreeOp, JSObject};
use js::jsapi::{JSPROP_READONLY, JSTracer, JS_DefinePropertyById};
use js::jsapi::{JS_ForwardGetPropertyTo, JS_ForwardSetPropertyTo};
use js::jsapi::{JS_GetOwnPropertyDescriptorById, JS_HasPropertyById};
use js::jsapi::{MutableHandle, MutableHandleObject, MutableHandleValue};
use js::jsapi::{ObjectOpResult, PropertyDescriptor};
use js::jsval::{UndefinedValue, PrivateValue};
use js::rust::get_object_class;
use msg::constellation_msg::PipelineId;
use std::cell::Cell;

#[dom_struct]
// NOTE: the browsing context for a window is managed in two places:
// here, in script, but also in the constellation. The constellation
// manages the session history, which in script is accessed through
// History objects, messaging the constellation.
pub struct BrowsingContext {
    reflector: Reflector,

    /// Indicates if reflow is required when reloading.
    needs_reflow: Cell<bool>,

    /// The current active document.
    /// Note that the session history is stored in the constellation,
    /// in the script thread we just track the current active document.
    active_document: MutNullableHeap<JS<Document>>,

    /// The containing iframe element, if this is a same-origin iframe
    frame_element: Option<JS<Element>>,
}

impl BrowsingContext {
    pub fn new_inherited(frame_element: Option<&Element>) -> BrowsingContext {
        BrowsingContext {
            reflector: Reflector::new(),
            needs_reflow: Cell::new(true),
            active_document: Default::default(),
            frame_element: frame_element.map(JS::from_ref),
        }
    }

    #[allow(unsafe_code)]
    pub fn new(window: &Window, frame_element: Option<&Element>) -> Root<BrowsingContext> {
        unsafe {
            let WindowProxyHandler(handler) = window.windowproxy_handler();
            assert!(!handler.is_null());

            let cx = window.get_cx();
            let parent = window.reflector().get_jsobject();
            assert!(!parent.get().is_null());
            assert!(((*get_object_class(parent.get())).flags & JSCLASS_IS_GLOBAL) != 0);
            let _ac = JSAutoCompartment::new(cx, parent.get());
            rooted!(in(cx) let window_proxy = NewWindowProxy(cx, parent, handler));
            assert!(!window_proxy.is_null());

            let object = box BrowsingContext::new_inherited(frame_element);

            let raw = Box::into_raw(object);
            SetProxyExtra(window_proxy.get(), 0, &PrivateValue(raw as *const _));

            (*raw).init_reflector(window_proxy.get());

            Root::from_ref(&*raw)
        }
    }

    pub fn set_active_document(&self, document: &Document) {
        self.active_document.set(Some(document))
    }

    pub fn active_document(&self) -> Root<Document> {
        self.active_document.get().expect("No active document.")
    }

    pub fn maybe_active_document(&self) -> Option<Root<Document>> {
        self.active_document.get()
    }

    pub fn active_window(&self) -> Root<Window> {
        Root::from_ref(self.active_document().window())
    }

    pub fn frame_element(&self) -> Option<&Element> {
        self.frame_element.r()
    }

    pub fn window_proxy(&self) -> *mut JSObject {
        let window_proxy = self.reflector.get_jsobject();
        assert!(!window_proxy.get().is_null());
        window_proxy.get()
    }

    pub fn set_reflow_status(&self, status: bool) -> bool {
        let old = self.needs_reflow.get();
        self.needs_reflow.set(status);
        old
    }

    pub fn active_pipeline_id(&self) -> Option<PipelineId> {
        self.active_document.get()
            .map(|doc| doc.window().upcast::<GlobalScope>().pipeline_id())
    }

    pub fn unset_active_document(&self) {
        self.active_document.set(None)
    }
}

#[allow(unsafe_code)]
unsafe fn GetSubframeWindow(cx: *mut JSContext,
                            proxy: HandleObject,
                            id: HandleId)
                            -> Option<Root<Window>> {
    let index = get_array_index_from_id(cx, id);
    if let Some(index) = index {
        rooted!(in(cx) let target = GetProxyPrivate(*proxy.ptr).to_object());
        let win = root_from_handleobject::<Window>(target.handle()).unwrap();
        let mut found = false;
        return win.IndexedGetter(index, &mut found);
    }

    None
}

#[allow(unsafe_code)]
unsafe extern "C" fn getOwnPropertyDescriptor(cx: *mut JSContext,
                                              proxy: HandleObject,
                                              id: HandleId,
                                              mut desc: MutableHandle<PropertyDescriptor>)
                                              -> bool {
    let window = GetSubframeWindow(cx, proxy, id);
    if let Some(window) = window {
        rooted!(in(cx) let mut val = UndefinedValue());
        window.to_jsval(cx, val.handle_mut());
        desc.value = val.get();
        fill_property_descriptor(desc, proxy.get(), JSPROP_READONLY);
        return true;
    }

    rooted!(in(cx) let target = GetProxyPrivate(proxy.get()).to_object());
    if !JS_GetOwnPropertyDescriptorById(cx, target.handle(), id, desc) {
        return false;
    }

    assert!(desc.obj.is_null() || desc.obj == target.get());
    if desc.obj == target.get() {
        // FIXME(#11868) Should assign to desc.obj, desc.get() is a copy.
        desc.get().obj = proxy.get();
    }

    true
}

#[allow(unsafe_code)]
unsafe extern "C" fn defineProperty(cx: *mut JSContext,
                                    proxy: HandleObject,
                                    id: HandleId,
                                    desc: Handle<PropertyDescriptor>,
                                    res: *mut ObjectOpResult)
                                    -> bool {
    if get_array_index_from_id(cx, id).is_some() {
        // Spec says to Reject whether this is a supported index or not,
        // since we have no indexed setter or indexed creator.  That means
        // throwing in strict mode (FIXME: Bug 828137), doing nothing in
        // non-strict mode.
        (*res).code_ = JSErrNum::JSMSG_CANT_DEFINE_WINDOW_ELEMENT as ::libc::uintptr_t;
        return true;
    }

    rooted!(in(cx) let target = GetProxyPrivate(*proxy.ptr).to_object());
    JS_DefinePropertyById(cx, target.handle(), id, desc, res)
}

#[allow(unsafe_code)]
unsafe extern "C" fn has(cx: *mut JSContext,
                         proxy: HandleObject,
                         id: HandleId,
                         bp: *mut bool)
                         -> bool {
    let window = GetSubframeWindow(cx, proxy, id);
    if window.is_some() {
        *bp = true;
        return true;
    }

    rooted!(in(cx) let target = GetProxyPrivate(*proxy.ptr).to_object());
    let mut found = false;
    if !JS_HasPropertyById(cx, target.handle(), id, &mut found) {
        return false;
    }

    *bp = found;
    true
}

#[allow(unsafe_code)]
unsafe extern "C" fn get(cx: *mut JSContext,
                         proxy: HandleObject,
                         receiver: HandleValue,
                         id: HandleId,
                         vp: MutableHandleValue)
                         -> bool {
    let window = GetSubframeWindow(cx, proxy, id);
    if let Some(window) = window {
        window.to_jsval(cx, vp);
        return true;
    }

    rooted!(in(cx) let target = GetProxyPrivate(*proxy.ptr).to_object());
    JS_ForwardGetPropertyTo(cx, target.handle(), id, receiver, vp)
}

#[allow(unsafe_code)]
unsafe extern "C" fn set(cx: *mut JSContext,
                         proxy: HandleObject,
                         id: HandleId,
                         v: HandleValue,
                         receiver: HandleValue,
                         res: *mut ObjectOpResult)
                         -> bool {
    if get_array_index_from_id(cx, id).is_some() {
        // Reject (which means throw if and only if strict) the set.
        (*res).code_ = JSErrNum::JSMSG_READ_ONLY as ::libc::uintptr_t;
        return true;
    }

    rooted!(in(cx) let target = GetProxyPrivate(*proxy.ptr).to_object());
    JS_ForwardSetPropertyTo(cx,
                            target.handle(),
                            id,
                            v,
                            receiver,
                            res)
}

#[allow(unsafe_code)]
unsafe extern "C" fn get_prototype_if_ordinary(_: *mut JSContext,
                                               _: HandleObject,
                                               is_ordinary: *mut bool,
                                               _: MutableHandleObject)
                                               -> bool {
    // Window's [[GetPrototypeOf]] trap isn't the ordinary definition:
    //
    //   https://html.spec.whatwg.org/multipage/#windowproxy-getprototypeof
    //
    // We nonetheless can implement it with a static [[Prototype]], because
    // wrapper-class handlers (particularly, XOW in FilteringWrapper.cpp) supply
    // all non-ordinary behavior.
    //
    // But from a spec point of view, it's the exact same object in both cases --
    // only the observer's changed.  So this getPrototypeIfOrdinary trap on the
    // non-wrapper object *must* report non-ordinary, even if static [[Prototype]]
    // usually means ordinary.
    *is_ordinary = false;
    return true;
}

static PROXY_HANDLER: ProxyTraps = ProxyTraps {
    enter: None,
    getOwnPropertyDescriptor: Some(getOwnPropertyDescriptor),
    defineProperty: Some(defineProperty),
    ownPropertyKeys: None,
    delete_: None,
    enumerate: None,
    getPrototypeIfOrdinary: Some(get_prototype_if_ordinary),
    preventExtensions: None,
    isExtensible: None,
    has: Some(has),
    get: Some(get),
    set: Some(set),
    call: None,
    construct: None,
    getPropertyDescriptor: Some(get_property_descriptor),
    hasOwn: None,
    getOwnEnumerablePropertyKeys: None,
    nativeCall: None,
    hasInstance: None,
    objectClassIs: None,
    className: None,
    fun_toString: None,
    boxedValue_unbox: None,
    defaultValue: None,
    trace: Some(trace),
    finalize: Some(finalize),
    objectMoved: None,
    isCallable: None,
    isConstructor: None,
};

#[allow(unsafe_code)]
unsafe extern fn finalize(_fop: *mut JSFreeOp, obj: *mut JSObject) {
    let this = GetProxyExtra(obj, 0).to_private() as *mut BrowsingContext;
    assert!(!this.is_null());
    let _ = Box::from_raw(this);
    debug!("BrowsingContext finalize: {:p}", this);
}

#[allow(unsafe_code)]
unsafe extern fn trace(trc: *mut JSTracer, obj: *mut JSObject) {
    let this = GetProxyExtra(obj, 0).to_private() as *const BrowsingContext;
    if this.is_null() {
        // GC during obj creation
        return;
    }
    (*this).trace(trc);
}

#[allow(unsafe_code)]
pub fn new_window_proxy_handler() -> WindowProxyHandler {
    unsafe {
        WindowProxyHandler(CreateWrapperProxyHandler(&PROXY_HANDLER))
    }
}