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/* 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 std::rc::Rc;

use dom_struct::dom_struct;
use js::jsval::{JSVal, NullValue};
use js::rust::HandleObject;

use super::bindings::codegen::Bindings::IntersectionObserverBinding::{
    IntersectionObserverCallback, IntersectionObserverMethods,
};
use super::bindings::codegen::UnionTypes::ElementOrDocument;
use super::types::{Element, IntersectionObserverEntry};
use crate::dom::bindings::codegen::Bindings::IntersectionObserverBinding::IntersectionObserverInit;
use crate::dom::bindings::reflector::{reflect_dom_object_with_proto, Reflector};
use crate::dom::bindings::root::DomRoot;
use crate::dom::bindings::str::DOMString;
use crate::dom::window::Window;
use crate::script_runtime::{CanGc, JSContext};

/// The Intersection Observer interface
///
/// > The IntersectionObserver interface can be used to observe changes in the intersection
/// > of an intersection root and one or more target Elements.
///
/// <https://w3c.github.io/IntersectionObserver/#intersection-observer-interface>
#[dom_struct]
pub struct IntersectionObserver {
    reflector_: Reflector,

    /// > This callback will be invoked when there are changes to a target’s intersection
    /// > with the intersection root, as per the processing model.
    /// <https://w3c.github.io/IntersectionObserver/#intersection-observer-callback>
    #[ignore_malloc_size_of = "Rc are hard"]
    callback: Rc<IntersectionObserverCallback>,
}

impl IntersectionObserver {
    pub fn new_inherited(
        callback: Rc<IntersectionObserverCallback>,
        _init: &IntersectionObserverInit,
    ) -> Self {
        Self {
            reflector_: Reflector::new(),
            callback,
        }
    }

    fn new(
        window: &Window,
        proto: Option<HandleObject>,
        callback: Rc<IntersectionObserverCallback>,
        init: &IntersectionObserverInit,
        can_gc: CanGc,
    ) -> DomRoot<Self> {
        let observer = Box::new(Self::new_inherited(callback, init));
        reflect_dom_object_with_proto(observer, window, proto, can_gc)
    }
}

impl IntersectionObserverMethods for IntersectionObserver {
    /// > The root provided to the IntersectionObserver constructor, or null if none was provided.
    ///
    /// <https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-root>
    fn GetRoot(&self) -> Option<ElementOrDocument> {
        None
    }

    /// > Offsets applied to the root intersection rectangle, effectively growing or
    /// > shrinking the box that is used to calculate intersections. These offsets are only
    /// > applied when handling same-origin-domain targets; for cross-origin-domain targets
    /// > they are ignored.
    ///
    /// <https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-rootmargin>
    fn RootMargin(&self) -> DOMString {
        DOMString::new()
    }

    /// > Offsets are applied to scrollports on the path from intersection root to target,
    /// > effectively growing or shrinking the clip rects used to calculate intersections.
    ///
    /// <https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-scrollmargin>
    fn ScrollMargin(&self) -> DOMString {
        DOMString::new()
    }

    /// > A list of thresholds, sorted in increasing numeric order, where each threshold
    /// > is a ratio of intersection area to bounding box area of an observed target.
    /// > Notifications for a target are generated when any of the thresholds are crossed
    /// > for that target. If no options.threshold was provided to the IntersectionObserver
    /// > constructor, or the sequence is empty, the value of this attribute will be [0].
    ///
    /// <https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-thresholds>
    fn Thresholds(&self, _context: JSContext) -> JSVal {
        NullValue()
    }

    /// > A number indicating the minimum delay in milliseconds between notifications from
    /// > this observer for a given target.
    ///
    /// <https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-delay>
    fn Delay(&self) -> i32 {
        0
    }

    /// > A boolean indicating whether this IntersectionObserver will track changes in a target’s visibility.
    ///
    /// <https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-trackvisibility>
    fn TrackVisibility(&self) -> bool {
        false
    }

    /// > Run the observe a target Element algorithm, providing this and target.
    ///
    /// <https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-observe>
    fn Observe(&self, _target: &Element) {}

    /// > Run the unobserve a target Element algorithm, providing this and target.
    ///
    /// <https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-unobserve>
    fn Unobserve(&self, _target: &Element) {}

    /// <https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-disconnect>
    fn Disconnect(&self) {}

    /// <https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-takerecords>
    fn TakeRecords(&self) -> Vec<DomRoot<IntersectionObserverEntry>> {
        vec![]
    }

    /// <https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-intersectionobserver>
    fn Constructor(
        window: &Window,
        proto: Option<HandleObject>,
        can_gc: CanGc,
        callback: Rc<IntersectionObserverCallback>,
        init: &IntersectionObserverInit,
    ) -> DomRoot<IntersectionObserver> {
        Self::new(window, proto, callback, init, can_gc)
    }
}