//! An event system that's less confusing than Traits + RC;
//! This should hopefully make it easier to port to other platforms.
//!
//! Unfortunately, it is less efficient than the original, but hopefully it's negligible.

use crate::{
    innerlude::Listener,
    innerlude::{ElementId, NodeFactory, ScopeId},
};
use bumpalo::boxed::Box as BumpBox;
use std::{
    any::Any,
    cell::{Cell, RefCell},
    fmt::Debug,
};

#[derive(Debug)]
pub struct UserEvent {
    /// The originator of the event trigger
    pub scope: ScopeId,

    /// The optional real node associated with the trigger
    pub mounted_dom_id: Option<ElementId>,

    /// The event type IE "onclick" or "onmouseover"
    ///
    /// The name that the renderer will use to mount the listener.
    pub name: &'static str,

    /// The type of event
    pub event: Box<dyn Any + Send>,
}

/// Priority of Event Triggers.
///
/// Internally, Dioxus will abort work that's taking too long if new, more important work arrives. Unlike React, Dioxus
/// won't be afraid to pause work or flush changes to the RealDOM. This is called "cooperative scheduling". Some Renderers
/// implement this form of scheduling internally, however Dioxus will perform its own scheduling as well.
///
/// The ultimate goal of the scheduler is to manage latency of changes, prioritizing "flashier" changes over "subtler" changes.
///
/// React has a 5-tier priority system. However, they break things into "Continuous" and "Discrete" priority. For now,
/// we keep it simple, and just use a 3-tier priority system.
///
/// - NoPriority = 0
/// - LowPriority = 1
/// - NormalPriority = 2
/// - UserBlocking = 3
/// - HighPriority = 4
/// - ImmediatePriority = 5
///
/// We still have a concept of discrete vs continuous though - discrete events won't be batched, but continuous events will.
/// This means that multiple "scroll" events will be processed in a single frame, but multiple "click" events will be
/// flushed before proceeding. Multiple discrete events is highly unlikely, though.
#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, PartialOrd, Ord)]
pub enum EventPriority {
    /// Work that must be completed during the EventHandler phase.
    ///
    /// Currently this is reserved for controlled inputs.
    Immediate = 3,

    /// "High Priority" work will not interrupt other high priority work, but will interrupt medium and low priority work.
    ///
    /// This is typically reserved for things like user interaction.
    ///
    /// React calls these "discrete" events, but with an extra category of "user-blocking" (Immediate).
    High = 2,

    /// "Medium priority" work is generated by page events not triggered by the user. These types of events are less important
    /// than "High Priority" events and will take precedence over low priority events.
    ///
    /// This is typically reserved for VirtualEvents that are not related to keyboard or mouse input.
    ///
    /// React calls these "continuous" events (e.g. mouse move, mouse wheel, touch move, etc).
    Medium = 1,

    /// "Low Priority" work will always be preempted unless the work is significantly delayed, in which case it will be
    /// advanced to the front of the work queue until completed.
    ///
    /// The primary user of Low Priority work is the asynchronous work system (Suspense).
    ///
    /// This is considered "idle" work or "background" work.
    Low = 0,
}