paneru 0.4.3

use bevy::app::{App, Plugin, PreUpdate, Update};
use bevy::ecs::component::Component;
use bevy::ecs::entity::Entity;
use bevy::ecs::hierarchy::ChildOf;
use bevy::ecs::lifecycle::Add;
use bevy::ecs::message::{MessageReader, MessageWriter};
use bevy::ecs::observer::On;
use bevy::ecs::query::{Has, With};
use bevy::ecs::system::{Commands, Local, NonSend, Query, Res};
use bevy::math::IRect;
use bevy::platform::collections::HashSet;
use objc2_app_kit::NSScreen;
use objc2_core_graphics::CGDirectDisplayID;
use std::pin::Pin;
use std::time::Duration;
use tracing::{Level, debug, error, instrument};

use crate::config::Config;
use crate::ecs::layout::LayoutStrip;
use crate::ecs::{
    ActiveDisplayMarker, ActiveWorkspaceMarker, ReadDisplayProperties, RefreshWindowSizes,
    SendMessageTrigger, SpawnCommandsExt, Timeout,
};
use crate::events::Event;
use crate::manager::{Display, WindowManager, irect_from};
use crate::platform::{PlatformCallbacks, WorkspaceId};
use crate::util::read_screen_property;

const ORPHANED_SPACES_TIMEOUT_SEC: u64 = 30;

pub struct DisplayEventsPlugin;

impl Plugin for DisplayEventsPlugin {
    fn build(&self, app: &mut App) {
        app.add_systems(PreUpdate, display_change_handler);
        app.add_systems(Update, reconcile_displays)
            .add_observer(read_display_properties_trigger)
            .add_observer(cleanup_active_display_marker);
    }
}

#[allow(clippy::needless_pass_by_value)]
#[instrument(level = Level::DEBUG, skip_all, fields(trigger))]
fn cleanup_active_display_marker(
    trigger: On<Add, ActiveDisplayMarker>,
    displays: Query<(Entity, Has<ActiveDisplayMarker>), With<Display>>,
    mut commands: Commands,
) {
    for (entity, active) in displays {
        if active
            && entity != trigger.entity
            && let Ok(mut cmd) = commands.get_entity(entity)
        {
            debug!("Display id {entity} lost active marker.");
            cmd.try_remove::<ActiveDisplayMarker>();
        }
    }
}

/// Handles display change events.
#[allow(clippy::needless_pass_by_value)]
#[instrument(level = Level::DEBUG, skip_all, fields(trigger))]
fn display_change_handler(
    mut messages: MessageReader<Event>,
    displays: Query<(&Display, Entity, Has<ActiveDisplayMarker>)>,
    window_manager: Res<WindowManager>,
    mut commands: Commands,
) {
    if !messages
        .read()
        .any(|event| matches!(event, Event::DisplayChanged))
    {
        return;
    }

    let Ok(active_id) = window_manager.active_display_id() else {
        error!("Unable to get active display id!");
        return;
    };

    for (display, entity, focused) in displays {
        let display_id = display.id();
        if !focused
            && display_id == active_id
            && let Ok(mut cmd) = commands.get_entity(entity)
        {
            debug!("Display id {display_id} is active");
            cmd.try_insert(ActiveDisplayMarker);
        }
    }
    commands.trigger(SendMessageTrigger(Event::SpaceChanged));
}

/// Full reconciliation of the ECS display set against the OS truth.
///
/// Runs on events where the per-display add/remove/move flags are unreliable or
/// absent: waking from sleep, resolution / arrangement changes, and configuration
/// events. Rather than trust a single `display_id` flag, it diffs the live
/// `present_displays()` list against the spawned `Display` entities and applies
/// the same add / remove / move primitives the event handlers use. It also
/// forces the active workspace to re-tile, because macOS relocates windows while
/// asleep even when the display set is unchanged.
#[allow(clippy::needless_pass_by_value, clippy::too_many_arguments)]
pub(crate) fn reconcile_displays(
    mut messages: MessageReader<Event>,
    workspaces: Query<(&LayoutStrip, Entity, Option<&ChildOf>)>,
    mut displays: Query<(&mut Display, Entity)>,
    active_strips: Query<Entity, (With<LayoutStrip>, With<ActiveWorkspaceMarker>)>,
    window_manager: Res<WindowManager>,
    mut retries: Local<HashSet<CGDirectDisplayID>>,
    mut commands: Commands,
) {
    let needs_reconcile = messages.read().any(|event| {
        matches!(
            event,
            Event::SystemWoke { .. }
                | Event::DisplayAdded { .. }
                | Event::DisplayRemoved { .. }
                | Event::DisplayMoved { .. }
                | Event::DisplayResized { .. }
                | Event::DisplayConfigured { .. }
        )
    });
    if !needs_reconcile {
        return;
    }

    debug!("reconciling displays against OS after wake / resize / configure");

    let present_ids: HashSet<CGDirectDisplayID> = window_manager
        .0
        .present_displays()
        .iter()
        .map(|(display, _)| display.id())
        .collect();
    let existing_ids: HashSet<CGDirectDisplayID> =
        displays.iter().map(|(display, _)| display.id()).collect();

    // Displays that vanished while we were away (e.g. unplugged during sleep).
    for display_id in existing_ids.difference(&present_ids).copied() {
        remove_display(display_id, &workspaces, &mut displays, &mut commands);
    }

    // Displays that appeared while we were away.
    for display_id in present_ids.difference(&existing_ids).copied() {
        add_display(
            display_id,
            &workspaces,
            &window_manager,
            &mut retries,
            &mut commands,
        );
    }

    // Displays that are still present: refresh their bounds (resolution or
    // menubar may have changed) and re-home any workspaces that drifted.
    for display_id in present_ids.intersection(&existing_ids).copied() {
        move_display(
            display_id,
            &mut displays,
            &window_manager,
            &workspaces,
            &mut commands,
        );
    }

    // Re-tile the active workspace even when the topology is unchanged — the OS
    // shuffles window frames across a sleep/wake cycle.
    for entity in active_strips {
        if let Ok(mut cmd) = commands.get_entity(entity) {
            cmd.insert(RefreshWindowSizes::default());
        }
    }

    commands.trigger(SendMessageTrigger(Event::DisplayChanged));
}

#[instrument(level = Level::DEBUG, skip_all, fields(display_id))]
fn add_display(
    display_id: CGDirectDisplayID,
    existing_strips: &Query<(&LayoutStrip, Entity, Option<&ChildOf>)>,
    window_manager: &WindowManager,
    retries: &mut HashSet<CGDirectDisplayID>,
    commands: &mut Commands,
) {
    debug!("Display Added: {display_id:?}");
    let Some((display, workspace_ids)) = window_manager
        .0
        .present_displays()
        .into_iter()
        .find(|(display, _)| display.id() == display_id)
    else {
        error!("Unable to find added display id {display_id}!");
        if retries.insert(display_id) {
            let retry_display = move |mut messages: MessageWriter<Event>| {
                debug!("Retrying to add display {display_id}");
                messages.write(Event::DisplayAdded { display_id });
            };
            let system_id = commands.register_system(retry_display);
            Timeout::callback(Duration::from_secs(5), system_id, commands);
        } else {
            retries.remove(&display_id);
        }
        return;
    };

    let display_bounds = display.bounds();
    let display_entity = commands.spawn(display).id();
    commands.trigger(ReadDisplayProperties(display_entity));

    reparent_existing_workspaces(
        &workspace_ids,
        display_entity,
        &display_bounds,
        existing_strips,
        commands,
    );
}

#[instrument(level = Level::DEBUG, skip_all, fields(display_id))]
fn remove_display(
    display_id: CGDirectDisplayID,
    workspaces: &Query<(&LayoutStrip, Entity, Option<&ChildOf>)>,
    displays: &mut Query<(&mut Display, Entity)>,
    commands: &mut Commands,
) {
    debug!("Display Removed: {display_id:?}");
    let Some((display, display_entity)) = displays
        .into_iter()
        .find(|(display, _)| display.id() == display_id)
    else {
        error!("Unable to find removed display!");
        return;
    };

    for (strip, entity, _) in workspaces
        .into_iter()
        .filter(|(_, _, child)| child.is_some_and(|child| child.parent() == display_entity))
    {
        let display_id = display.id();
        debug!(
            "orphaning strip {} after removal of display {display_id}.",
            strip.id(),
        );
        let timeout = Timeout::new(
            Duration::from_secs(ORPHANED_SPACES_TIMEOUT_SEC),
            Some(format!(
                "Orphaned strip {} ({strip}) could not be re-inserted after {ORPHANED_SPACES_TIMEOUT_SEC}s.",
                strip.id()
            )),
            commands,
        );
        if let Ok(mut commands) = commands.get_entity(entity) {
            commands.try_insert(timeout);
        }
        if let Ok(mut commands) = commands.get_entity(display_entity) {
            commands.detach_child(entity);
        }
    }

    if let Ok(mut commands) = commands.get_entity(display_entity) {
        commands.try_despawn();
    }
}

#[instrument(level = Level::DEBUG, skip_all, fields(display_id))]
fn move_display(
    display_id: CGDirectDisplayID,
    displays: &mut Query<(&mut Display, Entity)>,
    window_manager: &Res<WindowManager>,
    existing_strips: &Query<(&LayoutStrip, Entity, Option<&ChildOf>)>,
    commands: &mut Commands,
) {
    debug!("Display Moved: {display_id:?}");
    let Some((mut display, display_entity)) = displays
        .iter_mut()
        .find(|(display, _)| display.id() == display_id)
    else {
        error!("Unable to find moved display!");
        return;
    };
    let Some((moved_display, workspace_ids)) = window_manager
        .0
        .present_displays()
        .into_iter()
        .find(|(display, _)| display.id() == display_id)
    else {
        return;
    };
    *display = moved_display;
    commands.trigger(ReadDisplayProperties(display_entity));

    reparent_existing_workspaces(
        &workspace_ids,
        display_entity,
        &display.bounds(),
        existing_strips,
        commands,
    );
}

fn reparent_existing_workspaces(
    workspace_ids: &[WorkspaceId],
    display_entity: Entity,
    display_bounds: &IRect,
    existing_strips: &Query<(&LayoutStrip, Entity, Option<&ChildOf>)>,
    commands: &mut Commands,
) {
    // Verifies that a moved display has all the workspaces which it owns.
    for &id in workspace_ids {
        let mut found = false;
        for (strip, entity, child) in existing_strips {
            if strip.id() == id {
                found = true;
                if child.is_none_or(|child| child.parent() != display_entity) {
                    // Re-parent this workspace
                    if let Ok(mut cmd) = commands.get_entity(entity) {
                        debug!("reparenting workspace {id} to display {display_entity}");
                        cmd.try_remove::<Timeout>()
                            .try_remove::<ChildOf>()
                            .try_insert(ChildOf(display_entity));

                        cmd.try_insert(RefreshWindowSizes::default());
                    }
                }
            }
        }

        if !found {
            // New workspace.
            let origin = display_bounds.min;
            debug!("new workspace {id} on display {display_entity}");
            commands.spawn_layout_strip(LayoutStrip::new(id, 0), origin, display_entity, false);
        }
    }
}

/// Tracks whether floating windows on a workspace sit above or behind tiled
/// ones in the OS z-order. Default is `Front` (floats above tiles).
#[derive(Component, Default, Clone, Copy, PartialEq, Eq, Debug)]
pub enum FloatingLayer {
    #[default]
    Front,
    Behind,
}

impl FloatingLayer {
    pub fn flipped(self) -> Self {
        match self {
            Self::Front => Self::Behind,
            Self::Behind => Self::Front,
        }
    }
}

#[allow(clippy::needless_pass_by_value)]
fn read_display_properties_trigger(
    trigger: On<ReadDisplayProperties>,
    mut displays: Query<(&mut Display, Entity)>,
    platform: Option<NonSend<Pin<Box<PlatformCallbacks>>>>,
    config: Option<Res<Config>>,
    mut commands: Commands,
) {
    let Ok((mut display, entity)) = displays.get_mut(trigger.event().0) else {
        return;
    };
    let display_id = display.id();

    // NSScreen::screen needs to run in the main thread, thus we run it in a NonSend trigger.
    let Some(screens) = platform.map(|platform| NSScreen::screens(platform.main_thread_marker))
    else {
        return;
    };

    let notch = read_screen_property(&screens, display_id, |screen| {
        let insets = screen.safeAreaInsets();
        debug!("notch on display {display_id}: {insets:?}");
        insets.top as i32
    });
    if let Some(height) = notch {
        display.set_notch_height(height);
    }

    let dock = read_screen_property(&screens, display_id, |screen| {
        let visible_frame = irect_from(screen.visibleFrame());
        display.locate_dock(&visible_frame)
    });
    if let Some(dock) = dock {
        debug!("dock on display {display_id}: {:?}", dock);
        if let Ok(mut entity_commands) = commands.get_entity(entity) {
            entity_commands.try_insert(dock);
        }
    }

    if let Some(config) = config {
        let height = config.menubar_height();
        display.set_menubar_height_override(height);
    }
}