a7n-platform 0.43.1

// SPDX-License-Identifier: GPL-3.0-or-later

//! Edge glow, landing ring and haptic ticks on macOS; contract in [`super`].
//!
//! Two click-through, non-activating panels live on the process main thread,
//! which [`crate::main_thread::run`] keeps in its `CFRunLoop` (`AppKit` only
//! allows windows there). A bridge thread blocks on the tokio receiver, passes
//! commands over a std channel and signals a run-loop source on the main loop,
//! so nothing polls. The panels are created lazily inside that source's
//! callback, on the main thread. Without `main_thread::run` there is no main
//! run loop and [`start`] returns `None`, so tests never touch `AppKit`.

mod blit;

use std::ffi::c_void;
use std::sync::mpsc as sync;
use std::thread;
use std::time::Instant;

use objc2::MainThreadMarker;
use objc2::rc::{Retained, autoreleasepool};
use objc2_app_kit::{
    NSBackingStoreType, NSColor, NSEvent, NSHapticFeedbackManager, NSHapticFeedbackPattern,
    NSHapticFeedbackPerformanceTime, NSHapticFeedbackPerformer, NSImageView, NSPanel, NSScreen,
    NSStatusWindowLevel, NSWindowCollectionBehavior, NSWindowSharingType, NSWindowStyleMask,
    NSWorkspace,
};
use objc2_core_foundation::{
    CFAbsoluteTimeGetCurrent, CFRetained, CFRunLoop, CFRunLoopTimer, CFRunLoopTimerContext,
    kCFRunLoopDefaultMode,
};
use objc2_foundation::{NSPoint, NSRect, NSSize};
use tokio::sync::mpsc;

use super::look;
use super::macos_geometry::{self as geometry, Rect};
use super::raster::{self, Along, Arrival, EdgeEffect, Frame};
use super::timeline::{End, Timeline, frame_interval};
use super::{Command, Feedback, Look};
use crate::main_thread::{self, Waker};
use blit::Bitmap;

/// Never fires on its own; every landing re-arms it.
const TIMER_DISARMED_SECONDS: f64 = 1.0e12;

/// State of the main-thread callbacks. Leaked on purpose: it lives as long as
/// the process and is only touched from main run-loop callbacks.
struct Ui {
    commands: sync::Receiver<Command>,
    panels: Option<Panels>,
}

struct Panels {
    mtm: MainThreadMarker,
    glow: Retained<NSPanel>,
    glow_fill: Retained<NSImageView>,
    glow_frame: Frame,
    timeline: Timeline,
    edge_started: Instant,
    timer_running: bool,
    glow_bitmap: Bitmap,
    landing_frame: Frame,
    landing_bitmap: Bitmap,
    landing: Retained<NSPanel>,
    landing_fill: Retained<NSImageView>,
    landing_center: (f64, f64),
    landing_look: Look,
    animate: bool,
    hide_landing: CFRetained<CFRunLoopTimer>,
    timer_info: *mut c_void,
}

pub(super) fn start() -> Option<Feedback> {
    if !main_thread::active() {
        return None;
    }
    let (feedback, receiver) = super::channel();
    let (command_tx, command_rx) = sync::channel();
    let ui = Box::leak(Box::new(Ui {
        commands: command_rx,
        panels: None,
    }));
    // SAFETY: `ui` is leaked, so the pointer is valid forever, and
    // `drain_commands` only runs on the main thread, one callback at a time.
    let waker = unsafe {
        Waker::new(
            CFRunLoop::main()?,
            drain_commands,
            std::ptr::from_mut(ui).cast(),
        )
    }?;
    thread::Builder::new()
        .name("a7n-macos-feedback".into())
        .spawn(move || forward_commands(receiver, command_tx, &waker))
        .ok()?;
    Some(feedback)
}

fn forward_commands(
    mut receiver: mpsc::Receiver<Command>,
    commands: sync::Sender<Command>,
    waker: &Waker,
) {
    while let Some(command) = receiver.blocking_recv() {
        if commands.send(command).is_err() {
            return;
        }
        waker.wake();
    }
    // Waking with the sender gone lets the main thread hide the panels.
    drop(commands);
    waker.wake();
}

unsafe extern "C-unwind" fn drain_commands(info: *mut c_void) {
    autoreleasepool(|_| {
        // SAFETY: start passes a leaked, process-long Ui; main run-loop
        // callbacks run one at a time on the main thread.
        let ui = unsafe { &mut *info.cast::<Ui>() };
        loop {
            match ui.commands.try_recv() {
                Ok(command) => ui.apply(command),
                Err(sync::TryRecvError::Empty) => return,
                Err(sync::TryRecvError::Disconnected) => {
                    ui.hide_all();
                    return;
                }
            }
        }
    });
}

unsafe extern "C-unwind" fn hide_landing(_: *mut CFRunLoopTimer, info: *mut c_void) {
    // SAFETY: Same contract as drain_commands.
    let ui = unsafe { &mut *info.cast::<Ui>() };
    if let Some(panels) = &mut ui.panels {
        panels.animate_frame();
    }
}

impl Ui {
    fn apply(&mut self, command: Command) {
        match command {
            Command::Tick => tick_haptics(),
            Command::Clear | Command::Crossed => {
                if let Some(panels) = &mut self.panels {
                    panels.timeline.end(
                        if command == Command::Crossed {
                            End::Crossed
                        } else {
                            End::Abandoned
                        },
                        panels.edge_started.elapsed(),
                    );
                    panels.arm_timer();
                }
            }
            Command::Edge {
                display,
                edge,
                progress,
                look,
            } => {
                if let Some(panels) = self.panels() {
                    panels.show_glow(display, edge, progress, look);
                }
            }
            Command::Landing { x, y, look } => {
                if let Some(panels) = self.panels() {
                    panels.show_landing(x, y, look);
                }
            }
            Command::LandingAtCursor { look } => {
                if let Some(panels) = self.panels() {
                    let point = NSEvent::mouseLocation();
                    panels.show_landing_at((point.x, point.y), look);
                }
            }
        }
    }

    fn hide_glow(&mut self) {
        if let Some(panels) = &mut self.panels {
            panels.timeline = Timeline::default();
            panels.glow.orderOut(None);
            panels.arm_timer();
        }
    }

    fn hide_all(&mut self) {
        self.hide_glow();
        if let Some(panels) = &self.panels {
            panels.landing.orderOut(None);
            panels.hide_landing.invalidate();
        }
    }

    /// The panels, created on first use; callbacks run on the main thread.
    fn panels(&mut self) -> Option<&mut Panels> {
        if self.panels.is_none() {
            let info = std::ptr::from_mut(self).cast();
            self.panels = Panels::new(MainThreadMarker::new()?, info);
        }
        self.panels.as_mut()
    }
}

impl Panels {
    fn new(mtm: MainThreadMarker, timer_info: *mut c_void) -> Option<Self> {
        let glow_fill = image_view(mtm);
        let glow = make_panel(mtm, &glow_fill);
        let landing_fill = image_view(mtm);
        let landing = make_panel(mtm, &landing_fill);
        let hide_landing = frame_timer(timer_info, frame_interval(None).as_secs_f64())?;
        Some(Self {
            mtm,
            glow,
            glow_fill,
            glow_frame: Frame::default(),
            timeline: Timeline::default(),
            edge_started: Instant::now(),
            timer_running: false,
            glow_bitmap: Bitmap::default(),
            landing_frame: Frame::default(),
            landing_bitmap: Bitmap::default(),
            landing,
            landing_fill,
            landing_center: (0.0, 0.0),
            landing_look: Look::default(),
            animate: true,
            hide_landing,
            timer_info,
        })
    }

    fn show_glow(
        &mut self,
        display: crate::input::Bounds,
        edge: a7n_proto::v1::Edge,
        progress: u16,
        look: Look,
    ) {
        let screens = screen_frames(self.mtm);
        let Some(primary) = screens.first() else {
            return;
        };
        let top = primary.height - f64::from(display.y);
        let pointer = NSEvent::mouseLocation();
        let Some(mut screen) = geometry::screen_containing(&screens, pointer.x, pointer.y) else {
            return;
        };
        // The daemon narrows the display rectangle for a notch push.
        if f64::from(display.width) < screen.width {
            screen.x = f64::from(display.x);
            screen.width = f64::from(display.width);
            screen.height = top - screen.y;
        }
        let thickness = f64::from(raster::OVERLAY_DEPTH)
            .min(screen.width)
            .min(screen.height);
        let rect = geometry::glow_rect(screen, edge, 1000, super::Size::Medium).map(|mut rect| {
            match edge {
                a7n_proto::v1::Edge::Top => {
                    rect.height = thickness;
                    rect.y = screen.y + screen.height - thickness;
                }
                a7n_proto::v1::Edge::Bottom => rect.height = thickness,
                a7n_proto::v1::Edge::Left => rect.width = thickness,
                a7n_proto::v1::Edge::Right => {
                    rect.width = thickness;
                    rect.x = screen.x + screen.width - thickness;
                }
                a7n_proto::v1::Edge::Unspecified => {}
            }
            rect
        });
        let Some(rect) = rect else {
            self.timeline
                .end(End::Abandoned, self.edge_started.elapsed());
            self.glow.orderOut(None);
            self.arm_timer();
            return;
        };
        self.paint_glow(rect, screen, edge, progress, look);
    }

    fn paint_glow(
        &mut self,
        rect: Rect,
        screen: Rect,
        edge: a7n_proto::v1::Edge,
        progress: u16,
        look: Look,
    ) {
        self.glow.setFrame_display(ns_rect(rect), false);
        let scale = self.glow.backingScaleFactor();
        self.glow_frame.resize(
            pixel_size(rect.width * scale),
            pixel_size(rect.height * scale),
        );
        self.glow_frame.dark = true;
        self.glow_frame.opacity = 1.0;
        self.glow_frame.scale = scale;
        let pointer = NSEvent::mouseLocation();
        let horizontal = matches!(edge, a7n_proto::v1::Edge::Top | a7n_proto::v1::Edge::Bottom);
        let along = Along {
            origin: (screen.x, -screen.y - screen.height),
            start: if horizontal {
                (rect.x - screen.x) * scale
            } else {
                (screen.y + screen.height - rect.y - rect.height) * scale
            },
            span: if horizontal {
                screen.width * scale
            } else {
                screen.height * scale
            },
            push: if horizontal {
                (pointer.x - rect.x) * scale
            } else {
                (rect.y + rect.height - pointer.y) * scale
            },
        };
        self.glow_frame.animate = !reduce_motion();
        self.timeline.push(
            EdgeEffect {
                look,
                edge,
                progress,
                along,
            },
            self.edge_started.elapsed(),
        );
        self.render_edge();
        self.arm_timer();
        self.glow.orderFrontRegardless();
    }

    fn show_landing(&mut self, x: i32, y: i32, look: Look) {
        let primary_height = screen_frames(self.mtm)
            .first()
            .map_or(0.0, |frame| frame.height);
        let rect = geometry::landing_rect(x, y, primary_height);
        self.show_landing_at(
            (rect.x + rect.width / 2.0, rect.y + rect.height / 2.0),
            look,
        );
    }

    fn show_landing_at(&mut self, center: (f64, f64), look: Look) {
        self.landing_center = center;
        self.timeline.land(look, self.edge_started.elapsed());
        self.landing_look = look;
        self.animate = !reduce_motion();
        self.fade_landing();
        self.landing.orderFrontRegardless();
        self.arm_timer();
    }

    fn render_edge(&mut self) {
        if self
            .timeline
            .render_edge(&mut self.glow_frame, self.edge_started.elapsed())
        {
            self.glow_bitmap.show(&self.glow_fill, &self.glow_frame);
        } else {
            self.glow.orderOut(None);
        }
    }

    fn animate_frame(&mut self) {
        self.render_edge();
        if self.timeline.landing_visible() {
            self.fade_landing();
        }
        self.arm_timer();
    }

    fn arm_timer(&mut self) {
        let running = self
            .timeline
            .edge_playing(self.glow_frame.animate, self.edge_started.elapsed())
            || self.timeline.landing_visible();
        if running && self.timer_running {
            return;
        }
        self.timer_running = running;
        let delay = if running {
            self.pace_timer();
            self.hide_landing.interval()
        } else {
            TIMER_DISARMED_SECONDS
        };
        self.hide_landing
            .set_next_fire_date(CFAbsoluteTimeGetCurrent() + delay);
    }

    /// A repeating timer cannot change its interval, so a display with another
    /// refresh rate gets a new timer. `arm_timer` calls it once per effect, when it starts.
    fn pace_timer(&mut self) {
        let seconds = frame_interval(self.refresh_hz()).as_secs_f64();
        if (self.hide_landing.interval() - seconds).abs() < f64::EPSILON {
            return;
        }
        if let Some(timer) = frame_timer(self.timer_info, seconds) {
            self.hide_landing.invalidate();
            self.hide_landing = timer;
        }
    }

    /// The refresh rate of the screen the playing effect is on.
    fn refresh_hz(&self) -> Option<f64> {
        let panel = if self.timeline.landing_visible() {
            &self.landing
        } else {
            &self.glow
        };
        let frames = panel.screen()?.maximumFramesPerSecond();
        i32::try_from(frames).ok().map(f64::from)
    }

    fn fade_landing(&mut self) {
        let look = self.landing_look;
        let diameter = look.arrival_diameter();
        let point = (self.landing_center.0, -self.landing_center.1);
        let screens = screen_frames(self.mtm);
        let Some(screen) =
            geometry::screen_containing(&screens, self.landing_center.0, self.landing_center.1)
        else {
            return;
        };
        let area = Rect {
            y: -screen.y - screen.height,
            ..screen
        };
        let rect = look::landing_rect(area, point, diameter);
        self.landing.setFrame_display(
            ns_rect(Rect {
                y: -rect.y - rect.height,
                ..rect
            }),
            false,
        );
        let scale = self.landing.backingScaleFactor();
        self.landing_frame.resize(
            pixel_size(rect.width * scale),
            pixel_size(rect.height * scale),
        );
        self.landing_frame.arrival = Some(Arrival::at(rect, point, scale));
        self.landing_frame.animate = self.animate;
        self.landing_frame.dark = true;
        self.landing_frame.opacity = 1.0;
        self.landing_frame.scale = scale;
        if !self
            .timeline
            .render_landing(&mut self.landing_frame, self.edge_started.elapsed())
        {
            self.landing.orderOut(None);
            return;
        }
        self.landing_bitmap
            .show(&self.landing_fill, &self.landing_frame);
    }
}

/// The repeating frame timer on the main run loop; `info` is the leaked [`Ui`].
fn frame_timer(info: *mut c_void, seconds: f64) -> Option<CFRetained<CFRunLoopTimer>> {
    let mut context = CFRunLoopTimerContext {
        version: 0,
        info,
        retain: None,
        release: None,
        copyDescription: None,
    };
    // SAFETY: The default allocator accepts None; `info` is the leaked Ui
    // that `hide_landing` expects and the context is copied.
    let timer = unsafe {
        CFRunLoopTimer::new(
            None,
            CFAbsoluteTimeGetCurrent() + TIMER_DISARMED_SECONDS,
            seconds,
            0,
            0,
            Some(hide_landing),
            &raw mut context,
        )
    }?;
    // SAFETY: Core Foundation's default run-loop mode is an immutable global.
    CFRunLoop::current()?.add_timer(Some(&timer), unsafe { kCFRunLoopDefaultMode });
    Some(timer)
}

/// A borderless panel that cannot become key, ignores the mouse, floats over
/// every Space and full-screen app, and is excluded from screen capture.
fn make_panel(mtm: MainThreadMarker, content: &NSImageView) -> Retained<NSPanel> {
    let style = NSWindowStyleMask::Borderless | NSWindowStyleMask::NonactivatingPanel;
    let panel = NSPanel::initWithContentRect_styleMask_backing_defer(
        mtm.alloc::<NSPanel>(),
        NSRect::ZERO,
        style,
        NSBackingStoreType::Buffered,
        false,
    );
    panel.setOpaque(false);
    panel.setBackgroundColor(Some(&NSColor::clearColor()));
    panel.setHasShadow(false);
    panel.setIgnoresMouseEvents(true);
    panel.setLevel(NSStatusWindowLevel);
    panel.setSharingType(NSWindowSharingType::None);
    panel.setHidesOnDeactivate(false);
    panel.setCollectionBehavior(
        NSWindowCollectionBehavior::CanJoinAllSpaces
            | NSWindowCollectionBehavior::Stationary
            | NSWindowCollectionBehavior::IgnoresCycle
            | NSWindowCollectionBehavior::FullScreenAuxiliary,
    );
    panel.setContentView(Some(content));
    panel
}

fn image_view(mtm: MainThreadMarker) -> Retained<NSImageView> {
    NSImageView::initWithFrame(mtm.alloc::<NSImageView>(), NSRect::ZERO)
}

// Screen dimensions are finite, positive OS values in points.
#[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
fn pixel_size(value: f64) -> u32 {
    value.round().max(1.0) as u32
}

fn reduce_motion() -> bool {
    NSWorkspace::sharedWorkspace().accessibilityDisplayShouldReduceMotion()
}

fn tick_haptics() {
    NSHapticFeedbackManager::defaultPerformer().performFeedbackPattern_performanceTime(
        NSHapticFeedbackPattern::Alignment,
        NSHapticFeedbackPerformanceTime::Now,
    );
}

/// All screen frames in `AppKit` space, the primary screen first.
fn screen_frames(mtm: MainThreadMarker) -> Vec<Rect> {
    NSScreen::screens(mtm)
        .iter()
        .map(|screen| {
            let frame = screen.frame();
            Rect {
                x: frame.origin.x,
                y: frame.origin.y,
                width: frame.size.width,
                height: frame.size.height,
            }
        })
        .collect()
}

fn ns_rect(rect: Rect) -> NSRect {
    NSRect::new(
        NSPoint::new(rect.x, rect.y),
        NSSize::new(rect.width, rect.height),
    )
}