cursor-flasher/src/cursor_flasher/overlay.py

"""Native macOS overlay window that draws a pulsing border around a target window."""
import math

import objc
from Cocoa import (
    NSApplication,
    NSWindow,
    NSBorderlessWindowMask,
    NSColor,
    NSView,
    NSBezierPath,
    NSTimer,
    NSScreen,
)
from Foundation import NSInsetRect
from Quartz import (
    CGWindowListCopyWindowInfo,
    kCGWindowListOptionOnScreenOnly,
    kCGNullWindowID,
    kCGWindowOwnerPID,
    kCGWindowBounds,
    kCGWindowLayer,
    kCGWindowNumber,
)

from cursor_flasher.config import Config


def hex_to_nscolor(hex_str: str, alpha: float = 1.0) -> NSColor:
    """Convert a hex color string to NSColor."""
    hex_str = hex_str.lstrip("#")
    r = int(hex_str[0:2], 16) / 255.0
    g = int(hex_str[2:4], 16) / 255.0
    b = int(hex_str[4:6], 16) / 255.0
    return NSColor.colorWithCalibratedRed_green_blue_alpha_(r, g, b, alpha)


class PulseBorderView(NSView):
    """Custom view that draws a pulsing border rectangle."""

    def initWithFrame_config_(self, frame, config):
        self = objc.super(PulseBorderView, self).initWithFrame_(frame)
        if self is None:
            return None
        self._config = config
        self._phase = 0.0
        return self

    def drawRect_(self, rect):
        opacity_range = self._config.pulse_opacity_max - self._config.pulse_opacity_min
        alpha = self._config.pulse_opacity_min + opacity_range * (
            0.5 + 0.5 * math.sin(self._phase)
        )

        color = hex_to_nscolor(self._config.pulse_color, alpha)
        color.setStroke()

        width = self._config.pulse_width
        inset = width / 2.0
        bounds = objc.super(PulseBorderView, self).bounds()
        inset_rect = NSInsetRect(bounds, inset, inset)
        path = NSBezierPath.bezierPathWithRect_(inset_rect)
        path.setLineWidth_(width)
        path.stroke()

    def setPhase_(self, phase):
        self._phase = phase
        self.setNeedsDisplay_(True)


class _OverlayEntry:
    """A single overlay window + view pair."""
    __slots__ = ("window", "view")

    def __init__(self, window: NSWindow, view: PulseBorderView):
        self.window = window
        self.view = view


class OverlayManager:
    """Manages overlay windows for all Cursor windows belonging to a PID.

    Creates one transparent overlay per Cursor window and keeps them
    positioned and animated in sync.
    """

    def __init__(self, config: Config):
        self._config = config
        self._overlays: list[_OverlayEntry] = []
        self._timer: NSTimer | None = None
        self._phase = 0.0
        self._target_pid: int | None = None

    def show(self, pid: int) -> None:
        """Show pulsing overlays around every window belonging to `pid`."""
        self._target_pid = pid
        frames = self._get_all_window_frames(pid)
        if not frames:
            return

        self._sync_overlays(frames)

        for entry in self._overlays:
            entry.window.orderFrontRegardless()

        self._start_animation()

    def hide(self) -> None:
        """Hide all overlay windows."""
        self._stop_animation()
        for entry in self._overlays:
            entry.window.orderOut_(None)

    def update_positions(self) -> None:
        """Reposition overlays to track current Cursor window positions."""
        if self._target_pid is None:
            return
        frames = self._get_all_window_frames(self._target_pid)
        self._sync_overlays(frames)

    def _sync_overlays(self, frames: list[tuple]) -> None:
        """Ensure we have exactly len(frames) overlays, positioned correctly.

        Reuses existing overlay windows where possible, creates new ones
        if more windows appeared, and hides extras if windows closed.
        """
        needed = len(frames)
        existing = len(self._overlays)

        for i in range(needed):
            frame = frames[i]
            content_rect = ((0, 0), (frame[1][0], frame[1][1]))

            if i < existing:
                entry = self._overlays[i]
                entry.window.setFrame_display_(frame, True)
                entry.view.setFrame_(content_rect)
            else:
                entry = self._create_overlay(frame)
                self._overlays.append(entry)
                entry.window.orderFrontRegardless()

        for i in range(needed, existing):
            self._overlays[i].window.orderOut_(None)

        if needed < existing:
            self._overlays = self._overlays[:needed]

    def _create_overlay(self, frame) -> _OverlayEntry:
        window = NSWindow.alloc().initWithContentRect_styleMask_backing_defer_(
            frame, NSBorderlessWindowMask, 2, False  # NSBackingStoreBuffered
        )
        window.setOpaque_(False)
        window.setBackgroundColor_(NSColor.clearColor())
        window.setLevel_(25)  # Above normal windows
        window.setIgnoresMouseEvents_(True)
        window.setHasShadow_(False)

        content_rect = ((0, 0), (frame[1][0], frame[1][1]))
        view = PulseBorderView.alloc().initWithFrame_config_(
            content_rect, self._config
        )
        window.setContentView_(view)
        return _OverlayEntry(window, view)

    def _start_animation(self) -> None:
        if self._timer is not None:
            return
        interval = 1.0 / 30.0  # 30 fps
        self._timer = NSTimer.scheduledTimerWithTimeInterval_target_selector_userInfo_repeats_(
            interval, self, "_tick:", None, True
        )

    def _stop_animation(self) -> None:
        if self._timer is not None:
            self._timer.invalidate()
            self._timer = None
        self._phase = 0.0

    @objc.python_method
    def _tick_impl(self):
        speed = self._config.pulse_speed
        step = (2.0 * math.pi) / (speed * 30.0)
        self._phase += step
        for entry in self._overlays:
            entry.view.setPhase_(self._phase)
        self.update_positions()

    def _tick_(self, timer) -> None:
        self._tick_impl()

    def _get_all_window_frames(self, pid: int) -> list[tuple]:
        """Get screen frames for all on-screen windows belonging to `pid`."""
        window_list = CGWindowListCopyWindowInfo(
            kCGWindowListOptionOnScreenOnly, kCGNullWindowID
        )
        if not window_list:
            return []

        screen_height = NSScreen.mainScreen().frame().size.height
        frames = []

        for info in window_list:
            if info.get(kCGWindowOwnerPID) != pid:
                continue
            if info.get(kCGWindowLayer, 999) != 0:
                continue
            bounds = info.get(kCGWindowBounds)
            if bounds is None:
                continue
            w = bounds["Width"]
            h = bounds["Height"]
            if w < 100 or h < 100:
                continue
            x = bounds["X"]
            y = screen_height - bounds["Y"] - h
            frames.append(((x, y), (w, h)))

        return frames