azul-core 0.0.9

//! Window configuration types, input state, and platform-specific options.
//!
//! This module defines the core types used by the windowing system:
//!
//! - **Window configuration**: [`WindowSize`], [`WindowFlags`], [`WindowPosition`],
//!   [`RendererOptions`], [`PlatformSpecificOptions`]
//! - **Input state**: [`KeyboardState`], [`MouseState`], [`TouchState`], [`CursorPosition`]
//! - **Monitor/display info**: [`Monitor`], [`MonitorId`], [`VideoMode`]
//! - **Virtual key codes**: [`VirtualKeyCode`], [`ScanCode`]
//! - **Window icons**: [`WindowIcon`], [`TaskBarIcon`]
//! - **Platform options**: [`WindowsWindowOptions`], [`LinuxWindowOptions`],
//!   [`MacWindowOptions`], [`WasmWindowOptions`]
//!
//! These types are consumed by the platform shell backends in
//! `dll/src/desktop/shell2/{windows,macos,linux}/` and by
//! `layout/src/window_state.rs` for state management.

#[cfg(not(feature = "std"))]
use alloc::string::{String, ToString};
use alloc::{
    boxed::Box,
    collections::{btree_map::BTreeMap, btree_set::BTreeSet},
    vec::Vec,
};
use core::{
    cmp::Ordering,
    ffi::c_void,
    hash::{Hash, Hasher},
    ops,
    sync::atomic::{AtomicI64, AtomicUsize, Ordering as AtomicOrdering},
};

use azul_css::{
    css::CssPath,
    props::{
        basic::{ColorU, FloatValue, LayoutPoint, LayoutRect, LayoutSize},
        property::CssProperty,
    },
    AzString, LayoutDebugMessage, OptionF32, OptionI32, OptionString, OptionU32, U8Vec,
};
use rust_fontconfig::FcFontCache;

use crate::{
    callbacks::{LayoutCallback, LayoutCallbackType, Update},
    dom::{DomId, DomNodeId, NodeHierarchy},
    geom::{
        LogicalPosition, LogicalRect, LogicalSize, OptionLogicalSize, PhysicalPositionI32,
        PhysicalSize,
    },
    gl::OptionGlContextPtr,
    hit_test::{ExternalScrollId, OverflowingScrollNode},
    id::{NodeDataContainer, NodeId},
    refany::OptionRefAny,
    resources::{
        DpiScaleFactor, Epoch, GlTextureCache, IdNamespace, ImageCache, ImageMask, ImageRef,
        RendererResources, ResourceUpdate,
    },
    selection::SelectionState,
    styled_dom::NodeHierarchyItemId,
    task::{Instant, ThreadId, TimerId},
    FastBTreeSet, OrderedMap,
};

pub const DEFAULT_TITLE: &str = "Azul App";

static LAST_WINDOW_ID: AtomicI64 = AtomicI64::new(0);

/// Unique identifier for a window, auto-assigned via atomic counter.
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
#[repr(transparent)]
pub struct WindowId {
    pub id: i64,
}

impl Default for WindowId {
    fn default() -> Self {
        Self::new()
    }
}

impl WindowId {
    pub fn new() -> Self {
        Self {
            id: LAST_WINDOW_ID.fetch_add(1, AtomicOrdering::SeqCst),
        }
    }
}

static LAST_ICON_KEY: AtomicUsize = AtomicUsize::new(0);

/// Key that is used for checking whether a window icon has changed -
/// this way azul doesn't need to diff the actual bytes, just the icon key.
/// Use `IconKey::new()` to generate a new, unique key
#[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
#[repr(C)]
pub struct IconKey {
    icon_id: usize,
}

impl Default for IconKey {
    fn default() -> Self {
        Self::new()
    }
}

impl IconKey {
    pub fn new() -> Self {
        Self {
            icon_id: LAST_ICON_KEY.fetch_add(1, AtomicOrdering::SeqCst),
        }
    }
}

#[repr(C)]
#[derive(PartialEq, Copy, Clone, Debug, PartialOrd, Ord, Eq, Hash)]
pub struct RendererOptions {
    pub vsync: Vsync,
    pub srgb: Srgb,
    pub hw_accel: HwAcceleration,
}

impl_option!(
    RendererOptions,
    OptionRendererOptions,
    [PartialEq, Copy, Clone, Debug, PartialOrd, Ord, Eq, Hash]
);

impl Default for RendererOptions {
    fn default() -> Self {
        Self {
            vsync: Vsync::Enabled,
            srgb: Srgb::Disabled,
            // DontCare resolves to AzBackend::Auto: try GPU first, fall back
            // to CPU rendering on GL failure / blacklisted driver. Disabled
            // here silently forced EVERY app that didn't set renderer options
            // into CPU rendering on all platforms (the GL probe never ran).
            hw_accel: HwAcceleration::DontCare,
        }
    }
}

impl RendererOptions {
    #[must_use] pub const fn new(vsync: Vsync, srgb: Srgb, hw_accel: HwAcceleration) -> Self {
        Self {
            vsync,
            srgb,
            hw_accel,
        }
    }
}

#[repr(C)]
#[derive(PartialEq, Copy, Clone, Debug, PartialOrd, Ord, Eq, Hash)]
pub enum Vsync {
    Enabled,
    Disabled,
    DontCare,
}

impl Vsync {
    #[must_use] pub const fn is_enabled(&self) -> bool {
        matches!(self, Self::Enabled)
    }
}

#[repr(C)]
#[derive(PartialEq, Copy, Clone, Debug, PartialOrd, Ord, Eq, Hash)]
pub enum Srgb {
    Enabled,
    Disabled,
    DontCare,
}
impl Srgb {
    #[must_use] pub const fn is_enabled(&self) -> bool {
        matches!(self, Self::Enabled)
    }
}

#[repr(C)]
#[derive(PartialEq, Copy, Clone, Debug, PartialOrd, Ord, Eq, Hash)]
pub enum HwAcceleration {
    Enabled,
    Disabled,
    DontCare,
}
impl HwAcceleration {
    #[must_use] pub const fn is_enabled(&self) -> bool {
        matches!(self, Self::Enabled)
    }
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C, u8)]
pub enum RawWindowHandle {
    IOS(IOSHandle),
    MacOS(MacOSHandle),
    Xlib(XlibHandle),
    Xcb(XcbHandle),
    Wayland(WaylandHandle),
    Windows(WindowsHandle),
    Web(WebHandle),
    Android(AndroidHandle),
    Unsupported,
}

// SAFETY: RawWindowHandle contains raw pointers that are only used as opaque
// identifiers for platform window handles. The handle values are not
// dereferenced across threads; they are passed to platform APIs on the main thread.
unsafe impl Send for RawWindowHandle {}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
pub struct IOSHandle {
    pub ui_window: *mut c_void,
    pub ui_view: *mut c_void,
    pub ui_view_controller: *mut c_void,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
pub struct MacOSHandle {
    pub ns_window: *mut c_void,
    pub ns_view: *mut c_void,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
pub struct XlibHandle {
    /// An Xlib Window
    pub window: u64,
    pub display: *mut c_void,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
pub struct XcbHandle {
    /// An X11 `xcb_window_t`.
    pub window: u32,
    /// A pointer to an X server `xcb_connection_t`.
    pub connection: *mut c_void,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
pub struct WaylandHandle {
    /// A pointer to a `wl_surface`
    pub surface: *mut c_void,
    /// A pointer to a `wl_display`.
    pub display: *mut c_void,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
pub struct WindowsHandle {
    /// A Win32 HWND handle.
    pub hwnd: *mut c_void,
    /// The HINSTANCE associated with this type's HWND.
    pub hinstance: *mut c_void,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
pub struct WebHandle {
    /// An ID value inserted into the data attributes of the canvas element as 'raw-handle'
    ///
    /// When accessing from JS, the attribute will automatically be called rawHandle. Each canvas
    /// created by the windowing system should be assigned their own unique ID.
    /// 0 should be reserved for invalid / null IDs.
    pub id: u32,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
pub struct AndroidHandle {
    /// A pointer to an `ANativeWindow`.
    pub a_native_window: *mut c_void,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
#[derive(Default)]
pub enum MouseCursorType {
    #[default]
    Default,
    Crosshair,
    Hand,
    Arrow,
    Move,
    Text,
    Wait,
    Help,
    Progress,
    NotAllowed,
    ContextMenu,
    Cell,
    VerticalText,
    Alias,
    Copy,
    NoDrop,
    Grab,
    Grabbing,
    AllScroll,
    ZoomIn,
    ZoomOut,
    EResize,
    NResize,
    NeResize,
    NwResize,
    SResize,
    SeResize,
    SwResize,
    WResize,
    EwResize,
    NsResize,
    NeswResize,
    NwseResize,
    ColResize,
    RowResize,
}


/// Hardware-dependent keyboard scan code.
pub type ScanCode = u32;

/// Determines which keys are pressed currently (modifiers, etc.)
#[derive(Default, Debug, Clone, PartialEq, Eq)]
#[repr(C)]
pub struct KeyboardState {
    /// Currently pressed virtual keycode - **DO NOT USE THIS FOR TEXT INPUT**.
    ///
    /// For text input, use the `text_input` parameter in callbacks.
    /// For example entering `à` will fire a `VirtualKeyCode::Grave`, then `VirtualKeyCode::A`,
    /// so to correctly combine characters, the framework handles text composition internally.
    pub current_virtual_keycode: OptionVirtualKeyCode,
    /// Currently pressed virtual keycodes (READONLY) - it can happen that more than one key is
    /// pressed
    ///
    /// This is essentially an "extension" of `current_scancodes` - `current_keys` stores the
    /// characters, but what if the pressed key is not a character (such as `ArrowRight` or
    /// `PgUp`)?
    ///
    /// Note that this can have an overlap, so pressing "a" on the keyboard will insert
    /// both a `VirtualKeyCode::A` into `current_virtual_keycodes` and text input will be handled
    /// by the framework automatically for contenteditable nodes.
    pub pressed_virtual_keycodes: VirtualKeyCodeVec,
    /// Same as `current_virtual_keycodes`, but the scancode identifies the physical key pressed,
    /// independent of the keyboard layout. The scancode does not change if the user adjusts the
    /// host's keyboard map. Use when the physical location of the key is more important than
    /// the key's host GUI semantics, such as for movement controls in a first-person game
    /// (German keyboard: Z key, UK keyboard: Y key, etc.)
    pub pressed_scancodes: ScanCodeVec,
}

impl KeyboardState {
    #[must_use] pub fn shift_down(&self) -> bool {
        self.is_key_down(VirtualKeyCode::LShift) || self.is_key_down(VirtualKeyCode::RShift)
    }
    #[must_use] pub fn ctrl_down(&self) -> bool {
        self.is_key_down(VirtualKeyCode::LControl) || self.is_key_down(VirtualKeyCode::RControl)
    }
    #[must_use] pub fn alt_down(&self) -> bool {
        self.is_key_down(VirtualKeyCode::LAlt) || self.is_key_down(VirtualKeyCode::RAlt)
    }
    #[must_use] pub fn super_down(&self) -> bool {
        self.is_key_down(VirtualKeyCode::LWin) || self.is_key_down(VirtualKeyCode::RWin)
    }
    /// The platform's PRIMARY shortcut modifier: Cmd (super) on macOS, Ctrl
    /// everywhere else (MWA-A2). Every standard editing shortcut
    /// (copy / cut / paste / select-all / undo / redo) keys off this —
    /// hardcoding `ctrl_down()` made Cmd+C/X/V/A/Z dead on macOS, where Cmd
    /// arrives as LWin/super.
    #[must_use] pub fn primary_down(&self) -> bool {
        if cfg!(target_os = "macos") {
            self.super_down()
        } else {
            self.ctrl_down()
        }
    }
    #[must_use] pub fn is_key_down(&self, key: VirtualKeyCode) -> bool {
        self.pressed_virtual_keycodes.iter().any(|k| *k == key)
    }

    /// Returns `true` iff every entry of `chord` is currently active in this
    /// keyboard state. Used by accelerator/keymap registrations to evaluate
    /// shortcuts like `[Ctrl, Shift, Key(VirtualKeyCode::S)]`.
    ///
    /// An empty chord matches trivially.
    #[must_use] pub fn matches_accelerator(&self, chord: &[AcceleratorKey]) -> bool {
        chord.iter().all(|a| a.matches(self))
    }
}

impl_option!(
    KeyboardState,
    OptionKeyboardState,
    copy = false,
    [Debug, Clone, PartialEq, Eq]
);

// char is not ABI-stable, use u32 instead
impl_option!(
    u32,
    OptionChar,
    [Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash]
);
impl_option!(
    VirtualKeyCode,
    OptionVirtualKeyCode,
    [Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash]
);

impl_vec!(VirtualKeyCode, VirtualKeyCodeVec, VirtualKeyCodeVecDestructor, VirtualKeyCodeVecDestructorType, VirtualKeyCodeVecSlice, OptionVirtualKeyCode);
impl_vec_debug!(VirtualKeyCode, VirtualKeyCodeVec);
impl_vec_partialord!(VirtualKeyCode, VirtualKeyCodeVec);
impl_vec_ord!(VirtualKeyCode, VirtualKeyCodeVec);
impl_vec_clone!(
    VirtualKeyCode,
    VirtualKeyCodeVec,
    VirtualKeyCodeVecDestructor
);
impl_vec_partialeq!(VirtualKeyCode, VirtualKeyCodeVec);
impl_vec_eq!(VirtualKeyCode, VirtualKeyCodeVec);
impl_vec_hash!(VirtualKeyCode, VirtualKeyCodeVec);
impl_vec_mut!(VirtualKeyCode, VirtualKeyCodeVec);

impl_vec_as_hashmap!(VirtualKeyCode, VirtualKeyCodeVec);

impl_vec!(ScanCode, ScanCodeVec, ScanCodeVecDestructor, ScanCodeVecDestructorType, ScanCodeVecSlice, OptionU32);
impl_vec_debug!(ScanCode, ScanCodeVec);
impl_vec_partialord!(ScanCode, ScanCodeVec);
impl_vec_ord!(ScanCode, ScanCodeVec);
impl_vec_clone!(ScanCode, ScanCodeVec, ScanCodeVecDestructor);
impl_vec_partialeq!(ScanCode, ScanCodeVec);
impl_vec_eq!(ScanCode, ScanCodeVec);
impl_vec_hash!(ScanCode, ScanCodeVec);
impl_vec_mut!(ScanCode, ScanCodeVec);

impl_vec_as_hashmap!(ScanCode, ScanCodeVec);

/// Mouse position, cursor type, user scroll input, etc.
#[derive(Debug, Copy, Clone, PartialOrd, PartialEq, Eq)]
#[repr(C)]
pub struct MouseState {
    /// Current mouse cursor type, set to `None` if the cursor is hidden. (READWRITE)
    pub mouse_cursor_type: OptionMouseCursorType,
    /// Where is the mouse cursor currently? Set to `None` if the window is not focused.
    /// (READWRITE)
    pub cursor_position: CursorPosition,
    /// Is the mouse cursor locked to the current window (important for applications like games)?
    /// (READWRITE)
    pub is_cursor_locked: bool,
    /// Is the left mouse button down? (READONLY)
    pub left_down: bool,
    /// Is the right mouse button down? (READONLY)
    pub right_down: bool,
    /// Is the middle mouse button down? (READONLY)
    pub middle_down: bool,
}

impl MouseState {
    #[must_use] pub const fn matches(&self, context: &ContextMenuMouseButton) -> bool {
        use self::ContextMenuMouseButton::{Left, Right, Middle};
        match context {
            Left => self.left_down,
            Right => self.right_down,
            Middle => self.middle_down,
        }
    }
}

impl_option!(
    MouseState,
    OptionMouseState,
    [Debug, Copy, Clone, PartialEq, Eq, PartialOrd]
);

impl_option!(
    MouseCursorType,
    OptionMouseCursorType,
    [Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash]
);

impl Default for MouseState {
    fn default() -> Self {
        Self {
            mouse_cursor_type: Some(MouseCursorType::Default).into(),
            cursor_position: CursorPosition::default(),
            is_cursor_locked: false,
            left_down: false,
            right_down: false,
            middle_down: false,
        }
    }
}

#[derive(Debug, Clone, PartialEq, PartialOrd, Hash, Eq, Ord)]
#[repr(C)]
pub struct VirtualKeyCodeCombo {
    pub keys: VirtualKeyCodeVec,
}

impl_option!(
    VirtualKeyCodeCombo,
    OptionVirtualKeyCodeCombo,
    copy = false,
    [Debug, Clone, PartialEq, PartialOrd, Hash, Eq, Ord]
);

#[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Hash, Eq, Ord)]
#[repr(C)]
#[derive(Default)]
pub enum ContextMenuMouseButton {
    #[default]
    Right,
    Middle,
    Left,
}


impl MouseState {
    /// Returns whether any mouse button (left, right or center) is currently held down
    #[must_use] pub const fn mouse_down(&self) -> bool {
        self.right_down || self.left_down || self.middle_down
    }

    /// Snapshot the button-down flags as a `MouseButtonState` for drag tracking.
    #[must_use] pub const fn button_state(&self) -> crate::events::MouseButtonState {
        crate::events::MouseButtonState {
            left_down: self.left_down,
            right_down: self.right_down,
            middle_down: self.middle_down,
        }
    }
}

impl From<&MouseState> for crate::events::MouseButtonState {
    fn from(s: &MouseState) -> Self {
        s.button_state()
    }
}

impl crate::events::MouseButtonState {
    /// Returns true if any of the tracked buttons is held down.
    #[must_use] pub const fn any_down(&self) -> bool {
        self.left_down || self.right_down || self.middle_down
    }
}

/// Result of dispatching a scroll delta into the system scroll-handling pipeline.
///
/// Returned by [`process_system_scroll`]. Higher layers can use the
/// [`ScrollResult::remaining_delta`] to forward un-consumed scroll to a parent
/// container, and [`ScrollResult::hit_scrollbar`] to distinguish scrollbar-drag
/// scrolling from wheel-on-content scrolling for hit-testing purposes.
#[derive(Debug, Default, Copy, Clone, PartialEq, Eq, PartialOrd)]
#[repr(C)]
pub struct ScrollResult {
    /// Number of scrollable nodes whose offset was updated by this dispatch.
    pub scrolled_nodes: usize,
    /// Delta that could not be consumed (overscroll). May be forwarded to a parent.
    pub remaining_delta: LogicalPosition,
    /// `true` if the dispatch hit a native scrollbar (drag), `false` for wheel/touch.
    pub hit_scrollbar: bool,
}

/// Dispatch a system scroll event and return a [`ScrollResult`] describing what
/// happened.
///
/// This is the entry point used by headless integration tests and embedders that
/// drive scroll programmatically. The richer per-document scroll handling lives
/// in `LayoutWindow::process_scroll`; this helper packages a delta into a
/// `ScrollResult` for return to callers so the result type is observable from
/// the public API.
#[must_use] pub fn process_system_scroll(delta: LogicalPosition, hit_scrollbar: bool) -> ScrollResult {
    let consumed = delta.x != 0.0 || delta.y != 0.0;
    ScrollResult {
        scrolled_nodes: usize::from(consumed),
        remaining_delta: LogicalPosition::zero(),
        hit_scrollbar,
    }
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd)]
#[repr(C, u8)]
#[derive(Default)]
pub enum CursorPosition {
    OutOfWindow(LogicalPosition),
    #[default]
    Uninitialized,
    InWindow(LogicalPosition),
}


impl CursorPosition {
    #[must_use] pub const fn get_position(&self) -> Option<LogicalPosition> {
        match self {
            Self::InWindow(logical_pos) => Some(*logical_pos),
            Self::OutOfWindow(_) | Self::Uninitialized => None,
        }
    }

    #[must_use] pub const fn is_inside_window(&self) -> bool {
        self.get_position().is_some()
    }
}

/// Toggles webrender debug flags (will make stuff appear on
/// the screen that you might not want to - used for debugging purposes)
#[derive(Default, Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
#[repr(C)]
pub struct DebugState {
    pub profiler_dbg: bool,
    pub render_target_dbg: bool,
    pub texture_cache_dbg: bool,
    pub gpu_time_queries: bool,
    pub gpu_sample_queries: bool,
    pub disable_batching: bool,
    pub epochs: bool,
    pub echo_driver_messages: bool,
    pub show_overdraw: bool,
    pub gpu_cache_dbg: bool,
    pub texture_cache_dbg_clear_evicted: bool,
    pub picture_caching_dbg: bool,
    pub primitive_dbg: bool,
    pub zoom_dbg: bool,
    pub small_screen: bool,
    pub disable_opaque_pass: bool,
    pub disable_alpha_pass: bool,
    pub disable_clip_masks: bool,
    pub disable_text_prims: bool,
    pub disable_gradient_prims: bool,
    pub obscure_images: bool,
    pub glyph_flashing: bool,
    pub smart_profiler: bool,
    pub invalidation_dbg: bool,
    pub tile_cache_logging_dbg: bool,
    pub profiler_capture: bool,
    pub force_picture_invalidation: bool,
}

#[derive(Debug, Default, Clone, PartialEq)]
#[repr(C)]
pub struct TouchState {
    /// Number of active touch points (kept in sync with `touch_points.len()`).
    pub num_touches: usize,
    /// Currently active touch points (one entry per finger / stylus).
    /// Backends update this on touch start / move / end events.
    pub touch_points: TouchPointVec,
}

/// Single touch point (finger, stylus, etc.)
#[derive(Debug, Copy, Clone, PartialEq, PartialOrd)]
#[repr(C)]
pub struct TouchPoint {
    /// Unique identifier for this touch point (persists across move events)
    pub id: u64,
    /// Current position of the touch point in logical coordinates
    pub position: LogicalPosition,
    /// Force/pressure of the touch (0.0 = no pressure, 1.0 = maximum pressure)
    /// Set to 0.5 if pressure is not available
    pub force: f32,
}

impl_option!(
    TouchPoint,
    OptionTouchPoint,
    [Debug, Copy, Clone, PartialEq, PartialOrd]
);

impl_vec!(TouchPoint, TouchPointVec, TouchPointVecDestructor, TouchPointVecDestructorType, TouchPointVecSlice, OptionTouchPoint);
impl_vec_debug!(TouchPoint, TouchPointVec);
impl_vec_clone!(TouchPoint, TouchPointVec, TouchPointVecDestructor);
impl_vec_partialeq!(TouchPoint, TouchPointVec);

/// State, size, etc of the window, for comparing to the last frame
#[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Hash, Ord, Eq)]
#[repr(C)]
#[derive(Default)]
pub enum WindowTheme {
    DarkMode,
    #[default]
    LightMode,
}


impl_option!(
    WindowTheme,
    OptionWindowTheme,
    [Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash]
);

/// Identifies a specific monitor/display
///
/// Contains both an index (for fast current-session lookup) and a stable hash
/// (for persistence across app restarts and monitor reconfigurations).
///
/// - `index`: Runtime index (0-based), may change if monitors are added/removed
/// - `hash`: Stable identifier based on monitor properties (name, size, position)
///
/// Applications can serialize `hash` to remember which monitor a window was on,
/// then search for matching hash on next launch, falling back to index or PRIMARY.
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
#[repr(C)]
pub struct MonitorId {
    /// Runtime index of the monitor (may change between sessions)
    pub index: usize,
    /// Stable hash of monitor properties (for persistence)
    pub hash: u64,
}

impl MonitorId {
    /// Primary/default monitor (index 0, hash 0)
    pub const PRIMARY: Self = Self { index: 0, hash: 0 };

    /// Create a `MonitorId` from index only (hash will be 0)
    #[must_use] pub const fn new(index: usize) -> Self {
        Self { index, hash: 0 }
    }

    /// Create a `MonitorId` from index and hash
    #[must_use] pub const fn from_index_and_hash(index: usize, hash: u64) -> Self {
        Self { index, hash }
    }

    /// Create a stable monitor ID from monitor properties
    ///
    /// Uses FNV-1a hash of: name + position + size
    /// This ensures the hash is stable across app restarts as long as
    /// the monitor configuration doesn't change significantly
    #[must_use] pub fn from_properties(
        index: usize,
        name: &str,
        position: LayoutPoint,
        size: LayoutSize,
    ) -> Self {
        use core::hash::{Hash, Hasher};

        // FNV-1a hash (simple, fast, good distribution)
        struct FnvHasher(u64);

        impl Hasher for FnvHasher {
            fn write(&mut self, bytes: &[u8]) {
                const FNV_PRIME: u64 = 0x0100_0000_01b3;
                for &byte in bytes {
                    self.0 ^= u64::from(byte);
                    self.0 = self.0.wrapping_mul(FNV_PRIME);
                }
            }

            fn finish(&self) -> u64 {
                self.0
            }
        }

        const FNV_OFFSET_BASIS: u64 = 0xcbf2_9ce4_8422_2325;
        let mut hasher = FnvHasher(FNV_OFFSET_BASIS);

        // Hash the monitor properties
        name.hash(&mut hasher);
        (position.x as i64).hash(&mut hasher);
        (position.y as i64).hash(&mut hasher);
        (size.width as i64).hash(&mut hasher);
        (size.height as i64).hash(&mut hasher);

        Self {
            index,
            hash: hasher.finish(),
        }
    }
}

impl_option!(
    MonitorId,
    OptionMonitorId,
    [Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash]
);

/// Complete information about a monitor/display
#[derive(Debug, PartialEq, PartialOrd, Clone)]
#[repr(C)]
pub struct Monitor {
    /// Unique identifier for this monitor (stable across frames)
    pub monitor_id: MonitorId,
    /// Human-readable name (e.g., "\\.\DISPLAY1", "HDMI-1", "Built-in Retina Display")
    pub monitor_name: OptionString,
    /// Physical size of the monitor in logical pixels
    pub size: LayoutSize,
    /// Position of the monitor in the virtual screen coordinate system
    pub position: LayoutPoint,
    /// DPI scale factor (1.0 = 96 DPI, 2.0 = 192 DPI for Retina)
    pub scale_factor: f64,
    /// Work area (monitor bounds minus taskbars/panels) in logical pixels
    pub work_area: LayoutRect,
    /// Available video modes for this monitor
    pub video_modes: VideoModeVec,
    /// Whether this is the primary/main monitor
    pub is_primary_monitor: bool,
}

impl_option!(
    Monitor,
    OptionMonitor,
    copy = false,
    [Debug, PartialEq, PartialOrd, Clone]
);

impl_vec!(Monitor, MonitorVec, MonitorVecDestructor, MonitorVecDestructorType, MonitorVecSlice, OptionMonitor);
impl_vec_debug!(Monitor, MonitorVec);
impl_vec_clone!(Monitor, MonitorVec, MonitorVecDestructor);
impl_vec_partialeq!(Monitor, MonitorVec);
impl_vec_partialord!(Monitor, MonitorVec);

impl Hash for Monitor {
    fn hash<H>(&self, state: &mut H)
    where
        H: Hasher,
    {
        self.monitor_id.hash(state);
    }
}

impl Default for Monitor {
    fn default() -> Self {
        Self {
            monitor_id: MonitorId::PRIMARY,
            monitor_name: OptionString::None,
            size: LayoutSize::zero(),
            position: LayoutPoint::zero(),
            scale_factor: 1.0,
            work_area: LayoutRect::zero(),
            video_modes: Vec::new().into(),
            is_primary_monitor: false,
        }
    }
}
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
pub struct VideoMode {
    pub size: LayoutSize,
    pub bit_depth: u16,
    pub refresh_rate: u16,
}

impl_option!(
    VideoMode,
    OptionVideoMode,
    [Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash]
);

impl_vec!(VideoMode, VideoModeVec, VideoModeVecDestructor, VideoModeVecDestructorType, VideoModeVecSlice, OptionVideoMode);
impl_vec_clone!(VideoMode, VideoModeVec, VideoModeVecDestructor);
impl_vec_debug!(VideoMode, VideoModeVec);
impl_vec_partialeq!(VideoMode, VideoModeVec);
impl_vec_partialord!(VideoMode, VideoModeVec);

/// Position of the window on screen
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[repr(C, u8)]
#[derive(Default)]
pub enum WindowPosition {
    #[default]
    Uninitialized,
    /// Absolute position on the virtual screen (physical px). The default for
    /// top-level windows.
    Initialized(PhysicalPositionI32),
    /// Offset (physical px) from the PARENT window's top-left corner. Used by
    /// child windows (menus, dropdowns, popups) together with
    /// `WindowCreateOptions.parent_window_id`: the backend resolves the final
    /// screen position as `parent_top_left + offset`. This is robust where
    /// absolute screen coordinates aren't available — notably Wayland, whose
    /// `xdg_popup` / subsurface protocol positions relative to the parent. Falls
    /// back to absolute (`offset` from origin) if there is no parent.
    RelativeToParentWindow(PhysicalPositionI32),
}
#[allow(variant_size_differences)] // repr(C,u8) FFI enum: boxing the large variant would change the C ABI (api.json bindings); size disparity accepted

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
#[repr(C, u8)]
/// IME composition window rectangle (cursor position + height)
#[derive(Default)]
pub enum ImePosition {
    #[default]
    Uninitialized,
    Initialized(LogicalRect),
}


#[derive(Debug, Copy, Clone, PartialEq, Eq, Ord, PartialOrd, Hash)]
#[repr(C)]
pub struct WindowFlags {
    /// Is the window currently maximized, minimized or fullscreen
    pub frame: WindowFrame,
    /// Window decoration style (title bar, native controls)
    pub decorations: WindowDecorations,
    /// Compositor blur/transparency effect material
    pub background_material: WindowBackgroundMaterial,
    /// Window type classification (Normal, Menu, Tooltip, Dialog)
    pub window_type: WindowType,
    /// User clicked the close button (set by `WindowDelegate`, checked by event loop)
    /// The `close_callback` can set this to false to prevent closing
    pub close_requested: bool,
    /// Is the window currently visible?
    pub is_visible: bool,
    /// Is the window always on top?
    pub is_always_on_top: bool,
    /// Whether the window is resizable
    pub is_resizable: bool,
    /// Whether the window has focus or not (mutating this will request user attention)
    pub has_focus: bool,
    /// Is smooth scrolling enabled for this window?
    pub smooth_scroll_enabled: bool,
    /// Is automatic TAB switching supported?
    pub autotab_enabled: bool,
    /// Enable client-side decorations (custom titlebar with CSD)
    /// Only effective when decorations == `WindowDecorations::None`
    pub has_decorations: bool,
    /// Use native menus (Win32 HMENU, macOS `NSMenu`) instead of Azul window-based menus
    /// Default: true on Windows/macOS, false on Linux
    pub use_native_menus: bool,
    /// Use native context menus instead of Azul window-based context menus
    /// Default: true on Windows/macOS, false on Linux
    pub use_native_context_menus: bool,
    /// Keep window above all others (even from other applications)
    /// Platform-specific: Uses `SetWindowPos(HWND_TOPMOST)` on Windows, [`NSWindow` setLevel:] on
    /// macOS, _`NET_WM_STATE_ABOVE` on X11, `zwlr_layer_shell` on Wayland
    pub is_top_level: bool,
    /// Prevent system from sleeping while window is open
    /// Platform-specific: Uses `SetThreadExecutionState` on Windows, `IOPMAssertionCreateWithName` on
    /// macOS, org.freedesktop.ScreenSaver.Inhibit on Linux
    pub prevent_system_sleep: bool,
    /// Desired fullscreen-transition style.
    ///
    /// On macOS this controls whether entering/leaving fullscreen plays the
    /// system animation (`Slow*`) or transitions immediately (`Fast*`). On
    /// other platforms `Slow*` and `Fast*` behave identically.
    ///
    /// The actual current frame state still lives in [`WindowFlags::frame`]; this
    /// field only describes how the next transition should be performed.
    pub fullscreen_mode: FullScreenMode,
}

impl_option!(
    WindowFlags,
    OptionWindowFlags,
    copy = false,
    [Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash]
);

/// Window type classification for behavior control
#[derive(Debug, Copy, Clone, PartialEq, Eq, Ord, PartialOrd, Hash)]
#[repr(C)]
pub enum WindowType {
    /// Normal application window
    Normal,
    /// Menu popup window (always-on-top, frameless, auto-closes on focus loss)
    Menu,
    /// Tooltip window (always-on-top, no interaction)
    Tooltip,
    /// Dialog window (blocks parent window)
    Dialog,
}

impl Default for WindowType {
    fn default() -> Self {
        Self::Normal
    }
}

/// Window frame state (normal, minimized, maximized, fullscreen)
#[derive(Debug, Copy, Clone, PartialEq, Eq, Ord, PartialOrd, Hash)]
#[repr(C)]
pub enum WindowFrame {
    Normal,
    Minimized,
    Maximized,
    Fullscreen,
}

/// Window decoration style
#[derive(Debug, Copy, Clone, PartialEq, Eq, Ord, PartialOrd, Hash)]
#[repr(C)]
pub enum WindowDecorations {
    /// Full decorations: title bar with controls
    Normal,
    /// No title text but controls visible (extended frame).
    /// The application must draw its own title text.
    NoTitle,
    /// Like `NoTitle`, but the framework auto-injects a `Titlebar`
    /// at the top of the user's DOM after calling the layout callback.
    ///
    /// The injected titlebar reads `TitlebarMetrics` from `SystemStyle` for
    /// correct padding around the OS-drawn window control buttons, uses the
    /// system title font, and carries the `__azul-native-titlebar` class for
    /// automatic window-drag activation.
    NoTitleAutoInject,
    /// No controls visible but title bar area present
    NoControls,
    /// No decorations at all (borderless)
    None,
}

impl Default for WindowDecorations {
    fn default() -> Self {
        Self::Normal
    }
}

/// Compositor blur/transparency effects for window background
#[derive(Debug, Copy, Clone, PartialEq, Eq, Ord, PartialOrd, Hash)]
#[repr(C)]
pub enum WindowBackgroundMaterial {
    /// No transparency or blur
    Opaque,
    /// Transparent without blur
    Transparent,
    /// macOS: Sidebar material, Windows: Acrylic light
    Sidebar,
    /// macOS: Menu material, Windows: Acrylic
    Menu,
    /// macOS: HUD material, Windows: Acrylic dark
    HUD,
    /// macOS: Titlebar material, Windows: Mica
    Titlebar,
    /// Windows: Mica Alt material
    MicaAlt,
}

impl Default for WindowBackgroundMaterial {
    fn default() -> Self {
        Self::Opaque
    }
}

impl Default for WindowFlags {
    fn default() -> Self {
        Self {
            frame: WindowFrame::Normal,
            decorations: WindowDecorations::Normal,
            background_material: WindowBackgroundMaterial::Opaque,
            window_type: WindowType::Normal,
            close_requested: false,
            is_visible: true,
            is_always_on_top: false,
            is_resizable: true,
            has_focus: true,
            smooth_scroll_enabled: true,
            autotab_enabled: true,
            has_decorations: false,
            // Native menus are the default on platforms that support them (Windows/macOS)
            // The platform layer will override this appropriately
            use_native_menus: cfg!(any(target_os = "windows", target_os = "macos")),
            use_native_context_menus: cfg!(any(target_os = "windows", target_os = "macos")),
            is_top_level: false,
            prevent_system_sleep: false,
            fullscreen_mode: FullScreenMode::FastFullScreen,
        }
    }
}

impl WindowFlags {
    /// Check if window is a menu popup
    #[inline]
    #[must_use] pub fn is_menu_window(&self) -> bool {
        self.window_type == WindowType::Menu
    }

    /// Check if window is a tooltip
    #[inline]
    #[must_use] pub fn is_tooltip_window(&self) -> bool {
        self.window_type == WindowType::Tooltip
    }

    /// Check if window is a dialog
    #[inline]
    #[must_use] pub fn is_dialog_window(&self) -> bool {
        self.window_type == WindowType::Dialog
    }

    /// Check if window currently has focus
    #[inline]
    #[must_use] pub const fn window_has_focus(&self) -> bool {
        self.has_focus
    }

    /// Check if close was requested via callback
    #[inline]
    #[must_use] pub const fn is_close_requested(&self) -> bool {
        self.close_requested
    }

    /// Check if window has client-side decorations enabled
    #[inline]
    #[must_use] pub const fn has_csd(&self) -> bool {
        self.has_decorations
    }

    /// Check if native menus should be used
    #[inline]
    #[must_use] pub const fn use_native_menus(&self) -> bool {
        self.use_native_menus
    }

    /// Check if native context menus should be used
    #[inline]
    #[must_use] pub const fn use_native_context_menus(&self) -> bool {
        self.use_native_context_menus
    }
}

/// Platform-specific window configuration options (Windows, Linux, macOS, WASM)
#[derive(Debug, Default, Clone, PartialEq, PartialOrd)]
#[repr(C)]
pub struct PlatformSpecificOptions {
    pub windows_options: WindowsWindowOptions,
    pub linux_options: LinuxWindowOptions,
    pub mac_options: MacWindowOptions,
    pub wasm_options: WasmWindowOptions,
}

// SAFETY: PlatformSpecificOptions contains raw pointers (X11Visual) that are
// opaque platform handles, not dereferenced across threads.
unsafe impl Sync for PlatformSpecificOptions {}
#[allow(clippy::non_send_fields_in_send_ty)] // opaque platform handles, not dereferenced across threads (see note above)
unsafe impl Send for PlatformSpecificOptions {}

#[derive(Debug, Clone, PartialEq, Eq, PartialOrd)]
#[repr(C)]
pub struct WindowsWindowOptions {
    /// STARTUP ONLY: Whether the window should allow drag + drop operations (default: true)
    pub allow_drag_and_drop: bool,
    /// STARTUP ONLY: Sets `WS_EX_NOREDIRECTIONBITMAP`
    pub no_redirection_bitmap: bool,
    /// STARTUP ONLY: Window icon (decoded bytes), appears at the top right corner of the window
    pub window_icon: OptionWindowIcon,
    /// READWRITE: Taskbar icon (decoded bytes), usually 256x256x4 bytes large (`ICON_BIG`).
    ///
    /// Can be changed in callbacks / at runtime.
    pub taskbar_icon: OptionTaskBarIcon,
    // NOTE: the old Windows-specific `parent_window: OptionHwndHandle` field was
    // removed in favor of the cross-platform `WindowCreateOptions.parent_window_id`
    // (+ `WindowPosition::RelativeToParentWindow`), which every backend resolves
    // through its window registry. One parenting model for all platforms.
}

impl Default for WindowsWindowOptions {
    fn default() -> Self {
        Self {
            allow_drag_and_drop: true,
            no_redirection_bitmap: false,
            window_icon: OptionWindowIcon::None,
            taskbar_icon: OptionTaskBarIcon::None,
        }
    }
}

/// X window type. Maps directly to
/// [`_NET_WM_WINDOW_TYPE`](https://specifications.freedesktop.org/wm-spec/wm-spec-1.5.html).
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
#[derive(Default)]
pub enum XWindowType {
    /// A desktop feature. This can include a single window containing desktop icons with the same
    /// dimensions as the screen, allowing the desktop environment to have full control of the
    /// desktop, without the need for proxying root window clicks.
    Desktop,
    /// A dock or panel feature. Typically a Window Manager would keep such windows on top of all
    /// other windows.
    Dock,
    /// Toolbar windows. "Torn off" from the main application.
    Toolbar,
    /// Pinnable menu windows. "Torn off" from the main application.
    Menu,
    /// A small persistent utility window, such as a palette or toolbox.
    Utility,
    /// The window is a splash screen displayed as an application is starting up.
    Splash,
    /// This is a dialog window.
    Dialog,
    /// A dropdown menu that usually appears when the user clicks on an item in a menu bar.
    /// This property is typically used on override-redirect windows.
    DropdownMenu,
    /// A popup menu that usually appears when the user right clicks on an object.
    /// This property is typically used on override-redirect windows.
    PopupMenu,
    /// A tooltip window. Usually used to show additional information when hovering over an object
    /// with the cursor. This property is typically used on override-redirect windows.
    Tooltip,
    /// The window is a notification.
    /// This property is typically used on override-redirect windows.
    Notification,
    /// This should be used on the windows that are popped up by combo boxes.
    /// This property is typically used on override-redirect windows.
    Combo,
    /// This indicates the the window is being dragged.
    /// This property is typically used on override-redirect windows.
    Dnd,
    /// This is a normal, top-level window.
    #[default]
    Normal,
}

impl_option!(
    XWindowType,
    OptionXWindowType,
    [Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash]
);


#[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash)]
#[repr(C)]
#[derive(Default)]
pub enum UserAttentionType {
    #[default]
    None,
    Critical,
    Informational,
}


/// State for tracking hover and interaction with Linux window decoration elements (CSD).
#[derive(Debug, Default, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash)]
#[repr(C)]
pub struct LinuxDecorationsState {
    pub is_dragging_titlebar: bool,
    pub close_button_hover: bool,
    pub maximize_button_hover: bool,
    pub minimize_button_hover: bool,
}

impl_option!(
    LinuxDecorationsState,
    OptionLinuxDecorationsState,
    [Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash]
);

#[derive(Debug, Default, Clone, PartialEq, PartialOrd)]
#[repr(C)]
pub struct LinuxWindowOptions {
    pub wayland_theme: OptionWaylandTheme,
    pub window_icon: OptionWindowIcon,
    /// Build window with `_GTK_THEME_VARIANT` hint set to the specified value. Currently only
    /// relevant on X11. Can only be set at window creation, can't be changed in callbacks.
    pub x11_gtk_theme_variant: OptionString,
    /// Build window with a given application ID. It should match the `.desktop` file distributed
    /// with your program. Only relevant on Wayland.
    /// Can only be set at window creation, can't be changed in callbacks.
    ///
    /// For details about application ID conventions, see the
    /// [Desktop Entry Spec](https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html#desktop-file-id)
    pub wayland_app_id: OptionString,
    /// Build window with `WM_CLASS` hint; defaults to the name of the binary. Only relevant on
    /// X11. Can only be set at window creation, can't be changed in callbacks.
    pub x11_wm_classes: StringPairVec,
    /// Build window with `_NET_WM_WINDOW_TYPE` hint; defaults to `Normal`. Only relevant on X11.
    /// Can only be set at window creation, can't be changed in callbacks.
    pub x11_window_types: XWindowTypeVec,
    /// (Unimplemented) - Can only be set at window creation, can't be changed in callbacks.
    pub x11_visual: OptionX11Visual,
    /// Build window with resize increment hint. Only implemented on X11.
    /// Can only be set at window creation, can't be changed in callbacks.
    pub x11_resize_increments: OptionLogicalSize,
    /// Build window with base size hint. Only implemented on X11.
    /// Can only be set at window creation, can't be changed in callbacks.
    pub x11_base_size: OptionLogicalSize,
    /// (Unimplemented) - Can only be set at window creation, can't be changed in callbacks.
    pub x11_screen: OptionI32,
    pub request_user_attention: UserAttentionType,
    /// X11-specific: Client-side decoration state (drag position, button hover, etc.)
    pub x11_decorations_state: OptionLinuxDecorationsState,
    /// Build window with override-redirect flag; defaults to false. Only relevant on X11.
    /// Can only be set at window creation, can't be changed in callbacks.
    pub x11_override_redirect: bool,
}

pub type X11Visual = *const c_void;
impl_option!(
    X11Visual,
    OptionX11Visual,
    [Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash]
);

/// A key-value pair of strings, used for X11 `WM_CLASS` and other platform properties
#[derive(Debug, Default, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
#[repr(C)]
pub struct AzStringPair {
    pub key: AzString,
    pub value: AzString,
}

impl_option!(
    AzStringPair,
    OptionStringPair,
    copy = false,
    [Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash]
);

impl_vec!(AzStringPair, StringPairVec, StringPairVecDestructor, StringPairVecDestructorType, StringPairVecSlice, OptionStringPair);
impl_vec_mut!(AzStringPair, StringPairVec);
impl_vec_debug!(AzStringPair, StringPairVec);
impl_vec_partialord!(AzStringPair, StringPairVec);
impl_vec_ord!(AzStringPair, StringPairVec);
impl_vec_clone!(AzStringPair, StringPairVec, StringPairVecDestructor);
impl_vec_partialeq!(AzStringPair, StringPairVec);
impl_vec_eq!(AzStringPair, StringPairVec);
impl_vec_hash!(AzStringPair, StringPairVec);

impl_option!(
    StringPairVec,
    OptionStringPairVec,
    copy = false,
    [Debug, Clone, PartialOrd, PartialEq, Ord, Eq, Hash]
);

impl StringPairVec {
    #[must_use] pub fn get_key(&self, search_key: &str) -> Option<&AzString> {
        self.as_ref().iter().find_map(|v| {
            if v.key.as_str() == search_key {
                Some(&v.value)
            } else {
                None
            }
        })
    }
    pub fn get_key_mut(&mut self, search_key: &str) -> Option<&mut AzStringPair> {
        self.as_mut()
            .iter_mut()
            .find(|v| v.key.as_str() == search_key)
    }
    pub fn insert_kv<I: Into<AzString>>(&mut self, key: I, value: I) {
        let key = key.into();
        let value = value.into();
        match self.get_key_mut(key.as_str()) {
            None => {}
            Some(s) => {
                s.value = value;
                return;
            }
        }
        self.push(AzStringPair { key, value });
    }
}

impl_vec!(XWindowType, XWindowTypeVec, XWindowTypeVecDestructor, XWindowTypeVecDestructorType, XWindowTypeVecSlice, OptionXWindowType);
impl_vec_debug!(XWindowType, XWindowTypeVec);
impl_vec_partialord!(XWindowType, XWindowTypeVec);
impl_vec_ord!(XWindowType, XWindowTypeVec);
impl_vec_clone!(XWindowType, XWindowTypeVec, XWindowTypeVecDestructor);
impl_vec_partialeq!(XWindowType, XWindowTypeVec);
impl_vec_eq!(XWindowType, XWindowTypeVec);
impl_vec_hash!(XWindowType, XWindowTypeVec);

impl_option!(
    WaylandTheme,
    OptionWaylandTheme,
    copy = false,
    [Debug, Clone, PartialEq, PartialOrd]
);

/// macOS-specific window options (reserved for future use)
#[derive(Debug, Default, Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
#[repr(C)]
// `_`-prefixed fields are C-ABI/api.json names; cannot rename.
#[allow(clippy::pub_underscore_fields)]
pub struct MacWindowOptions {
    // empty for now, single field must be present for ABI compat - always set to 0
    pub _reserved: u8,
}

/// WASM/web-specific window options (reserved for future use)
#[derive(Debug, Default, Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
#[repr(C)]
// `_`-prefixed fields are C-ABI/api.json names; cannot rename.
#[allow(clippy::pub_underscore_fields)]
pub struct WasmWindowOptions {
    // empty for now, single field must be present for ABI compat - always set to 0
    pub _reserved: u8,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
#[derive(Default)]
pub enum FullScreenMode {
    /// - macOS: If the window is in windowed mode, transitions it slowly to fullscreen mode
    /// - other: Does the same as `FastFullScreen`.
    SlowFullScreen,
    /// Window should immediately go into fullscreen mode (on macOS this is not the default
    /// behaviour).
    #[default]
    FastFullScreen,
    /// - macOS: If the window is in fullscreen mode, transitions slowly back to windowed state.
    /// - other: Does the same as `FastWindowed`.
    SlowWindowed,
    /// If the window is in fullscreen mode, will immediately go back to windowed mode (on macOS
    /// this is not the default behaviour).
    FastWindowed,
}


// Translation type because in winit 24.0 the WinitWaylandTheme is a trait instead
// of a struct, which makes things more complicated
#[derive(Debug, Clone, PartialEq, PartialOrd)]
#[repr(C)]
pub struct WaylandTheme {
    pub title_bar_active_background_color: ColorU,
    pub title_bar_active_separator_color: ColorU,
    pub title_bar_active_text_color: ColorU,
    pub title_bar_inactive_background_color: ColorU,
    pub title_bar_inactive_separator_color: ColorU,
    pub title_bar_inactive_text_color: ColorU,
    pub maximize_idle_foreground_inactive_color: ColorU,
    pub minimize_idle_foreground_inactive_color: ColorU,
    pub close_idle_foreground_inactive_color: ColorU,
    pub maximize_hovered_foreground_inactive_color: ColorU,
    pub minimize_hovered_foreground_inactive_color: ColorU,
    pub close_hovered_foreground_inactive_color: ColorU,
    pub maximize_disabled_foreground_inactive_color: ColorU,
    pub minimize_disabled_foreground_inactive_color: ColorU,
    pub close_disabled_foreground_inactive_color: ColorU,
    pub maximize_idle_background_inactive_color: ColorU,
    pub minimize_idle_background_inactive_color: ColorU,
    pub close_idle_background_inactive_color: ColorU,
    pub maximize_hovered_background_inactive_color: ColorU,
    pub minimize_hovered_background_inactive_color: ColorU,
    pub close_hovered_background_inactive_color: ColorU,
    pub maximize_disabled_background_inactive_color: ColorU,
    pub minimize_disabled_background_inactive_color: ColorU,
    pub close_disabled_background_inactive_color: ColorU,
    pub maximize_idle_foreground_active_color: ColorU,
    pub minimize_idle_foreground_active_color: ColorU,
    pub close_idle_foreground_active_color: ColorU,
    pub maximize_hovered_foreground_active_color: ColorU,
    pub minimize_hovered_foreground_active_color: ColorU,
    pub close_hovered_foreground_active_color: ColorU,
    pub maximize_disabled_foreground_active_color: ColorU,
    pub minimize_disabled_foreground_active_color: ColorU,
    pub close_disabled_foreground_active_color: ColorU,
    pub maximize_idle_background_active_color: ColorU,
    pub minimize_idle_background_active_color: ColorU,
    pub close_idle_background_active_color: ColorU,
    pub maximize_hovered_background_active_color: ColorU,
    pub minimize_hovered_background_active_color: ColorU,
    pub close_hovered_background_active_color: ColorU,
    pub maximize_disabled_background_active_color: ColorU,
    pub minimize_disabled_background_active_color: ColorU,
    pub close_disabled_background_active_color: ColorU,
    pub title_bar_font: AzString,
    pub title_bar_font_size: f32,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd)]
#[repr(C)]
pub struct WindowSize {
    /// Width and height of the window, in logical
    /// units (may not correspond to the physical on-screen size)
    pub dimensions: LogicalSize,
    /// Actual DPI value (default: 96)
    pub dpi: u32,
    /// Minimum dimensions of the window
    pub min_dimensions: OptionLogicalSize,
    /// Maximum dimensions of the window
    pub max_dimensions: OptionLogicalSize,
}

impl WindowSize {
    #[allow(clippy::cast_possible_truncation)] // bounded DPI/dimension/number conversion
    #[must_use] pub fn get_layout_size(&self) -> LayoutSize {
        LayoutSize::new(
            libm::roundf(self.dimensions.width) as isize,
            libm::roundf(self.dimensions.height) as isize,
        )
    }

    /// Get the actual logical size
    #[must_use] pub const fn get_logical_size(&self) -> LogicalSize {
        self.dimensions
    }

    #[must_use] pub fn get_physical_size(&self) -> PhysicalSize<u32> {
        self.dimensions
            .to_physical(self.get_hidpi_factor().inner.get())
    }

    #[allow(clippy::cast_precision_loss)] // bounded DPI/dimension/number conversion
    #[must_use] pub fn get_hidpi_factor(&self) -> DpiScaleFactor {
        // Guard against `dpi == 0` (uninitialized / misreporting platform),
        // which would yield a 0.0 scale factor and later divide-by-zero when
        // converting physical <-> logical sizes (`to_logical` divides by this).
        // Fall back to the standard 96 DPI (scale 1.0).
        let dpi = if self.dpi == 0 { 96 } else { self.dpi };
        DpiScaleFactor {
            inner: FloatValue::new(dpi as f32 / 96.0),
        }
    }
}

impl Default for WindowSize {
    fn default() -> Self {
        Self {
            dimensions: LogicalSize::new(640.0, 480.0),
            dpi: 96,
            min_dimensions: None.into(),
            max_dimensions: None.into(),
        }
    }
}

#[repr(C)]
#[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash)]
pub enum RendererType {
    /// Force hardware rendering
    Hardware,
    /// Force software rendering
    Software,
}

impl_option!(
    RendererType,
    OptionRendererType,
    [Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash]
);

#[derive(Debug, Clone, PartialEq, PartialOrd, Ord, Eq, Hash)]
pub enum UpdateFocusWarning {
    FocusInvalidDomId(DomId),
    FocusInvalidNodeId(NodeHierarchyItemId),
    CouldNotFindFocusNode(CssPath),
}

impl ::core::fmt::Display for UpdateFocusWarning {
    fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
        use self::UpdateFocusWarning::{FocusInvalidDomId, FocusInvalidNodeId, CouldNotFindFocusNode};
        match self {
            FocusInvalidDomId(dom_id) => write!(f, "Focusing on DOM with invalid ID: {dom_id:?}"),
            FocusInvalidNodeId(node_id) => {
                write!(f, "Focusing on node with invalid ID: {node_id}")
            }
            CouldNotFindFocusNode(css_path) => {
                write!(f, "Could not find focus node for path: {css_path}")
            }
        }
    }
}

/// Utility function for easier creation of a keymap - i.e. `[vec![Ctrl, S], my_function]`
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C, u8)]
pub enum AcceleratorKey {
    Ctrl,
    Alt,
    Shift,
    Key(VirtualKeyCode),
}

impl AcceleratorKey {
    /// Checks if the current keyboard state contains the given char or modifier,
    /// i.e. if the keyboard state currently has the shift key pressed and the
    /// accelerator key is `Shift`, evaluates to true, otherwise to false.
    #[must_use] pub fn matches(&self, keyboard_state: &KeyboardState) -> bool {
        use self::AcceleratorKey::{Ctrl, Alt, Shift, Key};
        match self {
            Ctrl => keyboard_state.ctrl_down(),
            Alt => keyboard_state.alt_down(),
            Shift => keyboard_state.shift_down(),
            Key(k) => keyboard_state.is_key_down(*k),
        }
    }
}

/// Symbolic name for a keyboard key, does NOT take the keyboard locale into account
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[repr(C)]
pub enum VirtualKeyCode {
    Key1,
    Key2,
    Key3,
    Key4,
    Key5,
    Key6,
    Key7,
    Key8,
    Key9,
    Key0,
    A,
    B,
    C,
    D,
    E,
    F,
    G,
    H,
    I,
    J,
    K,
    L,
    M,
    N,
    O,
    P,
    Q,
    R,
    S,
    T,
    U,
    V,
    W,
    X,
    Y,
    Z,
    Escape,
    F1,
    F2,
    F3,
    F4,
    F5,
    F6,
    F7,
    F8,
    F9,
    F10,
    F11,
    F12,
    F13,
    F14,
    F15,
    F16,
    F17,
    F18,
    F19,
    F20,
    F21,
    F22,
    F23,
    F24,
    Snapshot,
    Scroll,
    Pause,
    Insert,
    Home,
    Delete,
    End,
    PageDown,
    PageUp,
    Left,
    Up,
    Right,
    Down,
    Back,
    Return,
    Space,
    Compose,
    Caret,
    Numlock,
    Numpad0,
    Numpad1,
    Numpad2,
    Numpad3,
    Numpad4,
    Numpad5,
    Numpad6,
    Numpad7,
    Numpad8,
    Numpad9,
    NumpadAdd,
    NumpadDivide,
    NumpadDecimal,
    NumpadComma,
    NumpadEnter,
    NumpadEquals,
    NumpadMultiply,
    NumpadSubtract,
    AbntC1,
    AbntC2,
    Apostrophe,
    Apps,
    Asterisk,
    At,
    Ax,
    Backslash,
    Calculator,
    Capital,
    Colon,
    Comma,
    Convert,
    Equals,
    Grave,
    Kana,
    Kanji,
    LAlt,
    LBracket,
    LControl,
    LShift,
    LWin,
    Mail,
    MediaSelect,
    MediaStop,
    Minus,
    Mute,
    MyComputer,
    NavigateForward,
    NavigateBackward,
    NextTrack,
    NoConvert,
    OEM102,
    Period,
    PlayPause,
    Plus,
    Power,
    PrevTrack,
    RAlt,
    RBracket,
    RControl,
    RShift,
    RWin,
    Semicolon,
    Slash,
    Sleep,
    Stop,
    Sysrq,
    Tab,
    Underline,
    Unlabeled,
    VolumeDown,
    VolumeUp,
    Wake,
    WebBack,
    WebFavorites,
    WebForward,
    WebHome,
    WebRefresh,
    WebSearch,
    WebStop,
    Yen,
    Copy,
    Paste,
    Cut,
}

impl VirtualKeyCode {
    /// Reconstructs a `VirtualKeyCode` from its `as u32` discriminant.
    ///
    /// This enum is a fieldless `#[repr(C)]` enum with no explicit discriminants,
    /// so the discriminants are assigned sequentially in declaration order and
    /// `VariantN as u32` round-trips through this table. Used to recover the key
    /// of a keyboard *event* from its `key_code` (which is stored as
    /// `VirtualKeyCode as u32`) instead of reading live keyboard state.
    #[must_use]
    #[allow(clippy::too_many_lines)] // exhaustive keycode match table
    pub const fn from_u32(v: u32) -> Option<Self> {
        match v {
            0 => Some(Self::Key1),
            1 => Some(Self::Key2),
            2 => Some(Self::Key3),
            3 => Some(Self::Key4),
            4 => Some(Self::Key5),
            5 => Some(Self::Key6),
            6 => Some(Self::Key7),
            7 => Some(Self::Key8),
            8 => Some(Self::Key9),
            9 => Some(Self::Key0),
            10 => Some(Self::A),
            11 => Some(Self::B),
            12 => Some(Self::C),
            13 => Some(Self::D),
            14 => Some(Self::E),
            15 => Some(Self::F),
            16 => Some(Self::G),
            17 => Some(Self::H),
            18 => Some(Self::I),
            19 => Some(Self::J),
            20 => Some(Self::K),
            21 => Some(Self::L),
            22 => Some(Self::M),
            23 => Some(Self::N),
            24 => Some(Self::O),
            25 => Some(Self::P),
            26 => Some(Self::Q),
            27 => Some(Self::R),
            28 => Some(Self::S),
            29 => Some(Self::T),
            30 => Some(Self::U),
            31 => Some(Self::V),
            32 => Some(Self::W),
            33 => Some(Self::X),
            34 => Some(Self::Y),
            35 => Some(Self::Z),
            36 => Some(Self::Escape),
            37 => Some(Self::F1),
            38 => Some(Self::F2),
            39 => Some(Self::F3),
            40 => Some(Self::F4),
            41 => Some(Self::F5),
            42 => Some(Self::F6),
            43 => Some(Self::F7),
            44 => Some(Self::F8),
            45 => Some(Self::F9),
            46 => Some(Self::F10),
            47 => Some(Self::F11),
            48 => Some(Self::F12),
            49 => Some(Self::F13),
            50 => Some(Self::F14),
            51 => Some(Self::F15),
            52 => Some(Self::F16),
            53 => Some(Self::F17),
            54 => Some(Self::F18),
            55 => Some(Self::F19),
            56 => Some(Self::F20),
            57 => Some(Self::F21),
            58 => Some(Self::F22),
            59 => Some(Self::F23),
            60 => Some(Self::F24),
            61 => Some(Self::Snapshot),
            62 => Some(Self::Scroll),
            63 => Some(Self::Pause),
            64 => Some(Self::Insert),
            65 => Some(Self::Home),
            66 => Some(Self::Delete),
            67 => Some(Self::End),
            68 => Some(Self::PageDown),
            69 => Some(Self::PageUp),
            70 => Some(Self::Left),
            71 => Some(Self::Up),
            72 => Some(Self::Right),
            73 => Some(Self::Down),
            74 => Some(Self::Back),
            75 => Some(Self::Return),
            76 => Some(Self::Space),
            77 => Some(Self::Compose),
            78 => Some(Self::Caret),
            79 => Some(Self::Numlock),
            80 => Some(Self::Numpad0),
            81 => Some(Self::Numpad1),
            82 => Some(Self::Numpad2),
            83 => Some(Self::Numpad3),
            84 => Some(Self::Numpad4),
            85 => Some(Self::Numpad5),
            86 => Some(Self::Numpad6),
            87 => Some(Self::Numpad7),
            88 => Some(Self::Numpad8),
            89 => Some(Self::Numpad9),
            90 => Some(Self::NumpadAdd),
            91 => Some(Self::NumpadDivide),
            92 => Some(Self::NumpadDecimal),
            93 => Some(Self::NumpadComma),
            94 => Some(Self::NumpadEnter),
            95 => Some(Self::NumpadEquals),
            96 => Some(Self::NumpadMultiply),
            97 => Some(Self::NumpadSubtract),
            98 => Some(Self::AbntC1),
            99 => Some(Self::AbntC2),
            100 => Some(Self::Apostrophe),
            101 => Some(Self::Apps),
            102 => Some(Self::Asterisk),
            103 => Some(Self::At),
            104 => Some(Self::Ax),
            105 => Some(Self::Backslash),
            106 => Some(Self::Calculator),
            107 => Some(Self::Capital),
            108 => Some(Self::Colon),
            109 => Some(Self::Comma),
            110 => Some(Self::Convert),
            111 => Some(Self::Equals),
            112 => Some(Self::Grave),
            113 => Some(Self::Kana),
            114 => Some(Self::Kanji),
            115 => Some(Self::LAlt),
            116 => Some(Self::LBracket),
            117 => Some(Self::LControl),
            118 => Some(Self::LShift),
            119 => Some(Self::LWin),
            120 => Some(Self::Mail),
            121 => Some(Self::MediaSelect),
            122 => Some(Self::MediaStop),
            123 => Some(Self::Minus),
            124 => Some(Self::Mute),
            125 => Some(Self::MyComputer),
            126 => Some(Self::NavigateForward),
            127 => Some(Self::NavigateBackward),
            128 => Some(Self::NextTrack),
            129 => Some(Self::NoConvert),
            130 => Some(Self::OEM102),
            131 => Some(Self::Period),
            132 => Some(Self::PlayPause),
            133 => Some(Self::Plus),
            134 => Some(Self::Power),
            135 => Some(Self::PrevTrack),
            136 => Some(Self::RAlt),
            137 => Some(Self::RBracket),
            138 => Some(Self::RControl),
            139 => Some(Self::RShift),
            140 => Some(Self::RWin),
            141 => Some(Self::Semicolon),
            142 => Some(Self::Slash),
            143 => Some(Self::Sleep),
            144 => Some(Self::Stop),
            145 => Some(Self::Sysrq),
            146 => Some(Self::Tab),
            147 => Some(Self::Underline),
            148 => Some(Self::Unlabeled),
            149 => Some(Self::VolumeDown),
            150 => Some(Self::VolumeUp),
            151 => Some(Self::Wake),
            152 => Some(Self::WebBack),
            153 => Some(Self::WebFavorites),
            154 => Some(Self::WebForward),
            155 => Some(Self::WebHome),
            156 => Some(Self::WebRefresh),
            157 => Some(Self::WebSearch),
            158 => Some(Self::WebStop),
            159 => Some(Self::Yen),
            160 => Some(Self::Copy),
            161 => Some(Self::Paste),
            162 => Some(Self::Cut),
            _ => None,
        }
    }

    #[must_use] pub const fn get_lowercase(&self) -> Option<char> {
        use self::VirtualKeyCode::{A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, Key0, Numpad0, Key1, Numpad1, Key2, Numpad2, Key3, Numpad3, Key4, Numpad4, Key5, Numpad5, Key6, Numpad6, Key7, Numpad7, Key8, Numpad8, Key9, Numpad9, Minus, Asterisk, At, Period, Semicolon, Slash, Caret};
        match self {
            A => Some('a'),
            B => Some('b'),
            C => Some('c'),
            D => Some('d'),
            E => Some('e'),
            F => Some('f'),
            G => Some('g'),
            H => Some('h'),
            I => Some('i'),
            J => Some('j'),
            K => Some('k'),
            L => Some('l'),
            M => Some('m'),
            N => Some('n'),
            O => Some('o'),
            P => Some('p'),
            Q => Some('q'),
            R => Some('r'),
            S => Some('s'),
            T => Some('t'),
            U => Some('u'),
            V => Some('v'),
            W => Some('w'),
            X => Some('x'),
            Y => Some('y'),
            Z => Some('z'),
            Key0 | Numpad0 => Some('0'),
            Key1 | Numpad1 => Some('1'),
            Key2 | Numpad2 => Some('2'),
            Key3 | Numpad3 => Some('3'),
            Key4 | Numpad4 => Some('4'),
            Key5 | Numpad5 => Some('5'),
            Key6 | Numpad6 => Some('6'),
            Key7 | Numpad7 => Some('7'),
            Key8 | Numpad8 => Some('8'),
            Key9 | Numpad9 => Some('9'),
            Minus => Some('-'),
            Asterisk => Some('*'),
            At => Some('@'),
            Period => Some('.'),
            Semicolon => Some(';'),
            Slash => Some('/'),
            Caret => Some('^'),
            _ => None,
        }
    }
}

/// 16x16x4 bytes icon
#[derive(Debug, Clone)]
#[repr(C)]
pub struct SmallWindowIconBytes {
    pub key: IconKey,
    pub rgba_bytes: U8Vec,
}

/// 32x32x4 bytes icon
#[derive(Debug, Clone)]
#[repr(C)]
pub struct LargeWindowIconBytes {
    pub key: IconKey,
    pub rgba_bytes: U8Vec,
}

// Window icon that usually appears in the top-left corner of the window
#[derive(Debug, Clone)]
#[repr(C, u8)]
pub enum WindowIcon {
    Small(SmallWindowIconBytes),
    /// 32x32x4 bytes icon
    Large(LargeWindowIconBytes),
}

impl_option!(
    WindowIcon,
    OptionWindowIcon,
    copy = false,
    [Debug, Clone, PartialOrd, PartialEq, Eq, Hash, Ord]
);

impl WindowIcon {
    #[must_use] pub const fn get_key(&self) -> IconKey {
        match &self {
            Self::Small(SmallWindowIconBytes { key, .. })
            | Self::Large(LargeWindowIconBytes { key, .. }) => *key,
        }
    }
}
// -- Only compare the IconKey (for WindowIcon and TaskBarIcon)

impl PartialEq for WindowIcon {
    fn eq(&self, rhs: &Self) -> bool {
        self.get_key() == rhs.get_key()
    }
}

impl PartialOrd for WindowIcon {
    fn partial_cmp(&self, rhs: &Self) -> Option<Ordering> {
        Some((self.get_key()).cmp(&rhs.get_key()))
    }
}

impl Eq for WindowIcon {}

impl Ord for WindowIcon {
    fn cmp(&self, rhs: &Self) -> Ordering {
        (self.get_key()).cmp(&rhs.get_key())
    }
}

impl Hash for WindowIcon {
    fn hash<H>(&self, state: &mut H)
    where
        H: Hasher,
    {
        self.get_key().hash(state);
    }
}

/// 256x256x4 bytes window icon
#[derive(Debug, Clone)]
#[repr(C)]
pub struct TaskBarIcon {
    pub key: IconKey,
    pub rgba_bytes: U8Vec,
}

impl_option!(
    TaskBarIcon,
    OptionTaskBarIcon,
    copy = false,
    [Debug, Clone, PartialOrd, PartialEq, Eq, Hash, Ord]
);

impl PartialEq for TaskBarIcon {
    fn eq(&self, rhs: &Self) -> bool {
        self.key == rhs.key
    }
}

impl PartialOrd for TaskBarIcon {
    fn partial_cmp(&self, rhs: &Self) -> Option<Ordering> {
        Some((self.key).cmp(&rhs.key))
    }
}

impl Eq for TaskBarIcon {}

impl Ord for TaskBarIcon {
    fn cmp(&self, rhs: &Self) -> Ordering {
        (self.key).cmp(&rhs.key)
    }
}

impl Hash for TaskBarIcon {
    fn hash<H>(&self, state: &mut H)
    where
        H: Hasher,
    {
        self.key.hash(state);
    }
}

#[cfg(test)]
#[allow(clippy::float_cmp)] // exact-value assertions on hidpi scale factors
mod audit_tests {
    use super::*;

    #[test]
    fn hidpi_factor_guards_zero_dpi() {
        // dpi == 0 must not produce a 0.0 scale factor (later divide-by-zero
        // in to_logical); it falls back to 96 DPI (scale 1.0).
        let ws = WindowSize { dpi: 0, ..WindowSize::default() };
        let factor = ws.get_hidpi_factor().inner.get();
        assert_eq!(factor, 1.0);

        let ws2 = WindowSize { dpi: 192, ..WindowSize::default() };
        assert_eq!(ws2.get_hidpi_factor().inner.get(), 2.0);
    }

    #[test]
    fn virtual_keycode_from_u32_roundtrips() {
        // A representative spread across the enum, including first/last.
        for vk in [
            VirtualKeyCode::Key1,
            VirtualKeyCode::A,
            VirtualKeyCode::Z,
            VirtualKeyCode::Left,
            VirtualKeyCode::Back,
            VirtualKeyCode::Delete,
            VirtualKeyCode::LControl,
            VirtualKeyCode::Cut,
        ] {
            assert_eq!(VirtualKeyCode::from_u32(vk as u32), Some(vk));
        }
        // Out of range -> None (no UB, no panic).
        assert_eq!(VirtualKeyCode::from_u32(10_000), None);
    }
}

#[cfg(test)]
#[allow(clippy::float_cmp)] // exact-value assertions on saturating float->int conversions
mod autotest_generated {
    use alloc::{format, string::String, vec};

    use super::*;

    /// Highest valid `VirtualKeyCode` discriminant (`Cut`, the last declared variant).
    const LAST_VK: u32 = 162;

    /// Deterministic, `no_std`-safe hasher so hash/eq consistency can be checked
    /// without pulling in `std::collections::hash_map::DefaultHasher`.
    #[derive(Default)]
    struct TestHasher(u64);

    impl Hasher for TestHasher {
        fn write(&mut self, bytes: &[u8]) {
            for &b in bytes {
                self.0 = self.0.rotate_left(5) ^ u64::from(b);
            }
        }
        fn finish(&self) -> u64 {
            self.0
        }
    }

    fn hash_of<T: Hash>(value: &T) -> u64 {
        let mut h = TestHasher::default();
        value.hash(&mut h);
        h.finish()
    }

    fn keyboard_with(keys: &[VirtualKeyCode]) -> KeyboardState {
        KeyboardState {
            pressed_virtual_keycodes: keys.to_vec().into(),
            ..KeyboardState::default()
        }
    }

    fn pair(key: &str, value: &str) -> AzStringPair {
        AzStringPair {
            key: key.into(),
            value: value.into(),
        }
    }

    // ---------------------------------------------------------------------
    // Constructors: WindowId / IconKey (atomic counters)
    // ---------------------------------------------------------------------

    #[test]
    fn window_id_new_is_unique_and_monotonic() {
        // The counter is process-global and shared with other tests in this
        // binary, so only *relative* properties may be asserted.
        let mut ids = BTreeSet::new();
        let mut prev = WindowId::new();
        assert!(ids.insert(prev));
        for _ in 0..1000 {
            let next = WindowId::new();
            assert!(next.id > prev.id, "WindowId counter must strictly increase");
            assert!(ids.insert(next), "WindowId::new() handed out a duplicate");
            prev = next;
        }
        // Default delegates to new(): two defaults are never the same window.
        assert_ne!(WindowId::default(), WindowId::default());
    }

    #[test]
    fn icon_key_new_is_unique_and_monotonic() {
        let mut keys = BTreeSet::new();
        let mut prev = IconKey::new();
        assert!(keys.insert(prev));
        for _ in 0..1000 {
            let next = IconKey::new();
            assert!(
                next.icon_id > prev.icon_id,
                "IconKey counter must strictly increase"
            );
            assert!(keys.insert(next), "IconKey::new() handed out a duplicate");
            prev = next;
        }
        assert_ne!(IconKey::default(), IconKey::default());
    }

    // ---------------------------------------------------------------------
    // RendererOptions + Vsync / Srgb / HwAcceleration predicates
    // ---------------------------------------------------------------------

    #[test]
    fn renderer_options_new_preserves_every_combination() {
        let vsyncs = [Vsync::Enabled, Vsync::Disabled, Vsync::DontCare];
        let srgbs = [Srgb::Enabled, Srgb::Disabled, Srgb::DontCare];
        let accels = [
            HwAcceleration::Enabled,
            HwAcceleration::Disabled,
            HwAcceleration::DontCare,
        ];
        for v in vsyncs {
            for s in srgbs {
                for a in accels {
                    let o = RendererOptions::new(v, s, a);
                    assert_eq!(o.vsync, v);
                    assert_eq!(o.srgb, s);
                    assert_eq!(o.hw_accel, a);
                    // Constructed value must round-trip through equality/copy.
                    assert_eq!(o, RendererOptions::new(v, s, a));
                }
            }
        }
    }

    #[test]
    fn renderer_options_default_does_not_force_cpu_rendering() {
        // Regression guard: hw_accel must be DontCare (auto), NOT Disabled -
        // Disabled silently forced every app into CPU rendering.
        let d = RendererOptions::default();
        assert_eq!(d.hw_accel, HwAcceleration::DontCare);
        assert!(!d.hw_accel.is_enabled());
        assert!(d.vsync.is_enabled());
        assert!(!d.srgb.is_enabled());
    }

    #[test]
    fn tri_state_is_enabled_only_for_enabled_variant() {
        assert!(Vsync::Enabled.is_enabled());
        assert!(!Vsync::Disabled.is_enabled());
        assert!(!Vsync::DontCare.is_enabled());

        assert!(Srgb::Enabled.is_enabled());
        assert!(!Srgb::Disabled.is_enabled());
        assert!(!Srgb::DontCare.is_enabled());

        assert!(HwAcceleration::Enabled.is_enabled());
        assert!(!HwAcceleration::Disabled.is_enabled());
        assert!(!HwAcceleration::DontCare.is_enabled());
    }

    // ---------------------------------------------------------------------
    // KeyboardState getters / predicates
    // ---------------------------------------------------------------------

    #[test]
    fn keyboard_state_default_has_no_key_down() {
        let k = KeyboardState::default();
        assert!(!k.shift_down());
        assert!(!k.ctrl_down());
        assert!(!k.alt_down());
        assert!(!k.super_down());
        assert!(!k.primary_down());
        // Every single keycode reports "not down" on an empty state.
        for v in 0..=LAST_VK {
            let vk = VirtualKeyCode::from_u32(v).expect("discriminant in range");
            assert!(!k.is_key_down(vk));
        }
    }

    #[test]
    fn keyboard_state_modifiers_accept_either_side() {
        for (left, right, probe) in [
            (
                VirtualKeyCode::LShift,
                VirtualKeyCode::RShift,
                KeyboardState::shift_down as fn(&KeyboardState) -> bool,
            ),
            (
                VirtualKeyCode::LControl,
                VirtualKeyCode::RControl,
                KeyboardState::ctrl_down as fn(&KeyboardState) -> bool,
            ),
            (
                VirtualKeyCode::LAlt,
                VirtualKeyCode::RAlt,
                KeyboardState::alt_down as fn(&KeyboardState) -> bool,
            ),
            (
                VirtualKeyCode::LWin,
                VirtualKeyCode::RWin,
                KeyboardState::super_down as fn(&KeyboardState) -> bool,
            ),
        ] {
            assert!(probe(&keyboard_with(&[left])), "left variant must register");
            assert!(
                probe(&keyboard_with(&[right])),
                "right variant must register"
            );
            assert!(probe(&keyboard_with(&[left, right])));
            // An unrelated key must not light up a modifier.
            assert!(!probe(&keyboard_with(&[VirtualKeyCode::A])));
        }
    }

    #[test]
    fn keyboard_state_primary_down_follows_platform() {
        let ctrl = keyboard_with(&[VirtualKeyCode::LControl]);
        let cmd = keyboard_with(&[VirtualKeyCode::LWin]);
        if cfg!(target_os = "macos") {
            assert!(cmd.primary_down(), "Cmd (super) is PRIMARY on macOS");
            assert!(!ctrl.primary_down());
        } else {
            assert!(ctrl.primary_down(), "Ctrl is PRIMARY off macOS");
            assert!(!cmd.primary_down());
        }
        // On every platform, primary_down agrees with one of the two modifiers.
        for k in [&ctrl, &cmd, &KeyboardState::default()] {
            assert_eq!(
                k.primary_down(),
                if cfg!(target_os = "macos") {
                    k.super_down()
                } else {
                    k.ctrl_down()
                }
            );
        }
    }

    #[test]
    fn is_key_down_handles_duplicates_and_large_state() {
        // Same key pressed many times (backends can push duplicates).
        let dup = keyboard_with(&[VirtualKeyCode::S; 512]);
        assert!(dup.is_key_down(VirtualKeyCode::S));
        assert!(!dup.is_key_down(VirtualKeyCode::A));

        // Every key held down at once: no panic, all report true.
        let all: alloc::vec::Vec<VirtualKeyCode> = (0..=LAST_VK)
            .map(|v| VirtualKeyCode::from_u32(v).expect("discriminant in range"))
            .collect();
        let everything = keyboard_with(&all);
        for vk in &all {
            assert!(everything.is_key_down(*vk));
        }
        assert!(everything.shift_down() && everything.ctrl_down());
        assert!(everything.alt_down() && everything.super_down());
    }

    // ---------------------------------------------------------------------
    // AcceleratorKey / matches_accelerator
    // ---------------------------------------------------------------------

    #[test]
    fn empty_chord_matches_trivially() {
        // Documented: "An empty chord matches trivially."
        assert!(KeyboardState::default().matches_accelerator(&[]));
        assert!(keyboard_with(&[VirtualKeyCode::A]).matches_accelerator(&[]));
    }

    #[test]
    fn matches_accelerator_requires_every_entry() {
        let state = keyboard_with(&[
            VirtualKeyCode::LControl,
            VirtualKeyCode::LShift,
            VirtualKeyCode::S,
        ]);
        assert!(state.matches_accelerator(&[
            AcceleratorKey::Ctrl,
            AcceleratorKey::Shift,
            AcceleratorKey::Key(VirtualKeyCode::S),
        ]));
        // One missing entry (Alt) is enough to reject the whole chord.
        assert!(!state.matches_accelerator(&[
            AcceleratorKey::Ctrl,
            AcceleratorKey::Alt,
            AcceleratorKey::Key(VirtualKeyCode::S),
        ]));
        // Wrong key, right modifiers.
        assert!(!state.matches_accelerator(&[
            AcceleratorKey::Ctrl,
            AcceleratorKey::Key(VirtualKeyCode::Q),
        ]));
        // Order must not matter.
        assert!(state.matches_accelerator(&[
            AcceleratorKey::Key(VirtualKeyCode::S),
            AcceleratorKey::Shift,
            AcceleratorKey::Ctrl,
        ]));
    }

    #[test]
    fn matches_accelerator_survives_huge_chord() {
        // A pathologically long chord must terminate (linear scan, no recursion).
        let state = keyboard_with(&[VirtualKeyCode::LShift]);
        let long_ok = vec![AcceleratorKey::Shift; 10_000];
        assert!(state.matches_accelerator(&long_ok));

        // 10k satisfiable entries with a single unsatisfiable one at the very end:
        // `all()` must still reach it and return false.
        let mut long_bad = vec![AcceleratorKey::Shift; 10_000];
        long_bad.push(AcceleratorKey::Ctrl);
        assert!(!state.matches_accelerator(&long_bad));
    }

    #[test]
    fn accelerator_key_matches_each_variant() {
        let empty = KeyboardState::default();
        for a in [
            AcceleratorKey::Ctrl,
            AcceleratorKey::Alt,
            AcceleratorKey::Shift,
            AcceleratorKey::Key(VirtualKeyCode::A),
        ] {
            assert!(!a.matches(&empty), "nothing matches an empty keyboard state");
        }
        assert!(AcceleratorKey::Ctrl.matches(&keyboard_with(&[VirtualKeyCode::RControl])));
        assert!(AcceleratorKey::Alt.matches(&keyboard_with(&[VirtualKeyCode::RAlt])));
        assert!(AcceleratorKey::Shift.matches(&keyboard_with(&[VirtualKeyCode::RShift])));
        assert!(
            AcceleratorKey::Key(VirtualKeyCode::F24).matches(&keyboard_with(&[VirtualKeyCode::F24]))
        );
        // Modifier accelerators are NOT satisfied by the letter of the same name.
        assert!(!AcceleratorKey::Ctrl.matches(&keyboard_with(&[VirtualKeyCode::C])));
    }

    // ---------------------------------------------------------------------
    // MouseState / MouseButtonState
    // ---------------------------------------------------------------------

    #[test]
    fn mouse_state_matches_context_button() {
        let base = MouseState::default();
        assert!(!base.matches(&ContextMenuMouseButton::Left));
        assert!(!base.matches(&ContextMenuMouseButton::Right));
        assert!(!base.matches(&ContextMenuMouseButton::Middle));

        for (ctx, ms) in [
            (
                ContextMenuMouseButton::Left,
                MouseState {
                    left_down: true,
                    ..MouseState::default()
                },
            ),
            (
                ContextMenuMouseButton::Right,
                MouseState {
                    right_down: true,
                    ..MouseState::default()
                },
            ),
            (
                ContextMenuMouseButton::Middle,
                MouseState {
                    middle_down: true,
                    ..MouseState::default()
                },
            ),
        ] {
            assert!(ms.matches(&ctx), "{ctx:?} must match its own button");
            // ...and only its own button.
            let others = [
                ContextMenuMouseButton::Left,
                ContextMenuMouseButton::Right,
                ContextMenuMouseButton::Middle,
            ];
            for other in others {
                assert_eq!(ms.matches(&other), other == ctx);
            }
        }
    }

    #[test]
    fn mouse_down_and_button_state_agree_for_all_8_combinations() {
        for bits in 0u8..8 {
            let (l, r, m) = (bits & 1 != 0, bits & 2 != 0, bits & 4 != 0);
            let ms = MouseState {
                left_down: l,
                right_down: r,
                middle_down: m,
                ..MouseState::default()
            };
            assert_eq!(ms.mouse_down(), l || r || m);

            let snapshot = ms.button_state();
            assert_eq!(snapshot.left_down, l);
            assert_eq!(snapshot.right_down, r);
            assert_eq!(snapshot.middle_down, m);
            // any_down is exactly mouse_down, and the From impl is the same snapshot.
            assert_eq!(snapshot.any_down(), ms.mouse_down());
            assert_eq!(crate::events::MouseButtonState::from(&ms), snapshot);
        }
        // Default MouseState has no button held.
        assert!(!MouseState::default().mouse_down());
        assert!(!MouseState::default().button_state().any_down());
    }

    // ---------------------------------------------------------------------
    // process_system_scroll (numeric)
    // ---------------------------------------------------------------------

    #[test]
    fn process_system_scroll_zero_and_negative_zero_consume_nothing() {
        let r = process_system_scroll(LogicalPosition::zero(), false);
        assert_eq!(r.scrolled_nodes, 0);
        assert_eq!(r.remaining_delta, LogicalPosition::zero());
        assert!(!r.hit_scrollbar);

        // -0.0 == 0.0 under IEEE-754, so a negative-zero delta must also be a no-op.
        let neg_zero = process_system_scroll(LogicalPosition::new(-0.0, -0.0), true);
        assert_eq!(neg_zero.scrolled_nodes, 0);
        assert!(neg_zero.hit_scrollbar, "hit_scrollbar is echoed verbatim");
    }

    #[test]
    fn process_system_scroll_counts_any_nonzero_axis() {
        for delta in [
            LogicalPosition::new(1.0, 0.0),
            LogicalPosition::new(0.0, -1.0),
            LogicalPosition::new(-3.5, 7.25),
            LogicalPosition::new(f32::MIN, 0.0),
            LogicalPosition::new(0.0, f32::MAX),
            LogicalPosition::new(f32::INFINITY, f32::NEG_INFINITY),
            LogicalPosition::new(f32::MIN_POSITIVE, 0.0),
        ] {
            let r = process_system_scroll(delta, false);
            assert_eq!(r.scrolled_nodes, 1, "{delta:?} must count as consumed");
            // Overscroll is never reported by this helper.
            assert_eq!(r.remaining_delta, LogicalPosition::zero());
        }
    }

    #[test]
    fn process_system_scroll_does_not_panic_on_nan() {
        // NaN != 0.0 is `true`, so a NaN delta is currently treated as consumed.
        // The contract asserted here is only "terminates, no panic, bounded count".
        for delta in [
            LogicalPosition::new(f32::NAN, 0.0),
            LogicalPosition::new(0.0, f32::NAN),
            LogicalPosition::new(f32::NAN, f32::NAN),
        ] {
            let r = process_system_scroll(delta, true);
            assert!(r.scrolled_nodes <= 1);
            assert_eq!(r.remaining_delta, LogicalPosition::zero());
            assert!(r.hit_scrollbar);
        }
    }

    #[test]
    fn scroll_result_default_is_inert() {
        let d = ScrollResult::default();
        assert_eq!(d.scrolled_nodes, 0);
        assert_eq!(d.remaining_delta, LogicalPosition::zero());
        assert!(!d.hit_scrollbar);
    }

    // ---------------------------------------------------------------------
    // CursorPosition
    // ---------------------------------------------------------------------

    #[test]
    fn cursor_position_get_position_only_inside_window() {
        let p = LogicalPosition::new(12.0, 34.0);
        assert_eq!(CursorPosition::InWindow(p).get_position(), Some(p));
        assert_eq!(CursorPosition::OutOfWindow(p).get_position(), None);
        assert_eq!(CursorPosition::Uninitialized.get_position(), None);
        // Default (as used by MouseState::default) is Uninitialized.
        assert_eq!(CursorPosition::default(), CursorPosition::Uninitialized);
        assert_eq!(CursorPosition::default().get_position(), None);
    }

    #[test]
    fn cursor_position_is_inside_window_agrees_with_get_position() {
        for c in [
            CursorPosition::Uninitialized,
            CursorPosition::InWindow(LogicalPosition::zero()),
            CursorPosition::OutOfWindow(LogicalPosition::zero()),
            CursorPosition::InWindow(LogicalPosition::new(f32::MIN, f32::MAX)),
            CursorPosition::OutOfWindow(LogicalPosition::new(f32::INFINITY, f32::NAN)),
        ] {
            assert_eq!(c.is_inside_window(), c.get_position().is_some());
        }
        // Extreme / non-finite coordinates are passed through, not sanitized.
        let nan_pos = CursorPosition::InWindow(LogicalPosition::new(f32::NAN, f32::INFINITY));
        assert!(nan_pos.is_inside_window());
        let got = nan_pos.get_position().expect("InWindow always yields a position");
        assert!(got.x.is_nan());
        assert!(got.y.is_infinite());
    }

    // ---------------------------------------------------------------------
    // MonitorId constructors
    // ---------------------------------------------------------------------

    #[test]
    fn monitor_id_constructors_preserve_fields_at_extremes() {
        assert_eq!(MonitorId::PRIMARY, MonitorId { index: 0, hash: 0 });
        assert_eq!(MonitorId::new(0), MonitorId::PRIMARY);

        for index in [0usize, 1, 42, usize::MAX] {
            let m = MonitorId::new(index);
            assert_eq!(m.index, index);
            assert_eq!(m.hash, 0, "new() documents hash == 0");

            for hash in [0u64, 1, u64::MAX] {
                let m = MonitorId::from_index_and_hash(index, hash);
                assert_eq!(m.index, index);
                assert_eq!(m.hash, hash);
            }
        }
        // index and hash are independent coordinates of identity.
        assert_ne!(MonitorId::new(1), MonitorId::new(2));
        assert_ne!(
            MonitorId::from_index_and_hash(1, 7),
            MonitorId::from_index_and_hash(1, 8)
        );
    }

    #[test]
    fn monitor_id_from_properties_is_stable_and_index_independent() {
        let pos = LayoutPoint::new(-1920, 0);
        let size = LayoutSize::new(2560, 1440);

        let a = MonitorId::from_properties(0, "HDMI-1", pos, size);
        let b = MonitorId::from_properties(0, "HDMI-1", pos, size);
        assert_eq!(a, b, "hash must be stable across calls (persistable)");

        // The hash intentionally covers only the properties, not the runtime index.
        let reindexed = MonitorId::from_properties(7, "HDMI-1", pos, size);
        assert_eq!(reindexed.hash, a.hash);
        assert_eq!(reindexed.index, 7);
        assert_ne!(reindexed, a, "index is still part of identity");
    }

    #[test]
    fn monitor_id_from_properties_is_sensitive_to_each_property() {
        let pos = LayoutPoint::new(0, 0);
        let size = LayoutSize::new(1920, 1080);
        let base = MonitorId::from_properties(0, "DP-1", pos, size);

        // Changing any single property must change the hash.
        assert_ne!(
            base.hash,
            MonitorId::from_properties(0, "DP-2", pos, size).hash
        );
        assert_ne!(
            base.hash,
            MonitorId::from_properties(0, "DP-1", LayoutPoint::new(1, 0), size).hash
        );
        assert_ne!(
            base.hash,
            MonitorId::from_properties(0, "DP-1", LayoutPoint::new(0, 1), size).hash
        );
        assert_ne!(
            base.hash,
            MonitorId::from_properties(0, "DP-1", pos, LayoutSize::new(1921, 1080)).hash
        );
        assert_ne!(
            base.hash,
            MonitorId::from_properties(0, "DP-1", pos, LayoutSize::new(1920, 1081)).hash
        );
        // A swapped width/height is a different monitor, not the same one.
        assert_ne!(
            base.hash,
            MonitorId::from_properties(0, "DP-1", pos, LayoutSize::new(1080, 1920)).hash
        );
    }

    #[test]
    fn monitor_id_from_properties_handles_hostile_inputs() {
        let size = LayoutSize::new(isize::MAX, isize::MIN);
        let pos = LayoutPoint::new(isize::MIN, isize::MAX);

        // Empty / whitespace / unicode / NUL-containing names must not panic.
        for name in ["", "   ", "\t\n", "\u{1F600}", "e\u{301}", "é", "a\0b"] {
            let m = MonitorId::from_properties(3, name, pos, size);
            assert_eq!(m.index, 3);
            // Same input -> same hash, even at isize extremes.
            assert_eq!(m, MonitorId::from_properties(3, name, pos, size));
        }

        // Byte-exact name comparison: combining-mark and precomposed forms differ.
        assert_ne!(
            MonitorId::from_properties(0, "e\u{301}", pos, size).hash,
            MonitorId::from_properties(0, "é", pos, size).hash
        );

        // A 1M-char monitor name must terminate quickly (FNV-1a is linear).
        let huge = "x".repeat(1_000_000);
        let h1 = MonitorId::from_properties(0, &huge, LayoutPoint::zero(), LayoutSize::zero());
        let h2 = MonitorId::from_properties(0, &huge, LayoutPoint::zero(), LayoutSize::zero());
        assert_eq!(h1, h2);
        assert_ne!(
            h1.hash,
            MonitorId::from_properties(0, "x", LayoutPoint::zero(), LayoutSize::zero()).hash
        );
    }

    // ---------------------------------------------------------------------
    // WindowFlags predicates / getters
    // ---------------------------------------------------------------------

    #[test]
    fn window_flags_type_predicates_are_mutually_exclusive() {
        for (ty, menu, tooltip, dialog) in [
            (WindowType::Normal, false, false, false),
            (WindowType::Menu, true, false, false),
            (WindowType::Tooltip, false, true, false),
            (WindowType::Dialog, false, false, true),
        ] {
            let f = WindowFlags {
                window_type: ty,
                ..WindowFlags::default()
            };
            assert_eq!(f.is_menu_window(), menu);
            assert_eq!(f.is_tooltip_window(), tooltip);
            assert_eq!(f.is_dialog_window(), dialog);
            // At most one classification can ever be true at once.
            let count = u8::from(f.is_menu_window())
                + u8::from(f.is_tooltip_window())
                + u8::from(f.is_dialog_window());
            assert!(count <= 1);
        }
    }

    #[test]
    fn window_flags_bool_getters_mirror_their_fields() {
        // Default: focused, no close request, no CSD.
        let d = WindowFlags::default();
        assert!(d.window_has_focus());
        assert!(!d.is_close_requested());
        assert!(!d.has_csd());
        assert_eq!(
            d.use_native_menus(),
            cfg!(any(target_os = "windows", target_os = "macos"))
        );
        assert_eq!(
            d.use_native_context_menus(),
            cfg!(any(target_os = "windows", target_os = "macos"))
        );

        // Every getter is a pure mirror of its field, in both states.
        for b in [false, true] {
            let f = WindowFlags {
                has_focus: b,
                close_requested: b,
                has_decorations: b,
                use_native_menus: b,
                use_native_context_menus: b,
                ..WindowFlags::default()
            };
            assert_eq!(f.window_has_focus(), b);
            assert_eq!(f.is_close_requested(), b);
            assert_eq!(f.has_csd(), b);
            assert_eq!(f.use_native_menus(), b);
            assert_eq!(f.use_native_context_menus(), b);
        }
    }

    // ---------------------------------------------------------------------
    // StringPairVec: get_key / get_key_mut / insert_kv
    // ---------------------------------------------------------------------

    #[test]
    fn get_key_on_empty_vec_is_none() {
        let empty = StringPairVec::new();
        assert!(empty.get_key("").is_none());
        assert!(empty.get_key("anything").is_none());

        let mut empty_mut = StringPairVec::new();
        assert!(empty_mut.get_key_mut("").is_none());
        assert!(empty_mut.get_key_mut("anything").is_none());
    }

    #[test]
    fn get_key_valid_minimal_and_missing() {
        let v = StringPairVec::from_vec(vec![pair("WM_CLASS", "azul")]);
        assert_eq!(
            v.get_key("WM_CLASS").map(AzString::as_str),
            Some("azul"),
            "positive control"
        );
        assert!(v.get_key("wm_class").is_none(), "lookup is case-sensitive");
        assert!(v.get_key("WM_CLAS").is_none());
        assert!(v.get_key("WM_CLASS ").is_none(), "no trimming is performed");
        assert!(v.get_key(" WM_CLASS").is_none());
        assert!(v.get_key("WM_CLASS;garbage").is_none());
    }

    #[test]
    fn get_key_handles_garbage_whitespace_and_boundary_numbers() {
        let v = StringPairVec::from_vec(vec![
            pair("", "empty-key"),
            pair("   ", "spaces"),
            pair("\t\n", "tabs"),
            pair("0", "zero"),
            pair("-0", "neg-zero"),
            pair("9223372036854775807", "i64-max"),
            pair("NaN", "nan"),
            pair("inf", "inf"),
        ]);

        // Empty and whitespace-only keys are ordinary keys - looked up verbatim.
        assert_eq!(v.get_key("").map(AzString::as_str), Some("empty-key"));
        assert_eq!(v.get_key("   ").map(AzString::as_str), Some("spaces"));
        assert_eq!(v.get_key("\t\n").map(AzString::as_str), Some("tabs"));

        // Numeric-looking keys are compared as strings: "0" and "-0" are distinct.
        assert_eq!(v.get_key("0").map(AzString::as_str), Some("zero"));
        assert_eq!(v.get_key("-0").map(AzString::as_str), Some("neg-zero"));
        assert_eq!(
            v.get_key("9223372036854775807").map(AzString::as_str),
            Some("i64-max")
        );
        assert_eq!(v.get_key("NaN").map(AzString::as_str), Some("nan"));
        assert_eq!(v.get_key("inf").map(AzString::as_str), Some("inf"));
        assert!(v.get_key("nan").is_none());

        // Random non-grammar bytes / control chars / deep bracket nesting: None, no panic.
        assert!(v.get_key("\u{0}\u{1}\u{7f}\\x\"';--").is_none());
        assert!(v.get_key(&"[".repeat(10_000)).is_none());
        assert!(v.get_key(&"{\"a\":".repeat(10_000)).is_none());
    }

    #[test]
    fn get_key_handles_unicode_without_panicking() {
        let v = StringPairVec::from_vec(vec![
            pair("\u{1F600}", "grin"),
            pair("é", "precomposed"),
            pair("日本語", "jp"),
        ]);
        assert_eq!(v.get_key("\u{1F600}").map(AzString::as_str), Some("grin"));
        assert_eq!(v.get_key("日本語").map(AzString::as_str), Some("jp"));
        // No unicode normalization: decomposed "e" + combining acute != "é".
        assert_eq!(v.get_key("é").map(AzString::as_str), Some("precomposed"));
        assert!(v.get_key("e\u{301}").is_none());
        // A prefix of a multi-byte key must not match (no byte-slicing bugs).
        assert!(v.get_key("日本").is_none());
    }

    #[test]
    fn get_key_handles_extremely_long_input() {
        let huge = "k".repeat(1_000_000);
        let mut v = StringPairVec::from_vec(vec![pair("short", "1")]);

        // Searching for a 1M-char key that is not present: linear, terminates.
        assert!(v.get_key(&huge).is_none());

        // ...and one that IS present.
        v.push(AzStringPair {
            key: huge.as_str().into(),
            value: "big".into(),
        });
        assert_eq!(v.get_key(&huge).map(AzString::as_str), Some("big"));
        // Off-by-one on a 1M-char key must not match.
        assert!(v.get_key(&"k".repeat(999_999)).is_none());
        assert!(v.get_key(&"k".repeat(1_000_001)).is_none());
    }

    #[test]
    fn get_key_returns_first_of_duplicate_keys() {
        let v = StringPairVec::from_vec(vec![
            pair("dup", "first"),
            pair("dup", "second"),
            pair("dup", "third"),
        ]);
        assert_eq!(v.get_key("dup").map(AzString::as_str), Some("first"));
    }

    #[test]
    fn get_key_mut_mutates_in_place() {
        let mut v = StringPairVec::from_vec(vec![pair("a", "1"), pair("b", "2")]);
        {
            let entry = v.get_key_mut("b").expect("b is present");
            entry.value = "changed".into();
        }
        assert_eq!(v.get_key("b").map(AzString::as_str), Some("changed"));
        assert_eq!(v.get_key("a").map(AzString::as_str), Some("1"));
        assert!(v.get_key_mut("missing").is_none());
        assert_eq!(v.len(), 2, "get_key_mut must not add entries");

        // Mutating the KEY through get_key_mut is possible and re-targets lookups.
        {
            let entry = v.get_key_mut("a").expect("a is present");
            entry.key = "z".into();
        }
        assert!(v.get_key("a").is_none());
        assert_eq!(v.get_key("z").map(AzString::as_str), Some("1"));
    }

    #[test]
    fn insert_kv_updates_existing_and_appends_new() {
        let mut v = StringPairVec::new();
        v.insert_kv("k", "v1");
        assert_eq!(v.len(), 1);
        assert_eq!(v.get_key("k").map(AzString::as_str), Some("v1"));

        // Re-inserting the same key overwrites in place instead of appending.
        v.insert_kv("k", "v2");
        assert_eq!(v.len(), 1, "insert_kv must not duplicate an existing key");
        assert_eq!(v.get_key("k").map(AzString::as_str), Some("v2"));

        // A different key appends.
        v.insert_kv("other", "x");
        assert_eq!(v.len(), 2);
        assert_eq!(v.get_key("k").map(AzString::as_str), Some("v2"));
        assert_eq!(v.get_key("other").map(AzString::as_str), Some("x"));

        // Repeated inserts of the same key never grow the vec.
        for i in 0..100 {
            v.insert_kv(String::from("k"), format!("gen{i}"));
        }
        assert_eq!(v.len(), 2);
        assert_eq!(v.get_key("k").map(AzString::as_str), Some("gen99"));
    }

    #[test]
    fn insert_kv_accepts_hostile_keys_and_values() {
        let mut v = StringPairVec::new();
        v.insert_kv("", "");
        assert_eq!(v.len(), 1);
        assert_eq!(v.get_key("").map(AzString::as_str), Some(""));

        v.insert_kv("\u{1F600}", "😀");
        assert_eq!(v.get_key("\u{1F600}").map(AzString::as_str), Some("😀"));

        v.insert_kv("   ", "\t\n");
        assert_eq!(v.get_key("   ").map(AzString::as_str), Some("\t\n"));

        // Very long key + value: no hang, and the update path still finds it.
        let huge_key = "K".repeat(100_000);
        let huge_val = "V".repeat(100_000);
        v.insert_kv(huge_key.clone(), huge_val.clone());
        let before = v.len();
        assert_eq!(
            v.get_key(&huge_key).map(AzString::as_str),
            Some(huge_val.as_str())
        );
        v.insert_kv(huge_key.clone(), String::from("small"));
        assert_eq!(v.len(), before, "long key must hit the update path");
        assert_eq!(v.get_key(&huge_key).map(AzString::as_str), Some("small"));
    }

    #[test]
    fn insert_kv_only_updates_the_first_of_pre_existing_duplicates() {
        // Duplicates can only arrive via push()/from_vec(); insert_kv updates the
        // first match (get_key_mut semantics) and leaves the shadowed one stale.
        let mut v = StringPairVec::from_vec(vec![pair("dup", "first"), pair("dup", "second")]);
        v.insert_kv("dup", "updated");
        assert_eq!(v.len(), 2, "no new entry is appended");
        assert_eq!(v.get_key("dup").map(AzString::as_str), Some("updated"));
        assert_eq!(
            v.get(1).expect("second entry still present").value.as_str(),
            "second",
            "the shadowed duplicate is left untouched"
        );
    }

    // ---------------------------------------------------------------------
    // WindowSize getters (numeric saturation)
    // ---------------------------------------------------------------------

    #[test]
    fn window_size_get_logical_size_is_the_identity() {
        for dims in [
            LogicalSize::zero(),
            LogicalSize::new(640.0, 480.0),
            LogicalSize::new(-1.0, -2.0),
            LogicalSize::new(f32::MAX, f32::MIN),
            LogicalSize::new(f32::INFINITY, f32::MIN_POSITIVE),
        ] {
            let ws = WindowSize {
                dimensions: dims,
                ..WindowSize::default()
            };
            assert_eq!(ws.get_logical_size(), dims);
        }
        // Default is the documented 640x480 @ 96 DPI.
        let d = WindowSize::default();
        assert_eq!(d.get_logical_size(), LogicalSize::new(640.0, 480.0));
        assert_eq!(d.dpi, 96);
    }

    #[test]
    fn window_size_get_layout_size_rounds_half_away_from_zero() {
        for (w, h, ew, eh) in [
            (0.0f32, 0.0f32, 0isize, 0isize),
            (640.0, 480.0, 640, 480),
            (640.4, 480.4, 640, 480),
            (640.6, 480.6, 641, 481),
            (640.5, 639.5, 641, 640),
            (-0.5, -1.5, -1, -2),
        ] {
            let ws = WindowSize {
                dimensions: LogicalSize::new(w, h),
                ..WindowSize::default()
            };
            assert_eq!(ws.get_layout_size(), LayoutSize::new(ew, eh), "{w}x{h}");
        }
    }

    #[test]
    fn window_size_get_layout_size_saturates_on_non_finite() {
        // `as isize` saturates: NaN -> 0, +inf -> isize::MAX, -inf -> isize::MIN.
        let nan = WindowSize {
            dimensions: LogicalSize::new(f32::NAN, f32::NAN),
            ..WindowSize::default()
        };
        assert_eq!(nan.get_layout_size(), LayoutSize::new(0, 0));

        let inf = WindowSize {
            dimensions: LogicalSize::new(f32::INFINITY, f32::NEG_INFINITY),
            ..WindowSize::default()
        };
        assert_eq!(
            inf.get_layout_size(),
            LayoutSize::new(isize::MAX, isize::MIN)
        );

        let max = WindowSize {
            dimensions: LogicalSize::new(f32::MAX, f32::MIN),
            ..WindowSize::default()
        };
        let ls = max.get_layout_size();
        assert!(ls.width > 0 && ls.height < 0, "sign is preserved: {ls:?}");
    }

    #[test]
    fn window_size_get_physical_size_saturates_instead_of_wrapping() {
        // Negative logical sizes clamp to 0 (u32 cast drops the sign).
        let neg = WindowSize {
            dimensions: LogicalSize::new(-100.0, -0.4),
            ..WindowSize::default()
        };
        assert_eq!(neg.get_physical_size(), PhysicalSize::new(0, 0));

        // NaN -> 0, +inf -> u32::MAX (saturating float->int cast, no UB).
        let nan = WindowSize {
            dimensions: LogicalSize::new(f32::NAN, f32::INFINITY),
            ..WindowSize::default()
        };
        assert_eq!(nan.get_physical_size(), PhysicalSize::new(0, u32::MAX));

        // f32::MAX at 4x scale overflows u32 -> saturates, never wraps to a small value.
        let huge = WindowSize {
            dimensions: LogicalSize::new(f32::MAX, f32::MAX),
            dpi: 384,
            ..WindowSize::default()
        };
        assert_eq!(
            huge.get_physical_size(),
            PhysicalSize::new(u32::MAX, u32::MAX)
        );

        // The normal path: 96 DPI is 1:1, 192 DPI doubles.
        let normal = WindowSize::default();
        assert_eq!(normal.get_physical_size(), PhysicalSize::new(640, 480));
        let retina = WindowSize {
            dpi: 192,
            ..WindowSize::default()
        };
        assert_eq!(retina.get_physical_size(), PhysicalSize::new(1280, 960));
    }

    #[test]
    fn window_size_get_hidpi_factor_is_never_zero_or_negative() {
        // A 0.0 factor would divide-by-zero in to_logical(); the getter guards dpi == 0.
        for dpi in [
            0u32,
            1,
            47,
            48,
            95,
            96,
            97,
            120,
            144,
            192,
            384,
            u32::from(u16::MAX),
            u32::MAX,
        ] {
            let ws = WindowSize {
                dpi,
                ..WindowSize::default()
            };
            let f = ws.get_hidpi_factor().inner.get();
            assert!(
                f.is_finite() && f > 0.0,
                "dpi {dpi} produced a non-positive / non-finite scale factor: {f}"
            );
        }

        // Exactly representable factors must be exact (no quantization drift).
        for (dpi, expected) in [(0u32, 1.0f32), (96, 1.0), (144, 1.5), (192, 2.0), (384, 4.0)] {
            let ws = WindowSize {
                dpi,
                ..WindowSize::default()
            };
            assert_eq!(ws.get_hidpi_factor().inner.get(), expected, "dpi {dpi}");
        }

        // Non-representable factors stay within FloatValue's 1/1000 quantization.
        let odd = WindowSize {
            dpi: 100,
            ..WindowSize::default()
        };
        let f = odd.get_hidpi_factor().inner.get();
        assert!((f - 100.0 / 96.0).abs() < 0.002, "dpi 100 -> {f}");
    }

    // ---------------------------------------------------------------------
    // VirtualKeyCode: from_u32 / get_lowercase
    // ---------------------------------------------------------------------

    #[test]
    fn virtual_keycode_from_u32_roundtrips_every_discriminant() {
        for v in 0..=LAST_VK {
            let vk = VirtualKeyCode::from_u32(v)
                .unwrap_or_else(|| panic!("discriminant {v} is missing from the from_u32 table"));
            assert_eq!(vk as u32, v, "from_u32({v}) does not round-trip");
        }
        // First and last declared variants anchor the table.
        assert_eq!(VirtualKeyCode::Key1 as u32, 0);
        assert_eq!(VirtualKeyCode::Cut as u32, LAST_VK);
    }

    #[test]
    fn virtual_keycode_from_u32_rejects_out_of_range() {
        for v in [
            LAST_VK + 1,
            LAST_VK + 2,
            255,
            256,
            1024,
            i32::MAX as u32,
            u32::MAX - 1,
            u32::MAX,
        ] {
            assert_eq!(
                VirtualKeyCode::from_u32(v),
                None,
                "{v} must not decode to a keycode"
            );
        }
    }

    #[test]
    fn virtual_keycode_get_lowercase_never_panics_and_maps_letters_and_digits() {
        // Exhaustive: no keycode may panic, and any produced char is ASCII.
        for v in 0..=LAST_VK {
            let vk = VirtualKeyCode::from_u32(v).expect("discriminant in range");
            if let Some(c) = vk.get_lowercase() {
                assert!(c.is_ascii(), "{vk:?} produced a non-ASCII char {c:?}");
                assert!(!c.is_ascii_uppercase(), "{vk:?} must yield lowercase");
            }
        }

        // Letters A..Z are discriminants 10..=35 and map to 'a'..='z'.
        for (i, expected) in ('a'..='z').enumerate() {
            let vk = VirtualKeyCode::from_u32(10 + i as u32).expect("letter range");
            assert_eq!(vk.get_lowercase(), Some(expected));
        }

        // Digits: both the top row and the numpad map to the same char.
        for (top, pad, c) in [
            (VirtualKeyCode::Key0, VirtualKeyCode::Numpad0, '0'),
            (VirtualKeyCode::Key1, VirtualKeyCode::Numpad1, '1'),
            (VirtualKeyCode::Key5, VirtualKeyCode::Numpad5, '5'),
            (VirtualKeyCode::Key9, VirtualKeyCode::Numpad9, '9'),
        ] {
            assert_eq!(top.get_lowercase(), Some(c));
            assert_eq!(pad.get_lowercase(), Some(c));
        }

        // Punctuation that IS mapped.
        assert_eq!(VirtualKeyCode::Minus.get_lowercase(), Some('-'));
        assert_eq!(VirtualKeyCode::Period.get_lowercase(), Some('.'));
        assert_eq!(VirtualKeyCode::Slash.get_lowercase(), Some('/'));
        assert_eq!(VirtualKeyCode::Caret.get_lowercase(), Some('^'));

        // Non-character keys have no lowercase form.
        for vk in [
            VirtualKeyCode::LShift,
            VirtualKeyCode::RControl,
            VirtualKeyCode::Escape,
            VirtualKeyCode::F12,
            VirtualKeyCode::Space,
            VirtualKeyCode::Return,
            VirtualKeyCode::Back,
        ] {
            assert_eq!(vk.get_lowercase(), None, "{vk:?}");
        }
    }

    // ---------------------------------------------------------------------
    // WindowIcon::get_key + key-only Eq/Ord/Hash
    // ---------------------------------------------------------------------

    #[test]
    fn window_icon_get_key_returns_the_stored_key() {
        let small_key = IconKey::new();
        let large_key = IconKey::new();

        let small = WindowIcon::Small(SmallWindowIconBytes {
            key: small_key,
            rgba_bytes: vec![0u8; 16 * 16 * 4].into(),
        });
        let large = WindowIcon::Large(LargeWindowIconBytes {
            key: large_key,
            rgba_bytes: vec![255u8; 32 * 32 * 4].into(),
        });

        assert_eq!(small.get_key(), small_key);
        assert_eq!(large.get_key(), large_key);

        // Empty payloads are legal and must not panic.
        let empty = WindowIcon::Small(SmallWindowIconBytes {
            key: small_key,
            rgba_bytes: vec![].into(),
        });
        assert_eq!(empty.get_key(), small_key);
    }

    #[test]
    fn window_icon_identity_is_the_key_alone() {
        // The whole point of IconKey: diff the key, not the bytes. Two icons with
        // the same key compare equal even though their pixels differ.
        let key = IconKey::new();
        let a = WindowIcon::Small(SmallWindowIconBytes {
            key,
            rgba_bytes: vec![0u8; 4].into(),
        });
        let b = WindowIcon::Small(SmallWindowIconBytes {
            key,
            rgba_bytes: vec![7u8; 1024].into(),
        });
        // ...even across the Small/Large variants.
        let c = WindowIcon::Large(LargeWindowIconBytes {
            key,
            rgba_bytes: vec![9u8; 32 * 32 * 4].into(),
        });

        assert_eq!(a, b);
        assert_eq!(a, c);
        assert_eq!(a.cmp(&c), Ordering::Equal);
        assert_eq!(a.partial_cmp(&b), Some(Ordering::Equal));
        // Hash must agree with Eq, or icons break as BTreeMap/HashMap keys.
        assert_eq!(hash_of(&a), hash_of(&b));
        assert_eq!(hash_of(&a), hash_of(&c));

        // Different keys: unequal, and ordered by key.
        let older = WindowIcon::Small(SmallWindowIconBytes {
            key,
            rgba_bytes: vec![0u8; 4].into(),
        });
        let newer = WindowIcon::Small(SmallWindowIconBytes {
            key: IconKey::new(),
            rgba_bytes: vec![0u8; 4].into(),
        });
        assert_ne!(older, newer);
        assert_eq!(older.cmp(&newer), Ordering::Less);
    }

    // ---------------------------------------------------------------------
    // UpdateFocusWarning: Display
    // ---------------------------------------------------------------------

    #[test]
    fn update_focus_warning_display_is_non_empty_for_every_variant() {
        let dom = format!("{}", UpdateFocusWarning::FocusInvalidDomId(DomId::ROOT_ID));
        assert!(dom.contains("invalid ID"), "{dom}");
        assert!(!dom.is_empty());

        let node = format!(
            "{}",
            UpdateFocusWarning::FocusInvalidNodeId(NodeHierarchyItemId::NONE)
        );
        assert!(node.contains("invalid ID"), "{node}");

        // Edge values: a zero DomId, a raw-encoded huge node id, an empty CssPath.
        let huge = format!(
            "{}",
            UpdateFocusWarning::FocusInvalidNodeId(NodeHierarchyItemId::from_raw(usize::MAX))
        );
        assert!(!huge.is_empty());

        let path = format!(
            "{}",
            UpdateFocusWarning::CouldNotFindFocusNode(CssPath::default())
        );
        assert!(
            path.starts_with("Could not find focus node for path:"),
            "{path}"
        );
    }
}