//! The `Event` enum and assorted supporting types.
//!
use bitflags::bitflags;
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};

/// Identifier for a specific analog axis on some device.
pub type AxisId = u32;

/// Identifier for a specific button on some device.
#[derive(Copy, Clone, Default, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub struct ButtonId(pub u32);

impl From<ButtonId> for u32 {
    fn from(val: ButtonId) -> Self {
        val.0
    }
}

pub use crate::DeviceId;

/// Represents raw hardware events that are not associated with any particular window.
///
/// Useful for interactions that diverge significantly from a conventional 2D GUI, such as 3D camera or first-person
/// game controls. Many physical actions, such as mouse movement, can produce both device and window events. Because
/// window events typically arise from virtual devices (corresponding to GUI cursors and keyboard focus) the device IDs
/// may not match.
///
/// Note that these events are delivered regardless of input focus.
#[derive(Clone, Debug, PartialEq)]
pub enum Event {
    Dummy,
    Added,
    Removed,

    MouseButton {
        button: MouseButton,
        state: ElementState,
    },

    /// Change in physical position of a pointing device.
    ///
    /// This represents raw, unfiltered physical motion. Not to be confused with `WindowEvent::CursorMoved`.
    MouseMotion {
        /// (x, y) change in position in unspecified units.
        ///
        /// Different devices may use different units.
        delta: (f64, f64),
    },

    /// Physical scroll event
    MouseWheel {
        delta: MouseScrollDelta,
    },

    /// Motion on some analog axis.  This event will be reported for all arbitrary input devices
    /// that winit supports on this platform, including mouse devices.  If the device is a mouse
    /// device then this will be reported alongside the MouseMotion event.
    Motion {
        axis: AxisId,
        value: f64,
    },

    Button {
        button: ButtonId,
        state: ElementState,
    },

    Key(KeyboardInput),

    Text {
        codepoint: char,
    },
}

/// Describes the input state of a key.
#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum ElementState {
    Pressed,
    Released,
    Repeated,
    Unknown,
}

impl Default for ElementState {
    fn default() -> Self {
        Self::Unknown
    }
}

/// Describes a keyboard input event.
#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct KeyboardInput {
    /// Identifies the physical key pressed
    ///
    /// This should 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.
    pub scancode: ScanCode,

    /// Identifies the key is pressed, released or repeated.
    pub state: ElementState,

    /// Identifies the semantic meaning of the key
    ///
    /// Use when the semantics of the key are more important than the physical location of the key, such as when
    /// implementing appropriate behavior for "page up."
    pub virtual_keycode: Option<VirtualKeyCode>,
}

impl KeyboardInput {
    // Determine the Key with `key_code` is in `Pressed` state.
    pub fn is_key_pressed(&self, key_code: VirtualKeyCode) -> bool {
        self.virtual_keycode == Some(key_code) && self.state == ElementState::Pressed
    }

    // Determine the Key with `key_code` is in `Released` state.
    pub fn is_key_released(&self, key_code: VirtualKeyCode) -> bool {
        self.virtual_keycode == Some(key_code) && self.state == ElementState::Released
    }

    // Determine the Key with `key_code` is in `Repeated` state.
    pub fn is_key_repeated(&self, key_code: VirtualKeyCode) -> bool {
        self.virtual_keycode == Some(key_code) && self.state == ElementState::Repeated
    }

    // Determine the Key with `key_code` is in `Pressed` or `Repeated` state.
    pub fn is_key_triggered(&self, key_code: VirtualKeyCode) -> bool {
        self.virtual_keycode == Some(key_code)
            && (self.state == ElementState::Pressed || self.state == ElementState::Repeated)
    }
}

/// Describes touch-screen input state.
#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum TouchPhase {
    Started,
    Moved,
    Ended,
    Cancelled,
}

/// Represents a touch event
///
/// Every time the user touches the screen, a new `Start` event with an unique
/// identifier for the finger is generated. When the finger is lifted, an `End`
/// event is generated with the same finger id.
///
/// After a `Start` event has been emitted, there may be zero or more `Move`
/// events when the finger is moved or the touch pressure changes.
///
/// The finger id may be reused by the system after an `End` event. The user
/// should assume that a new `Start` event received with the same id has nothing
/// to do with the old finger and is a new finger.
///
/// A `Cancelled` event is emitted when the system has canceled tracking this
/// touch, such as when the window loses focus, or on iOS if the user moves the
/// device against their face.
#[derive(Debug, Clone, Copy, PartialEq)]
pub struct Touch {
    pub device_id: DeviceId,
    pub phase: TouchPhase,
    pub location: PhysicalPosition<f64>,
    /// Describes how hard the screen was pressed. May be `None` if the platform
    /// does not support pressure sensitivity.
    ///
    /// ## Platform-specific
    ///
    /// - Only available on **iOS** 9.0+ and **Windows** 8+.
    pub force: Option<Force>,
    /// Unique identifier of a finger.
    pub id: u64,
}

/// Describes the force of a touch event
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum Force {
    /// On iOS, the force is calibrated so that the same number corresponds to
    /// roughly the same amount of pressure on the screen regardless of the
    /// device.
    Calibrated {
        /// The force of the touch, where a value of 1.0 represents the force of
        /// an average touch (predetermined by the system, not user-specific).
        ///
        /// The force reported by Apple Pencil is measured along the axis of the
        /// pencil. If you want a force perpendicular to the device, you need to
        /// calculate this value using the `altitude_angle` value.
        force: f64,
        /// The maximum possible force for a touch.
        ///
        /// The value of this field is sufficiently high to provide a wide
        /// dynamic range for values of the `force` field.
        max_possible_force: f64,
        /// The altitude (in radians) of the stylus.
        ///
        /// A value of 0 radians indicates that the stylus is parallel to the
        /// surface. The value of this property is Pi/2 when the stylus is
        /// perpendicular to the surface.
        altitude_angle: Option<f64>,
    },
    /// If the platform reports the force as normalized, we have no way of
    /// knowing how much pressure 1.0 corresponds to – we know it's the maximum
    /// amount of force, but as to how much force, you might either have to
    /// press really really hard, or not hard at all, depending on the device.
    Normalized(f64),
}

impl Force {
    /// Returns the force normalized to the range between 0.0 and 1.0 inclusive.
    /// Instead of normalizing the force, you should prefer to handle
    /// `Force::Calibrated` so that the amount of force the user has to apply is
    /// consistent across devices.
    pub fn normalized(&self) -> f64 {
        match self {
            Force::Calibrated {
                force,
                max_possible_force,
                altitude_angle,
            } => {
                let force = match altitude_angle {
                    Some(altitude_angle) => force / altitude_angle.sin(),
                    None => *force,
                };
                force / max_possible_force
            }
            Force::Normalized(force) => *force,
        }
    }
}

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

bitflags! {
    /// Represents the current state of the keyboard modifiers
    ///
    /// Each flag represents a modifier and is set if this modifier is active.
    #[derive(Default)]
    pub struct ModifiersState: u32 {
        // left and right modifiers are currently commented out, but we should be able to support
        // them in a future release
        /// The "shift" key.
        const SHIFT = 0b100;
        const LSHIFT = 0b010;
        const RSHIFT = 0b001;
        /// The "control" key.
        const CTRL = 0b100 << 3;
        const LCTRL = 0b010 << 3;
        const RCTRL = 0b001 << 3;
        /// The "alt" key.
        const ALT = 0b100 << 6;
        const LALT = 0b010 << 6;
        const RALT = 0b001 << 6;
        /// This is the "windows" key on PC and "command" key on Mac.
        const LOGO = 0b100 << 9;
        const LLOGO = 0b010 << 9;
        const RLOGO = 0b001 << 9;
    }
}

impl ModifiersState {
    /// Returns `true` if the shift key is pressed.
    pub fn shift(&self) -> bool {
        self.intersects(Self::SHIFT)
    }
    /// Returns `true` if the control key is pressed.
    pub fn ctrl(&self) -> bool {
        self.intersects(Self::CTRL)
    }
    /// Returns `true` if the alt key is pressed.
    pub fn alt(&self) -> bool {
        self.intersects(Self::ALT)
    }
    /// Returns `true` if the logo key is pressed.
    pub fn logo(&self) -> bool {
        self.intersects(Self::LOGO)
    }
}

#[cfg(feature = "serde")]
mod modifiers_serde {
    use super::ModifiersState;
    use serde::{Deserialize, Deserializer, Serialize, Serializer};

    #[derive(Default, Serialize, Deserialize)]
    #[serde(default)]
    #[serde(rename = "ModifiersState")]
    pub struct ModifiersStateSerialize {
        pub shift: bool,
        pub ctrl: bool,
        pub alt: bool,
        pub logo: bool,
    }

    impl Serialize for ModifiersState {
        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
        where
            S: Serializer,
        {
            let s = ModifiersStateSerialize {
                shift: self.shift(),
                ctrl: self.ctrl(),
                alt: self.alt(),
                logo: self.logo(),
            };
            s.serialize(serializer)
        }
    }

    impl<'de> Deserialize<'de> for ModifiersState {
        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
        where
            D: Deserializer<'de>,
        {
            let ModifiersStateSerialize {
                shift,
                ctrl,
                alt,
                logo,
            } = ModifiersStateSerialize::deserialize(deserializer)?;
            let mut m = ModifiersState::empty();
            m.set(ModifiersState::SHIFT, shift);
            m.set(ModifiersState::CTRL, ctrl);
            m.set(ModifiersState::ALT, alt);
            m.set(ModifiersState::LOGO, logo);
            Ok(m)
        }
    }
}

/// Describes a button of a mouse controller.
#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum MouseButton {
    Left,
    Right,
    Middle,
    Other(u8),
}

/// Describes a difference in the mouse scroll wheel state.
#[derive(Debug, Clone, Copy, PartialEq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum MouseScrollDelta {
    /// Amount in lines or rows to scroll in the horizontal
    /// and vertical directions.
    ///
    /// Positive values indicate movement forward
    /// (away from the user) or rightwards.
    LineDelta(f32, f32),
    /// Amount in pixels to scroll in the horizontal and
    /// vertical direction.
    ///
    /// Scroll events are expressed as a PixelDelta if
    /// supported by the device (eg. a touchpad) and
    /// platform.
    PixelDelta(PhysicalPosition<f64>),
}

/// A position represented in physical pixels.
#[derive(Debug, Copy, Clone, PartialEq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct PhysicalPosition<P> {
    pub x: P,
    pub y: P,
}

impl<P> PhysicalPosition<P> {
    #[inline]
    pub const fn new(x: P, y: P) -> Self {
        PhysicalPosition { x, y }
    }
}

/// Symbolic name for a keyboard key.
#[derive(Debug, Hash, Ord, PartialOrd, PartialEq, Eq, Clone, Copy)]
#[repr(u32)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum VirtualKeyCode {
    /// The '1' key over the letters.
    Key1,
    /// The '2' key over the letters.
    Key2,
    /// The '3' key over the letters.
    Key3,
    /// The '4' key over the letters.
    Key4,
    /// The '5' key over the letters.
    Key5,
    /// The '6' key over the letters.
    Key6,
    /// The '7' key over the letters.
    Key7,
    /// The '8' key over the letters.
    Key8,
    /// The '9' key over the letters.
    Key9,
    /// The '0' key over the 'O' and 'P' keys.
    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,

    /// The Escape key, next to F1.
    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,

    /// Print Screen/SysRq.
    Snapshot,
    /// Scroll Lock.
    Scroll,
    /// Pause/Break key, next to Scroll lock.
    Pause,

    /// `Insert`, next to Backspace.
    Insert,
    Home,
    Delete,
    End,
    PageDown,
    PageUp,

    Left,
    Up,
    Right,
    Down,

    /// The Backspace key, right over Enter.
    // TODO: rename
    Back,
    /// The Enter key.
    Return,
    /// The space bar.
    Space,

    /// The "Compose" key on Linux.
    Compose,

    Caret,

    Numlock,
    Numpad0,
    Numpad1,
    Numpad2,
    Numpad3,
    Numpad4,
    Numpad5,
    Numpad6,
    Numpad7,
    Numpad8,
    Numpad9,
    NumpadComma,
    NumpadEnter,
    NumpadEquals,
    NumpadSubtract,

    AbntC1,
    AbntC2,
    Apostrophe,
    Apps,
    At,
    Ax,
    Backslash,
    Calculator,
    Capital,
    Colon,
    Comma,
    Convert,
    Decimal,
    Divide,
    Equals,
    Grave,
    Kana,
    Kanji,
    LAlt,
    LBracket,
    LControl,
    LShift,
    LWin,
    Mail,
    MediaSelect,
    MediaStop,
    Minus,
    Multiply,
    Mute,
    MyComputer,
    // also called "Next"
    NavigateForward,
    // also called "Prior"
    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,
}