//! Back-end agnostic controller events.

use {Event, Input, Motion};

/// Components of a controller button event. Not guaranteed consistent across
/// backends.
#[derive(Copy, Clone, Deserialize, Serialize, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct ControllerButton {
    /// Which controller was the button on.
    pub id: u32,
    /// Which button was pressed.
    pub button: u8,
}

impl ControllerButton {
    /// Create a new ControllerButton object. Intended for use by backends when
    /// emitting events.
    pub fn new(id: u32, button: u8) -> Self {
        ControllerButton {
            id: id,
            button: button,
        }
    }
}

/// Components of a controller hat move event (d-Pad).
#[derive(Copy, Clone, Deserialize, Serialize, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
pub struct ControllerHat {
  /// Which Controller was the button on.
  pub id: u32,
  /// Which button was pressed.
  pub state: ::HatState,
  /// Which hat on the controller was changed
  pub which: u8,
}

impl ControllerHat {
  /// Create a new ControllerButton object. Intended for use by backends when
  /// emitting events.
  pub fn new(id: u32, which: u8, state: ::HatState) -> Self {
    ControllerHat {
      id, state, which,
    }
  }
}

/// Components of a controller axis move event. Not guaranteed consistent across
/// backends.
#[derive(Copy, Clone, Deserialize, Serialize, PartialEq, PartialOrd, Debug)]
pub struct ControllerAxisArgs {
    /// Which controller moved.
    pub id: u32,
    /// The axis that moved.
    pub axis: u8,
    /// Position of the controller. Usually [-1.0, 1.0], though backends may use
    /// a different range for various devices.
    pub position: f64,
}

impl ControllerAxisArgs {
    /// Create a new ControllerAxisArgs object. Intended for use by backends when
    /// emitting events.
    pub fn new(id: u32, axis: u8, position: f64) -> Self {
        ControllerAxisArgs {
            id: id,
            axis: axis,
            position: position,
        }
    }
}

/// The position of a controller axis changed.
pub trait ControllerAxisEvent: Sized {
    /// Creates a controller axis event.
    ///
    /// Preserves time stamp from original input event, if any.
    fn from_controller_axis_args(args: ControllerAxisArgs, old_event: &Self) -> Option<Self>;
    /// Calls closure if this is a controller axis event.
    fn controller_axis<U, F>(&self, f: F) -> Option<U> where F: FnMut(ControllerAxisArgs) -> U;
    /// Returns controller axis arguments.
    fn controller_axis_args(&self) -> Option<ControllerAxisArgs> {
        self.controller_axis(|args| args)
    }
}

impl ControllerAxisEvent for Event {
    fn from_controller_axis_args(args: ControllerAxisArgs, old_event: &Self) -> Option<Self> {
        let timestamp = if let Event::Input(_, x) = old_event {*x} else {None};
        Some(Event::Input(Input::Move(Motion::ControllerAxis(args)), timestamp))
    }

    fn controller_axis<U, F>(&self, mut f: F) -> Option<U>
        where F: FnMut(ControllerAxisArgs) -> U
    {
        match *self {
            Event::Input(Input::Move(Motion::ControllerAxis(args)), _) => Some(f(args)),
            _ => None,
        }
    }
}

#[cfg(test)]
mod controller_axis_tests {
    use super::*;

    #[test]
    fn test_input_controller_axis() {
        let e: Event = ControllerAxisArgs::new(0, 1, 0.9).into();
        let a: Option<Event> =
            ControllerAxisEvent::from_controller_axis_args(ControllerAxisArgs::new(0, 1, 0.9), &e);
        let b: Option<Event> = a.clone()
            .unwrap()
            .controller_axis(|cnt| {
                ControllerAxisEvent::from_controller_axis_args(
                ControllerAxisArgs::new(cnt.id, cnt.axis, cnt.position),
                a.as_ref().unwrap())
            })
            .unwrap();
        assert_eq!(a, b);
    }
}