/*! Managing the events belonging to virtual-keyboard interface. */

use ::keyboard::{ KeyState, PressType };

/// Gathers stuff defined in C or called by C
pub mod c {
    use std::os::raw::c_void;

    #[repr(transparent)]
    #[derive(Clone, Copy)]
    pub struct ZwpVirtualKeyboardV1(*const c_void);

    #[no_mangle]
    extern "C" {
        /// Checks if point falls within bounds,
        /// which are relative to origin and rotated by angle (I think)
        pub fn eek_virtual_keyboard_v1_key(
            virtual_keyboard: ZwpVirtualKeyboardV1,
            timestamp: u32,
            keycode: u32,
            press: u32,
        );
    }
}

pub struct Timestamp(pub u32);

/// Layout-independent backend. TODO: Have one instance per program or seat
pub struct VirtualKeyboard(pub c::ZwpVirtualKeyboardV1);

impl VirtualKeyboard {
    // TODO: split out keyboard state management
    pub fn switch(
        &self,
        key: &mut KeyState,
        action: PressType,
        timestamp: Timestamp,
    ) {
        key.pressed = action.clone();

        let keycodes_count = key.keycodes.len();
        for keycode in key.keycodes.iter() {
            let keycode = keycode - 8;
            match (&key.pressed, keycodes_count) {
                // Pressing a key made out of a single keycode is simple:
                // press on press, release on release.
                (_, 1) => unsafe {
                    c::eek_virtual_keyboard_v1_key(
                        self.0, timestamp.0, keycode, action.clone() as u32
                    );
                },
                // A key made of multiple keycodes
                // has to submit them one after the other
                (PressType::Pressed, _) => unsafe {
                    c::eek_virtual_keyboard_v1_key(
                        self.0, timestamp.0, keycode, PressType::Pressed as u32
                    );
                    c::eek_virtual_keyboard_v1_key(
                        self.0, timestamp.0, keycode, PressType::Released as u32
                    );
                },
                // Design choice here: submit multiple all at press time
                // and do nothing at release time
                (PressType::Released, _) => {},
            }
        }
    }
}