/*!
    Minimalist input lib based on [winit](https://github.com/tomaka/winit).
*/

#![deny(missing_docs)]

use winit::dpi::PhysicalPosition;
use winit::event::DeviceEvent::MouseMotion;
use winit::event::ElementState::{Pressed, Released};
use winit::event::Event::{self, DeviceEvent, WindowEvent};
use winit::event::KeyboardInput;
pub use winit::event::MouseButton;
use winit::event::MouseScrollDelta;
pub use winit::event::VirtualKeyCode as Key;
use winit::event::WindowEvent::KeyboardInput as WKeyboardInput;
use winit::event::WindowEvent::{
    AxisMotion, CursorMoved, MouseInput, MouseWheel, ReceivedCharacter,
};
use winit::window::Window;

/// struct for abstracting the state for all the inputs
pub struct Input {
    /// The position of the mouse
    pub mouse_pos: (f32, f32),
    /// The difference in mouse position from the last frame
    pub mouse_delta: (f32, f32),
    /// The raw difference in mouse position from the last frame
    pub raw_mouse_delta: (f32, f32),
    /// The mouse axis motion for the last frame
    pub mouse_axis_motion: (f32, f32),
    /// The difference in position of the mouse when from the previous frame
    pub mouse_wheel_delta: (f32, f32),
    /// The keys that are currently pressed down
    pub keys_down: Vec<Key>,
    /// The keys that have been pressed on this frame
    pub keys_pressed: Vec<Key>,
    /// The keys that have been released on this frame
    pub keys_released: Vec<Key>,
    /// Characters received that are pressed down
    pub characters_down: Vec<char>,
    /// The mouse buttons that are currently pressed down
    pub mouse_btns_down: Vec<MouseButton>,
    /// The mouse buttons that have been pressed down on this frame
    pub mouse_btns_pressed: Vec<MouseButton>,
    /// The mouse buttons that have been release on this frame
    pub mouse_btns_released: Vec<MouseButton>,
    /// Whether to show or hide the mouse
    pub hide_mouse: bool,
}

impl Default for Input {
    /// Create a default instance of Input
    fn default() -> Self {
        Self::new()
    }
}

impl Input {
    /// Creates a new Input instance
    pub fn new() -> Input {
        Input {
            mouse_pos: (0f32, 0f32),
            mouse_delta: (0f32, 0f32),
            raw_mouse_delta: (0f32, 0f32),
            mouse_axis_motion: (0f32, 0f32),
            mouse_wheel_delta: (0f32, 0f32),
            keys_down: Vec::new(),
            keys_pressed: Vec::new(),
            keys_released: Vec::new(),
            characters_down: Vec::new(),
            mouse_btns_down: Vec::new(),
            mouse_btns_pressed: Vec::new(),
            mouse_btns_released: Vec::new(),
            hide_mouse: true,
        }
    }

    /// This method updates the state of the inputs
    pub fn update_inputs(&mut self, window: &Window, events: &Vec<Event<()>>) {
        let (width, height): (u32, u32) = window.inner_size().into();
        let h_width = (width as u32 / 2u32) as f32;
        let h_height = (height / 2u32) as f32;

        // reset properties
        {
            // reset the delta in case the mouse does not move
            self.mouse_delta = (0f32, 0f32);
            self.mouse_wheel_delta = (0f32, 0f32);

           // keys pressed is only for a single frame so clear
            self.keys_pressed.clear();
            self.keys_released.clear();
            self.mouse_btns_pressed.clear();
            self.mouse_btns_released.clear();
            self.characters_down.clear();
        }

        let keys_down = &mut self.keys_down;
        let keys_pressed = &mut self.keys_pressed;
        let keys_released = &mut self.keys_released;
        let mouse_delta = &mut self.mouse_delta;
        let raw_mouse_delta = &mut self.raw_mouse_delta;
        let mouse_axis_motion = &mut self.mouse_axis_motion;
        let mouse_pos = &mut self.mouse_pos;
        let mouse_btns_down = &mut self.mouse_btns_down;
        let mouse_btns_pressed = &mut self.mouse_btns_pressed;
        let mouse_btns_released = &mut self.mouse_btns_released;
        let mouse_wheel_delta = &mut self.mouse_wheel_delta;
        let characters_down = &mut self.characters_down;

        // polling and handling the events received by the display
        for event in events {
            match event {
                WindowEvent { event, .. } => match event {
                    WKeyboardInput {
                        input:
                            KeyboardInput {
                                state: Pressed,
                                virtual_keycode: vkey,
                                ..
                            },
                        ..
                    } => {
                        if let Some(key) = vkey {
                            keys_down.push(*key);
                            keys_pressed.push(*key);
                        }
                    }
                    WKeyboardInput {
                        input:
                            KeyboardInput {
                                state: Released,
                                virtual_keycode: vkey,
                                ..
                            },
                        ..
                    } => {
                        if let Some(key) = vkey {
                            keys_down.retain(|&k| k != *key);
                            keys_released.push(*key);
                        }
                    }
                    CursorMoved { position: pos, .. } => {
                        let (x, y): (i32, i32) = (*pos).into();
                        mouse_delta.0 = (h_width - x as f32) / width as f32;
                        mouse_delta.1 = (h_height - y as f32) / height as f32;
                        (*mouse_pos) = (x as f32, y as f32);
                    }
                    AxisMotion { axis, value, .. } => match axis {
                        0 => mouse_axis_motion.0 = *value as f32,
                        1 => mouse_axis_motion.1 = *value as f32,
                        _ => {}
                    },
                    MouseInput {
                        state: Pressed,
                        button: btn,
                        ..
                    } => {
                        mouse_btns_down.push(*btn);
                        mouse_btns_pressed.push(*btn);
                    }
                    MouseInput {
                        state: Released,
                        button: btn,
                        ..
                    } => {
                        mouse_btns_down.retain(|&mb| mb != *btn);
                        mouse_btns_released.push(*btn);
                    }
                    MouseWheel { delta, .. } => {
                        (*mouse_wheel_delta) = match delta {
                            MouseScrollDelta::LineDelta(x, y) => (*x, *y),
                            MouseScrollDelta::PixelDelta(pos) => {
                                let (x, y): (i32, i32) = (*pos).into();
                                (x as f32, y as f32)
                            }
                        };
                    }
                    ReceivedCharacter(c) => characters_down.push(*c),
                    _ => (),
                },
                DeviceEvent { event, .. } => {
                    if let MouseMotion { delta } = event {
                        (*raw_mouse_delta) = (delta.0 as f32, delta.1 as f32);
                    }
                }
                _ => (),
            }
        }

        if self.hide_mouse {
            window.set_cursor_visible(false);
            window.set_cursor_grab(true).unwrap();
            let _ = window.set_cursor_position(PhysicalPosition::new(h_width, h_height));
        } else {
            window.set_cursor_visible(true);
            window.set_cursor_grab(false).unwrap();
        }
    }
}