//! This module helps us deal with controls and events.

use std::cell::RefCell;
use std::collections::{HashMap, VecDeque};
use std::rc::Rc;

use wasm_bindgen::prelude::*;
use wasm_bindgen::JsCast;

use crate::engine::vector::Vector;

use crate::{log, Result};

/// The different events that can be triggered.
#[derive(Debug, Copy, Clone)]
pub enum Event {
    /// A key has been pressed.
    KeyPressed(Key),

    /// A key has been released.
    KeyReleased(Key),

    /// A gamepad has been connected.
    GamepadConnected(u32),

    /// A button has been pressed on a certain gamepad.
    ButtonPressed(u32, Button),

    /// A button has been released on a certain gamepad.
    ButtonReleased(u32, Button),
}

/// The different keyboard keys we support.
#[derive(Debug, Hash, Copy, Clone, PartialEq, Eq)]
pub enum Key {
    /// The left arrow key.
    ArrowLeft,

    /// The right arrow key.
    ArrowRight,

    /// The up arrow key.
    ArrowUp,

    /// The down arrow key.
    ArrowDown,

    /// The space key.
    Space,
}

/// The different actions a user can do.
#[derive(Debug, Copy, Clone)]
pub enum Action {
    /// A certain button has been pressed.
    ButtonPressed(Button),

    /// A certain button has been released.
    ButtonReleased(Button),
}

/// The different actions that a user can do.
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub enum Button {
    /// The user asks to go to the left.
    Left,

    /// The user asks to go to the right.
    Right,

    /// The user asks to go up.
    Up,

    /// The user asks to go down.
    Down,

    /// The main action or validatation button.
    Button0,

    /// The user asks to do the secondary action.
    Button1,

    /// The user asks to do the tertiary action.
    Button2,

    /// The user asks to do the 4th action or cancel.
    Button3,
}

/// This structure holds what button are pressed or released, and stores the events.
pub struct InputManager {
    /// The state of the keyboard.
    keyboard: HashMap<Key, bool>,

    /// All the connected gamepads.
    gamepads: Vec<Gamepad>,

    /// The events that have occur.
    events: VecDeque<Event>,
}

impl InputManager {
    /// Creates a new input manager.
    pub fn new() -> InputManager {
        InputManager {
            keyboard: HashMap::new(),
            gamepads: vec![],
            events: VecDeque::new(),
        }
    }

    /// Gets the gamepad from its id.
    pub fn gamepad(&self, id: u32) -> Option<&Gamepad> {
        self.gamepads.iter().find(|x| x.inner.index() == id)
    }

    /// Parses a keyboard event to the key.
    pub fn key(event: web_sys::KeyboardEvent) -> Option<Key> {
        match event.code().as_str() {
            "ArrowDown" => Some(Key::ArrowDown),
            "ArrowUp" => Some(Key::ArrowUp),
            "ArrowLeft" => Some(Key::ArrowLeft),
            "ArrowRight" => Some(Key::ArrowRight),
            "Space" => Some(Key::Space),
            _ => None,
        }
    }

    /// Adds a key pressed event to the list of events.
    pub fn key_pressed_event(&mut self, event: web_sys::KeyboardEvent) {
        if let Some(key) = InputManager::key(event) {
            self.keyboard.insert(key, true);
            self.events.push_back(Event::KeyPressed(key));
        }
    }

    /// Adds a key released event to the list of events.
    pub fn key_released_event(&mut self, event: web_sys::KeyboardEvent) {
        if let Some(key) = InputManager::key(event) {
            self.keyboard.insert(key, false);
            self.events.push_back(Event::KeyReleased(key));
        }
    }

    /// Adds a gamepad to the input manager.
    pub fn add_gamepad(&mut self, gamepad: web_sys::Gamepad) {
        log!("Gamepad added {}", gamepad.id());
        self.events
            .push_back(Event::GamepadConnected(gamepad.index()));
        self.gamepads.push(Gamepad::new(gamepad));
    }

    /// Updates the gamepad states.
    pub fn update(&mut self) {
        for gamepad in &mut self.gamepads {
            gamepad.update(&mut self.events);
        }
    }

    /// Checks if a specific key is pressed.
    pub fn is_key_pressed(&self, key: Key) -> bool {
        *self.keyboard.get(&key).unwrap_or(&false)
    }
}

/// Holds the gamepad information.
#[derive(Clone)]
pub struct Gamepad {
    /// The javascript gamepad object.
    inner: web_sys::Gamepad,

    /// The main joystick.
    main_joystick: Joystick,

    /// What buttons are pressed or released.
    buttons: HashMap<Button, bool>,
}

/// The joysticks.
#[derive(Clone)]
pub struct Joystick {
    /// The id of the X axis of the joystick.
    pub x_id: u32,

    /// The id of the Y axis of the joystick.
    pub y_id: u32,
}

impl Gamepad {
    /// Creates a new gamepad from its javascript gamepad.
    pub fn new(inner: web_sys::Gamepad) -> Gamepad {
        Gamepad {
            inner,
            main_joystick: Joystick { x_id: 0, y_id: 1 },
            buttons: HashMap::new(),
        }
    }

    /// Returns the direction of the main joystick.
    pub fn main_direction(&self) -> Vector {
        let axes = self.inner.axes();
        let x = axes.get(self.main_joystick.x_id).as_f64().unwrap();
        let y = axes.get(self.main_joystick.y_id).as_f64().unwrap();
        Vector::new(x, y)
    }

    /// Updates the state of the gamepad and adds the corresponding events to the deque.
    pub fn update(&mut self, events: &mut VecDeque<Event>) {
        const BUTTONS: [Button; 4] = [
            Button::Button0,
            Button::Button1,
            Button::Button2,
            Button::Button3,
        ];

        for button in BUTTONS {
            // Finds the real state of the button
            let is_pressed = self.is_js_pressed(button);

            // Updates the map and returns the old state of the button
            let was_pressed = self.buttons.insert(button, is_pressed).unwrap_or(false);

            if was_pressed && !is_pressed {
                // Button was released
                events.push_back(Event::ButtonReleased(self.inner.index(), button));
            }

            if is_pressed && !was_pressed {
                // Button was pressed
                events.push_back(Event::ButtonPressed(self.inner.index(), button));
            }
        }
    }

    /// Checks if a button is pressed.
    pub fn is_pressed(&self, button: Button) -> bool {
        *self.buttons.get(&button).unwrap_or(&false)
    }

    /// Utility function to really check the state of the button.
    fn is_js_pressed(&self, button: Button) -> bool {
        let buttons = self.inner.buttons();
        match button {
            Button::Left => false,
            Button::Right => false,
            Button::Up => false,
            Button::Down => false,
            Button::Button0 => Into::<web_sys::GamepadButton>::into(buttons.get(0)).pressed(),
            Button::Button1 => Into::<web_sys::GamepadButton>::into(buttons.get(1)).pressed(),
            Button::Button2 => Into::<web_sys::GamepadButton>::into(buttons.get(2)).pressed(),
            Button::Button3 => Into::<web_sys::GamepadButton>::into(buttons.get(3)).pressed(),
        }
    }
}

/// A helper to easily deal with inputs.
#[derive(Clone)]
pub struct Inputs(pub Rc<RefCell<InputManager>>);

impl Inputs {
    /// Creates a new inputs object.
    pub fn new(window: &web_sys::Window) -> Result<Inputs> {
        let inputs = Inputs(Rc::new(RefCell::new(InputManager::new())));

        let clone = inputs.clone();
        let cb = Closure::<dyn FnMut(_)>::new(move |event: web_sys::GamepadEvent| {
            let mut inner = clone.0.borrow_mut();
            inner.add_gamepad(event.gamepad().unwrap());
        });
        window.add_event_listener_with_callback("gamepadconnected", cb.as_ref().unchecked_ref())?;
        cb.forget();

        let clone = inputs.clone();
        let cb = Closure::<dyn FnMut(_)>::new(move |event: web_sys::KeyboardEvent| {
            let mut inner = clone.0.borrow_mut();
            inner.key_pressed_event(event);
        });
        window.add_event_listener_with_callback("keydown", cb.as_ref().unchecked_ref())?;
        cb.forget();

        let clone = inputs.clone();
        let cb = Closure::<dyn FnMut(_)>::new(move |event: web_sys::KeyboardEvent| {
            let mut inner = clone.0.borrow_mut();
            inner.key_released_event(event);
        });
        window.add_event_listener_with_callback("keyup", cb.as_ref().unchecked_ref())?;
        cb.forget();

        Ok(inputs)
    }

    /// Updates the inputs.
    ///
    /// This function needs to be called at each frame.
    pub fn update(&mut self) {
        let mut inner = self.0.borrow_mut();
        inner.update();
    }

    /// Returns the next event.
    pub fn next(&mut self) -> Option<Event> {
        let mut inner = self.0.borrow_mut();
        inner.events.pop_front()
    }
}