use sdl2::event::{Event, WindowEvent};
use sdl2::keyboard::Scancode;
use sdl2::{EventPump, Sdl};
use specs::prelude::*;

use crate::components::{Player, Velocity};

pub const PLAYER_SPEED: f64 = 150.;

pub const ACTION_KEY_UP: u8 = 0b0001;
pub const ACTION_KEY_LEFT: u8 = 0b0010;
pub const ACTION_KEY_DOWN: u8 = 0b0100;
pub const ACTION_KEY_RIGHT: u8 = 0b1000;

pub struct SysInput
{
    pressed_action_keys: u8,
    event_pump:          EventPump,
}

impl SysInput
{
    pub fn new(sdl: &Sdl) -> Self
    {
        Self {
            pressed_action_keys: 0b0,
            event_pump:          sdl.event_pump().unwrap(),
        }
    }
}

impl<'a> System<'a> for SysInput
{
    type SystemData = (WriteStorage<'a, Velocity>, ReadStorage<'a, Player>);

    fn run(&mut self, (mut vel, player): Self::SystemData)
    {
        let mut player_movement_changed = false;
        for event in self.event_pump.poll_iter() {
            match event {
                Event::Quit { .. } => {
                    panic!("Quitting due to exit signal");
                },
                Event::Window {
                    win_event: WindowEvent::Resized(x, y),
                    ..
                } => {
                    println!("Window resized to {}x{}", x, y);
                },
                Event::KeyDown { scancode, .. } => match scancode {
                    Some(Scancode::W) => {
                        self.pressed_action_keys |= ACTION_KEY_UP;
                        player_movement_changed = true;
                    },
                    Some(Scancode::A) => {
                        self.pressed_action_keys |= ACTION_KEY_LEFT;
                        player_movement_changed = true;
                    },
                    Some(Scancode::S) => {
                        self.pressed_action_keys |= ACTION_KEY_DOWN;
                        player_movement_changed = true;
                    },
                    Some(Scancode::D) => {
                        self.pressed_action_keys |= ACTION_KEY_RIGHT;
                        player_movement_changed = true;
                    },
                    key => {
                        println!("keydown received: {:?}", key)
                    },
                },
                Event::KeyUp { scancode, .. } => match scancode {
                    Some(Scancode::W) => {
                        self.pressed_action_keys &= !ACTION_KEY_UP;
                        player_movement_changed = true;
                    },
                    Some(Scancode::A) => {
                        self.pressed_action_keys &= !ACTION_KEY_LEFT;
                        player_movement_changed = true;
                    },
                    Some(Scancode::S) => {
                        self.pressed_action_keys &= !ACTION_KEY_DOWN;
                        player_movement_changed = true;
                    },
                    Some(Scancode::D) => {
                        self.pressed_action_keys &= !ACTION_KEY_RIGHT;
                        player_movement_changed = true;
                    },
                    _ => {},
                },
                _ => {},
            }
        }

        /* Update player movement */
        if player_movement_changed {
            for (vel, _player) in (&mut vel, &player).join() {
                /* Vertical movement */
                if (self.pressed_action_keys & ACTION_KEY_UP) != 0 {
                    vel.0.y = -PLAYER_SPEED;
                }
                else if (self.pressed_action_keys & ACTION_KEY_DOWN) != 0 {
                    vel.0.y = PLAYER_SPEED;
                }
                else {
                    vel.0.y = 0.;
                }

                /* Horizontal movement */
                if (self.pressed_action_keys & ACTION_KEY_LEFT) != 0 {
                    vel.0.x = -PLAYER_SPEED;
                }
                else if (self.pressed_action_keys & ACTION_KEY_RIGHT) != 0 {
                    vel.0.x = PLAYER_SPEED;
                }
                else {
                    vel.0.x = 0.;
                }
            }
        }
    }
}