use std::fmt::Display;

use ecs::event::{Event, Id as EventId};
use ecs::{Component, Query, World};

#[derive(Component)]
struct Health
{
    health: u32,
}

#[derive(Component)]
enum AttackStrength
{
    Strong,
    Weak,
}

#[derive(Component)]
struct EnemyName
{
    name: String,
}

impl Display for EnemyName
{
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
    {
        self.name.fmt(formatter)
    }
}

fn do_attacks(
    attacker_query: Query<(AttackStrength,)>,
    enemy_query: Query<(Health, EnemyName)>,
)
{
    for (attack_strength,) in &attacker_query {
        for (mut health, enemy_name) in &enemy_query {
            let damage = match *attack_strength {
                AttackStrength::Strong => 20,
                AttackStrength::Weak => 10,
            };

            if health.health <= damage {
                println!("Enemy '{}' died", *enemy_name);

                health.health = 0;

                continue;
            }

            health.health -= damage;

            println!("Enemy '{}' took {damage} damage", *enemy_name);
        }
    }
}

#[derive(Debug, PartialEq, Eq, Hash)]
struct Start;

impl Event for Start
{
    fn id(&self) -> EventId
    {
        EventId::of::<Self>()
    }
}

fn main()
{
    let mut world = World::new();

    world.register_system(&Start, do_attacks);

    world.create_entity((
        Health { health: 100 },
        EnemyName { name: "Big spider".to_string() },
    ));

    world.create_entity((
        Health { health: 30 },
        EnemyName { name: "Small goblin".to_string() },
    ));

    world.create_entity((
        Health { health: 30 },
        EnemyName { name: "Headcrab".to_string() },
    ));

    world.create_entity((AttackStrength::Strong,));
    world.create_entity((AttackStrength::Weak,));

    world.emit(&Start);
}