use bevy::prelude::*;

pub struct HelloPlugin;

impl Plugin for HelloPlugin
{
	fn build(&self, app: &mut App) 
	{
        app.insert_resource(GreetTimer(Timer::from_seconds(2.0, TimerMode::Repeating)))
            .add_systems(Startup, add_people)
            .add_systems(Update, (hello_world, (update_people, greet_people).chain()));
    }

}

#[derive(Resource)]
struct GreetTimer(Timer);

#[derive(Component)]
struct Person;

#[derive(Component)]
struct Name(String);

fn add_people(mut commands: Commands) 
{
    commands.spawn((Person, Name("Elaina Proctor".to_string())));
    commands.spawn((Person, Name("Renzo Hume".to_string())));
    commands.spawn((Person, Name("Zayna Nieves".to_string())));
}

// Just reading the timer in this one since greet_people already ticks it
// We could use ().chain() to force hello_world to happen after greet_people
// so the print out is always on the same frame.
fn hello_world(timer: ResMut<GreetTimer>,) 
{
    if timer.0.finished()
    {
        println!("hello world!");
    }
}

fn greet_people(time: Res<Time>, mut timer: ResMut<GreetTimer>, query: Query<&Name, With<Person>>) 
{
    // update our timer with the time elapsed since the last update
    // if that caused the timer to finish, we say hello to everyone
    if timer.0.tick(time.delta()).just_finished() 
    {
        for name in &query 
        {
            println!("hello {}!", name.0);
        }
    }
}

fn update_people(mut query: Query<&mut Name, With<Person>>) 
{
    for mut name in &mut query 
    {
        if name.0 == "Elaina Proctor" 
        {
            name.0 = "Elaina Hume".to_string();
            break; // We don’t need to change any other names
        }
    }
}