use bevy::{audio::Volume, prelude::*};
use rand::random_range;

pub struct MusicPlayerPlugin;

impl Plugin for MusicPlayerPlugin {
    fn build(&self, app: &mut App) {
        app.add_systems(Startup, setup)
            .add_systems(Update, try_play);
    }
}

#[derive(Resource)]
struct Soundtrack(Vec<Handle<AudioSource>>);

#[derive(Component)]
struct MusicPlayer;

fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
    commands.insert_resource(Soundtrack(vec![
        asset_server.load("music/fostral.wav"),
        asset_server.load("music/glorx.wav"),
        asset_server.load("music/rocknrolldixie.wav"),
        asset_server.load("music/whistler.wav"),
    ]));

    commands.spawn(MusicPlayer);
}

fn try_play(
    mut commands: Commands,
    player: Option<Single<Entity, (With<MusicPlayer>, Without<AudioPlayer>)>>,
    soundtrack: Res<Soundtrack>,
) {
    if let Some(music_player) = player {
        commands.entity(music_player.entity()).insert((
            AudioPlayer::new(soundtrack.0[random_range(0..soundtrack.0.len())].clone()),
            PlaybackSettings {
                volume: Volume::Linear(0.2),
                mode: bevy::audio::PlaybackMode::Remove,
                ..default()
            },
        ));
    }
}