use bevy::prelude::*;
use crate::level::Level;

#[derive(States, Debug, Clone, PartialEq, Eq, Hash, Default)]
pub enum GameState {
    #[default]
    Loading,
    Main,
    LoadingSceneData(Level),
    LoadingLevel(Level),
    Level(Level)
}

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

impl ComputedStates for LoadingLevelState {
    type SourceStates = GameState;

    fn compute(sources: Self::SourceStates) -> Option<Self> {
        match sources {
            GameState::LoadingLevel(_) => Some(LoadingLevelState),
            _ => None
        }
    }
}

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

impl ComputedStates for LevelState {
    type SourceStates = GameState;

    fn compute(sources: Self::SourceStates) -> Option<Self> {
        match sources {
            GameState::Level(_) => Some(LevelState),
            _ => None
        }
    }
}

#[derive(Resource)]
pub struct GameAssets {
    pub terminal_primitive0: Handle<Mesh>,
    pub terminal_primitive1: Handle<Mesh>,
    pub terminal_chassis_mat: Handle<StandardMaterial>
}

pub fn plugin(app: &mut App) {
    app.add_computed_state::<LoadingLevelState>()
        .add_computed_state::<LevelState>()
        .add_systems(OnEnter(LoadingLevelState), load_terminal);
}

fn load_terminal(mut commands: Commands, asset_server: Res<AssetServer>) {
    let assets = GameAssets{
        terminal_primitive0: asset_server.load("models/terminal.glb#Mesh0/Primitive0"),
        terminal_primitive1: asset_server.load("models/terminal.glb#Mesh0/Primitive1"),
        terminal_chassis_mat: asset_server.load("models/terminal.glb#Material0")
    };

    commands.insert_resource(assets);
}