use bevy::prelude::*;
use bevy::window::{CursorGrabMode, CursorOptions};

use common::block::Blocks;

// TODO: Use picking system instead of manually raycasting.

pub fn place_break_blocks(
    mut commands: Commands,
    mut blocks: Blocks,
    mut ray_cast: MeshRayCast,
    mouse_button_input: Res<ButtonInput<MouseButton>>,
    window: Single<(&Window, &CursorOptions)>,
    camera: Single<(&GlobalTransform, &Camera)>,
) {
    let (window, cursor) = window.into_inner();
    let (cam_transform, camera) = camera.into_inner();

    let ray = if cursor.grab_mode == CursorGrabMode::Locked {
        Ray3d::new(cam_transform.translation(), cam_transform.forward())
    } else if let Some(cursor_pos) = window.cursor_position() {
        camera.viewport_to_world(cam_transform, cursor_pos).unwrap()
    } else {
        return; // cursor outside window area
    };

    let settings = &MeshRayCastSettings::default();
    let Some((block, hit)) = ray_cast.cast_ray(ray, settings).first() else {
        return; // ray didn't hit anything
    };
    let Some(block_pos) = blocks.position(*block) else {
        return; // entity hit is not a block
    };

    if mouse_button_input.just_pressed(MouseButton::Left) {
        // Destroy the block clicked.
        commands.entity(*block).despawn();
    } else if mouse_button_input.just_pressed(MouseButton::Right) {
        // Create a new block next to the one that was just clicked.

        // FIXME: This only works for axis-aligned normals.
        let offset = hit.normal.normalize().round().as_ivec3();

        blocks.spawn(block_pos + offset);
    }
}