//! A more complex scene with a moving "unit" that demonstrates how to jump to a location or lock
//! onto a particular entity.

use std::f32::consts::TAU;

use bevy::prelude::*;

use bevy_rts_camera::{Ground, RtsCamera, RtsCameraControls, RtsCameraPlugin, RtsCameraSystemSet};

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugins(RtsCameraPlugin)
        .add_systems(Startup, setup)
        .add_systems(
            Update,
            (move_unit, (lock_or_jump, toggle_controls))
                .chain()
                .before(RtsCameraSystemSet),
        )
        .run();
}

#[derive(Component)]
struct Move;

fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    // Ground
    commands.spawn((
        Mesh3d(meshes.add(Plane3d::default().mesh().size(80.0, 80.0))),
        MeshMaterial3d(materials.add(Color::srgb(0.3, 0.5, 0.3))),
        // Add `Ground` component to any entity you want the camera to treat as ground.
        Ground,
    ));
    // Some "terrain"
    let terrain_material = materials.add(Color::srgb(0.8, 0.7, 0.6));
    commands.spawn((
        Mesh3d(meshes.add(Cuboid::new(15.0, 1.0, 5.0))),
        MeshMaterial3d(terrain_material.clone()),
        Transform::from_xyz(15.0, 0.5, -5.0),
        Ground,
    ));
    commands.spawn((
        Mesh3d(meshes.add(Cuboid::new(10.0, 5.0, 15.0))),
        MeshMaterial3d(terrain_material.clone()),
        Transform::from_xyz(-15.0, 2.5, 0.0),
        Ground,
    ));
    commands.spawn((
        Mesh3d(meshes.add(Sphere::new(12.5))),
        MeshMaterial3d(terrain_material.clone()),
        Transform::from_xyz(0.0, 0.0, -23.0),
        Ground,
    ));
    // Some generic units that are not part of the 'Ground' (ignored for height calculation)
    for x in -5..5 {
        for z in -5..5 {
            commands.spawn((
                Mesh3d(meshes.add(Capsule3d::new(0.25, 1.25))),
                MeshMaterial3d(terrain_material.clone()),
                Transform::from_xyz(x as f32 * 0.7, 0.75, z as f32 * 0.7),
            ));
        }
    }
    // A moving unit that can be locked onto
    commands
        .spawn((
            Mesh3d(meshes.add(Capsule3d::new(0.25, 1.25))),
            MeshMaterial3d(terrain_material.clone()),
            Transform::from_xyz(0.0, 0.75, 0.0),
        ))
        .insert(Move);
    // Light
    commands.spawn((
        DirectionalLight {
            illuminance: 1000.0,
            shadows_enabled: true,
            ..default()
        },
        Transform::from_rotation(Quat::from_euler(
            EulerRot::YXZ,
            150.0f32.to_radians(),
            -40.0f32.to_radians(),
            0.0,
        )),
    ));
    // Help text
    commands.spawn(Text::new(
        "\
Press K to jump to the moving unit
Hold L to lock onto the moving unit
Press T to toggle controls (K and L will still work)",
    ));
    // Camera
    commands.spawn((
        RtsCamera {
            // Increase min height (decrease max zoom)
            // height_min: 10.0,
            // Increase max height (decrease min zoom)
            height_max: 50.0,
            // Change the angle of the camera to 35 degrees
            min_angle: 35.0f32.to_radians(),
            // Decrease smoothing
            smoothness: 0.1,
            // Change starting position
            target_focus: Transform::from_xyz(3.0, 0.0, -3.0),
            // Change starting zoom level
            target_zoom: 0.2,
            // Disable dynamic angle (angle of camera will stay at `min_angle`)
            // dynamic_angle: false,
            ..default()
        },
        RtsCameraControls {
            // Change pan controls to WASD
            key_up: KeyCode::KeyW,
            key_down: KeyCode::KeyS,
            key_left: KeyCode::KeyA,
            key_right: KeyCode::KeyD,
            // Rotate the camera with right click
            button_rotate: MouseButton::Right,
            // Keep the mouse cursor in place when rotating
            lock_on_rotate: true,
            // Drag pan with middle click
            button_drag: Some(MouseButton::Middle),
            // Keep the mouse cursor in place when dragging
            lock_on_drag: true,
            // Change the width of the area that triggers edge pan. 0.1 is 10% of the window height.
            edge_pan_width: 0.1,
            // Increase pan speed
            pan_speed: 25.0,
            ..default()
        },
    ));
}

// Move a unit in a circle
fn move_unit(
    time: Res<Time>,
    mut cube_q: Query<&mut Transform, With<Move>>,
    mut angle: Local<f32>,
) {
    if let Ok(mut cube_tfm) = cube_q.get_single_mut() {
        // Rotate 20 degrees a second, wrapping around to 0 after a full rotation
        *angle += 20f32.to_radians() * time.delta_secs() % TAU;
        // Convert angle to position
        let pos = Vec3::new(angle.sin() * 7.5, 0.75, angle.cos() * 7.5);
        cube_tfm.translation = pos;
    }
}

// Either jump to the moving unit (press K) or lock onto it (hold L)
fn lock_or_jump(
    key_input: Res<ButtonInput<KeyCode>>,
    cube_q: Query<&Transform, With<Move>>,
    mut cam_q: Query<&mut RtsCamera>,
) {
    for cube in cube_q.iter() {
        for mut cam in cam_q.iter_mut() {
            if key_input.pressed(KeyCode::KeyL) {
                cam.target_focus.translation = cube.translation;
                cam.snap = true;
            }
            if key_input.just_pressed(KeyCode::KeyK) {
                cam.target_focus.translation = cube.translation;
                cam.target_zoom = 0.4;
            }
        }
    }
}

fn toggle_controls(
    mut controls_q: Query<&mut RtsCameraControls>,
    key_input: Res<ButtonInput<KeyCode>>,
) {
    for mut controls in controls_q.iter_mut() {
        if key_input.just_pressed(KeyCode::KeyT) {
            controls.enabled = !controls.enabled;
        }
    }
}