use std::fmt;

use bevy::{prelude::*, window::PrimaryWindow};
use bevy_inspector_egui::quick::WorldInspectorPlugin;
use bevy_mod_picking::debug::DebugPickingMode;

use crate::{
    camera_controller::{CameraController, CameraMotionSystem},
    input::{Action, InputAction, Lifecycle},
    is_editor,
    scene::SkeletalJoint,
    MainCamera,
};

#[derive(Resource, Deref, DerefMut)]
pub struct DebugMode(bool);

#[derive(Component, Clone, Copy, Debug)]
pub struct DebugPoint {
    pub point: Vec3,
    pub color: Color,
}

pub struct DebugPlugin;
impl Plugin for DebugPlugin {
    fn build(&self, app: &mut App) {
        app.insert_resource(DebugMode(false))
            .add_plugins(WorldInspectorPlugin::new().run_if(is_debug_mode))
            .insert_resource(State::new(DebugPickingMode::Disabled))
            .insert_resource(GizmoConfig {
                enabled: true,
                depth_bias: -0.1,
                line_perspective: false,
                line_width: 2.,
                ..default()
            })
            .add_systems(
                Update,
                (
                    toggle_debug_mode,
                    update_debug_picking_mode
                        .run_if(is_editor)
                        .run_if(resource_changed::<DebugMode>()),
                    update_gizmo_line_thickness,
                    (draw_world_axes, draw_debug_points, draw_skeletal_joints)
                        .after(CameraMotionSystem)
                        .run_if(is_debug_mode),
                ),
            );
    }
}

fn toggle_debug_mode(mut input: EventReader<InputAction>, mut r_debug: ResMut<DebugMode>) {
    if input
        .read()
        .any(|action| matches!(action, InputAction(Lifecycle::Stop, Action::ToggleDebug)))
    {
        **r_debug = !**r_debug;
    }
}

fn update_debug_picking_mode(
    r_debug: Res<DebugMode>,
    mut s_debug_picking: ResMut<NextState<DebugPickingMode>>,
) {
    s_debug_picking.set(match **r_debug {
        true => DebugPickingMode::Normal,
        false => DebugPickingMode::Disabled,
    });
}

pub fn is_debug_mode(r_debug: Res<DebugMode>) -> bool {
    **r_debug
}

fn update_gizmo_line_thickness(
    mut config: ResMut<GizmoConfig>,
    q_window: Query<&Window, (Changed<Window>, With<PrimaryWindow>)>,
) {
    if let Ok(scale_factor) = q_window.get_single().map(|win| win.scale_factor() as f32) {
        config.line_width = 2. * scale_factor;
    }
}

fn draw_world_axes(mut gizmos: Gizmos, q: Query<&CameraController>) {
    let &CameraController { focus, radius, .. } = q.single();

    let mut draw_axis = |direction: Vec3, color: Color| {
        let end = focus + direction * radius / 15.;
        gizmos.line(focus, end, color);
    };

    draw_axis(Vec3::X, Color::RED);
    draw_axis(Vec3::Y, Color::GREEN);
    draw_axis(Vec3::Z, Color::BLUE);
}

fn draw_debug_points(
    mut gizmos: Gizmos,
    q_debug_points: Query<&DebugPoint>,
    q_cam_xform: Query<&GlobalTransform, With<MainCamera>>,
) {
    let Ok(cam_xform) = q_cam_xform.get_single() else {
        return;
    };
    for &DebugPoint { point, color } in q_debug_points.iter() {
        let dist = cam_xform.translation().distance(point);
        gizmos.cuboid(
            Transform::from_translation(point).with_scale(Vec3::splat(dist / 300.)),
            color,
        );
    }
}

fn draw_skeletal_joints(
    mut gizmos: Gizmos,
    q_joints: Query<(&GlobalTransform, Option<&Parent>, &SkeletalJoint)>,
) {
    for (world_xform, parent, joint) in q_joints.iter() {
        let (_, rotation, xlation) = world_xform.to_scale_rotation_translation();

        if let Some((parent_xform, _, _)) = parent.and_then(|parent| q_joints.get(**parent).ok()) {
            let parent_xlation = parent_xform.translation();
            let bone_len = Vec3::distance(xlation, parent_xlation);
            let joint_radius = f32::min(0.01, bone_len / 6.);

            gizmos.sphere(xlation, rotation, joint_radius, joint.0);
            gizmos.line(xlation, parent_xlation, joint.0);

            let local_x = world_xform.right() * 0.05;
            let local_y = world_xform.up() * 0.05;
            let local_z = world_xform.back() * 0.05;

            gizmos.line(xlation, xlation + local_x, Color::RED);
            gizmos.line(xlation, xlation + local_y, Color::GREEN);
            gizmos.line(xlation, xlation + local_z, Color::BLUE);
        } else {
            gizmos.sphere(xlation, rotation, 0.01, joint.0);
        }
    }
}

#[rustfmt::skip]
#[allow(dead_code)]
pub fn write_mat3(w: &mut impl fmt::Write, m: &Mat3) -> fmt::Result {
    writeln!(w, "  {:+.3} {:+.3} {:+.3}", m.x_axis.x, m.x_axis.y, m.x_axis.z)?;
	writeln!(w, "  {:+.3} {:+.3} {:+.3}", m.y_axis.x, m.y_axis.y, m.y_axis.z)?;
	writeln!(w, "  {:+.3} {:+.3} {:+.3}", m.z_axis.x, m.z_axis.y, m.z_axis.z)?;
	Ok(())
}

#[allow(dead_code)]
pub fn print_mat3(m: &Mat3, label: impl fmt::Display) -> fmt::Result {
    let mut s = String::new();
    write_mat3(&mut s, m)?;
    info!("\n{label}\n{}", s.replace('+', " "));

    Ok(())
}