use crate::physics::{PhysicsEvents, PhysicsState};
use rapier::dynamics::{IntegrationParameters, JointSet, RigidBodySet};
use rapier::geometry::{BroadPhase, ColliderSet, NarrowPhase};
use rapier::math::Vector;
use rapier::pipeline::{ChannelEventCollector, PhysicsPipeline, QueryPipeline};

pub mod plugin;

use plugin::HarnessPlugin;

// #[derive(PartialEq)]
// pub enum RunState {
//     Initialized,
//     Running,
//     Pausing,
//     Paused,
//     Finished,
// }

pub struct HarnessState {
    #[cfg(feature = "parallel")]
    pub thread_pool: rapier::rayon::ThreadPool,
    pub timestep_id: usize,
    // pub run_state: RunState,
}

pub struct Harness {
    physics: PhysicsState,
    max_steps: usize,
    callbacks: Callbacks,
    plugins: Vec<Box<dyn HarnessPlugin>>,
    time: f32,
    events: PhysicsEvents,
    event_handler: ChannelEventCollector,
    pub state: HarnessState,
}

type Callbacks = Vec<Box<dyn FnMut(&mut PhysicsState, &PhysicsEvents, &HarnessState, f32)>>;

#[allow(dead_code)]
impl Harness {
    pub fn new_empty() -> Self {
        #[cfg(feature = "parallel")]
        let num_threads = num_cpus::get_physical();

        #[cfg(feature = "parallel")]
        let thread_pool = rapier::rayon::ThreadPoolBuilder::new()
            .num_threads(num_threads)
            .build()
            .unwrap();

        // #[cfg(feature = "parallel")]
        // println!("Rapier Harness Parallel, num_threads: {}", num_threads);

        let contact_channel = crossbeam::channel::unbounded();
        let proximity_channel = crossbeam::channel::unbounded();
        let event_handler = ChannelEventCollector::new(proximity_channel.0, contact_channel.0);
        let events = PhysicsEvents {
            contact_events: contact_channel.1,
            proximity_events: proximity_channel.1,
        };
        let physics = PhysicsState::new();
        let state = HarnessState {
            #[cfg(feature = "parallel")]
            thread_pool,
            timestep_id: 0,
            // run_state: RunState::Initialized
        };

        Self {
            physics,
            max_steps: 1000,
            callbacks: Vec::new(),
            plugins: Vec::new(),
            time: 0.0,
            events,
            event_handler,
            state,
        }
    }

    pub fn new(bodies: RigidBodySet, colliders: ColliderSet, joints: JointSet) -> Self {
        let mut res = Self::new_empty();
        res.set_world(bodies, colliders, joints);
        res
    }

    // pub fn pause_at_next_step(&mut self) {
    //     if self.state.run_state == RunState::Running {
    //         self.state.run_state = RunState::Pausing
    //     }
    // }

    pub fn set_max_steps(&mut self, max_steps: usize) {
        self.max_steps = max_steps
    }

    pub fn integration_parameters_mut(&mut self) -> &mut IntegrationParameters {
        &mut self.physics.integration_parameters
    }

    pub fn physics_state_mut(&mut self) -> &mut PhysicsState {
        &mut self.physics
    }

    pub fn set_world(&mut self, bodies: RigidBodySet, colliders: ColliderSet, joints: JointSet) {
        self.set_world_with_gravity(bodies, colliders, joints, Vector::y() * -9.81)
    }

    pub fn set_world_with_gravity(
        &mut self,
        bodies: RigidBodySet,
        colliders: ColliderSet,
        joints: JointSet,
        gravity: Vector<f32>,
    ) {
        // println!("Num bodies: {}", bodies.len());
        // println!("Num joints: {}", joints.len());
        self.physics.gravity = gravity;
        self.physics.bodies = bodies;
        self.physics.colliders = colliders;
        self.physics.joints = joints;
        self.physics.broad_phase = BroadPhase::new();
        self.physics.narrow_phase = NarrowPhase::new();
        self.time = 0.0;
        // self.state.timestep_id = 0;
        // self.state.highlighted_body = None;
        self.physics.query_pipeline = QueryPipeline::new();
        self.physics.pipeline = PhysicsPipeline::new();
        self.physics.pipeline.counters.enable();
    }

    // fn clear(&mut self) {
    //     self.callbacks.clear();
    //
    //     for plugin in &mut self.plugins {
    //         plugin.clear_graphics(window);
    //     }
    //
    //     self.plugins.clear();
    // }

    pub fn add_plugin(&mut self, plugin: impl HarnessPlugin + 'static) {
        self.plugins.push(Box::new(plugin));
    }

    // type StepCallback = FnMut(&mut PhysicsState, &PhysicsEvents, f32);
    pub fn add_callback<F: FnMut(&mut PhysicsState, &PhysicsEvents, &HarnessState, f32) + 'static>(
        &mut self,
        callback: F,
    ) {
        self.callbacks.push(Box::new(callback));
    }

    pub fn step(&mut self) {
        #[cfg(feature = "parallel")]
        {
            let physics = &mut self.physics;
            let event_handler = &self.event_handler;
            self.state.thread_pool.install(|| {
                physics.pipeline.step(
                    &physics.gravity,
                    &physics.integration_parameters,
                    &mut physics.broad_phase,
                    &mut physics.narrow_phase,
                    &mut physics.bodies,
                    &mut physics.colliders,
                    &mut physics.joints,
                    None,
                    None,
                    event_handler,
                );
            });
        }

        #[cfg(not(feature = "parallel"))]
        self.physics.pipeline.step(
            &self.physics.gravity,
            &self.physics.integration_parameters,
            &mut self.physics.broad_phase,
            &mut self.physics.narrow_phase,
            &mut self.physics.bodies,
            &mut self.physics.colliders,
            &mut self.physics.joints,
            None,
            None,
            &self.event_handler,
        );

        self.physics
            .query_pipeline
            .update(&self.physics.bodies, &self.physics.colliders);

        for plugin in &mut self.plugins {
            plugin.step(&mut self.physics)
        }

        for f in &mut self.callbacks {
            f(
                &mut self.physics,
                &self.events,
                &self.state,
                self.time,
            )
        }

        for plugin in &mut self.plugins {
            plugin.run_callbacks(&mut self.physics, &self.events,&self.state, self.time)
        }

        self.events.poll_all();

        self.time += self.physics.integration_parameters.dt();
    }

    pub fn run(&mut self) {
        for _ in 0..self.max_steps {
            self.step();
            self.state.timestep_id += 1;
        }
    }
}