use std::error::Error;
use std::net::SocketAddr;
use async_std::io::WriteExt;
use async_std::sync::Arc;
use async_std::net::{TcpListener, TcpStream};
use entity::{EntityHandler};
use manager::PhysicsData;
use nalgebra::vector;
use rapier2d_f64::prelude::{MultibodyJointSet, ImpulseJointSet, ColliderSet, RigidBodySet, NarrowPhase, BroadPhase, IslandManager, CCDSolver, IntegrationParameters};
use lazy_static::lazy_static;
use log::{error, info, Level, warn};
use serde::{Deserialize, Serialize};
use crate::entity::Entity;
use crate::manager::{ClientHandler, ClientManager};
use crate::timer::timer_main;
use async_std::sync::RwLock;
use futures::StreamExt;
use starkingdoms_protocol::PROTOCOL_VERSION;
use crate::handler::handle_client;

pub mod handler;
pub mod manager;
pub mod timer;
#[macro_use]
pub mod macros;
pub mod planet;
pub mod orbit;
pub mod entity;
pub mod api;

const SCALE: f64 = 1.0;

async fn handle_request(conn: TcpStream, remote_addr: SocketAddr, mgr: ClientManager,
                        entities: Arc<RwLock<EntityHandler>>, physics_data: Arc<RwLock<PhysicsData>>) {
    match _handle_request(conn, remote_addr, mgr, entities, physics_data).await {
        Ok(_) => (),
        Err(e) => {
            error!("[{}] error in handler thread: {}", remote_addr, e);
        }
    }
}

async fn _handle_request(mut conn: TcpStream, remote_addr: SocketAddr, mgr: ClientManager,
                         entities: Arc<RwLock<EntityHandler>>, physics_data: Arc<RwLock<PhysicsData>>) -> Result<(), Box<dyn Error>> {
    let mut peek_buf = [0u8; 9];

    loop {
        let read = conn.peek(&mut peek_buf).await?;
        if read == 9 {
            break;
        }
    }

    if peek_buf == *b"GET /ping" {
        info!("[{}] incoming http connection", remote_addr);
        let ping_resp = serde_json::to_string(&ServerPingResponse {
            version: ServerPingResponseVersion {
                name: env!("STK_VERSION_NAME").to_string(), // Set by build.rs
                number: env!("STK_VERSION").to_string(), // Set by build.rs
                protocol: PROTOCOL_VERSION,
                channel: env!("STK_CHANNEL").to_string(),
                build: env!("STK_BUILD").to_string()
            },
            players: CMGR.usernames.read().await.len() as u32,
            description: env!("STK_SLP_DESCRIPTION").to_string(),
        }).unwrap();

        let resp_str = format!("HTTP/1.0 200 OK\nAccess-Control-Allow-Origin: *\nContent-Length: {}\n\n{}", ping_resp.len(), ping_resp);
        let http_resp = resp_str.as_bytes();

        conn.write_all(http_resp).await?;
        info!("[{}] sent ping response (200 OK {} bytes)", remote_addr, ping_resp.len());
        return Ok(());
    }
    info!("[{}] incoming websocket connection", remote_addr);

    // if its not GET /ping, assume its websocket and attempt to handshake with them
    let ws_stream = async_tungstenite::accept_async(conn).await?;

    let (ws_write, ws_read) = ws_stream.split();

    let (tx, rx) = async_std::channel::unbounded();

    let client = ClientHandler { tx };

    // Acquire the write lock in a small scope, so it's dropped as quickly as possible
    {
        mgr.handlers.write().await.insert(remote_addr, client);
    }

    info!("[{}] passing to client handler", remote_addr);

    //forward the stream to the sink to achieve echo
    match handle_client(mgr.clone(), entities.clone(), physics_data.clone(), remote_addr, rx, ws_write, ws_read).await {
        Ok(_) => (),
        Err(e) if e.is::<async_tungstenite::tungstenite::error::Error>() => {
            let e = e.downcast::<async_tungstenite::tungstenite::error::Error>().unwrap();
            if matches!(*e, async_tungstenite::tungstenite::Error::ConnectionClosed) {
                info!("[{}] connection closed normally", remote_addr);
            } else {
                error!("[{}] error in client thread: {}", remote_addr, e);
            }
        },
        Err(e) => {
            error!("[{}] error in client thread: {}", remote_addr, e);
        }
    }

    // clean up values left over
    {
        mgr.handlers.write().await.remove(&remote_addr);
        mgr.usernames.write().await.remove(&remote_addr);
        // remove player physics body
        let mut data = physics_data.write().await;
        let mut rigid_body_set = data.rigid_body_set.clone();
        let mut island_manager = data.island_manager.clone();
        let mut collider_set = data.collider_set.clone();
        let mut impulse_joint_set = data.impulse_joint_set.clone();
        let mut multibody_joint_set = data.multibody_joint_set.clone();
        let player_id = match entities.read().await.get_player_id(remote_addr) {
            Some(s) => s,
            None => {
                warn!("[{}] player missing from entities.players", remote_addr);
                return Err("Player missing from entities.players".into());
            }
        };
        if let Entity::Player(player) = entities.read().await.entities.get(&player_id).unwrap() {
            rigid_body_set.remove(player.handle, &mut island_manager, &mut collider_set,
                                    &mut impulse_joint_set, &mut multibody_joint_set, true);
        }
        data.rigid_body_set = rigid_body_set;
        data.collider_set = collider_set;
        data.island_manager = island_manager;
        data.impulse_joint_set = impulse_joint_set;
        data.multibody_joint_set = multibody_joint_set;
        entities.write().await.entities.remove(&player_id);
    }

    Ok(())
}

lazy_static! {
    static ref CMGR: ClientManager = ClientManager {
        handlers: Arc::new(RwLock::new(Default::default())),
        usernames: Arc::new(RwLock::new(Default::default())),
    };
    static ref DATA: Arc<RwLock<PhysicsData>> = Arc::new(RwLock::new(PhysicsData { 
        gravity: vector![0.0, 0.0],
        integration_parameters: IntegrationParameters {
            dt: 1.0 / 20.0,
            ..Default::default() },
        island_manager: IslandManager::new(),
        broad_phase: BroadPhase::new(),
        narrow_phase: NarrowPhase::new(),
        rigid_body_set: RigidBodySet::new(),
        collider_set: ColliderSet::new(),
        impulse_joint_set: ImpulseJointSet::new(),
        multibody_joint_set: MultibodyJointSet::new(),
        ccd_solver: CCDSolver::new(), }));
    static ref ENTITIES: Arc<RwLock<EntityHandler>> = Arc::new(RwLock::new(EntityHandler::new()));
}

#[async_std::main]
async fn main() {
    simple_logger::init_with_level(Level::Debug).expect("Unable to start logging service");

    info!("StarKingdoms server (v: {}, build {}) - initializing", env!("STK_VERSION"), env!("STK_BUILD"));

    if std::env::var("STK_API_KEY").is_err() {
        error!("Unable to read the API key from STK_API_KEY. Ensure it is set, and has a valid value.");
        std::process::exit(1);
    }
    if std::env::var("STK_API_URL").is_err() {
        error!("Unable to read the API server URL from STK_API_URL. Ensure it is set, and has a valid value.");
        std::process::exit(1);
    }

    let addr = SocketAddr::from(([0, 0, 0, 0], 3000));

    info!("Listening on {} for HTTP/WebSocket connections", addr);

    let mgr_timer = CMGR.clone();
    let physics_data = DATA.clone();
    let entities_timer = ENTITIES.clone();
    let _timer_thread = async_std::task::spawn(async move {
        timer_main(mgr_timer, physics_data, entities_timer).await;
    });

    let try_socket = TcpListener::bind(&addr).await;

    let listener = match try_socket {
        Ok(l) => l,
        Err(e) => {
            error!("error binding to socket: {}", e);
            std::process::exit(1);
        }
    };

    while let Ok((stream, peer_addr)) = listener.accept().await {
        async_std::task::spawn(handle_request(stream, peer_addr, CMGR.clone(),
                                ENTITIES.clone(), DATA.clone()));
    }
}

#[derive(Serialize, Deserialize)]
pub struct ServerPingResponse {
    pub version: ServerPingResponseVersion,
    pub players: u32,
    pub description: String
}

#[derive(Serialize, Deserialize)]
pub struct ServerPingResponseVersion {
    pub name: String,
    pub number: String,
    pub protocol: u32,
    pub channel: String,
    pub build: String
}