use clap::Parser;
use common::{
    comp,
    terrain::{CoordinateConversions, TerrainChunkSize},
    vol::RectVolSize,
};
use hashbrown::HashSet;
use std::{
    sync::{
        atomic::{AtomicU32, Ordering},
        Arc,
    },
    thread,
    time::{Duration, SystemTime},
};
use tokio::runtime::Runtime;
use vek::*;
use veloren_client::{addr::ConnectionArgs, Client};

const CHUNK_SIZE: f32 = TerrainChunkSize::RECT_SIZE.x as f32;

#[derive(Clone, Copy, Parser)]
struct Opt {
    /// Number of clients to spin up
    #[arg(value_name = "CLIENT_COUNT")]
    size: u32,
    /// View distance of each client
    #[arg(value_name = "VIEW_DISTANCE")]
    vd: u32,
    /// Distribution of the clients, if not clustered they are dispersed
    #[arg(short, long)]
    clustered: bool,
    /// Whether the clients should move
    #[arg(short, long)]
    movement: bool,
}

fn main() {
    let opt = Opt::parse();
    // Start logging
    let _guards = common_frontend::init_stdout(None);
    // Run clients and stuff
    //
    // NOTE:  "swarm0" is assumed to be an admin already
    //
    // Since this requires a no-auth server use this command to add swarm0 as an
    // admin:
    //
    // --no-auth admin add swarm0 Admin
    //
    let admin_username = "swarm0".to_owned();
    let usernames = (1..opt.size)
        .map(|i| format!("swarm{}", i))
        .collect::<Vec<_>>();
    let to_adminify = usernames.clone();

    let finished_init = Arc::new(AtomicU32::new(0));
    let runtime = Arc::new(Runtime::new().unwrap());

    // TODO: calculate and log the required chunks per second to maintain the
    // selected scenario with full vd loaded

    run_client_new_thread(
        admin_username,
        0,
        to_adminify,
        &runtime,
        opt,
        &finished_init,
    );

    usernames.into_iter().enumerate().for_each(|(index, name)| {
        run_client_new_thread(
            name,
            index as u32,
            Vec::new(),
            &runtime,
            opt,
            &finished_init,
        );
    });

    std::thread::park();
}

fn run_client_new_thread(
    username: String,
    index: u32,
    to_adminify: Vec<String>,
    runtime: &Arc<Runtime>,
    opt: Opt,
    finished_init: &Arc<AtomicU32>,
) {
    let runtime = Arc::clone(runtime);
    let finished_init = Arc::clone(finished_init);
    thread::spawn(move || {
        if let Err(err) = run_client(username, index, to_adminify, runtime, opt, finished_init) {
            tracing::error!("swarm member {} exited with an error: {:?}", index, err);
        }
    });
}

fn run_client(
    username: String,
    index: u32,
    to_adminify: Vec<String>,
    runtime: Arc<Runtime>,
    opt: Opt,
    finished_init: Arc<AtomicU32>,
) -> Result<(), veloren_client::Error> {
    let mut client = loop {
        // Connect to localhost
        let addr = ConnectionArgs::Tcp {
            prefer_ipv6: false,
            hostname: "localhost".into(),
        };
        let runtime_clone = Arc::clone(&runtime);
        // NOTE: use a no-auth server
        match runtime.block_on(Client::new(
            addr,
            runtime_clone,
            &mut None,
            &username,
            "",
            |_| false,
        )) {
            Err(e) => tracing::warn!(?e, "Client {} disconnected", index),
            Ok(client) => break client,
        }
    };

    let mut clock = common::clock::Clock::new(Duration::from_secs_f32(1.0 / 30.0));

    let mut tick = |client: &mut Client| -> Result<(), veloren_client::Error> {
        clock.tick();
        client.tick_network(clock.dt())?;
        Ok(())
    };

    // Wait for character list to load
    client.load_character_list();
    while client.character_list().loading {
        tick(&mut client)?;
    }

    // Create character if none exist
    if client.character_list().characters.is_empty() {
        client.create_character(
            username.clone(),
            Some("common.items.weapons.sword.starter".into()),
            None,
            body(),
            None,
        );

        client.load_character_list();

        while client.character_list().loading || client.character_list().characters.is_empty() {
            tick(&mut client)?;
        }
    }

    // Select the first character
    client.request_character(
        client
            .character_list()
            .characters
            .first()
            .expect("Just created new character if non were listed!!!")
            .character
            .id
            .expect("Why is this an option?"),
        common::ViewDistances {
            terrain: opt.vd,
            entity: opt.vd,
        },
    );

    // If this is the admin client then adminify the other swarm members
    if !to_adminify.is_empty() {
        // Wait for other clients to connect
        loop {
            tick(&mut client)?;
            // NOTE: it's expected that each swarm member will have a unique alias
            let players = client.players().collect::<HashSet<&str>>();
            if to_adminify
                .iter()
                .all(|name| players.contains(&name.as_str()))
            {
                break;
            }
        }
        // Assert that we are a moderator (assumes we are an admin if so)
        assert!(
            client.is_moderator(),
            "The user needs to ensure \"{}\" is registered as an admin on the server",
            username
        );
        // Send commands to adminify others
        to_adminify.iter().for_each(|name| {
            client.send_command("adminify".into(), vec![name.into(), "admin".into()])
        });
    }

    // Wait for moderator
    while !client.is_moderator() {
        tick(&mut client)?;
    }

    finished_init.fetch_add(1, Ordering::Relaxed);
    // Wait for initialization of all other swarm clients to finish
    while !finished_init.load(Ordering::Relaxed) == opt.size {
        tick(&mut client)?;
    }

    // Use this check so this is only printed once
    if !to_adminify.is_empty() {
        println!("Initialization of all clients finished!");
    }

    // Main loop
    let world_center = client.world_data().chunk_size().as_::<f32>().cpos_to_wpos() / 2.0;
    loop {
        // TODO: doesn't seem to produce an error when server is shutdown (process keeps
        // running)
        tick(&mut client)?;
        let entity = client.entity();
        // Move or stay still depending on specified options
        // TODO: make sure server cheat protections aren't triggering
        let pos = comp::Pos(position(index, opt) + world_center);
        let vel = comp::Vel(Default::default());
        client
            .state_mut()
            .write_component_ignore_entity_dead(entity, pos);
        client
            .state_mut()
            .write_component_ignore_entity_dead(entity, vel);
    }
}

// Use client index, opts, and current system time to determine position
fn position(index: u32, opt: Opt) -> Vec3<f32> {
    let width = (opt.size as f32).sqrt().round() as u32;

    let spacing = if opt.clustered {
        5.0
    } else {
        use common::region::REGION_SIZE;
        // Attempt to make regions subscribed to by each client not overlapping
        opt.vd as f32 * 2.0 * CHUNK_SIZE + 2.0 * REGION_SIZE as f32
    };

    // Offset to center the grid of clients
    let offset = Vec2::new(
        width as f32 * spacing / 2.0,
        (opt.size / width) as f32 / 2.0,
    );
    // Position clients in a grid
    let base_pos = Vec2::new(
        (index % width) as f32 * spacing,
        (index / width) as f32 * spacing,
    ) - offset;

    let movement_offset: Vec2<_> = if opt.movement {
        // blocks per second
        const SPEED: f32 = 9.0; // typical super fast veloren walking speed

        // move in a square route
        // in blocks
        let route_side_length = CHUNK_SIZE * opt.vd as f32 * 3.0;
        let route_length = route_side_length * 4.0;
        // in secs
        let route_time = route_length / SPEED;
        let route_progress = (SystemTime::UNIX_EPOCH.elapsed().unwrap().as_secs_f64()
            % route_time as f64) as f32
            / route_time;

        // clockwise square
        (match route_progress * 4.0 {
            // going up left side
            t if t < 1.0 => Vec2::new(0.0, 0.0 + t),
            // going across top side
            t if t < 2.0 => Vec2::new(0.0 + (t - 1.0), 1.0),
            // going down right side
            t if t < 3.0 => Vec2::new(1.0, 1.0 - (t - 2.0)),
            // going across bottom
            t => Vec2::new(1.0 - (t - 3.0), 0.0),
        }) * route_side_length
    } else {
        Vec2::zero()
    };

    Vec3::from(base_pos + movement_offset)
}

fn body() -> comp::Body {
    comp::body::humanoid::Body {
        species: comp::body::humanoid::Species::Human,
        body_type: comp::body::humanoid::BodyType::Male,
        hair_style: 0,
        beard: 0,
        eyes: 0,
        accessory: 0,
        hair_color: 0,
        skin: 0,
        eye_color: 0,
    }
    .into()
}