use crate::db::user_repo;
use crate::state::OmegaState;
use crate::transport::connection::OmikronConnection;
use crate::transport::omikron_connection::OmikronResult;
use dashmap::DashMap;
use mtp::codec::{CommunicationType, CommunicationValue, DataType, DataValue};
use once_cell::sync::Lazy;
use rand::prelude::IteratorRandom;
use std::sync::Arc;

pub static OMIKRON_CONNECTIONS: Lazy<DashMap<i64, Arc<OmikronConnection>>> =
    Lazy::new(|| DashMap::new());

pub async fn add_omikron(conn: Arc<OmikronConnection>) {
    let id = match conn.clone().get_omikron_id().await {
        Some(id) => id,
        _ => {
            conn.close().await;
            return;
        }
    };

    if let Some(old) = OMIKRON_CONNECTIONS.insert(id, conn.clone()) {
        old.close().await;
    }
}

pub async fn remove_omikron(omikron_id: i64, connection: &Arc<OmikronConnection>) -> bool {
    OMIKRON_CONNECTIONS
        .remove_if(&omikron_id, |_, current| Arc::ptr_eq(current, connection))
        .is_some()
}

pub fn get_connected_omikron(omikron_id: i64) -> Option<Arc<OmikronConnection>> {
    OMIKRON_CONNECTIONS
        .get(&omikron_id)
        .map(|connection| connection.clone())
}

pub fn get_state() -> Option<Arc<OmegaState>> {
    OMIKRON_CONNECTIONS
        .iter()
        .next()
        .map(|connection| connection.value().state())
}

pub fn get_iota_primary_omikron_connection(iota_id: i64) -> Option<i64> {
    get_state().and_then(|state| state.presence.primary_iota_route(iota_id))
}

pub async fn get_all_connections()
-> Result<std::collections::HashMap<i64, std::collections::HashMap<i64, Vec<i64>>>, ()> {
    match get_state() {
        Some(state) => {
            let mut result = state.presence.connection_routes();
            let iota_ids = state
                .presence
                .all_iota_routes()
                .keys()
                .copied()
                .collect::<Vec<_>>();
            let users = user_repo::get_users_by_iota_ids(&iota_ids)
                .await
                .map_err(|_| ())?;
            for user in users {
                for route in state.presence.routes_for_user(user.id.0) {
                    if let Some(iotas) = result.get_mut(&route.omikron_id) {
                        if let Some(iota_id) = user.iota_id
                            && let Some(users) = iotas.get_mut(&iota_id.0) {
                            users.push(user.id.0);
                        }
                    }
                }
            }
            for iotas in result.values_mut() {
                for users in iotas.values_mut() {
                    users.sort_unstable();
                    users.dedup();
                }
            }
            Ok(result)
        }
        None => Ok(std::collections::HashMap::new()),
    }
}

pub async fn send_state_batch(
    omikron_id: i64,
    notifications: Vec<CommunicationValue>,
) -> OmikronResult<()> {
    let connection =
        get_connected_omikron(omikron_id).ok_or(crate::error::OmegaError::NotConnected)?;
    connection.send_messages(&notifications).await
}

pub async fn get_random_omikron() -> Result<Arc<OmikronConnection>, ()> {
    let keys: Vec<_> = OMIKRON_CONNECTIONS.iter().map(|e| *e.key()).collect();

    if let Some(key) = keys.into_iter().choose(&mut rand::rng()) {
        if let Some(connection) = get_connected_omikron(key) {
            return Ok(connection);
        }
    }

    Err(())
}

pub async fn send_to_user(user_id: i64, cv: &CommunicationValue) {
    if let Some(state) = get_state() {
        for user_route in state.presence.routes_for_user(user_id) {
            if let Some(omikron_conn) = OMIKRON_CONNECTIONS.get(&user_route.omikron_id) {
                let _ = omikron_conn.value().clone().send_message(cv).await;
            }
        }
    }
}

/// Publish the authoritative membership list after an attach, migration, or
/// release. Omikron replaces its full local index from this snapshot.
pub async fn publish_iota_user_snapshot(iota_id: i64) {
    let Some(omikron_id) = get_iota_primary_omikron_connection(iota_id) else { return; };
    let Some(connection) = get_connected_omikron(omikron_id) else { return; };
    let Ok(users) = user_repo::get_users_by_iota_id(crate::models::IotaId::from(iota_id)).await else { return; };
    let user_ids = users.into_iter().map(|user| DataValue::SignedNumber(user.id.0.into())).collect();
    let snapshot = CommunicationValue::new(CommunicationType::IotaUserData)
        .add_typed_default(DataType::IotaId, DataValue::SignedNumber(iota_id.into()))
        .add_typed_default(DataType::UserIds, DataValue::Array(user_ids));
    let _ = connection.send(&snapshot).await;
}

pub async fn deliver_pending_erasures(iota_id: i64) {
    let Ok(users) = user_repo::pending_erasures_for_iota(crate::models::IotaId::from(iota_id)).await else { return; };
    let Some(omikron_id) = get_iota_primary_omikron_connection(iota_id) else { return; };
    let Some(connection) = get_connected_omikron(omikron_id) else { return; };
    for user_id in users {
        let request = CommunicationValue::new(CommunicationType::EraseHostedUserData)
            .add_typed_default(DataType::UserId, DataValue::SignedNumber(user_id.0.into()))
            .add_typed_default(DataType::IotaId, DataValue::SignedNumber(iota_id.into()));
        let _ = connection.clone().send(&request).await;
    }
}