use super::{Node, NodeContext, NodeKind, NodeRequest, NodeResponse};
use crate::{config::DynNode, error::ServiceError};
use anyhow::Result;
use rand_distr::Distribution;
use serde::Deserialize;
use serde_yml::Value;
use std::{future::Future, pin::Pin, sync::Arc, time::Duration};
use tokio::time::sleep;

pub struct DelayKind;

#[derive(Deserialize)]
struct Delay {
    duration: u64,
    stdev: u64,
    next: DynNode,
}

impl NodeKind for DelayKind {
    fn name(&self) -> &'static str {
        "delay"
    }
    fn instanciate(&self, config: Value) -> Result<Arc<dyn Node>> {
        Ok(Arc::new(serde_yml::from_value::<Delay>(config)?))
    }
}
impl Node for Delay {
    fn handle<'a>(
        &'a self,
        context: &'a mut NodeContext,
        request: NodeRequest,
    ) -> Pin<Box<dyn Future<Output = Result<NodeResponse, ServiceError>> + Send + Sync + 'a>> {
        Box::pin(async move {
            sleep(Duration::from_millis(if self.stdev == 0 {
                self.duration
            } else {
                self.duration.saturating_add_signed(
                    rand_distr::Normal::new(0., self.stdev as f32)
                        .unwrap()
                        .sample(&mut rand::rng()) as i64,
                )
            }))
            .await;
            self.next.handle(context, request).await
        })
    }
}