sabi_redis 0.7.0

// Copyright (C) 2026 Takayuki Sato. All Rights Reserved.
// This program is free software under MIT License.
// See the file LICENSE in this distribution for more details.

use super::retry::Retry;
use futures::{stream::StreamExt, Future};
use redis::aio::PubSub;
use redis::{Client, ControlFlow, IntoConnectionInfo, Msg, ToRedisArgs};
use std::fmt::Debug;

/// Errors that can occur during Redis Pub/Sub operations in async standalone mode.
#[derive(Debug)]
pub enum RedisPubSubAsyncError {
    /// The Redis server address has already been consumed and is no longer available.
    AddressAlreadyConsumed,
    /// Failed to open a Redis client with the provided address.
    FailToOpenClient,
    /// Failed to establish an async Pub/Sub connection to the Redis server.
    FailToGetAsyncPubSub,
    /// Failed to subscribe to the specified channels.
    FailToSubscribeToChannels,
    /// Failed to subscribe to the specified patterns.
    FailToSubscribeToChannelsWithPatterns,
    /// Failed to receive a message from the Redis server.
    FailToGetMessage,
}

/// An async Redis Pub/Sub subscriber for standalone Redis instances.
///
/// This structure provides a way to subscribe to channels and patterns on a standalone
/// Redis server and process received messages asynchronously. It includes built-in
/// retry logic for connection and subscription failures.
pub struct RedisPubSubAsync<I, A>
where
    I: IntoConnectionInfo + Sized + Debug + Clone,
    A: ToRedisArgs,
{
    addr: Option<I>,
    channels: Vec<A>,
    patterns: Vec<A>,
    retry: Retry,
}

impl<I, A> RedisPubSubAsync<I, A>
where
    I: IntoConnectionInfo + Sized + Debug + Clone,
    A: ToRedisArgs,
{
    /// Creates a new `RedisPubSubAsync` instance for the given Redis address.
    pub fn new(addr: I) -> Self {
        Self {
            addr: Some(addr),
            channels: Vec::new(),
            patterns: Vec::new(),
            retry: Retry::new(),
        }
    }

    /// Sets the retry parameters for connection and subscription failures.
    ///
    /// # Arguments
    ///
    /// * `max_count` - The maximum number of retry attempts.
    /// * `init_delay_ms` - The initial delay between retries in milliseconds.
    /// * `max_delay_ms` - The maximum delay between retries in milliseconds.
    pub fn set_retry(&mut self, max_count: u32, init_delay_ms: u64, max_delay_ms: u64) {
        self.retry = Retry::with_params(max_count, init_delay_ms, max_delay_ms);
    }

    /// Subscribes to a channel.
    pub fn subscribe(&mut self, channels: A) {
        self.channels.push(channels);
    }

    /// Subscribes to a pattern.
    pub fn psubscribe(&mut self, patterns: A) {
        self.patterns.push(patterns);
    }

    /// Starts receiving messages asynchronously and processes them with the provided closure.
    ///
    /// This method will continuously listen for messages. If a connection
    /// or subscription error occurs, it will attempt to reconnect based on the
    /// retry configuration.
    ///
    /// The closure `f` is called for each received message. It should return
    /// a future that resolves to `ControlFlow::Continue` to keep listening or
    /// `ControlFlow::Break(value)` to stop and return the value.
    pub async fn receive_async<F, Fut, U>(mut self, mut f: F) -> errs::Result<U>
    where
        F: FnMut(Msg) -> Fut,
        Fut: Future<Output = ControlFlow<U>>,
    {
        let addr = self
            .addr
            .take()
            .ok_or_else(|| errs::Err::new(RedisPubSubAsyncError::AddressAlreadyConsumed))?;
        let client = Client::open(addr)
            .map_err(|e| errs::Err::with_source(RedisPubSubAsyncError::FailToOpenClient, e))?;

        loop {
            let pubsub: PubSub = match client.get_async_pubsub().await {
                Ok(pubsub) => pubsub,
                Err(e) => {
                    if self.retry.wait_with_backoff_async().await {
                        continue;
                    }
                    return Err(errs::Err::with_source(
                        RedisPubSubAsyncError::FailToGetAsyncPubSub,
                        e,
                    ));
                }
            };
            let (mut sink, mut stream) = pubsub.split();

            for c in self.channels.iter() {
                sink.subscribe(c).await.map_err(|e| {
                    errs::Err::with_source(RedisPubSubAsyncError::FailToSubscribeToChannels, e)
                })?;
            }

            for p in self.patterns.iter() {
                sink.psubscribe(p).await.map_err(|e| {
                    errs::Err::with_source(
                        RedisPubSubAsyncError::FailToSubscribeToChannelsWithPatterns,
                        e,
                    )
                })?;
            }

            loop {
                match stream.next().await {
                    Some(msg) => {
                        self.retry.reset();
                        if let ControlFlow::Break(value) = f(msg).await {
                            return Ok(value);
                        }
                    }
                    None => {
                        if self.retry.wait_with_backoff_async().await {
                            continue;
                        }
                        return Err(errs::Err::new(RedisPubSubAsyncError::FailToGetMessage));
                    }
                }
            }
        }
    }
}

#[cfg(test)]
mod unit_tests {
    use super::*;
    use crate::pubsub::{RedisPubSubMsgAsyncDataConn, RedisPubSubMsgAsyncDataSrc};
    use crate::standalone_async::{RedisAsyncDataConn, RedisAsyncDataSrc};
    use override_macro::{overridable, override_with};
    use redis::{AsyncTypedCommands, ControlFlow};
    use sabi::tokio::{logic, DataAcc, DataHub};
    use tokio::time;

    #[overridable]
    trait PublishData {
        async fn say_greet_async(&mut self, s: &str) -> errs::Result<()>;
    }

    async fn publish_logic_async(data: &mut impl PublishData) -> errs::Result<()> {
        data.say_greet_async("Hello").await?;
        Ok(())
    }

    #[overridable]
    trait SubscribeData {
        async fn receive_greet_async(&mut self) -> errs::Result<String>;
    }

    async fn subscribe_logic_async(data: &mut impl SubscribeData) -> errs::Result<()> {
        assert_eq!(data.receive_greet_async().await?, "Hello");
        Ok(())
    }

    #[overridable]
    trait RedisPubSubAsyncDataAcc: DataAcc {
        async fn say_greet_async(&mut self, s: &str) -> errs::Result<()> {
            let data_conn = self
                .get_data_conn_async::<RedisAsyncDataConn>("redis")
                .await?;
            let conn = data_conn.get_connection();
            time::sleep(time::Duration::from_millis(100)).await;
            conn.publish("channel-1", s).await.unwrap();
            Ok(())
        }

        async fn receive_greet_async(&mut self) -> errs::Result<String> {
            let data_conn = self
                .get_data_conn_async::<RedisPubSubMsgAsyncDataConn>("redis/pubsub")
                .await?;
            let msg = data_conn.get_message();
            let payload: String = msg.get_payload().unwrap();
            Ok(payload)
        }
    }
    impl RedisPubSubAsyncDataAcc for DataHub {}

    #[override_with(RedisPubSubAsyncDataAcc)]
    impl PublishData for DataHub {}

    #[override_with(RedisPubSubAsyncDataAcc)]
    impl SubscribeData for DataHub {}

    #[tokio::test]
    async fn test() {
        // publish
        {
            let _ = tokio::spawn(async {
                let mut data = DataHub::new();
                data.uses("redis", RedisAsyncDataSrc::new("redis://127.0.0.1:6379/8"));
                data.run_async(logic!(publish_logic_async)).await.unwrap();
            });
        }

        // subscribe
        {
            let mut pubsub = RedisPubSubAsync::new("redis://127.0.0.1:6379/8");
            pubsub.subscribe("channel-1");
            let n = pubsub
                .receive_async(async |msg| {
                    let mut data = DataHub::new();
                    data.uses("redis/pubsub", RedisPubSubMsgAsyncDataSrc::new(msg));
                    data.run_async(logic!(subscribe_logic_async)).await.unwrap();
                    ControlFlow::Break(1)
                })
                .await
                .unwrap();
            assert_eq!(n, 1);
        }
    }
}