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mod ip_extractor;
pub mod ip_hash;
pub mod round_robin;
use super::worker::WorkerState;
use crate::client::Client;
use crate::error::FaucetResult;
use hyper::Request;
pub use ip_extractor::IpExtractor;
use std::net::{IpAddr, SocketAddr};
use std::str::FromStr;
use std::sync::Arc;

use self::ip_hash::IpHash;
use self::round_robin::RoundRobin;

#[async_trait::async_trait]
trait LoadBalancingStrategy {
    async fn entry(&self, ip: IpAddr) -> Client;
}

#[derive(Debug, Clone, Copy, clap::ValueEnum, Eq, PartialEq)]
pub enum Strategy {
    RoundRobin,
    IpHash,
}

impl FromStr for Strategy {
    type Err = &'static str;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "round_robin" => Ok(Self::RoundRobin),
            "ip_hash" => Ok(Self::IpHash),
            _ => Err("invalid strategy"),
        }
    }
}

type DynLoadBalancer = Arc<dyn LoadBalancingStrategy + Send + Sync>;

pub(crate) struct LoadBalancer {
    strategy: DynLoadBalancer,
    extractor: IpExtractor,
}

impl LoadBalancer {
    pub fn new(
        strategy: Strategy,
        extractor: IpExtractor,
        workers: &[WorkerState],
    ) -> FaucetResult<Self> {
        let strategy: DynLoadBalancer = match strategy {
            Strategy::RoundRobin => Arc::new(RoundRobin::new(workers)?),
            Strategy::IpHash => Arc::new(IpHash::new(workers)?),
        };
        Ok(Self {
            strategy,
            extractor,
        })
    }
    pub async fn get_client(&self, ip: IpAddr) -> FaucetResult<Client> {
        Ok(self.strategy.entry(ip).await)
    }
    pub fn extract_ip<B>(&self, request: &Request<B>, socket: SocketAddr) -> FaucetResult<IpAddr> {
        self.extractor.extract(request, socket)
    }
}

impl Clone for LoadBalancer {
    fn clone(&self) -> Self {
        Self {
            strategy: Arc::clone(&self.strategy),
            extractor: self.extractor,
        }
    }
}

#[cfg(test)]
mod tests {
    use std::sync::atomic::AtomicBool;

    use super::*;

    #[test]
    fn test_strategy_from_str() {
        assert_eq!(
            Strategy::from_str("round_robin").unwrap(),
            Strategy::RoundRobin
        );
        assert_eq!(Strategy::from_str("ip_hash").unwrap(), Strategy::IpHash);
        assert!(Strategy::from_str("invalid").is_err());
    }

    #[test]
    fn test_load_balancer_new_round_robin() {
        let workers_state = Vec::new();
        let _ = LoadBalancer::new(
            Strategy::RoundRobin,
            IpExtractor::XForwardedFor,
            &workers_state,
        )
        .expect("failed to create load balancer");
    }

    #[test]
    fn test_load_balancer_new_ip_hash() {
        let workers_state = Vec::new();
        let _ = LoadBalancer::new(Strategy::IpHash, IpExtractor::XForwardedFor, &workers_state)
            .expect("failed to create load balancer");
    }

    #[test]
    fn test_load_balancer_extract_ip() {
        let workers_state = Vec::new();
        let load_balancer = LoadBalancer::new(
            Strategy::RoundRobin,
            IpExtractor::XForwardedFor,
            &workers_state,
        )
        .expect("failed to create load balancer");
        let request = Request::builder()
            .header("x-forwarded-for", "192.168.0.1")
            .body(())
            .unwrap();
        let ip = load_balancer
            .extract_ip(&request, "127.0.0.1:9532".parse().unwrap())
            .expect("failed to extract ip");

        assert_eq!(ip, "192.168.0.1".parse::<IpAddr>().unwrap());
    }

    #[tokio::test]
    async fn test_load_balancer_get_client() {
        use crate::client::ExtractSocketAddr;
        let workers_state = [
            WorkerState {
                target: "test",
                is_online: Arc::new(AtomicBool::new(true)),
                socket_addr: "127.0.0.1:9999".parse().unwrap(),
            },
            WorkerState {
                target: "test",
                is_online: Arc::new(AtomicBool::new(true)),
                socket_addr: "127.0.0.1:9998".parse().unwrap(),
            },
        ];
        let load_balancer = LoadBalancer::new(
            Strategy::RoundRobin,
            IpExtractor::XForwardedFor,
            &workers_state,
        )
        .expect("failed to create load balancer");
        let ip = "192.168.0.1".parse().unwrap();
        let client = load_balancer
            .get_client(ip)
            .await
            .expect("failed to get client");
        assert_eq!(client.socket_addr(), "127.0.0.1:9999".parse().unwrap());

        let client = load_balancer
            .get_client(ip)
            .await
            .expect("failed to get client");

        assert_eq!(client.socket_addr(), "127.0.0.1:9998".parse().unwrap());
    }

    #[test]
    fn test_clone_load_balancer() {
        let workers_state = Vec::new();
        let load_balancer = LoadBalancer::new(
            Strategy::RoundRobin,
            IpExtractor::XForwardedFor,
            &workers_state,
        )
        .expect("failed to create load balancer");
        let _ = load_balancer.clone();
    }
}