use std::cmp;
use std::time::Duration;
use log::*;
use tokio::sync::watch;
use tokio::time::delay_for;
use anyhow::Result;
use serde::{Serialize, Deserialize};
use serde_lexpr::{from_str,error};
use crate::messages;
use crate::consul;
use std::collections::HashSet;

#[derive(Serialize, Deserialize, Debug)]
pub enum DiplonatParameter {
  tcp_port(HashSet<u16>),
  udp_port(HashSet<u16>)
}

#[derive(Serialize, Deserialize, Debug)]
pub enum DiplonatConsul {
  diplonat(Vec<DiplonatParameter>)
}

pub struct ConsulActor {
  pub rx_open_ports: watch::Receiver<messages::PublicExposedPorts>,

  consul: consul::Consul,
  node: String,
  retries: u32,
  tx_open_ports: watch::Sender<messages::PublicExposedPorts>
}

fn retry_to_time(retries: u32, max_time: Duration) -> Duration {
  // 1.2^x seems to be a good value to exponentially increase time at a good pace
  // eg. 1.2^32 = 341 seconds ~= 5 minutes - ie. after 32 retries we wait 5 minutes
  return Duration::from_secs(cmp::min(max_time.as_secs(), 1.2f64.powf(retries as f64) as u64))
}

fn to_parameters(catalog: &consul::CatalogNode) -> Vec<DiplonatConsul> {
  let mut r = Vec::new();

  for (_, service_info) in &catalog.Services {
    for tag in &service_info.Tags {
      let diplo_conf: error::Result<DiplonatConsul> = from_str(tag);
      match diplo_conf {
        Ok(conf) => r.push(conf),
        Err(e) => debug!("Failed to parse entry {}. {}", tag, e),
      };
    }
  }

  return r;
}

fn to_open_ports(params: &Vec<DiplonatConsul>) -> messages::PublicExposedPorts {
  let mut op = messages::PublicExposedPorts { 
    tcp_ports: HashSet::new(),
    udp_ports: HashSet::new()
  };

  for conf in params {
    let DiplonatConsul::diplonat(c) = conf;
    for parameter in c {
      match parameter {
        DiplonatParameter::tcp_port(p) => op.tcp_ports.extend(p),
        DiplonatParameter::udp_port(p) => op.udp_ports.extend(p),
      };
    }
  }

  return op;
}

impl ConsulActor {
  pub fn new(url: &str, node: &str) -> Self {
    let (tx, rx) = watch::channel(messages::PublicExposedPorts{
      tcp_ports: HashSet::new(),
      udp_ports: HashSet::new()
    });

    return Self {
      consul: consul::Consul::new(url),
      rx_open_ports: rx,
      tx_open_ports: tx,
      node: node.to_string(),
      retries: 0,
    };
  }

  pub async fn listen(&mut self) -> Result<()> {
    loop {
      let catalog = match self.consul.watch_node(&self.node).await {
        Ok(c) => c,
        Err(e) => {
          self.consul.watch_node_reset();
          self.retries = cmp::min(std::u32::MAX - 1, self.retries) + 1;
          let will_retry_in = retry_to_time(self.retries, Duration::from_secs(600));
          error!("Failed to query consul. Will retry in {}s. {}", will_retry_in.as_secs(), e);
          delay_for(will_retry_in).await;
          continue;
        }
      };
      self.retries = 0;
      let msg = to_open_ports(&to_parameters(&catalog));
      debug!("Extracted configuration: {:#?}", msg);

      self.tx_open_ports.broadcast(msg)?;
    }
  }
}