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extern crate consul;
#[macro_use]
extern crate error_chain;
#[macro_use]
extern crate serde_derive;

use consul::Client;
use std::collections::HashMap;
use std::iter::FromIterator;

#[derive(Debug, Serialize)]
pub struct Node {
    pub name: String,
    pub address: String,
    pub service_port: u16,
    pub service_tags: Vec<String>,
}

#[derive(Debug, Serialize)]
pub struct Catalog {
    services: HashMap<String, Vec<String>>,
    nodes_by_service: HashMap<String, Vec<Node>>,
    healthy_nodes_by_service: HashMap<String, Vec<String>>,
}

impl Catalog {
    pub fn services(&self) -> Vec<&String> {
        self.services.keys().collect()
    }

    pub fn service_tags(&self, service_name: &str) -> Option<Vec<&String>> {
        self.services.get(service_name).map(|x| x.iter().collect())
    }

    pub fn nodes_by_service(&self, service_name: &str) -> Option<Vec<&Node>> {
        self.nodes_by_service.get(service_name).map(|x| {
            x.iter().collect()
        })
    }

    pub fn is_node_healthy_for_service(&self, node: &Node, service_name: &str) -> bool {
        self.healthy_nodes_by_service.get(service_name).map_or(
            false,
            |x| {
                x.contains(&node.address)
            },
        )
    }
}

pub struct Consul {
    url: String,
}

impl Consul {
    pub fn new(url: String) -> Self {
        Consul { url }
    }

    pub fn catalog(&self) -> Result<Catalog> {
        self.catalog_by(None, None)
    }

    pub fn catalog_by(
        &self,
        services: Option<Vec<String>>,
        tags: Option<Vec<String>>,
    ) -> Result<Catalog> {
        let client = Client::new(&self.url);

        let service_filter: Box<Fn(&String) -> bool> = if let Some(services) = services {
            Box::new(move |x| services.contains(x))
        } else {
            Box::new(|_x| true)
        };

        let tag_filter: Box<Fn(&String) -> bool> = if let Some(tags) = tags {
            Box::new(move |x| tags.contains(x))
        } else {
            Box::new(|_x| true)
        };

        // consul library isn't really friendly to chain error, because it return String as Error type
        let services: HashMap<String, Vec<String>> = match client.catalog.services() {
            Ok(x) => x,
            Err(cause) => bail!(ErrorKind::ConsulError(cause)),
        }.into_iter()
            .filter(|&(ref key, _)| service_filter(key))
            .filter(|&(_, ref values)| values.iter().any(|x| tag_filter(x)))
            .collect();

        let nodes_by_service: HashMap<String, Vec<_>> =
            HashMap::from_iter(services.keys().map(|service| {
                (
                    service.to_string(),
                    client
                        .catalog
                        .get_nodes(service.clone())
                        .unwrap()
                        .into_iter()
                        .filter(|node| node.ServiceTags.iter().any(|x| tag_filter(x)))
                        .map(|node| {
                            Node {
                                name: node.Node,
                                address: node.Address,
                                service_port: node.ServicePort,
                                service_tags: node.ServiceTags,
                            }
                        })
                        .collect::<Vec<_>>(),
                )
            }));

        let healthy_nodes_by_service: HashMap<String, Vec<_>> =
            HashMap::from_iter(services.keys().map(|service| {
                (
                    service.to_string(),
                    client.health.healthy_nodes_by_service(service).unwrap(),
                )
            }));

        Ok(Catalog {
            services,
            nodes_by_service,
            healthy_nodes_by_service,
        })
    }
}

error_chain! {
    errors {
        ConsulError(cause: String) {
            description("Failed get data from Consul")
            display("Failed get data from Consul because {}", cause)
        }
    }
}