//! Manages sending/receiving EppObject request and responses to the registry connection
//!
//! ## Example
//!
//! ```rust
//! use epp_client::EppClient;
//! use epp_client::epp::{EppDomainCheck, EppDomainCheckResponse};
//! use epp_client::epp::generate_client_tr_id;
//!
//! #[tokio::main]
//! async fn main() {
//!     // Create an instance of EppClient, specifying the name of the registry as in
//!     // the config file
//!     let mut client = match EppClient::new("verisign").await {
//!         Ok(client) => client,
//!         Err(e) => panic!("Failed to create EppClient: {}",  e)
//!     };
//!
//!     // Make a EPP Hello call to the registry
//!     let greeting = client.hello().await.unwrap();
//!     println!("{:?}", greeting);
//!
//!     // Execute an EPP Command against the registry with distinct request and response objects
//!     let domain_check = EppDomainCheck::new(vec!["eppdev.com", "eppdev.net"], generate_client_tr_id(&client).as_str());
//!     let response = client.transact::<_, EppDomainCheckResponse>(&domain_check).await.unwrap();
//!     println!("{:?}", response);
//! }
//! ```

use futures::executor::block_on;
use std::{error::Error, fmt::Debug};
use std::time::SystemTime;
use std::sync::mpsc;
// use std::sync::Arc;

use crate::config::CONFIG;
use crate::connection::registry::{epp_connect, EppConnection};
use crate::error;
use crate::epp::request::{generate_client_tr_id, EppHello, EppLogin, EppLogout};
use crate::epp::response::{EppGreeting, EppCommandResponse, EppLoginResponse, EppLogoutResponse, EppCommandResponseError};
use crate::epp::xml::EppXml;

/// Connects to the registry and returns an logged-in instance of EppClient for further transactions
async fn connect(registry: &'static str) -> Result<EppClient, Box<dyn Error>> {
    let registry_creds = match CONFIG.registry(registry) {
        Some(creds) => creds,
        None => return Err(format!("missing credentials for {}", registry).into())
    };

    let (tx, rx) = mpsc::channel();

    tokio::spawn(async move {
        let stream = epp_connect(registry_creds).await.unwrap();
        let credentials = registry_creds.credentials();
        let ext_uris = registry_creds.ext_uris();

        let ext_uris = ext_uris.map(|uris| uris
                    .iter()
                    .map(|u| u.to_string())
                    .collect::<Vec<String>>());

        let connection = EppConnection::new(
            registry.to_string(),
            stream
        ).await.unwrap();

        let client = EppClient::build(connection, credentials, ext_uris).await.unwrap();

        tx.send(client).unwrap();
    });

    let client = rx.recv()?;

    Ok(client)
}

/// Instances of the EppClient type are used to transact with the registry.
/// Once initialized, the EppClient instance can serialize EPP requests to XML and send them
/// to the registry and deserialize the XML responses from the registry to local types
pub struct EppClient {
    credentials: (String, String),
    ext_uris: Option<Vec<String>>,
    connection: EppConnection,
    // pub client_tr_id_fn: Arc<dyn Fn(&EppClient) -> String + Send + Sync>,
}

/// A function to generate a simple client TRID. Should only be used for testing, library users
/// should generate a client TRID according to their own requirements
pub fn default_client_tr_id_fn(client: &EppClient) -> String {
    let timestamp = match SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
        Ok(time) => time,
        Err(e) => panic!("Error in client TRID gen function: {}", e)
    };
    format!("{}:{}", &client.username(), timestamp.as_secs())
}

impl EppClient {
    /// Fetches the username used in the registry connection
    pub fn username(&self) -> String {
        self.credentials.0.to_string()
    }

    // pub fn set_client_tr_id_fn<F>(&mut self, func: F)
    // where F: Fn(&EppClient) -> String + Send + Sync + 'static {
    //     self.client_tr_id_fn = Arc::new(func);
    // }

    /// Creates a new EppClient object and does an EPP Login to a given registry to become ready
    /// for subsequent transactions on this client instance
    pub async fn new(registry: &'static str) -> Result<EppClient, Box<dyn Error>> {
        connect(registry).await
    }

    /// Makes a login request to the registry and initializes an EppClient instance with it
    async fn build(connection: EppConnection, credentials: (String, String), ext_uris: Option<Vec<String>>) -> Result<EppClient, Box<dyn Error>> {
        let mut client = EppClient {
            connection,
            credentials,
            ext_uris,
            // client_tr_id_fn: Arc::new(default_client_tr_id_fn),
        };

        let client_tr_id = generate_client_tr_id(&client.credentials.0)?;
        let login_request = EppLogin::new(&client.credentials.0, &client.credentials.1, &client.ext_uris, client_tr_id.as_str());

        client.transact::<_, EppLoginResponse>(&login_request).await?;

        Ok(client)
    }

    /// Executes an EPP Hello call and returns the response as an `EppGreeting`
    pub async fn hello(&mut self) -> Result<EppGreeting, Box<dyn Error>> {
        let hello = EppHello::new();
        let hello_xml = hello.serialize()?;

        let response = self.connection.transact(&hello_xml).await?;

        Ok(EppGreeting::deserialize(&response)?)
    }

    /// Accepts an EPP request object to convert to a request to send to the registry. The response from the
    /// registry is deserialized to response type E and returned.
    pub async fn transact<T: EppXml + Debug, E: EppXml + Debug>(&mut self, request: &T) -> Result<E::Output, error::Error> {
        let epp_xml = request.serialize()?;

        let response = self.connection.transact(&epp_xml).await?;

        let status = EppCommandResponse::deserialize(&response)?;

        if status.data.result.code < 2000 {
            let response = E::deserialize(&response)?;
            Ok(response)
        } else {
            let epp_error = EppCommandResponseError::deserialize(&response)?;
            Err(error::Error::EppCommandError(epp_error))
        }
    }

    /// Accepts raw EPP XML and returns the raw EPP XML response to it.
    /// Not recommended for direct use but sometimes can be useful for debugging
    pub async fn transact_xml(&mut self, xml: &str) -> Result<String, Box<dyn Error>> {
        self.connection.transact(xml).await
    }

    /// Returns the greeting received on establishment of the connection in raw xml form
    pub fn xml_greeting(&self) -> String {
        String::from(&self.connection.greeting)
    }

    /// Returns the greeting received on establishment of the connection as an `EppGreeting`
    pub fn greeting(&self) -> Result<EppGreeting, error::Error> {
        EppGreeting::deserialize(&self.connection.greeting)
    }

    /// Sends the EPP Logout command to log out of the EPP session
    pub async fn logout(&mut self) -> Result<EppLogoutResponse, error::Error> {
        let client_tr_id = generate_client_tr_id(&self.credentials.0).unwrap();
        let epp_logout = EppLogout::new(client_tr_id.as_str());

        self.transact::<_, EppLogoutResponse>(&epp_logout).await
    }
}

impl Drop for EppClient {
    fn drop(&mut self) {
        block_on(self.logout());
    }
}