mod address;
pub mod error;
mod parser;
mod refs;
mod state;
#[cfg(test)]
mod tests;

use log::trace;
use serde::{Deserialize, Serialize};
use std::{
    convert::Infallible,
    fmt,
    str::FromStr,
    sync::atomic::{AtomicU64, Ordering},
};
use tokio::sync::mpsc::Sender as MpscSender;

use crate::util;

pub use self::{
    address::Address,
    refs::{ClientRef, ClientRefMut, StableMutexGuard},
    state::{ClientState, ConnectionState, StateTransition, StateTransitionResult},
};

///////////////////////////////////////////////////////////////////////////////////////////////////

/// The [`INFO`](https://nats-io.github.io/docs/nats_protocol/nats-protocol.html#info) message sent by the server
#[derive(Clone, Debug, Default, Deserialize, PartialEq)]
pub struct Info {
    pub(crate) server_id: String,
    pub(crate) version: String,
    pub(crate) go: String,
    pub(crate) host: String,
    pub(crate) port: u16,
    pub(crate) max_payload: usize,
    #[serde(default)]
    pub(crate) proto: i32,
    pub(crate) client_id: Option<u64>,
    #[serde(default)]
    pub(crate) auth_required: bool,
    #[serde(default)]
    pub(crate) tls_required: bool,
    #[serde(default)]
    pub(crate) tls_verify: bool,
    #[serde(default)]
    pub(crate) connect_urls: Vec<Address>,
}

impl Info {
    /// Construct a new default `Info`
    pub(crate) fn new() -> Self {
        Self::default()
    }

    /// The unique identifier of the NATS server
    pub fn server_id(&self) -> &str {
        &self.server_id
    }

    /// The version of the NATS server
    pub fn version(&self) -> &str {
        &self.version
    }

    /// The version of golang the NATS server was built with
    pub fn go(&self) -> &str {
        &self.go
    }

    /// The IP address used to start the NATS server, by default this will be 0.0.0.0 and can be
    /// configured with -client_advertise host:port
    pub fn host(&self) -> &str {
        &self.host
    }

    /// The port number the NATS server is configured to listen on
    pub fn port(&self) -> u16 {
        self.port
    }

    /// Maximum payload size, in bytes, that the server will accept from the client.
    pub fn max_payload(&self) -> usize {
        self.max_payload
    }

    /// An integer indicating the protocol version of the server. The server version 1.2.0 sets
    /// this to 1 to indicate that it supports the "Echo" feature.
    pub fn proto(&self) -> i32 {
        self.proto
    }

    /// An optional unsigned integer (64 bits) representing the internal client identifier in the
    /// server. This can be used to filter client connections in monitoring, correlate with error
    /// logs, etc...
    pub fn client_id(&self) -> Option<u64> {
        self.client_id
    }

    /// If this is set, then the client should try to authenticate upon connect.
    pub fn auth_required(&self) -> bool {
        self.auth_required
    }

    /// If this is set, then the client must perform the TLS/1.2 handshake. Note, this used to be
    /// ssl_required and has been updated along with the protocol from SSL to TLS.
    pub fn tls_required(&self) -> bool {
        self.tls_required
    }

    /// If this is set, the client must provide a valid certificate during the TLS handshake.
    pub fn tls_verify(&self) -> bool {
        self.tls_verify
    }

    /// An optional list of server urls that a client can connect to.
    pub fn connect_urls(&self) -> &[Address] {
        &self.connect_urls
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// The methods of client authorization set in the [`Connect`](struct.Connect.html) message
#[derive(Clone, Debug, PartialEq, Serialize)]
#[serde(untagged)]
pub enum Authorization {
    /// Use the `auth_token` authorization method
    Token {
        #[serde(rename = "auth_token")]
        token: String,
    },
    /// Use the `user` and `pass` authorization method
    UsernamePassword {
        #[serde(rename = "user")]
        username: String,
        #[serde(rename = "pass")]
        password: String,
    },
}

impl Authorization {
    /// Create a `Authorization::token`
    pub fn token(token: String) -> Self {
        Authorization::Token { token }
    }

    /// Create a `Authorization::UsernamePassword`
    pub fn username_password(username: String, password: String) -> Self {
        Authorization::UsernamePassword { username, password }
    }
}

impl FromStr for Authorization {
    type Err = Infallible;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match util::split_after(s, util::USERNAME_PASSWORD_SEPARATOR) {
            (token, None) => Ok(Authorization::token(String::from(token))),
            (username, Some(password)) => Ok(Authorization::username_password(
                String::from(username),
                String::from(password),
            )),
        }
    }
}

impl fmt::Display for Authorization {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match &self {
            Authorization::Token { token } => write!(f, "{}", token)?,
            Authorization::UsernamePassword { username, password } => {
                write!(f, "{}:{}", username, password)?
            }
        }
        Ok(())
    }
}

/// The [`CONNECT`](https://nats-io.github.io/docs/nats_protocol/nats-protocol.html#connect) message sent by the client
#[derive(Clone, Debug, PartialEq, Serialize)]
pub struct Connect {
    verbose: bool,
    pedantic: bool,
    tls_required: bool,
    #[serde(flatten)]
    authorization: Option<Authorization>,
    name: Option<String>,
    #[serde(rename = "lang")]
    language: String,
    version: String,
    protocol: i32,
    echo: bool,
}

impl Connect {
    /// Construct a new default `Connect`
    pub fn new() -> Self {
        Self::default()
    }

    /// Return `true` if the connection is verbose.
    pub fn is_verbose(&self) -> bool {
        self.verbose
    }

    /// Turns on +OK protocol acknowledgements. [default = `false`]
    pub fn verbose(&mut self, verbose: bool) -> &mut Self {
        self.verbose = verbose;
        self
    }

    /// Return `true` if the connection is pedantic.
    pub fn is_pedantic(&self) -> bool {
        self.pedantic
    }

    /// Turns on additional strict format checking, e.g. for properly formed subjects [default =
    /// `false`]
    pub fn pedantic(&mut self, pedantic: bool) -> &mut Self {
        self.pedantic = pedantic;
        self
    }

    /// Return `true` if the connection requires TLS.
    pub fn is_tls_required(&self) -> bool {
        self.tls_required
    }

    /// Indicates whether the client requires an SSL connection. [default = `false`]
    pub fn tls_required(&mut self, tls_required: bool) -> &mut Self {
        self.tls_required = tls_required;
        self
    }

    /// Get the [`Authorization`](enum.Authorization.html)
    pub fn authorization(&self) -> Option<&Authorization> {
        self.authorization.as_ref()
    }

    /// Set the authorization to use a token
    pub fn token(&mut self, token: String) -> &mut Self {
        self.set_authorization(Some(Authorization::token(token)))
    }

    /// Set the authorization to use a username and password
    pub fn username_password(&mut self, username: String, password: String) -> &mut Self {
        self.set_authorization(Some(Authorization::username_password(username, password)))
    }

    /// Set the authorization
    pub fn set_authorization(&mut self, authorization: Option<Authorization>) -> &mut Self {
        self.authorization = authorization;
        self
    }

    /// Remove the authorization
    pub fn clear_authorization(&mut self) -> &mut Self {
        self.set_authorization(None)
    }

    /// Get the optional name of the client.
    pub fn get_name(&self) -> Option<&str> {
        self.name.as_deref()
    }

    /// Set the optional client name. [default = `None`]
    pub fn name(&mut self, name: String) -> &mut Self {
        self.name = Some(name);
        self
    }

    /// Remove the optional client name [default = `None`]
    pub fn clear_name(&mut self) -> &mut Self {
        self.name = None;
        self
    }

    /// The implementation language of the client. [always = `"rust"`]
    pub fn get_lang(&self) -> &str {
        &self.language
    }

    /// The version of the client. [always = `"<the crate version>"`]
    pub fn get_version(&self) -> &str {
        &self.version
    }

    /// Optional int. Sending 0 (or absent) indicates client supports original protocol. Sending 1
    /// indicates that the client supports dynamic reconfiguration of cluster topology changes by
    /// asynchronously receiving INFO messages with known servers it can reconnect to. [always =
    /// `1`]
    pub fn get_protocol(&self) -> i32 {
        self.protocol
    }

    /// Return `true` if echo is enabled on the connection.
    pub fn is_echo(&self) -> bool {
        self.echo
    }

    /// Optional boolean. If set to true, the server (version 1.2.0+) will send originating
    /// messages from this connection to its own subscriptions. Clients should set this to true
    /// only for server supporting this feature, which is when proto in the INFO protocol is set to
    /// at least 1 [default = `false`]
    pub fn echo(&mut self, echo: bool) -> &mut Self {
        self.echo = echo;
        self
    }
}

impl Default for Connect {
    fn default() -> Self {
        Self {
            verbose: false,
            pedantic: false,
            tls_required: false,
            authorization: None,
            name: None,
            language: String::from("rust"),
            version: String::from(util::CLIENT_VERSION),
            protocol: 1,
            echo: false,
        }
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// The [`-ERR`](https://nats-io.github.io/docs/nats_protocol/nats-protocol.html#okerr) messages sent from the server
#[derive(Clone, Debug, PartialEq)]
pub enum ProtocolError {
    /// Unknown protocol error
    UnknownProtocolOperation,
    /// Client attempted to connect to a route port instead of the client port
    AttemptedToConnectToRoutePort,
    /// Client failed to authenticate to the server with credentials specified in the CONNECT
    /// message
    AuthorizationViolation,
    /// Client took too long to authenticate to the server after establishing a connection
    /// (default 1 second)
    AuthorizationTimeout,
    /// Client specified an invalid protocol version in the CONNECT message
    InvalidClientProtocol,
    /// Message destination subject and reply subject length exceeded the maximum control line
    /// value specified by the max_control_line server option. The default is 1024 bytes.
    MaximumControlLineExceeded,
    /// Cannot parse the protocol message sent by the client
    ParserError,
    /// The server requires TLS and the client does not have TLS enabled.
    SecureConnectionTlsRequired,
    /// The server hasn't received a message from the client, including a PONG in too long.
    StaleConnection,
    /// This error is sent by the server when creating a new connection and the server has exceeded
    /// the maximum number of connections specified by the max_connections server option. The
    /// default is 64k.
    MaximumConnectionsExceeded,
    /// The server pending data size for the connection has reached the maximum size (default 10MB).
    SlowConsumer,
    /// Client attempted to publish a message with a payload size that exceeds the max_payload size
    /// configured on the server. This value is supplied to the client upon connection in the
    /// initial INFO message. The client is expected to do proper accounting of byte size to be
    /// sent to the server in order to handle this error synchronously.
    MaximumPayloadViolation,
    /// Client sent a malformed subject (e.g. sub foo. 90)
    InvalidSubject,
    /// The user specified in the CONNECT message does not have permission to subscribe to the
    /// subject.
    PermissionsViolationForSubscription(Subject),
    /// The user specified in the CONNECT message does not have permissions to publish to the
    /// subject.
    PermissionsViolationForPublish(Subject),
}

impl fmt::Display for ProtocolError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            ProtocolError::UnknownProtocolOperation => {
                write!(f, "{}", util::UNKNOWN_PROTOCOL_OPERATION)?
            }
            ProtocolError::AttemptedToConnectToRoutePort => {
                write!(f, "{}", util::ATTEMPTED_TO_CONNECT_TO_ROUTE_PORT)?
            }
            ProtocolError::AuthorizationViolation => {
                write!(f, "{}", util::AUTHORIZATION_VIOLATION)?
            }
            ProtocolError::AuthorizationTimeout => write!(f, "{}", util::AUTHORIZATION_TIMEOUT)?,
            ProtocolError::InvalidClientProtocol => write!(f, "{}", util::INVALID_CLIENT_PROTOCOL)?,
            ProtocolError::MaximumControlLineExceeded => {
                write!(f, "{}", util::MAXIMUM_CONTROL_LINE_EXCEEDED)?
            }
            ProtocolError::ParserError => write!(f, "{}", util::PARSER_ERROR)?,
            ProtocolError::SecureConnectionTlsRequired => {
                write!(f, "{}", util::SECURE_CONNECTION_TLS_REQUIRED)?
            }
            ProtocolError::StaleConnection => write!(f, "{}", util::STALE_CONNECTION)?,
            ProtocolError::MaximumConnectionsExceeded => {
                write!(f, "{}", util::MAXIMUM_CONNECTIONS_EXCEEDED)?
            }
            ProtocolError::SlowConsumer => write!(f, "{}", util::SLOW_CONSUMER)?,
            ProtocolError::MaximumPayloadViolation => {
                write!(f, "{}", util::MAXIMUM_PAYLOAD_VIOLATION)?
            }
            ProtocolError::InvalidSubject => write!(f, "{}", util::INVALID_SUBJECT)?,
            ProtocolError::PermissionsViolationForSubscription(subject) => write!(
                f,
                "{} {}",
                util::PERMISSIONS_VIOLATION_FOR_SUBSCRIPTION,
                subject
            )?,
            ProtocolError::PermissionsViolationForPublish(subject) => {
                write!(f, "{} {}", util::PERMISSIONS_VIOLATION_FOR_PUBLISH, subject)?
            }
        }
        Ok(())
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// A [subject](https://nats-io.github.io/docs/nats_protocol/nats-protocol.html#protocol-conventions) to publish or subscribe to
///
/// `Subject`s can be created by parsing a String or via a SubjectBuilder
///
/// # Example
///  ```
/// use rants::{ Subject, SubjectBuilder };
///
/// let subject = "foo.bar.*.>".parse::<Subject>();
/// assert!(subject.is_ok());
///
/// let subject = SubjectBuilder::new()
///   .add("foo")
///   .add("bar")
///   .add_wildcard()
///   .build_full_wildcard();
///
/// assert_eq!(format!("{}", subject), "foo.bar.*.>");
/// ```
#[derive(Clone, Debug, Eq, PartialEq, Hash)]
pub struct Subject {
    tokens: Vec<String>,
    full_wildcard: bool,
}

impl fmt::Display for Subject {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        // Is the whole subject a full wildcard
        if self.tokens.is_empty() {
            write!(f, ">")?;
            return Ok(());
        }
        write!(f, "{}", self.tokens.join("."))?;
        if self.full_wildcard {
            write!(f, ".>")?;
        }
        Ok(())
    }
}

#[derive(Default)]
pub struct SubjectBuilder {
    tokens: Vec<String>,
}

impl SubjectBuilder {
    /// Create a new `SubjectBuilder`
    pub fn new() -> Self {
        Self::default()
    }

    /// Add a component to the subject
    #[allow(clippy::should_implement_trait)]
    pub fn add(mut self, subject: impl Into<String>) -> Self {
        // Need to add some checks here to check for illegal characters
        self.tokens.push(subject.into());
        self
    }

    /// Add a wildcard to the subject
    pub fn add_wildcard(mut self) -> Self {
        self.tokens.push("*".to_string());
        self
    }

    /// Generate the subject
    pub fn build(self) -> Subject {
        let fwc = self.tokens.is_empty();
        Subject {
            tokens: self.tokens,
            full_wildcard: fwc,
        }
    }

    /// Generate the subject with a full wildcard ending
    pub fn build_full_wildcard(self) -> Subject {
        Subject {
            tokens: self.tokens,
            full_wildcard: true,
        }
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// The [`MSG`](https://nats-io.github.io/docs/nats_protocol/nats-protocol.html#msg) message sent by the server
#[derive(Debug, PartialEq)]
pub struct Msg {
    subject: Subject,
    sid: Sid,
    reply_to: Option<Subject>,
    payload: Vec<u8>,
}

impl Msg {
    pub(crate) fn new(
        subject: Subject,
        sid: Sid,
        reply_to: Option<Subject>,
        payload: Vec<u8>,
    ) -> Self {
        Self {
            subject,
            sid,
            reply_to,
            payload,
        }
    }

    /// Get the [`Subject`](struct.Subject.html)
    pub fn subject(&self) -> &Subject {
        &self.subject
    }

    /// Get the subscription id
    pub fn sid(&self) -> Sid {
        self.sid
    }

    /// Get the optional reply to [`Subject`](struct.Subject.html)
    pub fn reply_to(&self) -> Option<&Subject> {
        self.reply_to.as_ref()
    }

    /// Get the payload
    pub fn payload(&self) -> &[u8] {
        &self.payload
    }

    /// Take ownership of the payload
    pub fn into_payload(self) -> Vec<u8> {
        self.payload
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// The type used for subscription IDs
///
/// This is a unique identifier the client uses when routing messages from the server. A
/// subscription ID can be any ASCII string, but within this client library, we always use
/// the string representation of an atomically increasing `u64` counter.
pub type Sid = u64;
static SID: AtomicU64 = AtomicU64::new(0);

/// A subscription to receive messages from a particular [`Subject`](struct.Subject.html)
pub struct Subscription {
    subject: Subject,
    sid: Sid,
    queue_group: Option<String>,
    pub(crate) unsubscribe_after: Option<u64>,
    pub(crate) tx: MpscSender<Msg>,
}

impl Subscription {
    pub(crate) fn new(subject: Subject, queue_group: Option<String>, tx: MpscSender<Msg>) -> Self {
        Self {
            subject,
            sid: SID.fetch_add(1, Ordering::Relaxed),
            queue_group,
            unsubscribe_after: None,
            tx,
        }
    }

    /// The [`Subject`](struct.Subject.html) of the subscription
    pub fn subject(&self) -> &Subject {
        &self.subject
    }

    /// The unique subscription ID
    pub fn sid(&self) -> Sid {
        self.sid
    }

    /// The optional queue group of the subscription
    pub fn queue_group(&self) -> Option<&str> {
        self.queue_group.as_ref().map(String::as_ref)
    }

    /// If this is of type `Some`, it means the subscription will automatically unsubscribe
    /// after receiving the indicated number of messages
    pub fn unsubscribe_after(&self) -> Option<u64> {
        self.unsubscribe_after
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Representation of all possible server control lines. A control line is the first line of a
/// message
#[derive(Debug, PartialEq)]
pub enum ServerControl {
    Info(Info),
    Msg {
        subject: Subject,
        sid: Sid,
        reply_to: Option<Subject>,
        len: u64,
    },
    Ping,
    Pong,
    Ok,
    Err(ProtocolError),
}

/// Representation of all possible server messages. This is similar to `ServerControl` however it
/// contains a full message type
#[derive(Debug, PartialEq)]
pub enum ServerMessage {
    Info(Info),
    Msg(Msg),
    Ping,
    Pong,
    Ok,
    Err(ProtocolError),
}

impl From<ServerControl> for ServerMessage {
    fn from(control: ServerControl) -> Self {
        match control {
            ServerControl::Info(info) => ServerMessage::Info(info),
            // We should never try to directly convert a `ServerControl::Msg` to
            // `ServerMessage::Msg`. The reason is the `Msg` message has a payload and therefore
            // requires further parsing.
            ServerControl::Msg { .. } => unreachable!(),
            ServerControl::Ping => ServerMessage::Ping,
            ServerControl::Pong => ServerMessage::Pong,
            ServerControl::Ok => ServerMessage::Ok,
            ServerControl::Err(e) => ServerMessage::Err(e),
        }
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

pub enum ClientControl<'a> {
    Connect(&'a Connect),
    Pub(&'a Subject, Option<&'a Subject>, usize),
    Sub(&'a Subscription),
    Unsub(Sid, Option<u64>),
    Ping,
    Pong,
}

impl fmt::Display for ClientControl<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Connect(connect) => write!(
                f,
                "{} {}{}",
                util::CONNECT_OP_NAME,
                serde_json::to_string(connect).expect("to serialize Connect"),
                util::MESSAGE_TERMINATOR
            ),
            Self::Pub(subject, reply_to, len) => {
                if let Some(reply_to) = reply_to {
                    write!(
                        f,
                        "{} {} {} {}{}",
                        util::PUB_OP_NAME,
                        subject,
                        reply_to,
                        len,
                        util::MESSAGE_TERMINATOR
                    )
                } else {
                    write!(
                        f,
                        "{} {} {}{}",
                        util::PUB_OP_NAME,
                        subject,
                        len,
                        util::MESSAGE_TERMINATOR
                    )
                }
            }
            Self::Sub(subscription) => {
                if let Some(queue_group) = &subscription.queue_group {
                    write!(
                        f,
                        "{} {} {} {}{}",
                        util::SUB_OP_NAME,
                        subscription.subject(),
                        queue_group,
                        subscription.sid(),
                        util::MESSAGE_TERMINATOR
                    )
                } else {
                    write!(
                        f,
                        "{} {} {}{}",
                        util::SUB_OP_NAME,
                        subscription.subject(),
                        subscription.sid(),
                        util::MESSAGE_TERMINATOR
                    )
                }
            }
            Self::Unsub(sid, max_msgs) => {
                if let Some(max_msgs) = max_msgs {
                    write!(
                        f,
                        "{} {} {}{}",
                        util::UNSUB_OP_NAME,
                        sid,
                        max_msgs,
                        util::MESSAGE_TERMINATOR
                    )
                } else {
                    write!(
                        f,
                        "{} {}{}",
                        util::UNSUB_OP_NAME,
                        sid,
                        util::MESSAGE_TERMINATOR
                    )
                }
            }
            Self::Ping => write!(f, "{}{}", util::PING_OP_NAME, util::MESSAGE_TERMINATOR),
            Self::Pong => write!(f, "{}{}", util::PONG_OP_NAME, util::MESSAGE_TERMINATOR),
        }
    }
}

impl ClientControl<'_> {
    pub fn to_line(&self) -> String {
        let s = self.to_string();
        trace!("->> {:?}", s);
        s
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////