path: root/src/ls_client.rs

use crate::client_listener::ClientListener;
use crate::client_message_listener::ClientMessageListener;
use crate::connection_details::ConnectionDetails;
use crate::connection_options::ConnectionOptions;
use crate::error::IllegalStateException;
use crate::item_update::ItemUpdate;
use crate::subscription::{Snapshot, Subscription, SubscriptionMode};
use crate::util::*;

use cookie::Cookie;
use futures_util::{SinkExt, StreamExt};
use std::collections::HashMap;
use std::error::Error;
use std::fmt::{self, Debug, Formatter};
use std::sync::Arc;
use tokio::sync::Notify;
use tokio_tungstenite::{
    connect_async,
    tungstenite::{
        http::{HeaderName, HeaderValue, Request},
        Message,
    },
};
use tracing::{debug, error, info, instrument, trace, warn, Level};
use url::Url;

/// Represents the current status of the `LightstreamerClient`.
pub enum ClientStatus {
    Connecting,
    Connected(ConnectionType),
    Stalled,
    Disconnected(DisconnectionType),
}

pub enum ConnectionType {
    HttpPolling,
    HttpStreaming,
    StreamSensing,
    WsPolling,
    WsStreaming,
}

pub enum DisconnectionType {
    WillRetry,
    TryingRecovery,
}

pub enum LogType {
    TracingLogs,
    StdLogs,
}

/// Facade class for the management of the communication to Lightstreamer Server. Used to provide
/// configuration settings, event handlers, operations for the control of the connection lifecycle,
/// Subscription handling and to send messages.
///
/// An instance of `LightstreamerClient` handles the communication with Lightstreamer Server on a
/// specified endpoint. Hence, it hosts one "Session"; or, more precisely, a sequence of Sessions,
/// since any Session may fail and be recovered, or it can be interrupted on purpose. So, normally,
/// a single instance of `LightstreamerClient` is needed.
///
/// However, multiple instances of `LightstreamerClient` can be used, toward the same or multiple
/// endpoints.
///
/// You can listen to the events generated by a session by registering an event listener, such as
/// `ClientListener` or `SubscriptionListener`. These listeners allow you to handle various events,
/// such as session creation, connection status, subscription updates, and server messages. However,
/// you should be aware that the event notifications are dispatched by a single thread, the so-called
/// event thread. This means that if the operations of a listener are slow or blocking, they will
/// delay the processing of the other listeners and affect the performance of your application.
/// Therefore, you should delegate any slow or blocking operations to a dedicated thread, and keep
/// the listener methods as fast and simple as possible. Note that even if you create multiple
/// instances of `LightstreamerClient`, they will all use a single event thread, that is shared
/// among them.
///
/// # Parameters
///
/// * `server_address`: the address of the Lightstreamer Server to which this `LightstreamerClient`
///   will connect to. It is possible to specify it later by using `None` here. See
///   `ConnectionDetails.setServerAddress()` for details.
/// * `adapter_set`: the name of the Adapter Set mounted on Lightstreamer Server to be used to handle
///   all requests in the Session associated with this `LightstreamerClient`. It is possible not to
///   specify it at all or to specify it later by using `None` here. See `ConnectionDetails.setAdapterSet()`
///   for details.
///
/// # Raises
///
/// * `IllegalArgumentException`: if a not valid address is passed. See `ConnectionDetails.setServerAddress()`
///   for details.
pub struct LightstreamerClient {
    /// The address of the Lightstreamer Server to which this `LightstreamerClient` will connect.
    server_address: Option<String>,
    /// The name of the Adapter Set mounted on Lightstreamer Server to be used to handle all
    /// requests in the Session associated with this `LightstreamerClient`.
    adapter_set: Option<String>,
    /// Data object that contains the details needed to open a connection to a Lightstreamer Server.
    /// This instance is set up by the `LightstreamerClient` object at its own creation. Properties
    /// of this object can be overwritten by values received from a Lightstreamer Server.
    pub connection_details: ConnectionDetails,
    /// Data object that contains options and policies for the connection to the server. This instance
    /// is set up by the `LightstreamerClient` object at its own creation. Properties of this object
    /// can be overwritten by values received from a Lightstreamer Server.
    pub connection_options: ConnectionOptions,
    /// A list of listeners that will receive events from the `LightstreamerClient` instance.
    listeners: Vec<Box<dyn ClientListener>>,
    /// A list containing all the `Subscription` instances that are currently "active" on this
    /// `LightstreamerClient`.
    subscriptions: Vec<Subscription>,
    /// The current status of the client.
    status: ClientStatus,
    /// Logging Type to be used
    logging: LogType,
}

impl Debug for LightstreamerClient {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        f.debug_struct("LightstreamerClient")
            .field("server_address", &self.server_address)
            .field("adapter_set", &self.adapter_set)
            .field("connection_details", &self.connection_details)
            .field("connection_options", &self.connection_options)
            .field("listeners", &self.listeners)
            .field("subscriptions", &self.subscriptions)
            .finish()
    }
}

impl LightstreamerClient {
    /// A constant string representing the name of the library.
    pub const LIB_NAME: &'static str = "rust_client";

    /// A constant string representing the version of the library.
    pub const LIB_VERSION: &'static str = "0.1.0";

    //
    // Constants for WebSocket connection.
    //
    pub const SEC_WEBSOCKET_KEY: &'static str = "PNDUibe9ex7PnsrLbt0N4w==";
    pub const SEC_WEBSOCKET_PROTOCOL: &'static str = "TLCP-2.4.0.lightstreamer.com";
    pub const SEC_WEBSOCKET_VERSION: &'static str = "13";
    pub const SEC_WEBSOCKET_UPGRADE: &'static str = "websocket";

    /// A constant string representing the version of the TLCP protocol used by the library.
    pub const TLCP_VERSION: &'static str = "TLCP-2.4.0";

    /// Static method that can be used to share cookies between connections to the Server (performed by
    /// this library) and connections to other sites that are performed by the application. With this
    /// method, cookies received by the application can be added (or replaced if already present) to
    /// the cookie set used by the library to access the Server. Obviously, only cookies whose domain
    /// is compatible with the Server domain will be used internally.
    ///
    /// This method should be invoked before calling the `LightstreamerClient.connect()` method.
    /// However it can be invoked at any time; it will affect the internal cookie set immediately
    /// and the sending of cookies on the next HTTP request or WebSocket establishment.
    ///
    /// # Parameters
    ///
    /// * `uri`: the URI from which the supplied cookies were received. It cannot be `None`.
    /// * `cookies`: an instance of `http.cookies.SimpleCookie`.
    ///
    /// See also `getCookies()`
    pub fn add_cookies(_uri: &str, _cookies: &Cookie) {
        // Implementation for add_cookies
        unimplemented!("Implement mechanism to add cookies to LightstreamerClient");
    }

    /// Adds a listener that will receive events from the `LightstreamerClient` instance.
    ///
    /// The same listener can be added to several different `LightstreamerClient` instances.
    ///
    /// A listener can be added at any time. A call to add a listener already present will be ignored.
    ///
    /// # Parameters
    ///
    /// * `listener`: An object that will receive the events as documented in the `ClientListener`
    ///   interface.
    ///
    /// See also `removeListener()`
    pub fn add_listener(&mut self, listener: Box<dyn ClientListener>) {
        self.listeners.push(listener);
    }

    /// Operation method that requests to open a Session against the configured Lightstreamer Server.
    ///
    /// When `connect()` is called, unless a single transport was forced through `ConnectionOptions.setForcedTransport()`,
    /// the so called "Stream-Sense" mechanism is started: if the client does not receive any answer
    /// for some seconds from the streaming connection, then it will automatically open a polling
    /// connection.
    ///
    /// A polling connection may also be opened if the environment is not suitable for a streaming
    /// connection.
    ///
    /// Note that as "polling connection" we mean a loop of polling requests, each of which requires
    /// opening a synchronous (i.e. not streaming) connection to Lightstreamer Server.
    ///
    /// Note that the request to connect is accomplished by the client in a separate thread; this
    /// means that an invocation to `getStatus()` right after `connect()` might not reflect the change
    /// yet.
    ///
    /// When the request to connect is finally being executed, if the current status of the client
    /// is not `DISCONNECTED`, then nothing will be done.
    ///
    /// # Raises
    ///
    /// * `IllegalStateException`: if no server address was configured.
    ///
    /// See also `getStatus()`
    ///
    /// See also `disconnect()`
    ///
    /// See also `ClientListener.onStatusChange()`
    ///
    /// See also `ConnectionDetails.setServerAddress()`
    #[instrument]
    pub async fn connect(&mut self, shutdown_signal: Arc<Notify>) -> Result<(), Box<dyn Error>> {
        // Check if the server address is configured.
        if self.server_address.is_none() {
            return Err(Box::new(IllegalStateException::new(
                "No server address was configured.",
            )));
        }
        //
        // Only WebSocket streaming transport is currently supported.
        //
        let forced_transport = self.connection_options.get_forced_transport();
        if forced_transport.is_none()
            || *forced_transport.unwrap() /* unwrap() is safe here */ != Transport::WsStreaming
        {
            return Err(Box::new(IllegalStateException::new(
                "Only WebSocket streaming transport is currently supported.",
            )));
        }
        //
        // Convert the HTTP URL to a WebSocket URL.
        //
        let http_url = self.connection_details.get_server_address().unwrap(); // unwrap() is safe here.
        let mut url = Url::parse(&http_url)
            .expect("Failed to parse server address URL from connection details.");
        match url.scheme() {
            "http" => url
                .set_scheme("ws")
                .expect("Failed to set scheme to ws for WebSocket URL."),
            "https" => url
                .set_scheme("wss")
                .expect("Failed to set scheme to wss for WebSocket URL."),
            invalid_scheme => {
                return Err(Box::new(IllegalStateException::new(&format!(
                    "Unsupported scheme '{}' found when converting HTTP URL to WebSocket URL.",
                    invalid_scheme
                ))));
            }
        }
        let ws_url = url.as_str();

        // Build the WebSocket request with the necessary headers.
        let request = Request::builder()
            .uri(ws_url)
            .header(
                HeaderName::from_static("connection"),
                HeaderValue::from_static("Upgrade"),
            )
            .header(
                HeaderName::from_static("host"),
                HeaderValue::from_str(url.host_str().unwrap_or("localhost")).map_err(|err| {
                    IllegalStateException::new(&format!(
                        "Invalid header value for header with name 'host': {}",
                        err
                    ))
                })?,
            )
            .header(
                HeaderName::from_static("sec-websocket-key"),
                HeaderValue::from_static(Self::SEC_WEBSOCKET_KEY),
            )
            .header(
                HeaderName::from_static("sec-websocket-protocol"),
                HeaderValue::from_static(Self::SEC_WEBSOCKET_PROTOCOL),
            )
            .header(
                HeaderName::from_static("sec-websocket-version"),
                HeaderValue::from_static(Self::SEC_WEBSOCKET_VERSION),
            )
            .header(
                HeaderName::from_static("upgrade"),
                HeaderValue::from_static(Self::SEC_WEBSOCKET_UPGRADE),
            )
            .body(())?;

        // Connect to the Lightstreamer server using WebSocket.
        let ws_stream = match connect_async(request).await {
            Ok((ws_stream, response)) => {
                if let Some(server_header) = response.headers().get("server") {
                    self.make_log(
                        Level::INFO,
                        &format!(
                            "Connected to Lightstreamer server: {}",
                            server_header.to_str().unwrap_or("")
                        ),
                    );
                } else {
                    self.make_log(Level::INFO, "Connected to Lightstreamer server");
                }
                ws_stream
            }
            Err(err) => {
                return Err(Box::new(std::io::Error::new(
                    std::io::ErrorKind::ConnectionRefused,
                    format!(
                        "Failed to connect to Lightstreamer server with WebSocket: {}",
                        err
                    ),
                )));
            }
        };

        // Split the WebSocket stream into a write and a read stream.
        let (mut write_stream, mut read_stream) = ws_stream.split();

        //
        // Initiate communication with the server by sending a 'wsok' message.
        //
        write_stream.send(Message::Text("wsok".into())).await?;

        //
        // Start reading and processing messages from the server.
        //
        let mut request_id: usize = 0;
        let mut _session_id: Option<String> = None;
        let mut subscription_id: usize = 0;
        let mut subscription_item_updates: HashMap<usize, HashMap<usize, ItemUpdate>> =
            HashMap::new();
        loop {
            tokio::select! {
                message = read_stream.next() => {
                    match message {
                        Some(Ok(Message::Text(text))) => {
                            // Messages could include multiple submessages separated by /r/n.
                            // Split the message into submessages and process each one separately.
                            let submessages: Vec<&str> = text.split("\r\n")
                                .filter(|&line| !line.trim().is_empty()) // Filter out empty lines.
                                .collect();
                            for submessage in submessages {
                                let clean_text = clean_message(&submessage);
                                let submessage_fields: Vec<&str> = clean_text.split(",").collect();
                                match *submessage_fields.first().unwrap_or(&"") {
                                    //
                                    // Errors from server.
                                    //
                                    "conerr" | "reqerr" => {
                                        self.make_log( Level::ERROR, &format!("Received connection error from Lightstreamer server: {}", clean_text) );
                                        break;
                                    },
                                    //
                                    // Session created successfully.
                                    //
                                    "conok" => {
                                        if let Some(session_id) = submessage_fields.get(1).as_deref() {
                                            self.make_log( Level::DEBUG, &format!("Session creation confirmed by server: {}", clean_text) );
                                            self.make_log( Level::DEBUG, &format!("Session created with ID: {:?}", session_id) );
                                            //
                                            // Subscribe to the desired items.
                                            //
                                            while let Some(subscription) = self.subscriptions.get(subscription_id) {
                                                //
                                                // Gather all the necessary subscription parameters.
                                                //
                                                request_id += 1;
                                                let ls_req_id = request_id.to_string();
                                                subscription_id += 1;
                                                let ls_sub_id = subscription_id.to_string();
                                                let ls_mode = subscription.get_mode().to_string();
                                                let ls_group = match subscription.get_item_group() {
                                                    Some(item_group) => item_group.to_string(),
                                                    None => match subscription.get_items() {
                                                        Some(items) => {
                                                            items.join(" ")
                                                        },
                                                        None => {
                                                            return Err(Box::new(std::io::Error::new(
                                                                std::io::ErrorKind::InvalidData,
                                                                "No item group or items found in subscription.",
                                                            )));
                                                        },
                                                    },
                                                };
                                                let ls_schema = match subscription.get_field_schema() {
                                                    Some(field_schema) => field_schema.to_string(),
                                                    None => match subscription.get_fields() {
                                                        Some(fields) => {
                                                            fields.join(" ")
                                                        },
                                                        None => {
                                                            return Err(Box::new(std::io::Error::new(
                                                                std::io::ErrorKind::InvalidData,
                                                                "No field schema or fields found in subscription.",
                                                            )));
                                                        },
                                                    },
                                                };
                                                let ls_data_adapter = match subscription.get_data_adapter() {
                                                    Some(data_adapter) => data_adapter.to_string(),
                                                    None => "".to_string(),
                                                };
                                                let ls_snapshot = subscription.get_requested_snapshot().unwrap_or_default().to_string();
                                                //
                                                // Prepare the subscription request.
                                                //
                                                let mut params: Vec<(&str, &str)> = vec![
                                                    ("LS_data_adapter", &ls_data_adapter),
                                                    ("LS_reqId", &ls_req_id),
                                                    ("LS_op", "add"),
                                                    ("LS_subId", &ls_sub_id),
                                                    ("LS_mode", &ls_mode),
                                                    ("LS_group", &ls_group),
                                                    ("LS_schema", &ls_schema),
                                                    ("LS_ack", "false"),
                                                ];
                                                // Remove the data adapter parameter if not specified.
                                                if ls_data_adapter == "" {
                                                    params.remove(0);
                                                }
                                                if ls_snapshot != "" {
                                                    params.push(("LS_snapshot", &ls_snapshot));
                                                }
                                                let encoded_params = serde_urlencoded::to_string(&params)?;
                                                write_stream
                                                    .send(Message::Text(format!("control\r\n{}", encoded_params)))
                                                    .await?;
                                                info!("Sent subscription request: '{}'", encoded_params);
                                            }
                                        } else {
                                            return Err(Box::new(std::io::Error::new(
                                                std::io::ErrorKind::InvalidData,
                                                "Session ID not found in 'conok' message from server",
                                            )));
                                        }
                                    },
                                    //
                                    // Notifications from server.
                                    //
                                    "conf" | "cons" | "clientip" | "servname" | "prog" | "sync" => {
                                        self.make_log( Level::INFO, &format!("Received notification from server: {}", clean_text) );
                                        // Don't do anything with these notifications for now.
                                    },
                                    "probe" => {
                                        self.make_log( Level::DEBUG, &format!("Received probe message from server: {}", clean_text ) );
                                    },
                                    "reqok" => {
                                        self.make_log( Level::DEBUG, &format!("Received reqok message from server: '{}'", clean_text ) );
                                    },
                                    //
                                    // Subscription confirmation from server.
                                    //
                                    "subok" => {
                                        self.make_log( Level::INFO, &format!("Subscription confirmed by server: '{}'", clean_text) );
                                    },
                                    //
                                    // Data updates from server.
                                    //
                                    "u" => {
                                        // Parse arguments from the received message.
                                        let arguments = clean_text.split(",").collect::<Vec<&str>>();
                                        //
                                        // Extract the subscription from the first argument.
                                        //
                                        let subscription_index = arguments.get(1).unwrap_or(&"").parse::<usize>().unwrap_or(0);
                                        let subscription = match self.get_subscriptions().get(subscription_index-1) {
                                            Some(subscription) => subscription,
                                            None => {
                                                self.make_log( Level::WARN, &format!("Subscription not found for index: {}", subscription_index) );
                                                continue;

                                            }
                                        };
                                        //
                                        // Extract the item from the second argument.
                                        //
                                        let item_index = arguments.get(2).unwrap_or(&"").parse::<usize>().unwrap_or(0);
                                        let item = match subscription.get_items() {
                                            Some(items) => items.get(item_index-1),
                                            None => {
                                                self.make_log( Level::WARN, &format!("No items found in subscription: {:?}", subscription) );
                                                continue;
                                            }
                                        };
                                        //
                                        // Determine if the update is a snapshot or real-time update based on the subscription parameters.
                                        //
                                        let is_snapshot = match subscription.get_requested_snapshot() {
                                            Some(ls_snapshot) => {
                                                match ls_snapshot {
                                                    Snapshot::No => false,
                                                    Snapshot::Yes => {
                                                        match subscription.get_mode() {
                                                            SubscriptionMode::Merge => {
                                                                if arguments.len() == 4 && arguments[3] == "$" {
                                                                    // EOS notification received
                                                                    true
                                                                } else {
                                                                    // If item doesn't exist in item_updates yet, the first update
                                                                    // is always a snapshot.
                                                                    if let Some(item_updates) = subscription_item_updates.get(&(subscription_index)) {
                                                                        if let Some(_) = item_updates.get(&(item_index)) {
                                                                            // Item update already exists in item_updates, so it's not a snapshot.
                                                                            false
                                                                        } else {
                                                                            // Item update doesn't exist in item_updates, so the first update is always a snapshot.
                                                                            true
                                                                        }
                                                                    } else {
                                                                        // Item updates not found for subscription, so the first update is always a snapshot.
                                                                        true
                                                                    }
                                                                }
                                                            },
                                                            SubscriptionMode::Distinct | SubscriptionMode::Command => {
                                                                if !subscription.is_subscribed() {
                                                                    true
                                                                } else {
                                                                    false
                                                                }
                                                            },
                                                            _ => false,
                                                        }
                                                    },
                                                    _ => false,
                                                }
                                            },
                                            None => false,
                                        };

                                        // Extract the field values from the third argument.
                                        let field_values: Vec<&str> = arguments.get(3).unwrap_or(&"").split('|').collect();

                                        //
                                        // Get fields from subscription and create a HashMap of field names and values.
                                        //
                                        let subscription_fields = subscription.get_fields();
                                        let mut field_map: HashMap<String, Option<String>> = subscription_fields
                                            .map(|fields| fields.iter().map(|field_name| (field_name.to_string(), None)).collect())
                                            .unwrap_or_default();

                                        let mut field_index = 0;
                                        for value in field_values {
                                            match value {
                                                "" => {
                                                    // An empty value means the field is unchanged compared to the previous update of the same field.
                                                    if let Some(field_name) = subscription_fields.and_then(|fields| fields.get(field_index)) {
                                                        field_map.insert(field_name.to_string(), None);
                                                    }
                                                    field_index += 1;
                                                }
                                                "#" | "$" => {
                                                    // A value corresponding to a hash sign "#" or dollar sign "$" means the field is null or empty.
                                                    if let Some(field_name) = subscription_fields.and_then(|fields| fields.get(field_index)) {
                                                        field_map.insert(field_name.to_string(), Some("".to_string()));
                                                    }
                                                    field_index += 1;
                                                }
                                                value if value.starts_with('^') => {
                                                    let command = value.chars().nth(1).unwrap_or(' ');
                                                    match command {
                                                        '0'..='9' => {
                                                            let count = value[1..].parse().unwrap_or(0);
                                                            for i in 0..count {
                                                                if let Some(field_name) = subscription_fields.and_then(|fields| fields.get(field_index + i)) {
                                                                    field_map.insert(field_name.to_string(), None);
                                                                }
                                                            }
                                                            field_index += count;
                                                        }
                                                        'P' | 'T' => {
                                                            let diff_value = serde_urlencoded::from_str(&value[2..]).unwrap_or_else(|_| value[2..].to_string());
                                                            if let Some(field_name) = subscription_fields.and_then(|fields| fields.get(field_index)) {
                                                                if let Some(prev_value) = field_map.get(field_name).and_then(|v| v.as_ref()) {
                                                                    let new_value = match command {
                                                                        'P' => {
                                                                            // Apply JSON Patch
                                                                            let patch: serde_json::Value = serde_json::from_str(&diff_value).unwrap_or(serde_json::Value::Null);
                                                                            let mut prev_json: serde_json::Value = serde_json::from_str(prev_value).unwrap_or(serde_json::Value::Null);
                                                                            let patch_operations: Vec<json_patch::PatchOperation> = serde_json::from_value(patch).unwrap_or_default();
                                                                            let _ = json_patch::patch(&mut prev_json, &patch_operations);
                                                                            prev_json.to_string()
                                                                        }
                                                                        'T' => {
                                                                            // Apply TLCP-diff
                                                                            //tlcp_diff::apply_diff(prev_value, &diff_value).unwrap_or_else(|_| prev_value.to_string())
                                                                            unimplemented!("Implement TLCP-diff");
                                                                        }
                                                                        _ => unreachable!(),
                                                                    };
                                                                    field_map.insert(field_name.to_string(), Some(new_value.to_string()));
                                                                }
                                                            }
                                                            field_index += 1;
                                                        }
                                                        _ => {
                                                            let decoded_value = serde_urlencoded::from_str(value).unwrap_or_else(|_| value.to_string());
                                                            if let Some(field_name) = subscription_fields.and_then(|fields| fields.get(field_index)) {
                                                                field_map.insert(field_name.to_string(), Some(decoded_value));
                                                            }
                                                            field_index += 1;
                                                        }
                                                    }
                                                }
                                                _ => {
                                                    let decoded_value = serde_urlencoded::from_str(value).unwrap_or_else(|_| value.to_string());
                                                    if let Some(field_name) = subscription_fields.and_then(|fields| fields.get(field_index)) {
                                                        field_map.insert(field_name.to_string(), Some(decoded_value));
                                                    }
                                                    field_index += 1;
                                                }
                                            }
                                        }

                                        // Store only item_update's changed fields.
                                        let changed_fields: HashMap<String, String> = field_map.iter()
                                            .filter_map(|(k, v)| {
                                                if let Some(v) = v {
                                                    Some((k.clone(), v.clone()))
                                                } else {
                                                    None
                                                }
                                            })
                                            .collect();

                                        //
                                        // Take the proper item_update from item_updates and update it with changed fields.
                                        // If the item_update doesn't exist yet, create a new one.
                                        //
                                        let current_item_update: ItemUpdate;
                                        match subscription_item_updates.get_mut(&(subscription_index)) {
                                            Some(item_updates) => match item_updates.get_mut(&(item_index)) {
                                                Some(item_update) => {
                                                    //
                                                    // Iterate changed_fields and update existing item_update.fields assigning the new values.
                                                    //
                                                    for (field_name, new_value) in &changed_fields {
                                                        if item_update.fields.contains_key(field_name) {
                                                            item_update.fields.insert((*field_name).clone(), Some(new_value.clone()));
                                                        }
                                                    }
                                                    item_update.changed_fields = changed_fields;
                                                    item_update.is_snapshot = is_snapshot;
                                                    current_item_update = item_update.clone();
                                                },
                                                None => {
                                                    // Create a new item_update and add it to item_updates.
                                                    let item_update = ItemUpdate {
                                                        item_name: item.cloned(),
                                                        item_pos: item_index,
                                                        fields: field_map,
                                                        changed_fields: changed_fields,
                                                        is_snapshot: is_snapshot,
                                                    };
                                                    current_item_update = item_update.clone();
                                                    item_updates.insert(item_index, item_update);
                                                }
                                            },
                                            None => {
                                                // Create a new item_update and add it to item_updates.
                                                let item_update = ItemUpdate {
                                                    item_name: item.cloned(),
                                                    item_pos: item_index,
                                                    fields: field_map,
                                                    changed_fields: changed_fields,
                                                    is_snapshot: is_snapshot,
                                                };
                                                current_item_update = item_update.clone();
                                                let mut item_updates = HashMap::new();
                                                item_updates.insert(item_index, item_update);
                                                subscription_item_updates.insert(subscription_index, item_updates);
                                            }
                                        };

                                        // Get mutable subscription listeners directly.
                                        let subscription_listeners = subscription.get_listeners();

                                        // Iterate subscription listeners and call on_item_update for each listener.
                                        for listener in subscription_listeners {
                                            listener.on_item_update(&current_item_update);
                                        }
                                    }
                                    //
                                    // Connection confirmation from server.
                                    //
                                    "wsok" => {
                                        self.make_log( Level::INFO, &format!("Connection confirmed by server: '{}'", clean_text) );
                                        //
                                        // Request session creation.
                                        //
                                        let ls_adapter_set = match self.connection_details.get_adapter_set() {
                                            Some(adapter_set) => adapter_set,
                                            None => {
                                                return Err(Box::new(IllegalStateException::new(
                                                    "No adapter set found in connection details.",
                                                )));
                                            },
                                        };
                                        let ls_send_sync = self.connection_options.get_send_sync().to_string();
                                        let mut params: Vec<(&str, &str)> = vec![
                                            ("LS_adapter_set", &ls_adapter_set),
                                            ("LS_cid", "mgQkwtwdysogQz2BJ4Ji kOj2Bg"),
                                            ("LS_send_sync", &ls_send_sync),
                                        ];
                                        if let Some(user) = &self.connection_details.get_user() {
                                            params.push(("LS_user", user));
                                        }
                                        if let Some(password) = &self.connection_details.get_password() {
                                            params.push(("LS_password", password));
                                        }
                                        params.push(("LS_protocol", Self::TLCP_VERSION));
                                        let encoded_params = serde_urlencoded::to_string(&params)?;
                                        write_stream
                                            .send(Message::Text(format!("create_session\r\n{}\n", encoded_params)))
                                            .await?;
                                        self.make_log( Level::DEBUG, &format!("Sent create session request: '{}'", encoded_params) );
                                    },
                                    unexpected_message => {
                                        return Err(Box::new(std::io::Error::new(
                                            std::io::ErrorKind::InvalidData,
                                            format!(
                                                "Unexpected message received from server: '{:?}'",
                                                unexpected_message
                                            ),
                                        )));
                                    },
                                }
                            }
                        },
                        Some(Ok(non_text_message)) => {
                            return Err(Box::new(std::io::Error::new(
                                std::io::ErrorKind::InvalidData,
                                format!(
                                    "Unexpected non-text message from server: {:?}",
                                    non_text_message
                                ),
                            )));
                        },
                        Some(Err(err)) => {
                            return Err(Box::new(std::io::Error::new(
                                std::io::ErrorKind::InvalidData,
                                format!("Error reading message from server: {}", err),
                            )));
                        },
                        None => {
                            self.make_log( Level::DEBUG, "No more messages from server" );
                            break;
                        },
                    }
                },
                _ = shutdown_signal.notified() => {
                    self.make_log( Level::INFO, &format!("Received shutdown signal") );
                    break;
                },
            }
        }

        Ok(())
    }

    /// Operation method that requests to close the Session opened against the configured Lightstreamer
    /// Server (if any).
    ///
    /// When `disconnect()` is called, the "Stream-Sense" mechanism is stopped.
    ///
    /// Note that active `Subscription` instances, associated with this `LightstreamerClient` instance,
    /// are preserved to be re-subscribed to on future Sessions.
    ///
    /// Note that the request to disconnect is accomplished by the client in a separate thread; this
    /// means that an invocation to `getStatus()` right after `disconnect()` might not reflect the
    /// change yet.
    ///
    /// When the request to disconnect is finally being executed, if the status of the client is
    /// "DISCONNECTED", then nothing will be done.
    ///
    /// See also `connect()`
    #[instrument]
    pub async fn disconnect(&mut self) {
        // Implementation for disconnect
        self.make_log( Level::INFO, "Disconnecting from Lightstreamer server" );
    }

    /// Static inquiry method that can be used to share cookies between connections to the Server
    /// (performed by this library) and connections to other sites that are performed by the application.
    /// With this method, cookies received from the Server can be extracted for sending through other
    /// connections, according with the URI to be accessed.
    ///
    /// See `addCookies()` for clarifications on when cookies are directly stored by the library and
    /// when not.
    ///
    /// # Parameters
    ///
    /// * `uri`: the URI to which the cookies should be sent, or `None`.
    ///
    /// # Returns
    ///
    /// A list with the various cookies that can be sent in a HTTP request for the specified URI.
    /// If a `None` URI was supplied, all available non-expired cookies will be returned.
    pub fn get_cookies(_uri: Option<&str>) -> Cookie {
        // Implementation for get_cookies
        unimplemented!()
    }

    /// Returns a list containing the `ClientListener` instances that were added to this client.
    ///
    /// # Returns
    ///
    /// A list containing the listeners that were added to this client.
    ///
    /// See also `addListener()`
    pub fn get_listeners(&self) -> &Vec<Box<dyn ClientListener>> {
        &self.listeners
    }

    /// Inquiry method that gets the current client status and transport (when applicable).
    ///
    /// # Returns
    ///
    /// The current client status. It can be one of the following values:
    ///
    /// - `"CONNECTING"`: the client is waiting for a Server's response in order to establish a connection;
    /// - `"CONNECTED:STREAM-SENSING"`: the client has received a preliminary response from the server
    ///   and is currently verifying if a streaming connection is possible;
    /// - `"CONNECTED:WS-STREAMING"`: a streaming connection over WebSocket is active;
    /// - `"CONNECTED:HTTP-STREAMING"`: a streaming connection over HTTP is active;
    /// - `"CONNECTED:WS-POLLING"`: a polling connection over WebSocket is in progress;
    /// - `"CONNECTED:HTTP-POLLING"`: a polling connection over HTTP is in progress;
    /// - `"STALLED"`: the Server has not been sending data on an active streaming connection for
    ///   longer than a configured time;
    /// - `"DISCONNECTED:WILL-RETRY"`: no connection is currently active but one will be opened
    ///   (possibly after a timeout);
    /// - `"DISCONNECTED:TRYING-RECOVERY"`: no connection is currently active, but one will be opened
    ///   as soon as possible, as an attempt to recover the current session after a connection issue;
    /// - `"DISCONNECTED"`: no connection is currently active.
    ///
    /// See also `ClientListener.onStatusChange()`
    pub fn get_status(&self) -> &ClientStatus {
        &self.status
    }

    /// Inquiry method that returns a list containing all the `Subscription` instances that are
    /// currently "active" on this `LightstreamerClient`.
    ///
    /// Internal second-level `Subscription` are not included.
    ///
    /// # Returns
    ///
    /// A list, containing all the `Subscription` currently "active" on this `LightstreamerClient`.
    /// The list can be empty.
    ///
    /// See also `subscribe()`
    pub fn get_subscriptions(&self) -> &Vec<Subscription> {
        &self.subscriptions
    }

    /// Creates a new instance of `LightstreamerClient`.
    ///
    /// The constructor initializes the client with the server address and adapter set, if provided.
    /// It sets up the connection details and options for the client. If no server address or
    /// adapter set is specified, those properties on the client will be `None`. This allows
    /// for late configuration of these details before connecting to the Lightstreamer server.
    ///
    /// # Arguments
    /// * `server_address` - An optional reference to a string slice that represents the server
    ///   address to connect to. If `None`, the server address must be set later.
    /// * `adapter_set` - An optional reference to a string slice that specifies the adapter set name.
    ///   If `None`, the adapter set must be set later.
    ///
    /// # Returns
    /// A result containing the new `LightstreamerClient` instance if successful, or an
    /// `IllegalStateException` if the initialization fails due to invalid state conditions.
    ///
    /// # Panics
    /// Does not panic under normal circumstances. However, unexpected internal errors during
    /// the creation of internal components could cause panics, which should be considered when
    /// using this function in production code.
    ///
    /// # Example
    /// ```
    /// // Example usage of `new` to create a LightstreamerClient with specified server address and
    /// // adapter set.
    /// let server_address = Some("http://myserver.com");
    /// let adapter_set = Some("MY_ADAPTER_SET");
    /// let ls_client = LightstreamerClient::new(server_address, adapter_set);
    ///
    /// assert!(ls_client.is_ok());
    /// if let Ok(client) = ls_client {
    ///     assert_eq!(client.server_address.unwrap(), "http://myserver.com".to_string());
    ///     assert_eq!(client.adapter_set.unwrap(), "MY_ADAPTER_SET".to_string());
    /// }
    /// ```
    pub fn new(
        server_address: Option<&str>,
        adapter_set: Option<&str>,
        username: Option<&str>,
        password: Option<&str>,
    ) -> Result<LightstreamerClient, Box<dyn Error>> {
        let connection_details =
            ConnectionDetails::new(server_address, adapter_set, username, password)?;
        let connection_options = ConnectionOptions::default();

        Ok(LightstreamerClient {
            server_address: server_address.map(|s| s.to_string()),
            adapter_set: adapter_set.map(|s| s.to_string()),
            connection_details,
            connection_options,
            listeners: Vec::new(),
            subscriptions: Vec::new(),
            status: ClientStatus::Disconnected(DisconnectionType::WillRetry),
            logging: LogType::StdLogs,
        })
    }

    /// Removes a listener from the `LightstreamerClient` instance so that it will not receive
    /// events anymore.
    ///
    /// A listener can be removed at any time.
    ///
    /// # Parameters
    ///
    /// * `listener`: The listener to be removed.
    ///
    /// See also `addListener()`
    pub fn remove_listener(&mut self, _listener: Box<dyn ClientListener>) {
        unimplemented!("Implement mechanism to remove listener from LightstreamerClient");
        //self.listeners.remove(&listener);
    }

    /// Operation method that sends a message to the Server. The message is interpreted and handled
    /// by the Metadata Adapter associated to the current Session. This operation supports in-order
    /// guaranteed message delivery with automatic batching. In other words, messages are guaranteed
    /// to arrive exactly once and respecting the original order, whatever is the underlying transport
    /// (HTTP or WebSockets). Furthermore, high frequency messages are automatically batched, if
    /// necessary, to reduce network round trips.
    ///
    /// Upon subsequent calls to the method, the sequential management of the involved messages is
    /// guaranteed. The ordering is determined by the order in which the calls to `sendMessage` are
    /// issued.
    ///
    /// If a message, for any reason, doesn't reach the Server (this is possible with the HTTP transport),
    /// it will be resent; however, this may cause the subsequent messages to be delayed. For this
    /// reason, each message can specify a "delayTimeout", which is the longest time the message,
    /// after reaching the Server, can be kept waiting if one of more preceding messages haven't
    /// been received yet. If the "delayTimeout" expires, these preceding messages will be discarded;
    /// any discarded message will be notified to the listener through `ClientMessageListener.onDiscarded()`.
    /// Note that, because of the parallel transport of the messages, if a zero or very low timeout
    /// is set for a message and the previous message was sent immediately before, it is possible
    /// that the latter gets discarded even if no communication issues occur. The Server may also
    /// enforce its own timeout on missing messages, to prevent keeping the subsequent messages for
    /// long time.
    ///
    /// Sequence identifiers can also be associated with the messages. In this case, the sequential
    /// management is restricted to all subsets of messages with the same sequence identifier associated.
    ///
    /// Notifications of the operation outcome can be received by supplying a suitable listener. The
    /// supplied listener is guaranteed to be eventually invoked; listeners associated with a sequence
    /// are guaranteed to be invoked sequentially.
    ///
    /// The "UNORDERED_MESSAGES" sequence name has a special meaning. For such a sequence, immediate
    /// processing is guaranteed, while strict ordering and even sequentialization of the processing
    /// is not enforced. Likewise, strict ordering of the notifications is not enforced. However,
    /// messages that, for any reason, should fail to reach the Server whereas subsequent messages
    /// had succeeded, might still be discarded after a server-side timeout, in order to ensure that
    /// the listener eventually gets a notification.
    ///
    /// Moreover, if "UNORDERED_MESSAGES" is used and no listener is supplied, a "fire and forget"
    /// scenario is assumed. In this case, no checks on missing, duplicated or overtaken messages
    /// are performed at all, so as to optimize the processing and allow the highest possible throughput.
    ///
    /// Since a message is handled by the Metadata Adapter associated to the current connection, a
    /// message can be sent only if a connection is currently active. If the special `enqueueWhileDisconnected`
    /// flag is specified it is possible to call the method at any time and the client will take
    /// care of sending the message as soon as a connection is available, otherwise, if the current
    /// status is "DISCONNECTED*", the message will be abandoned and the `ClientMessageListener.onAbort()`
    /// event will be fired.
    ///
    /// Note that, in any case, as soon as the status switches again to "DISCONNECTED*", any message
    /// still pending is aborted, including messages that were queued with the `enqueueWhileDisconnected`
    /// flag set to `true`.
    ///
    /// Also note that forwarding of the message to the server is made in a separate thread, hence,
    /// if a message is sent while the connection is active, it could be aborted because of a subsequent
    /// disconnection. In the same way a message sent while the connection is not active might be
    /// sent because of a subsequent connection.
    ///
    /// # Parameters
    ///
    /// * `message`: a text message, whose interpretation is entirely demanded to the Metadata Adapter
    ///   associated to the current connection.
    /// * `sequence`: an alphanumeric identifier, used to identify a subset of messages to be managed
    ///   in sequence; underscore characters are also allowed. If the "UNORDERED_MESSAGES" identifier
    ///   is supplied, the message will be processed in the special way described above. The parameter
    ///   is optional; if set to `None`, "UNORDERED_MESSAGES" is used as the sequence name.
    /// * `delay_timeout`: a timeout, expressed in milliseconds. If higher than the Server configured
    ///   timeout on missing messages, the latter will be used instead. The parameter is optional; if
    ///   a negative value is supplied, the Server configured timeout on missing messages will be applied.
    ///   This timeout is ignored for the special "UNORDERED_MESSAGES" sequence, although a server-side
    ///   timeout on missing messages still applies.
    /// * `listener`: an object suitable for receiving notifications about the processing outcome. The
    ///   parameter is optional; if not supplied, no notification will be available.
    /// * `enqueue_while_disconnected`: if this flag is set to `true`, and the client is in a disconnected
    ///   status when the provided message is handled, then the message is not aborted right away but
    ///   is queued waiting for a new session. Note that the message can still be aborted later when
    ///   a new session is established.
    pub fn send_message(
        &mut self,
        message: &str,
        sequence: Option<&str>,
        _delay_timeout: Option<u64>,
        listener: Option<Box<dyn ClientMessageListener>>,
        enqueue_while_disconnected: bool,
    ) {
        let _sequence = sequence.unwrap_or_else(|| "UNORDERED_MESSAGES");

        // Handle the message based on the current connection status
        match &self.status {
            ClientStatus::Connected(_connection_type) => {
                // Send the message to the server in a separate thread
                // ...
            }
            ClientStatus::Disconnected(_disconnection_type) => {
                if enqueue_while_disconnected {
                    // Enqueue the message to be sent when a connection is available
                    // ...
                } else {
                    // Abort the message and notify the listener
                    if let Some(listener) = listener {
                        listener.on_abort(message, false);
                    }
                }
            }
            _ => {
                // Enqueue the message to be sent when a connection is available
                // ...
            }
        }
        unimplemented!("Complete mechanism to send message to LightstreamerClient.");
    }

    /// Static method that permits to configure the logging system used by the library. The logging
    /// system must respect the `LoggerProvider` interface. A custom class can be used to wrap any
    /// third-party logging system.
    ///
    /// If no logging system is specified, all the generated log is discarded.
    ///
    /// The following categories are available to be consumed:
    ///
    /// - `lightstreamer.stream`: logs socket activity on Lightstreamer Server connections; at INFO
    ///   level, socket operations are logged; at DEBUG level, read/write data exchange is logged.
    /// - `lightstreamer.protocol`: logs requests to Lightstreamer Server and Server answers; at INFO
    ///   level, requests are logged; at DEBUG level, request details and events from the Server are logged.
    /// - `lightstreamer.session`: logs Server Session lifecycle events; at INFO level, lifecycle events
    ///   are logged; at DEBUG level, lifecycle event details are logged.
    /// - `lightstreamer.subscriptions`: logs subscription requests received by the clients and the related
    ///   updates; at WARN level, alert events from the Server are logged; at INFO level, subscriptions
    ///   and unsubscriptions are logged; at DEBUG level, requests batching and update details are logged.
    /// - `lightstreamer.actions`: logs settings / API calls.
    ///
    /// # Parameters
    ///
    /// * `provider`: A `LoggerProvider` instance that will be used to generate log messages by the
    ///   library classes.
    pub fn set_logger_provider() {
        unimplemented!("Implement mechanism to set logger provider for LightstreamerClient.");
    }
    /*
    pub fn set_logger_provider(provider: LoggerProvider) {
        // Implementation for set_logger_provider
    }
    */

    /// Provides a mean to control the way TLS certificates are evaluated, with the possibility to
    /// accept untrusted ones.
    ///
    /// May be called only once before creating any `LightstreamerClient` instance.
    ///
    /// # Parameters
    ///
    /// * `factory`: an instance of `ssl.SSLContext`
    ///
    /// # Raises
    ///
    /// * `IllegalArgumentException`: if the factory is `None`
    /// * `IllegalStateException`: if a factory is already installed
    pub fn set_trust_manager_factory() {
        unimplemented!("Implement mechanism to set trust manager factory for LightstreamerClient.");
    }
    /*
    pub fn set_trust_manager_factory(factory: Option<SslContext>) -> Result<(), IllegalArgumentException> {
        if factory.is_none() {
            return Err(IllegalArgumentException::new(
                "Factory cannot be None",
            ));
        }

        // Implementation for set_trust_manager_factory
        Ok(())
    }
    */

    /// Operation method that adds a `Subscription` to the list of "active" Subscriptions. The `Subscription`
    /// cannot already be in the "active" state.
    ///
    /// Active subscriptions are subscribed to through the server as soon as possible (i.e. as soon
    /// as there is a session available). Active `Subscription` are automatically persisted across different
    /// sessions as long as a related unsubscribe call is not issued.
    ///
    /// Subscriptions can be given to the `LightstreamerClient` at any time. Once done the `Subscription`
    /// immediately enters the "active" state.
    ///
    /// Once "active", a `Subscription` instance cannot be provided again to a `LightstreamerClient`
    /// unless it is first removed from the "active" state through a call to `unsubscribe()`.
    ///
    /// Also note that forwarding of the subscription to the server is made in a separate thread.
    ///
    /// A successful subscription to the server will be notified through a `SubscriptionListener.onSubscription()`
    /// event.
    ///
    /// # Parameters
    ///
    /// * `subscription`: A `Subscription` object, carrying all the information needed to process real-time
    ///   values.
    ///
    /// See also `unsubscribe()`
    pub fn subscribe(&mut self, subscription: Subscription) {
        self.subscriptions.push(subscription);
        // Implementation for subscribe
    }

    /// Operation method that removes a `Subscription` that is currently in the "active" state.
    ///
    /// By bringing back a `Subscription` to the "inactive" state, the unsubscription from all its
    /// items is requested to Lightstreamer Server.
    ///
    /// Subscription can be unsubscribed from at any time. Once done the `Subscription` immediately
    /// exits the "active" state.
    ///
    /// Note that forwarding of the unsubscription to the server is made in a separate thread.
    ///
    /// The unsubscription will be notified through a `SubscriptionListener.onUnsubscription()` event.
    ///
    /// # Parameters
    ///
    /// * `subscription`: An "active" `Subscription` object that was activated by this `LightstreamerClient`
    ///   instance.
    pub fn unsubscribe(&mut self, _subscription: Subscription) {
        unimplemented!("Implement mechanism to unsubscribe from LightstreamerClient.");
    }
    /*
    pub fn unsubscribe(&mut self, subscription: &Subscription) {
        if let Some(index) = self.subscriptions.iter().position(|s| s == subscription) {
            self.subscriptions.remove(index);
            // Implementation for unsubscribe
        }
    }
    */

    /// Method setting enum for the logging of this instance.
    ///
    /// Default logging type is StdLogs, corresponding to `stdout`
    ///
    /// `LightstreamerClient` has methods for logging that are compatible with the `Tracing` crate.
    /// Enabling logging for the `Tracing` crate requires implementation of a tracing subscriber
    /// and its configuration and formatting.
    ///
    /// # Parameters
    ///
    /// * `logging`: An enum declaring the logging type of this `LightstreamerClient` instance.
    pub fn set_logging_type(&mut self, logging: LogType) {
        self.logging = logging;
    }

    /// Method for logging messages
    ///
    /// Match case wraps log types. `loglevel` param ignored in StdLogs case, all output to stdout.
    ///
    /// # Parameters
    ///
    /// * `loglevel` Enum determining use of stdout or Tracing subscriber.
    pub fn make_log(&mut self, loglevel: Level, log: &str) {
        match self.logging {
            LogType::StdLogs => {
                println!("{}", log);
            }
            LogType::TracingLogs => match loglevel {
                Level::INFO => {
                    info!(log);
                }
                Level::WARN => {
                    warn!(log);
                }
                Level::ERROR => {
                    error!(log);
                }
                Level::TRACE => {
                    trace!(log);
                }
                Level::DEBUG => {
                    debug!(log);
                }
            },
        }
    }
}

/// The transport type to be used by the client.
/// - WS: the Stream-Sense algorithm is enabled as in the `None` case but the client will
///   only use WebSocket based connections. If a connection over WebSocket is not possible
///   because of the environment the client will not connect at all.
/// - HTTP: the Stream-Sense algorithm is enabled as in the `None` case but the client
///   will only use HTTP based connections. If a connection over HTTP is not possible because
///   of the environment the client will not connect at all.
/// - WS-STREAMING: the Stream-Sense algorithm is disabled and the client will only connect
///   on Streaming over WebSocket. If Streaming over WebSocket is not possible because of
///   the environment the client will not connect at all.
/// - HTTP-STREAMING: the Stream-Sense algorithm is disabled and the client will only
///   connect on Streaming over HTTP. If Streaming over HTTP is not possible because of the
///   browser/environment the client will not connect at all.
/// - WS-POLLING: the Stream-Sense algorithm is disabled and the client will only connect
///   on Polling over WebSocket. If Polling over WebSocket is not possible because of the
///   environment the client will not connect at all.
/// - HTTP-POLLING: the Stream-Sense algorithm is disabled and the client will only connect
///   on Polling over HTTP. If Polling over HTTP is not possible because of the environment
///   the client will not connect at all.
#[derive(Debug, PartialEq)]
pub enum Transport {
    Ws,
    Http,
    WsStreaming,
    HttpStreaming,
    WsPolling,
    HttpPolling,
}