/// Url handler based on dbus
///
/// Note:
/// On linux, we use dbus to communicate multiple rustdesk process.
/// [Flutter]: handle uni links for linux
use dbus::blocking::Connection;
use dbus_crossroads::{Crossroads, IfaceBuilder};
use hbb_common::{log};
use std::{error::Error, fmt, time::Duration};
#[cfg(feature = "flutter")]
use std::collections::HashMap;

const DBUS_NAME: &str = "org.rustdesk.rustdesk";
const DBUS_PREFIX: &str = "/dbus";
const DBUS_METHOD_NEW_CONNECTION: &str = "NewConnection";
const DBUS_METHOD_NEW_CONNECTION_ID: &str = "id";
const DBUS_METHOD_RETURN: &str = "ret";
const DBUS_METHOD_RETURN_SUCCESS: &str = "ok";
const DBUS_TIMEOUT: Duration = Duration::from_secs(5);

#[derive(Debug)]
struct DbusError(String);

impl fmt::Display for DbusError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "RustDesk DBus Error: {}", self.0)
    }
}

impl Error for DbusError {}

/// invoke new connection from dbus
/// 
/// [Tips]:
/// How to test by CLI:
/// - use dbus-send command:
/// `dbus-send --session --print-reply --dest=org.rustdesk.rustdesk /dbus org.rustdesk.rustdesk.NewConnection string:'PEER_ID'`
pub fn invoke_new_connection(peer_id: String) -> Result<(), Box<dyn Error>> {
    let conn = Connection::new_session()?;
    let proxy = conn.with_proxy(DBUS_NAME, DBUS_PREFIX, DBUS_TIMEOUT);
    let (ret,): (String,) = proxy.method_call(DBUS_NAME, DBUS_METHOD_NEW_CONNECTION, (peer_id,))?;
    if ret != DBUS_METHOD_RETURN_SUCCESS {
        log::error!("error on call new connection to dbus server");
        return Err(Box::new(DbusError("not success".to_string())));
    }
    Ok(())
}

/// start dbus server
///
/// [Blocking]:
/// The function will block current thread to serve dbus server.
/// So it's suitable to spawn a new thread dedicated to dbus server.
pub fn start_dbus_server() -> Result<(), Box<dyn Error>> {
    let conn: Connection = Connection::new_session()?;
    let _ = conn.request_name(DBUS_NAME, false, true, false)?;
    let mut cr = Crossroads::new();
    let token = cr.register(DBUS_NAME, handle_client_message);
    cr.insert(DBUS_PREFIX, &[token], ());
    cr.serve(&conn)?;
    Ok(())
}

fn handle_client_message(builder: &mut IfaceBuilder<()>) {
    // register new connection dbus
    builder.method(
        DBUS_METHOD_NEW_CONNECTION,
        (DBUS_METHOD_NEW_CONNECTION_ID,),
        (DBUS_METHOD_RETURN,),
        move |_, _, (_peer_id,): (String,)| {
            #[cfg(feature = "flutter")]
            {
                use crate::flutter::{self, APP_TYPE_MAIN};

                if let Some(stream) = flutter::GLOBAL_EVENT_STREAM
                    .write()
                    .unwrap()
                    .get(APP_TYPE_MAIN)
                {
                    let data = HashMap::from([
                        ("name", "new_connection"),
                        ("peer_id", _peer_id.as_str())
                    ]);
                    if !stream.add(serde_json::ser::to_string(&data).unwrap_or("".to_string())) {
                        log::error!("failed to add dbus message to flutter global dbus stream.");
                    }
                } else {
                    log::error!("failed to find main event stream");
                }
            }
            return Ok((DBUS_METHOD_RETURN_SUCCESS.to_string(),));
        },
    );
}