mod broadcaster;
mod sender;

use std::fmt;
use std::sync::{Arc, Mutex};
use std::time::Duration;

use crate::model::Model;
use crate::ports::InputFn;
use crate::ports::{LineError, LineId};
use crate::simulation::Address;
use crate::time::{
    Action, ActionKey, KeyedOnceAction, KeyedPeriodicAction, OnceAction, PeriodicAction,
};
use crate::util::slot;

use broadcaster::ReplyIterator;
use broadcaster::{EventBroadcaster, QueryBroadcaster};
use sender::{InputSender, ReplierSender};

use super::ReplierFn;

/// An event source port.
///
/// The `EventSource` port is similar to an [`Output`](crate::ports::Output)
/// port in that it can send events to connected input ports. It is not meant,
/// however, to be instantiated as a member of a model, but rather as a
/// simulation monitoring endpoint instantiated during bench assembly.
pub struct EventSource<T: Clone + Send + 'static> {
    broadcaster: Arc<Mutex<EventBroadcaster<T>>>,
    next_line_id: u64,
}

impl<T: Clone + Send + 'static> EventSource<T> {
    /// Creates a new, disconnected `EventSource` port.
    pub fn new() -> Self {
        Self::default()
    }

    /// Adds a connection to an input port of the model specified by the
    /// address.
    ///
    /// The input port must be an asynchronous method of a model of type `M`
    /// taking as argument a value of type `T` plus, optionally, a scheduler
    /// reference.
    pub fn connect<M, F, S>(&mut self, input: F, address: impl Into<Address<M>>) -> LineId
    where
        M: Model,
        F: for<'a> InputFn<'a, M, T, S> + Clone,
        S: Send + 'static,
    {
        assert!(self.next_line_id != u64::MAX);
        let line_id = LineId(self.next_line_id);
        self.next_line_id += 1;
        let sender = Box::new(InputSender::new(input, address.into().0));
        self.broadcaster.lock().unwrap().add(sender, line_id);

        line_id
    }

    /// Removes the connection specified by the `LineId` parameter.
    ///
    /// It is a logic error to specify a line identifier from another
    /// [`EventSource`], [`QuerySource`], [`Output`](crate::ports::Output) or
    /// [`Requestor`](crate::ports::Requestor) instance and may result in the
    /// disconnection of an arbitrary endpoint.
    pub fn disconnect(&mut self, line_id: LineId) -> Result<(), LineError> {
        if self.broadcaster.lock().unwrap().remove(line_id) {
            Ok(())
        } else {
            Err(LineError {})
        }
    }

    /// Removes all connections.
    pub fn disconnect_all(&mut self) {
        self.broadcaster.lock().unwrap().clear();
    }

    /// Returns an action which, when processed, broadcasts an event to all
    /// connected input ports.
    ///
    /// Note that the action broadcasts the event to those models that are
    /// connected to the event source at the time the action is processed.
    pub fn event(&mut self, arg: T) -> Action {
        let fut = self.broadcaster.lock().unwrap().broadcast(arg);
        let fut = async {
            fut.await.unwrap();
        };

        Action::new(OnceAction::new(fut))
    }

    /// Returns a cancellable action and a cancellation key; when processed, the
    /// action broadcasts an event to all connected input ports.
    ///
    /// Note that the action broadcasts the event to those models that are
    /// connected to the event source at the time the action is processed.
    pub fn keyed_event(&mut self, arg: T) -> (Action, ActionKey) {
        let action_key = ActionKey::new();
        let fut = self.broadcaster.lock().unwrap().broadcast(arg);

        let action = Action::new(KeyedOnceAction::new(
            // Cancellation is ignored once the action is already spawned on the
            // executor. This means the action cannot be cancelled while the
            // simulation is running, but since an event source is meant to be
            // used outside the simulator, this shouldn't be an issue in
            // practice.
            |_| async {
                fut.await.unwrap();
            },
            action_key.clone(),
        ));

        (action, action_key)
    }

    /// Returns a periodically recurring action which, when processed,
    /// broadcasts an event to all connected input ports.
    ///
    /// Note that the action broadcasts the event to those models that are
    /// connected to the event source at the time the action is processed.
    pub fn periodic_event(&mut self, period: Duration, arg: T) -> Action {
        let broadcaster = self.broadcaster.clone();

        Action::new(PeriodicAction::new(
            || async move {
                let fut = broadcaster.lock().unwrap().broadcast(arg);
                fut.await.unwrap();
            },
            period,
        ))
    }

    /// Returns a cancellable, periodically recurring action and a cancellation
    /// key; when processed, the action broadcasts an event to all connected
    /// input ports.
    ///
    /// Note that the action broadcasts the event to those models that are
    /// connected to the event source at the time the action is processed.
    pub fn keyed_periodic_event(&mut self, period: Duration, arg: T) -> (Action, ActionKey) {
        let action_key = ActionKey::new();
        let broadcaster = self.broadcaster.clone();

        let action = Action::new(KeyedPeriodicAction::new(
            // Cancellation is ignored once the action is already spawned on the
            // executor. This means the action cannot be cancelled while the
            // simulation is running, but since an event source is meant to be
            // used outside the simulator, this shouldn't be an issue in
            // practice.
            |_| async move {
                let fut = broadcaster.lock().unwrap().broadcast(arg);
                fut.await.unwrap();
            },
            period,
            action_key.clone(),
        ));

        (action, action_key)
    }
}

impl<T: Clone + Send + 'static> Default for EventSource<T> {
    fn default() -> Self {
        Self {
            broadcaster: Arc::new(Mutex::new(EventBroadcaster::default())),
            next_line_id: 0,
        }
    }
}

impl<T: Clone + Send + 'static> fmt::Debug for EventSource<T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(
            f,
            "Event source ({} connected ports)",
            self.broadcaster.lock().unwrap().len()
        )
    }
}

/// A request source port.
///
/// The `QuerySource` port is similar to an
/// [`Requestor`](crate::ports::Requestor) port in that it can send events to
/// connected input ports. It is not meant, however, to be instantiated as a
/// member of a model, but rather as a simulation monitoring endpoint
/// instantiated during bench assembly.
pub struct QuerySource<T: Clone + Send + 'static, R: Send + 'static> {
    broadcaster: Arc<Mutex<QueryBroadcaster<T, R>>>,
    next_line_id: u64,
}

impl<T: Clone + Send + 'static, R: Send + 'static> QuerySource<T, R> {
    /// Creates a new, disconnected `EventSource` port.
    pub fn new() -> Self {
        Self::default()
    }

    /// Adds a connection to a replier port of the model specified by the
    /// address.
    ///
    /// The replier port must be an asynchronous method of a model of type `M`
    /// returning a value of type `R` and taking as argument a value of type `T`
    /// plus, optionally, a scheduler reference.
    pub fn connect<M, F, S>(&mut self, replier: F, address: impl Into<Address<M>>) -> LineId
    where
        M: Model,
        F: for<'a> ReplierFn<'a, M, T, R, S> + Clone,
        S: Send + 'static,
    {
        assert!(self.next_line_id != u64::MAX);
        let line_id = LineId(self.next_line_id);
        self.next_line_id += 1;
        let sender = Box::new(ReplierSender::new(replier, address.into().0));
        self.broadcaster.lock().unwrap().add(sender, line_id);

        line_id
    }

    /// Removes the connection specified by the `LineId` parameter.
    ///
    /// It is a logic error to specify a line identifier from another
    /// [`QuerySource`], [`EventSource`], [`Output`](crate::ports::Output) or
    /// [`Requestor`](crate::ports::Requestor) instance and may result in the
    /// disconnection of an arbitrary endpoint.
    pub fn disconnect(&mut self, line_id: LineId) -> Result<(), LineError> {
        if self.broadcaster.lock().unwrap().remove(line_id) {
            Ok(())
        } else {
            Err(LineError {})
        }
    }

    /// Removes all connections.
    pub fn disconnect_all(&mut self) {
        self.broadcaster.lock().unwrap().clear();
    }

    /// Returns an action which, when processed, broadcasts a query to all
    /// connected replier ports.
    ///
    /// Note that the action broadcasts the query to those models that are
    /// connected to the query source at the time the action is processed.
    pub fn query(&mut self, arg: T) -> (Action, ReplyReceiver<R>) {
        let (writer, reader) = slot::slot();
        let fut = self.broadcaster.lock().unwrap().broadcast(arg);
        let fut = async move {
            let replies = fut.await.unwrap();
            let _ = writer.write(replies);
        };

        let action = Action::new(OnceAction::new(fut));

        (action, ReplyReceiver::<R>(reader))
    }
}

impl<T: Clone + Send + 'static, R: Send + 'static> Default for QuerySource<T, R> {
    fn default() -> Self {
        Self {
            broadcaster: Arc::new(Mutex::new(QueryBroadcaster::default())),
            next_line_id: 0,
        }
    }
}

impl<T: Clone + Send + 'static, R: Send + 'static> fmt::Debug for QuerySource<T, R> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(
            f,
            "Query source ({} connected ports)",
            self.broadcaster.lock().unwrap().len()
        )
    }
}

/// A receiver for all replies collected from a single query broadcast.
pub struct ReplyReceiver<R>(slot::SlotReader<ReplyIterator<R>>);

impl<R> ReplyReceiver<R> {
    /// Returns all replies to a query.
    ///
    /// Returns `None` if the replies are not yet available or if they were
    /// already taken in a previous call to `take`.
    pub fn take(&mut self) -> Option<impl Iterator<Item = R>> {
        self.0.try_read().ok()
    }
}

impl<R> fmt::Debug for ReplyReceiver<R> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Replies")
    }
}