use std::sync::{Arc, Mutex, Condvar};
use std::sync::atomic::Ordering;
use crate::protocol::ComponentCreationError;

use crate::protocol::eval::ValueGroup;
use crate::ProtocolDescription;
use crate::runtime2::connector::{Branch, find_ports_in_value_group};
use crate::runtime2::global_store::ConnectorKey;
use crate::runtime2::inbox::MessageContents;
use crate::runtime2::port::{Port, PortKind};
use crate::runtime2::scheduler::ConnectorCtx;

use super::RuntimeInner;
use super::global_store::ConnectorId;
use super::port::{Channel, PortIdLocal};
use super::connector::{ConnectorPDL, ConnectorScheduling, RunDeltaState};
use super::inbox::Message;

/// Generic connector interface from the scheduler's point of view.
pub trait Connector {
    /// Handle a new message (preprocessed by the scheduler). You probably only
    /// want to handle `Data`, `Sync`, and `Solution` messages. The others are
    /// intended for the scheduler itself.
    fn handle_message(&mut self, message: MessageContents, ctx: &ConnectorCtx, delta_state: &mut RunDeltaState);

    /// Should run the connector's behaviour up until the next blocking point.
    fn run(&mut self, protocol_description: &ProtocolDescription, ctx: &ConnectorCtx, delta_state: &mut RunDeltaState) -> ConnectorScheduling;
}

type SyncDone = Arc<(Mutex<bool>, Condvar)>;
type JobQueue = Arc<Mutex<Vec<ApplicationJob>>>;

enum ApplicationJob {
    NewChannel((Port, Port)),
    NewConnector(ConnectorPDL),
}

/// The connector which an application can directly interface with. Once may set
/// up the next synchronous round, and retrieve the data afterwards.
pub struct ConnectorApplication {
    sync_done: SyncDone,
    job_queue: JobQueue,
}

impl ConnectorApplication {
    pub(crate) fn new(runtime: Arc<RuntimeInner>) -> (Self, ApplicationInterface) {
        let sync_done = Arc::new(( Mutex::new(false), Condvar::new() ));
        let job_queue = Arc::new(Mutex::new(Vec::with_capacity(32)));

        let connector = ConnectorApplication { sync_done: sync_done.clone(), job_queue: job_queue.clone() };
        let interface = ApplicationInterface::new(sync_done, job_queue, runtime);

        return (connector, interface);
    }
}

impl Connector for ConnectorApplication {
    fn handle_message(&mut self, message: MessageContents, ctx: &ConnectorCtx, delta_state: &mut RunDeltaState) {
        todo!("handling messages in ConnectorApplication (API for runtime)")
    }

    fn run(&mut self, protocol_description: &ProtocolDescription, ctx: &ConnectorCtx, delta_state: &mut RunDeltaState) -> ConnectorScheduling {
        let mut queue = self.job_queue.lock().unwrap();
        while let Some(job) = queue.pop() {
            match job {
                ApplicationJob::NewChannel((endpoint_a, endpoint_b)) => {
                    delta_state.new_ports.reserve(2);
                    delta_state.new_ports.push(endpoint_a);
                    delta_state.new_ports.push(endpoint_b);
                }
                ApplicationJob::NewConnector(connector) => {
                    delta_state.new_connectors.push(connector);
                }
            }
        }

        return ConnectorScheduling::NotNow;
    }
}

/// The interface to a `ApplicationConnector`. This allows setting up the
/// interactions the `ApplicationConnector` performs within a synchronous round.
pub struct ApplicationInterface {
    sync_done: SyncDone,
    job_queue: JobQueue,
    runtime: Arc<RuntimeInner>,
    connector_id: ConnectorId,
    owned_ports: Vec<PortIdLocal>,
}

impl ApplicationInterface {
    pub(crate) fn new(sync_done: SyncDone, job_queue: JobQueue, runtime: Arc<RuntimeInner>) -> Self {
        return Self{
            sync_done, job_queue, runtime,
            connector_id: ConnectorId::new_invalid(),
            owned_ports: Vec::new(),
        }
    }

    /// Creates a new channel.
    pub fn create_channel(&mut self) -> Channel {
        // TODO: Duplicated logic in scheduler
        let getter_id = self.runtime.global_store.connectors.port_counter.fetch_add(2, Ordering::SeqCst);
        let putter_id = PortIdLocal::new(getter_id + 1);
        let getter_id = PortIdLocal::new(getter_id);

        // Create ports and add a job such that they are transferred to the
        // API component. (note that we do not send a ping, this is only
        // necessary once we create a connector)
        let getter_port = Port{
            self_id: getter_id,
            peer_id: putter_id,
            kind: PortKind::Getter,
            peer_connector: self.connector_id,
        };
        let putter_port = Port{
            self_id: putter_id,
            peer_id: getter_id,
            kind: PortKind::Putter,
            peer_connector: self.connector_id,
        };

        {
            let mut lock = self.job_queue.lock().unwrap();
            lock.push(ApplicationJob::NewChannel((getter_port, putter_port)));
        }

        // Add to owned ports for error checking while creating a connector
        self.owned_ports.reserve(2);
        self.owned_ports.push(putter_id);
        self.owned_ports.push(getter_id);

        return Channel{ putter_id, getter_id };
    }

    /// Creates a new connector. Note that it is not scheduled immediately, but
    /// depends on the `ApplicationConnector` to run, followed by the created
    /// connector being scheduled.
    // TODO: Optimize by yanking out scheduler logic for common use.
    pub fn create_connector(&mut self, module: &str, routine: &str, arguments: ValueGroup) -> Result<(), ComponentCreationError> {
        // Retrieve ports and make sure that we own the ones that are currently
        // specified. This is also checked by the scheduler, but that is done
        // asynchronously.
        let mut initial_ports = Vec::new();
        find_ports_in_value_group(&arguments, &mut initial_ports);
        for port_to_remove in &initial_ports {
            match self.owned_ports.iter().position(|v| v == port_to_remove) {
                Some(index_to_remove) => {
                    // We own the port, so continue
                    self.owned_ports.remove(index_to_remove);
                },
                None => {
                    // We don't own the port
                    return Err(ComponentCreationError::UnownedPort);
                }
            }
        }

        let state = self.runtime.protocol_description.new_component_v2(module.as_bytes(), routine.as_bytes(), arguments)?;
        let connector = ConnectorPDL::new(Branch::new_initial_branch(state), initial_ports);

        // Put on job queue
        {
            let mut queue = self.job_queue.lock().unwrap();
            queue.push(ApplicationJob::NewConnector(connector));
        }

        // Send ping message to wake up connector
        let connector = self.runtime.global_store.connectors.get_shared(self.connector_id);
        connector.inbox.insert_message(Message{
            sending_connector: ConnectorId::new_invalid(),
            receiving_port: PortIdLocal::new_invalid(),
            contents: MessageContents::Ping,
        });

        let should_wake_up = connector.sleeping
            .compare_exchange(true, false, Ordering::SeqCst, Ordering::Acquire)
            .is_ok();

        if should_wake_up {
            let key = unsafe{ ConnectorKey::from_id(self.connector_id) };
            self.runtime.global_store.connector_queue.push_back(key);
        }

        return Ok(());
    }

    /// Check if the next sync-round is finished.
    pub fn try_wait(&self) -> bool {
        let (is_done, _) = &*self.sync_done;
        let lock = is_done.lock().unwrap();
        return *lock;
    }

    /// Wait until the next sync-round is finished
    pub fn wait(&self) {
        let (is_done, condition) = &*self.sync_done;
        let lock = is_done.lock().unwrap();
        condition.wait_while(lock, |v| !*v); // wait while not done
    }

    /// Called by runtime to set associated connector's ID.
    pub(crate) fn set_connector_id(&mut self, id: ConnectorId) {
        self.connector_id = id;
    }
}