/// Called if the component is created by another component and the messages

    /// are being transferred between the two.

    fn adopt_message(&mut self, comp_ctx: &mut CompCtx, message: DataMessage);

    /// Called if the component receives a new message. The component is

    /// responsible for deciding where that messages goes.

    fn handle_message(&mut self, sched_ctx: &mut SchedulerCtx, comp_ctx: &mut CompCtx, message: Message);

    /// Called if the component's routine should be executed. The return value

    /// can be used to indicate when the routine should be run again.

    fn run(&mut self, sched_ctx: &mut SchedulerCtx, comp_ctx: &mut CompCtx) -> CompScheduling;

}

/// Representation of the generic operating mode of a component. Although not

/// every state may be used by every kind of (builtin) component, this allows

/// writing standard handlers for particular events in a component's lifetime.

#[derive(Debug, Copy, Clone, PartialEq, Eq)]

pub(crate) enum CompMode {

    NonSync, // not in sync mode

    Sync, // in sync mode, can interact with other components

    SyncEnd, // awaiting a solution, i.e. encountered the end of the sync block

    BlockedGet, // blocked because we need to receive a message on a particular port

    BlockedPut, // component is blocked because the port is blocked

    BlockedSelect, // waiting on message to complete the select statement

    StartExit, // temporary state: if encountered then we start the shutdown process.

    BusyExit, // temporary state: waiting for Acks for all the closed ports, potentially waiting for sync round to finish

    Exit, // exiting: shutdown process started, now waiting until the reference count drops to 0

}

impl CompMode {

    pub(crate) fn is_in_sync_block(&self) -> bool {

        use CompMode::*;

        match self {

            NonSync | StartExit | BusyExit | Exit => false,

        }

    }

    pub(crate) fn is_busy_exiting(&self) -> bool {

        use CompMode::*;

        match self {

            StartExit | BusyExit => true,

            Exit => false,

        }

    }

}

#[derive(Debug)]

pub(crate) enum ExitReason {

    Termination, // regular termination of component

    ErrorInSync,

    ErrorNonSync,

}

impl ExitReason {

    pub(crate) fn is_in_sync(&self) -> bool {

        use ExitReason::*;

        match self {

            Termination | ErrorNonSync => false,

            ErrorInSync => true,

        }

    }

    pub(crate) fn is_error(&self) -> bool {

            mode: CompMode::NonSync,

            mode_port: PortId::new_invalid(),

            mode_value: ValueGroup::default(),

            exit_reason: ExitReason::Termination,

        }

    }

    pub(crate) fn set_as_start_exit(&mut self, reason: ExitReason) {

        self.mode = CompMode::StartExit;

        self.exit_reason = reason;

    }

    pub(crate) fn set_as_blocked_get(&mut self, port: PortId) {

        self.mode = CompMode::BlockedGet;

        self.mode_port = port;

        debug_assert!(self.mode_value.values.is_empty());

    }

    pub(crate) fn is_blocked_on_get(&self, port: PortId) -> bool {

        return

            self.mode == CompMode::BlockedGet &&

            self.mode_port == port;

    }

        self.mode = CompMode::BlockedPut;

        self.mode_port = port;

        self.mode_value = value;

    }

        return

            self.mode == CompMode::BlockedPut &&

            self.mode_port == port;

    }

}

// TODO: Replace when implementing port sending. Should probably be incorporated

//  into CompCtx (and rename CompCtx into CompComms)

pub(crate) type InboxMain = Vec<Option<DataMessage>>;

pub(crate) type InboxMainRef = [Option<DataMessage>];

pub(crate) type InboxBackup = Vec<DataMessage>;

/// Creates a new component based on its definition. Meaning that if it is a

/// user-defined component then we set up the PDL code state. Otherwise we

/// construct a custom component. This does NOT take care of port and message

/// management.

pub(crate) fn create_component(

    protocol: &ProtocolDescription,

    definition_id: ProcedureDefinitionId, type_id: TypeId,

    arguments: ValueGroup, num_ports: usize

) -> Box<dyn Component> {

    let definition = &protocol.heap[definition_id];

    debug_assert!(definition.kind == ProcedureKind::Primitive || definition.kind == ProcedureKind::Composite);

    if definition.source.is_builtin() {

        // Builtin component

        let component: Box<dyn Component> = match definition.source {

            ProcedureSource::CompRandomU32 => Box::new(ComponentRandomU32::new(arguments)),

// Generic component messaging utilities (for sending and receiving)

// -----------------------------------------------------------------------------

/// Default handling of sending a data message. In case the port is blocked then

/// the `ExecState` will become blocked as well. Note that

/// `default_handle_control_message` will ensure that the port becomes

/// unblocked if so instructed by the receiving component. The returned

/// scheduling value must be used.

#[must_use]

pub(crate) fn default_send_data_message(

    exec_state: &mut CompExecState, transmitting_port_id: PortId,

    port_instruction: PortInstruction, value: ValueGroup,

    sched_ctx: &SchedulerCtx, consensus: &mut Consensus,

    control: &mut ControlLayer, comp_ctx: &mut CompCtx

) -> Result<CompScheduling, (PortInstruction, String)> {

    debug_assert_eq!(exec_state.mode, CompMode::Sync);

    let port_handle = comp_ctx.get_port_handle(transmitting_port_id);

    let port_info = comp_ctx.get_port_mut(port_handle);

    port_info.last_instruction = port_instruction;

    let port_info = comp_ctx.get_port(port_handle);

    debug_assert_eq!(port_info.kind, PortKind::Putter);

    if port_info.state.is_closed() {

        // Note: normally peer is eventually consistent, but if it has shut down

        // then we can be sure it is consistent (I think?)

        return Err((

            port_info.last_instruction,

            format!("Cannot send on this port, as the peer (id:{}) has shut down", port_info.peer_comp_id.0)

        ))

    } else if port_info.state.is_blocked() {

        // Port is blocked, so we cannot send

        return Ok(CompScheduling::Sleep);

    } else {

    }

}

pub(crate) enum IncomingData {

    PlacedInSlot,

    SlotFull(DataMessage),

}

/// Default handling of receiving a data message. In case there is no room for

/// the message it is returned from this function. Note that this function is

/// different from PDL code performing a `get` on a port; this is the case where

/// the message first arrives at the component.

// NOTE: This is supposed to be a somewhat temporary implementation. It would be

//  nicest if the sending component can figure out it cannot send any more data.

#[must_use]

pub(crate) fn default_handle_incoming_data_message(

    exec_state: &mut CompExecState, inbox_main: &mut InboxMain,

    comp_ctx: &mut CompCtx, incoming_message: DataMessage,

    sched_ctx: &SchedulerCtx, control: &mut ControlLayer

) -> IncomingData {

    let port_handle = comp_ctx.get_port_handle(incoming_message.data_header.target_port);

    let port_index = comp_ctx.get_port_index(port_handle);

    comp_ctx.get_port_mut(port_handle).received_message_for_sync = true;

    let port_value_slot = &mut inbox_main[port_index];

                    let closed_before_sync_round = !content.closed_in_sync_round && !port_has_had_message;

                    if closed_during_sync_round || closed_before_sync_round {

                        return Err((

                            last_instruction,

                            format!("Peer component (id:{}) shut down, so communication cannot (have) succeed(ed)", peer_comp_id.0)

                        ));

                    }

                } else {

                    let port_info = comp_ctx.get_port_mut(port_handle);

                    port_info.state.set(PortStateFlag::Closed);

                }

            }

        },

        ControlMessageContent::UnblockPort => {

            // We were previously blocked (or already closed)

            let port_to_unblock = message.target_port_id.unwrap();

            let port_handle = comp_ctx.get_port_handle(port_to_unblock);

            let port_info = comp_ctx.get_port_mut(port_handle);

            debug_assert_eq!(port_info.kind, PortKind::Putter);

            debug_assert!(port_info.state.is_set(PortStateFlag::BlockedDueToFullBuffers));

            port_info.state.clear(PortStateFlag::BlockedDueToFullBuffers);

        },

        ControlMessageContent::PortPeerChangedBlock => {

            // The peer of our port has just changed. So we are asked to

            // temporarily block the port (while our original recipient is

            // potentially rerouting some of the in-flight messages) and

            // Ack. Then we wait for the `unblock` call.

            let port_to_change = message.target_port_id.unwrap();

            let port_handle = comp_ctx.get_port_handle(port_to_change);

            let port_info = comp_ctx.get_port_mut(port_handle);

            let peer_comp_id = port_info.peer_comp_id;

            port_info.state.set(PortStateFlag::BlockedDueToPeerChange);

            let peer_handle = comp_ctx.get_peer_handle(peer_comp_id);

            default_send_ack(message.id, peer_handle, sched_ctx, comp_ctx);

        },

        ControlMessageContent::PortPeerChangedUnblock(new_port_id, new_comp_id) => {

            let port_to_change = message.target_port_id.unwrap();

            let port_handle = comp_ctx.get_port_handle(port_to_change);

            let port_info = comp_ctx.get_port(port_handle);

            debug_assert!(port_info.state.is_set(PortStateFlag::BlockedDueToPeerChange));

            let port_info = comp_ctx.get_port_mut(port_handle);

            port_info.peer_port_id = new_port_id;

            port_info.state.clear(PortStateFlag::BlockedDueToPeerChange);

            comp_ctx.change_port_peer(sched_ctx, port_handle, Some(new_comp_id));

        }

    }

    return Ok(());

}

/// Handles a component entering the synchronous block. Will ensure that the

/// `Consensus` and the `ComponentCtx` are initialized properly.

pub(crate) fn default_handle_sync_start(

    exec_state: &mut CompExecState, inbox_main: &mut InboxMainRef,

    sched_ctx: &SchedulerCtx, comp_ctx: &mut CompCtx, consensus: &mut Consensus

) {

    sched_ctx.info("Component starting sync mode");

    // If any messages are present for this sync round, set the appropriate flag

    // and notify the consensus handler of the present messages

    consensus.notify_sync_start(comp_ctx);

    for (port_index, message) in inbox_main.iter().enumerate() {

        if let Some(message) = message {

            consensus.handle_incoming_data_message(comp_ctx, message);

            let port_info = comp_ctx.get_port_by_index_mut(port_index);

            port_info.received_message_for_sync = true;

        }

    }

            ));

        }

        if transmit_port_info.state.is_set(PortStateFlag::Transmitted) {

            return Err((

                sending_port_instruction,

                String::from("Cannot transmit one of the ports in this message, as that port is already transmitted")

            ));

        }

        // Set the flag for transmission

        transmit_port_info.state.set(PortStateFlag::Transmitted);

        // Block the peer of the port

        let message = control.create_port_transfer_message(unblock_put_control_id, comp_ctx.id, peer_port_id);

        println!("DEBUG: Port transfer message\nControl ID: {:?}\nMessage: {:?}", unblock_put_control_id, message);

        let peer_handle = comp_ctx.get_peer_handle(peer_comp_id);

        let peer_info = comp_ctx.get_peer(peer_handle);

        peer_info.handle.send_message_logged(sched_ctx, message, true);

    }

    // We've set up the protocol, once all the PPC's are blocked we are supposed

    // to transfer the message to the recipient. So store it temporarily

    return Ok(());

}

/// Performs the transmission of a data message that contains ports. These were

/// all stored in the component's execution state by the

fn perform_send_message_with_ports(

    exec_state: &mut CompExecState, sched_ctx: &SchedulerCtx, comp_ctx: &CompCtx, consensus: &mut Consensus,

    inbox_main: &mut InboxMain, inbox_backup: &mut InboxBackup

) {

    // Find all ports again

    let mut transmit_ports = Vec::new();

    find_ports_in_value_group(&exec_state.mode_value, &mut transmit_ports);

    let port_handle = comp_ctx.get_port_handle(exec_state.mode_port);

    let port_info = comp_ctx.get_port(port_handle);

    let peer_handle = comp_ctx.get_peer_handle(port_info.peer_comp_id);

    // Annotate the data message

    let message_value = exec_state.mode_value.take();

    let mut annotated_message = consensus.annotate_data_message(comp_ctx, port_info, message_value);

    // And further enhance the message by adding data about the ports that are

    // being transferred

    for (port_locations, transmit_port_id) in transmit_ports {

        let transmit_port_handle = comp_ctx.get_port_handle(transmit_port_id);

        let transmit_port_info = comp_ctx.get_port(transmit_port_handle);

        let transmit_messages = take_port_messages(comp_ctx, transmit_port_id, inbox_main, inbox_backup);

        let mut transmit_port_state = transmit_port_info.state;

        debug_assert!(transmit_port_state.is_set(PortStateFlag::Transmitted));

        transmit_port_state.clear(PortStateFlag::Transmitted);

        annotated_message.ports.push(TransmittedPort{

            locations: port_locations,

            messages: transmit_messages,

            peer_comp: transmit_port_info.peer_comp_id,

            peer_port: transmit_port_info.peer_port_id,

            kind: transmit_port_info.kind,

    loop {

        let (action, new_to_ack) = control.handle_ack(to_ack, sched_ctx, comp_ctx);

        match action {

            AckAction::SendMessage(target_comp, message) => {

                // FIX @NoDirectHandle

                let mut handle = sched_ctx.runtime.get_component_public(target_comp);

                handle.send_message_logged(sched_ctx, Message::Control(message), true);

                let _should_remove = handle.decrement_users();

                debug_assert!(_should_remove.is_none());

            },

            AckAction::ScheduleComponent(to_schedule) => {

                // FIX @NoDirectHandle

                let mut handle = sched_ctx.runtime.get_component_public(to_schedule);

                // Note that the component is intentionally not

                // sleeping, so we just wake it up

                debug_assert!(!handle.sleeping.load(std::sync::atomic::Ordering::Acquire));

                let key = unsafe { to_schedule.upgrade() };

                sched_ctx.runtime.enqueue_work(key);

                let _should_remove = handle.decrement_users();

                debug_assert!(_should_remove.is_none());

            },

            AckAction::UnblockPutWithPorts => {

                println!("DEBUG: Unblocking put with ports");

            },

            AckAction::None => {}

        }

        match new_to_ack {

            Some(new_to_ack) => to_ack = new_to_ack,

            None => break,

        }

    }

}

/// Little helper for sending the most common kind of `Ack`

fn default_send_ack(

    causer_of_ack_id: ControlId, peer_handle: LocalPeerHandle,

    sched_ctx: &SchedulerCtx, comp_ctx: &CompCtx

) {

    let peer_info = comp_ctx.get_peer(peer_handle);

    peer_info.handle.send_message_logged(sched_ctx, Message::Control(ControlMessage{

        id: causer_of_ack_id,

        sender_comp_id: comp_ctx.id,

        target_port_id: None,

        content: ControlMessageContent::Ack

    }), true);

}

/// Handles the unblocking of a putter port. In case there is a pending message

fn default_handle_recently_unblocked_port(

    exec_state: &mut CompExecState, consensus: &mut Consensus,

    port_handle: LocalPortHandle, sched_ctx: &SchedulerCtx, comp_ctx: &mut CompCtx,

) {

    let port_info = comp_ctx.get_port_mut(port_handle);

    let port_id = port_info.self_id;

        // Return to the regular execution mode

        exec_state.mode = CompMode::Sync;

        exec_state.mode_port = PortId::new_invalid();

        // Annotate the message that we're going to send

        let port_info = comp_ctx.get_port(port_handle); // for immutable access

        debug_assert_eq!(port_info.kind, PortKind::Putter);

        let to_send = exec_state.mode_value.take();

        let to_send = consensus.annotate_data_message(comp_ctx, port_info, to_send);

        // Retrieve peer to send the message

        let peer_handle = comp_ctx.get_peer_handle(port_info.peer_comp_id);

        let peer_info = comp_ctx.get_peer(peer_handle);

        peer_info.handle.send_message_logged(sched_ctx, Message::Data(to_send), true);

        exec_state.mode = CompMode::Sync; // because we're blocked on a `put`, we must've started in the sync state.

        exec_state.mode_port = PortId::new_invalid();

    }

}

#[inline]

pub(crate) fn port_id_from_eval(port_id: EvalPortId) -> PortId {

    return PortId(port_id.id);

}

#[inline]

pub(crate) fn port_id_to_eval(port_id: PortId) -> EvalPortId {

    return EvalPortId{ id: port_id.0 };

}

// TODO: Optimize double vec

type EncounteredPorts = Vec<(Vec<ValueId>, PortId)>;

/// Recursively goes through the value group, attempting to find ports.

/// Duplicates will only be added once.

pub(crate) fn find_ports_in_value_group(value_group: &ValueGroup, ports: &mut EncounteredPorts) {

    // Helper to check a value for a port and recurse if needed.

    fn find_port_in_value(group: &ValueGroup, value: &Value, value_location: ValueId, ports: &mut EncounteredPorts) {

        match value {

            Value::Input(port_id) | Value::Output(port_id) => {

                // This is an actual port

                self.handle_incoming_data_message(sched_ctx, comp_ctx, message);

            },

            Message::Sync(message) => {

                let decision = self.consensus.receive_sync_message(sched_ctx, comp_ctx, message);

                component::default_handle_sync_decision(sched_ctx, &mut self.exec_state, comp_ctx, decision, &mut self.consensus);

            },

            Message::Control(message) => {

                if let Err(location_and_message) = component::default_handle_control_message(

                    &mut self.exec_state, &mut self.control, &mut self.consensus,

                    message, sched_ctx, comp_ctx, &mut self.inbox_main, &mut self.inbox_backup

                ) {

                    component::default_handle_error_for_builtin(&mut self.exec_state, sched_ctx, location_and_message);

                }

            },

            Message::Poll => {

                sched_ctx.info("Received polling event");

            },

        }

    }

    fn run(&mut self, sched_ctx: &mut SchedulerCtx, comp_ctx: &mut CompCtx) -> CompScheduling {

        sched_ctx.info(&format!("Running component ComponentTcpClient (mode: {:?}, sync state: {:?})", self.exec_state.mode, self.sync_state));

        match self.exec_state.mode {

                // Not possible: we never enter this state

                unreachable!();

            },

            CompMode::NonSync => {

                // When in non-sync mode

                match &mut self.socket_state {

                    SocketState::Connected(_socket) => {

                        if self.sync_state == SyncState::FinishSyncThenQuit {

                            // Previous request was to let the component shut down

                            self.exec_state.set_as_start_exit(ExitReason::Termination);

                        } else {

                            // Reset for a new request

                            self.sync_state = SyncState::AwaitingCmd;

                            component::default_handle_sync_start(

                                &mut self.exec_state, &mut self.inbox_main, sched_ctx, comp_ctx, &mut self.consensus

                            );

                        }

                        return CompScheduling::Immediate;

                    },

                    SocketState::Error => {

                        // Could potentially send an error message to the

                        // connected component.

                        self.exec_state.set_as_start_exit(ExitReason::ErrorNonSync);

                        return CompScheduling::Immediate;

                ) {

                    self.handle_generic_component_error(sched_ctx, location_and_message);

                }

            },

            Message::Sync(message) => {

                self.handle_incoming_sync_message(sched_ctx, comp_ctx, message);

            },

            Message::Poll => {

                unreachable!(); // because we never register at the polling thread

            }

        }

    }

    fn run(&mut self, sched_ctx: &mut SchedulerCtx, comp_ctx: &mut CompCtx) -> CompScheduling {

        use EvalContinuation as EC;

        sched_ctx.info(&format!("Running component (mode: {:?})", self.exec_state.mode));

        // Depending on the mode don't do anything at all, take some special

        // actions, or fall through and run the PDL code.

        match self.exec_state.mode {

            CompMode::NonSync | CompMode::Sync => {

                // continue and run PDL code

            },

                return CompScheduling::Sleep;

            }

            CompMode::StartExit => return component::default_handle_start_exit(

                &mut self.exec_state, &mut self.control, sched_ctx, comp_ctx, &mut self.consensus

            ),

            CompMode::BusyExit => return component::default_handle_busy_exit(

                &mut self.exec_state, &self.control, sched_ctx

            ),

            CompMode::Exit => return component::default_handle_exit(&self.exec_state),

        }

        let run_result = self.execute_prompt(&sched_ctx);

        if let Err(error) = run_result {

            self.handle_component_error(sched_ctx, CompError::Executor(error));

            return CompScheduling::Immediate;

        }

        let run_result = run_result.unwrap();

        match run_result {

            EC::Stepping => unreachable!(), // execute_prompt runs until this is no longer returned

            EC::BranchInconsistent | EC::NewFork | EC::BlockFires(_) => todo!("remove these"),

            // Results that can be returned in sync mode

            EC::SyncBlockEnd => {

    fn handle_message(&mut self, sched_ctx: &mut SchedulerCtx, comp_ctx: &mut CompCtx, message: Message) {

        match message {

            Message::Data(_message) => unreachable!(),

            Message::Sync(message) => {

                let decision = self.consensus.receive_sync_message(sched_ctx, comp_ctx, message);

                component::default_handle_sync_decision(sched_ctx, &mut self.exec_state, comp_ctx, decision, &mut self.consensus);

            },

            Message::Control(message) => {

                if let Err(location_and_message) = component::default_handle_control_message(

                    &mut self.exec_state, &mut self.control, &mut self.consensus,

                    message, sched_ctx, comp_ctx, &mut self.inbox_main, &mut self.inbox_backup

                ) {

                    component::default_handle_error_for_builtin(&mut self.exec_state, sched_ctx, location_and_message);

                }

            },

            Message::Poll => unreachable!(),

        }

    }

    fn run(&mut self, sched_ctx: &mut SchedulerCtx, comp_ctx: &mut CompCtx) -> CompScheduling {

        sched_ctx.info(&format!("Running component ComponentRandomU32 (mode: {:?})", self.exec_state.mode));

        match self.exec_state.mode {

                // impossible for this component, no input ports and no select

                // blocks

                unreachable!();

            }

            CompMode::NonSync => {

                // If in non-sync mode then we check if the arguments make sense

                // (at some point in the future, this is just a testing

                // component).

                if self.random_minimum >= self.random_maximum {

                    // Could throw an evaluation error, but lets just panic

                    panic!("going to crash 'n burn your system now, please provide valid arguments");

                }

                if self.num_sends >= self.max_num_sends {

                    self.exec_state.set_as_start_exit(ExitReason::Termination);

                } else {

                    sched_ctx.info("Entering sync mode");

                    self.did_perform_send = false;

                    component::default_handle_sync_start(

                        &mut self.exec_state, &mut [], sched_ctx, comp_ctx, &mut self.consensus

                    );

                }

                return CompScheduling::Immediate;