use crate::protocol::eval::*;
use crate::protocol::*;
use crate::runtime2::*;
use super::{CompCtx, CompPDL};

pub enum CompScheduling {
    Immediate,
    Requeue,
    Sleep,
    Exit,
}

/// Generic representation of a component (as viewed by a scheduler).
pub(crate) trait Component {
    /// 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) -> Result<CompScheduling, EvalError>;
}

/// 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
        todo!("implement")
    } else {
        // User-defined component
        let prompt = Prompt::new(
            &protocol.types, &protocol.heap,
            definition_id, type_id, arguments
        );
        let component = CompPDL::new(prompt, num_ports);
        return Box::new(component);
    }
}