use core::task::Poll;
use thiserror::Error;
use topola::{
    autorouter::{
        execution::ExecutionStepper,
        invoker::{GetGhosts, GetMaybeNavmesh, GetMaybeTrace, GetObstacles, Invoker, InvokerError},
    },
    board::mesadata::AccessMesadata,
    drawing::graph::PrimitiveIndex,
    geometry::primitive::PrimitiveShape,
    router::{navmesh::Navmesh, trace::TraceStepper},
    specctra::mesadata::SpecctraMesadata,
    stepper::{Abort, PollStep, StepError},
};

use crate::interaction::{InteractionContext, InteractionError, InteractionStepper};

pub struct ActivityContext<'a> {
    pub interaction: InteractionContext,
    pub invoker: &'a mut Invoker<SpecctraMesadata>,
}

#[derive(Error, Debug, Clone)]
pub enum ActivityError {
    #[error(transparent)]
    Interaction(#[from] InteractionError),
    #[error(transparent)]
    Invoker(#[from] InvokerError),
}

pub enum ActivityStepper {
    Interaction(InteractionStepper),
    Execution(ExecutionStepper),
}

impl StepError for ActivityStepper {
    type Error = ActivityError;
}

impl PollStep<ActivityContext<'_>, String> for ActivityStepper {
    fn poll_step(
        &mut self,
        context: &mut ActivityContext<'_>,
    ) -> Poll<Result<String, ActivityError>> {
        match self {
            ActivityStepper::Interaction(interaction) => interaction
                .poll_step(&mut context.interaction)
                .map(|x| x.map_err(Into::into)),
            ActivityStepper::Execution(execution) => execution
                .poll_step(context.invoker)
                .map(|x| x.map_err(Into::into)),
        }
    }
}

impl Abort<ActivityContext<'_>> for ActivityStepper {
    fn abort(&mut self, context: &mut ActivityContext) {
        match self {
            ActivityStepper::Interaction(interaction) => {
                interaction.abort(&mut context.interaction);
            }
            ActivityStepper::Execution(execution) => {
                PollStep::finish(execution, context.invoker); // TODO.
            }
        };
    }
}

impl GetMaybeNavmesh for ActivityStepper {
    /// Implemented manually instead of with `enum_dispatch` because it doesn't work across crates.
    fn maybe_navmesh(&self) -> Option<&Navmesh> {
        match self {
            ActivityStepper::Interaction(interaction) => interaction.maybe_navmesh(),
            ActivityStepper::Execution(execution) => execution.maybe_navmesh(),
        }
    }
}

impl GetMaybeTrace for ActivityStepper {
    /// Implemented manually instead of with `enum_dispatch` because it doesn't work across crates.
    fn maybe_trace(&self) -> Option<&TraceStepper> {
        match self {
            ActivityStepper::Interaction(interaction) => interaction.maybe_trace(),
            ActivityStepper::Execution(execution) => execution.maybe_trace(),
        }
    }
}

impl GetGhosts for ActivityStepper {
    /// Implemented manually instead of with `enum_dispatch` because it doesn't work across crates.
    fn ghosts(&self) -> &[PrimitiveShape] {
        match self {
            ActivityStepper::Interaction(interaction) => interaction.ghosts(),
            ActivityStepper::Execution(execution) => execution.ghosts(),
        }
    }
}

impl GetObstacles for ActivityStepper {
    /// Implemented manually instead of with `enum_dispatch` because it doesn't work across crates.
    fn obstacles(&self) -> &[PrimitiveIndex] {
        match self {
            ActivityStepper::Interaction(interaction) => interaction.obstacles(),
            ActivityStepper::Execution(execution) => execution.obstacles(),
        }
    }
}

#[derive(Default)]
pub struct ActivityStepperWithStatus {
    pub maybe_activity: Option<ActivityStepper>,
    pub maybe_status: Option<Poll<String>>,
}

impl ActivityStepperWithStatus {
    pub fn new_execution(execution: ExecutionStepper) -> ActivityStepperWithStatus {
        Self {
            maybe_activity: Some(ActivityStepper::Execution(execution)),
            maybe_status: None,
        }
    }

    pub fn is_busy(&self) -> bool {
        if self.maybe_activity.is_none() {
            return false;
        }
        // this might be left over from a previous execution
        //if let Some(Poll::Ready(_)) = &self.maybe_status {
        //    return false;
        //}
        true
    }
}

impl StepError for ActivityStepperWithStatus {
    type Error = ActivityError;
}

impl PollStep<ActivityContext<'_>, String> for ActivityStepperWithStatus {
    fn poll_step(
        &mut self,
        context: &mut ActivityContext<'_>,
    ) -> Poll<Result<String, ActivityError>> {
        let res = match &mut self.maybe_activity {
            None => return Poll::Pending,
            Some(act) => act.poll_step(context),
        };
        // fused stepping
        if let Poll::Ready(_) = &res {
            self.maybe_activity = None;
        }
        self.maybe_status = match &res {
            Poll::Pending => Some(Poll::Pending),
            Poll::Ready(Ok(msg)) => Some(Poll::Ready(msg.clone())),
            Poll::Ready(Err(_)) => None,
        };
        res
    }
}

impl Abort<ActivityContext<'_>> for ActivityStepperWithStatus {
    fn abort(&mut self, context: &mut ActivityContext<'_>) {
        if let Some(mut act) = self.maybe_activity.take() {
            self.maybe_status = Some(Poll::Ready("aborted".to_string()));
            act.abort(context);
        }
    }
}

impl GetMaybeNavmesh for ActivityStepperWithStatus {
    fn maybe_navmesh(&self) -> Option<&Navmesh> {
        self.maybe_activity.as_ref()?.maybe_navmesh()
    }
}

impl GetMaybeTrace for ActivityStepperWithStatus {
    fn maybe_trace(&self) -> Option<&TraceStepper> {
        self.maybe_activity.as_ref()?.maybe_trace()
    }
}

impl GetGhosts for ActivityStepperWithStatus {
    fn ghosts(&self) -> &[PrimitiveShape] {
        match &self.maybe_activity {
            None => &[],
            Some(act) => act.ghosts(),
        }
    }
}

impl GetObstacles for ActivityStepperWithStatus {
    fn obstacles(&self) -> &[PrimitiveIndex] {
        match &self.maybe_activity {
            None => &[],
            Some(act) => act.obstacles(),
        }
    }
}