use crate::{
    ErrorKind, Promise, Result, message::BasicReturnMessage, returned_messages::ReturnedMessages,
};
use std::{
    fmt,
    future::Future,
    pin::Pin,
    task::{Context, Poll},
};
use tracing::trace;

pub struct PublisherConfirm {
    inner: Option<Promise<Confirmation>>,
    returned_messages: ReturnedMessages,
}

#[derive(Debug, PartialEq)]
pub enum Confirmation {
    Ack(Option<BasicReturnMessage>),
    Nack(Option<BasicReturnMessage>),
    NotRequested,
}

impl Confirmation {
    pub fn take_message(self) -> Option<BasicReturnMessage> {
        if let Confirmation::Ack(msg) | Confirmation::Nack(msg) = self {
            msg
        } else {
            None
        }
    }

    pub fn is_ack(&self) -> bool {
        matches!(self, Confirmation::Ack(_))
    }

    pub fn is_nack(&self) -> bool {
        matches!(self, Confirmation::Nack(_))
    }
}

impl PublisherConfirm {
    pub(crate) fn new(inner: Promise<Confirmation>, returned_messages: ReturnedMessages) -> Self {
        Self {
            inner: Some(inner),
            returned_messages,
        }
    }

    pub(crate) fn not_requested(returned_messages: ReturnedMessages) -> Self {
        Self {
            inner: Some(Promise::new_with_data(
                "publisher-confirms.not-requested",
                Ok(Confirmation::NotRequested),
            )),
            returned_messages,
        }
    }
}

impl fmt::Debug for PublisherConfirm {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("PublisherConfirm").finish()
    }
}

impl Future for PublisherConfirm {
    type Output = Result<Confirmation>;

    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        let mut this = self.as_mut();
        let Some(inner) = this.inner.as_mut() else {
            return Poll::Ready(Err(ErrorKind::FutureCompleted.into()));
        };
        let res = Pin::new(inner).poll(cx);
        if res.is_ready() {
            this.inner.take();
        }
        res
    }
}

impl Drop for PublisherConfirm {
    fn drop(&mut self) {
        if let Some(promise) = self.inner.take() {
            trace!("PublisherConfirm dropped without use, registering it for wait_for_confirms");
            self.returned_messages.register_dropped_confirm(promise);
        }
    }
}
