use std::collections::HashMap;

use serde::Serialize;

use crate::{ErrorCode, Request, RequestId, Response, ResponseError};

/// Manages the set of pending requests, both incoming and outgoing.
#[derive(Debug)]
pub struct ReqQueue<I, O> {
    pub incoming: Incoming<I>,
    pub outgoing: Outgoing<O>,
}

impl<I, O> Default for ReqQueue<I, O> {
    fn default() -> ReqQueue<I, O> {
        ReqQueue {
            incoming: Incoming { pending: HashMap::default() },
            outgoing: Outgoing { next_id: 0, pending: HashMap::default() },
        }
    }
}

#[derive(Debug)]
pub struct Incoming<I> {
    pending: HashMap<RequestId, I>,
}

#[derive(Debug)]
pub struct Outgoing<O> {
    next_id: i32,
    pending: HashMap<RequestId, O>,
}

impl<I> Incoming<I> {
    pub fn register(&mut self, id: RequestId, data: I) {
        self.pending.insert(id, data);
    }

    pub fn cancel(&mut self, id: RequestId) -> Option<Response> {
        let _data = self.complete(id.clone())?;
        let error = ResponseError {
            code: ErrorCode::RequestCanceled as i32,
            message: "canceled by client".to_string(),
            data: None,
        };
        Some(Response { id, result: None, error: Some(error) })
    }

    pub fn complete(&mut self, id: RequestId) -> Option<I> {
        self.pending.remove(&id)
    }

    pub fn is_completed(&self, id: &RequestId) -> bool {
        !self.pending.contains_key(id)
    }
}

impl<O> Outgoing<O> {
    pub fn register<P: Serialize>(&mut self, method: String, params: P, data: O) -> Request {
        let id = RequestId::from(self.next_id);
        self.pending.insert(id.clone(), data);
        self.next_id += 1;
        Request::new(id, method, params)
    }

    pub fn complete(&mut self, id: RequestId) -> Option<O> {
        self.pending.remove(&id)
    }
}