// list of jobs: job (cmd, args) OR rust fn OR python func + cron-like timing
// job runner (thread)
// every job runs in other thread/process

use crate::{models::*, UResult, UError};

use std::collections::HashMap;
use std::pin::Pin;
use std::thread::sleep;
use std::time::{Duration, Instant};
use std::task::Poll;
use tokio::process::Command;

use futures::{lock::Mutex, prelude::*, poll};
use lazy_static::lazy_static;
use tokio::{prelude::*, spawn, task::JoinHandle};
use uuid::Uuid;

pub type FutRes = UResult<JobResult>;

lazy_static! {
    static ref FUT_RESULTS: Mutex<HashMap<Uuid, JoinHandle<FutRes>>> = Mutex::new(HashMap::new());
}

//TODO: waiter struct
pub async fn append_task(task: impl Future<Output=FutRes> + Send + 'static) -> Uuid {
    let fid = Uuid::new_v4();
    let result = spawn(Box::pin(task));
    FUT_RESULTS.lock().await.insert(fid, result);
    fid
}

pub async fn append_tasks(tasks: Vec<impl Future<Output=FutRes> + Send + 'static>) -> Vec<Uuid> {
    let mut fids = Vec::<Uuid>::new();
    for f in tasks.into_iter() {
        let fid = append_task(f).await;
        fids.push(fid);
    }
    fids
}

pub async fn pop_task(fid: Uuid) -> JoinHandle<FutRes> {
    FUT_RESULTS.lock().await.remove(&fid).expect(&UError::NoTask(fid).to_string())
}

pub async fn task_present(fid: Uuid) -> bool {
    FUT_RESULTS.lock().await.get(&fid).is_some()
}

pub async fn pop_task_if_completed(fid: Uuid) -> Option<FutRes>{
    let mut tasks = FUT_RESULTS
        .lock()
        .await;
    let task = tasks
        .get_mut(&fid)
        .expect(&UError::NoTask(fid).to_string());
    let status = match poll!(task) {
        Poll::Pending => None,
        Poll::Ready(r) => Some(r.unwrap())
    };
    if status.is_some() {
        pop_task(fid).await;
    }
    status
}

pub async fn pop_completed(fids: Option<Vec<Uuid>>) -> Vec<Option<FutRes>> {
    let fids = match fids {
        Some(v) => v,
        None => FUT_RESULTS.lock()
            .await
            .keys()
            .map(|k| *k)
            .collect::<Vec<Uuid>>()
    };
    let mut completed: Vec<Option<FutRes>> = vec![];
    for fid in fids {
        completed.push(pop_task_if_completed(fid).await)
    }
    completed
}

pub async fn wait_for_task(fid: Uuid) -> FutRes {
    pop_task(fid).await.await.unwrap()
}

pub async fn wait_for_tasks(fids: Vec<Uuid>) -> Vec<FutRes> {
    let mut results = vec![];
    for fid in fids {
        results.push(wait_for_task(fid).await);
    }
    results
}

pub async fn run_until_complete(task: impl Future<Output=FutRes> + Send + 'static) -> FutRes {
    let fid = append_task(task).await;
    wait_for_task(fid).await
}