use core::arch;

// WasmContext
use crate::{arch::sloop, interp::WasmContext};
use alloc::vec::Vec;
use log::trace;

pub type ProcId = u64;

pub struct Scheduler {
    running: Vec<WasmContext>,
    halted: Vec<(ContextWake, WasmContext)>,
    // time_halt: Vec<(ContextWake, WasmContext)>,
    next_proc_id: ProcId,
}

impl Scheduler {
    pub fn new() -> Scheduler {
        Self {
            running: Vec::new(),
            halted: Vec::new(),
            // time_halt: Vec::new(),
            next_proc_id: 0,
        }
    }
    pub fn run(&mut self) -> ! {
        loop {
            let proc = self.running.pop();

            // self.time_halt.sort();

            match proc {
                Some(proc) => {
                    // trace!("SWAP WasmContext");
                    self.running.push(proc);
                }

                None => {
                    panic!("nothing scheduled.");
                    sloop();
                }
            }
        }
    }
    fn sleep_inner(&self, id: ProcId) -> Result<usize, SchedulerError> {
        let proc_len = self.running.len();
        let mut proc_found = true;
        let mut sleep_index = 0;
        let mut i = 0;
        for wc in &self.running {
            if wc.proc_id == Some(id) {
                sleep_index = i;
                proc_found = true;
                break;
            }
            if i == proc_len {
                proc_found = false;
                trace!("no process with ID {} found", id);
                return Err(SchedulerError::ProcessIDNotFound(id));
            }
            i += 1;
        }

        Ok(sleep_index)
    }
    pub fn sleep(&mut self, id: ProcId, time: u64) -> Result<(), SchedulerError> {
        match self.sleep_inner(id) {
            Ok(sid) => self
                .halted
                .push((ContextWake::Time(time), self.running.remove(sid))),
            Err(error) => return Err(error),
        }

        Ok(())
    }

    pub fn schedule(&mut self, wc: WasmContext, cw: ContextWake) -> Result<(), SchedulerError> {
        if wc.proc_id != None {
            panic!("Already Scheduled with PROC_ID {}", wc.proc_id.unwrap());
        }
        trace!("Scheduling WC with ProcID {}", self.next_proc_id);

        if cw == ContextWake::None {
            self.running.push(wc)
        } else {
            self.halted.push((cw, wc));
        }

        self.next_proc_id += 1;
        Ok(())
    }
}
#[derive(PartialEq)]
pub enum ContextWake {
    /// Used when spawning a new process to have it instantly start
    None,
    Time(u64),
    ObjectEvent,
}

pub enum SchedulerError {
    ProcessIDNotFound(ProcId),
    AlreadyScheduled(),
}