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// Copyright © 2021 Alexandra Frydl
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

use crate::prelude::*;
use crate::task;
use crate::thread;
use signal_hook::consts::TERM_SIGNALS;
use signal_hook::iterator::Signals;
use std::process::exit;

/// Starts a task from the given future, waits for it to stop, then exits the
/// process.
///
/// If the task fails, this function logs the error and exits the process with
/// a non-zero exit code.
pub fn run<T, E>(future: impl Future<Output = Result<T, E>> + Send + 'static) -> !
where
  T: Send + 'static,
  E: Display + Send + 'static,
{
  let task = task::start(future);

  match thread::block_on(task.join()) {
    Ok(Err(err)) => {
      error!("The main task failed. {}", err);

      thread::sleep(Duration::hz(60));
      exit(1)
    }

    Err(err) => {
      if let Some(value) = err.value_str() {
        error!("The main task panicked with `{}`.", value);
      } else {
        error!("The main task panicked.")
      }

      thread::sleep(Duration::hz(60));
      exit(-1)
    }

    _ => exit(0),
  }
}

/// Starts a task from the given function, waits for it to stop, then exits the
/// process.
///
/// If the task fails, this function logs the error and exits the process with
/// a non-zero exit code.
///
/// The provided function is passed a [`task::CancelSignal`] that is triggered
/// when the process receives a termination signal (SIGINT, SIGTERM, or
/// SIGQUIT).
pub fn run_with<T, E, F>(func: impl FnOnce(task::CancelSignal) -> F + Send + 'static) -> !
where
  T: Send + 'static,
  E: Display + Send + 'static,
  F: Future<Output = Result<T, E>> + Send + 'static,
{
  let canceler = task::Canceler::new();
  let cancel = canceler.signal();

  let mut signals = Signals::new(TERM_SIGNALS).expect("Failed to register signal handler");

  thread::start("af_core::run canceler", move || {
    let mut iter = signals.into_iter();

    iter.next();

    warn!("The process received a termination signal. Canceling the main task…");

    canceler.cancel();
  });

  run(async { func(cancel).await })
}