// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
use std::sync::Arc;
use std::sync::Mutex;

#[derive(Clone, Default)]
pub struct Progress(Arc<Mutex<Inner>>);

impl Progress {
  pub fn new() -> Self {
    Progress::default()
  }

  pub fn set_callback<F>(&self, f: F)
  where
    F: Fn(bool, usize, usize, &str) + Send + Sync + 'static,
  {
    let mut s = self.0.lock().unwrap();
    assert!(s.callback.is_none());
    s.callback = Some(Arc::new(f));
  }

  /// Returns job counts: (complete, total)
  pub fn progress(&self) -> (usize, usize) {
    let s = self.0.lock().unwrap();
    s.progress()
  }

  pub fn history(&self) -> Vec<String> {
    let s = self.0.lock().unwrap();
    s.job_names.clone()
  }

  pub fn add(&self, name: String) -> Job {
    let mut s = self.0.lock().unwrap();
    let id = s.job_names.len();
    s.maybe_call_callback(false, s.complete, s.job_names.len() + 1, &name);
    s.job_names.push(name);
    Job {
      id,
      inner: self.0.clone(),
    }
  }

  pub fn done(&self) {
    let s = self.0.lock().unwrap();
    s.maybe_call_callback(true, s.complete, s.job_names.len(), "");
  }
}

type Callback = dyn Fn(bool, usize, usize, &str) + Send + Sync;

#[derive(Default)]
struct Inner {
  job_names: Vec<String>,
  complete: usize,
  callback: Option<Arc<Callback>>,
}

impl Inner {
  pub fn maybe_call_callback(
    &self,
    done: bool,
    complete: usize,
    total: usize,
    msg: &str,
  ) {
    if let Some(ref cb) = self.callback {
      cb(done, complete, total, msg);
    }
  }

  /// Returns job counts: (complete, total)
  pub fn progress(&self) -> (usize, usize) {
    let total = self.job_names.len();
    (self.complete, total)
  }
}

pub struct Job {
  inner: Arc<Mutex<Inner>>,
  id: usize,
}

impl Drop for Job {
  fn drop(&mut self) {
    let mut s = self.inner.lock().unwrap();
    s.complete += 1;
    let name = &s.job_names[self.id];
    let (complete, total) = s.progress();
    s.maybe_call_callback(false, complete, total, name);
  }
}

#[cfg(test)]
mod tests {
  use super::*;

  #[test]
  fn progress() {
    let p = Progress::new();
    assert_eq!(p.progress(), (0, 0));
    {
      let _j1 = p.add("hello".to_string());
      assert_eq!(p.progress(), (0, 1));
    }
    assert_eq!(p.progress(), (1, 1));
    {
      let _j2 = p.add("hello".to_string());
      assert_eq!(p.progress(), (1, 2));
    }
    assert_eq!(p.progress(), (2, 2));
  }

  #[test]
  fn history() {
    let p = Progress::new();
    let _a = p.add("a".to_string());
    let _b = p.add("b".to_string());
    assert_eq!(p.history(), vec!["a", "b"]);
  }

  #[test]
  fn callback() {
    let callback_history: Arc<Mutex<Vec<(usize, usize, String)>>> =
      Arc::new(Mutex::new(Vec::new()));
    {
      let p = Progress::new();
      let callback_history_ = callback_history.clone();

      p.set_callback(move |_done, complete, total, msg| {
        // println!("callback: {}, {}, {}", complete, total, msg);
        let mut h = callback_history_.lock().unwrap();
        h.push((complete, total, String::from(msg)));
      });
      {
        let _a = p.add("a".to_string());
        let _b = p.add("b".to_string());
      }
      let _c = p.add("c".to_string());
    }

    let h = callback_history.lock().unwrap();
    assert_eq!(
      h.to_vec(),
      vec![
        (0, 1, "a".to_string()),
        (0, 2, "b".to_string()),
        (1, 2, "b".to_string()),
        (2, 2, "a".to_string()),
        (2, 3, "c".to_string()),
        (3, 3, "c".to_string()),
      ]
    );
  }

  #[test]
  fn thread_safe() {
    fn f<S: Send + Sync>(_: S) {}
    f(Progress::new());
  }
}