#![deny(
    // The following are allowed by default lints according to
    // https://doc.rust-lang.org/rustc/lints/listing/allowed-by-default.html
    anonymous_parameters,
    bare_trait_objects,
    // box_pointers, // use box pointer to allocate on heap
    // elided_lifetimes_in_paths, // allow anonymous lifetime
    missing_copy_implementations,
    missing_debug_implementations,
    // missing_docs, // TODO: add documents
    // single_use_lifetimes, // TODO: fix lifetime names only used once
    // trivial_casts,
    trivial_numeric_casts,
    // unreachable_pub, allow clippy::redundant_pub_crate lint instead
    // unsafe_code,
    unstable_features,
    unused_extern_crates,
    unused_import_braces,
    unused_qualifications,
    unused_results,
    variant_size_differences,

    warnings, // treat all wanings as errors

    clippy::all,
    // clippy::restriction,
    clippy::pedantic,
    // clippy::nursery, // It's still under development
    clippy::cargo,
)]
#![allow(
    // Some explicitly allowed Clippy lints, must have clear reason to allow
    clippy::blanket_clippy_restriction_lints, // allow clippy::restriction
    clippy::implicit_return, // actually omitting the return keyword is idiomatic Rust code
    clippy::module_name_repetitions, // repeation of module name in a struct name is not big deal
    clippy::multiple_crate_versions, // multi-version dependency crates is not able to fix
    clippy::missing_errors_doc, // TODO: add error docs
    clippy::missing_panics_doc, // TODO: add panic docs
    clippy::panic_in_result_fn,
    clippy::shadow_same, // Not too much bad
    clippy::shadow_reuse, // Not too much bad
    clippy::exhaustive_enums,
    clippy::exhaustive_structs,
    clippy::indexing_slicing,
    clippy::separated_literal_suffix, // conflicts with clippy::unseparated_literal_suffix
    clippy::single_char_lifetime_names, // TODO: change lifetime names
)]

use std::collections::vec_deque::{Iter, IterMut};
use std::collections::VecDeque;
use std::time::{Duration, SystemTime, UNIX_EPOCH};

const NANOS_PER_SEC: u64 = 1_000_000_000;

// get the current wall clock in ns
#[allow(clippy::cast_possible_truncation)]
#[must_use]
#[inline]
pub fn now() -> u64 {
    SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .expect("1970-01-01 00:00:00 UTC was {} seconds ago!")
        .as_nanos() as u64
}

#[must_use]
#[inline]
pub fn dur_to_ns(dur: Duration) -> u64 {
    // Note that a duration is a (u64, u32) (seconds, nanoseconds) pair
    dur.as_secs()
        .saturating_mul(NANOS_PER_SEC)
        .saturating_add(u64::from(dur.subsec_nanos()))
}

#[must_use]
pub fn get_timeout_time(dur: Duration) -> u64 {
    add_timeout_time(dur_to_ns(dur))
}

#[must_use]
pub fn add_timeout_time(time: u64) -> u64 {
    let now = now();
    match now.checked_add(time) {
        Some(time) => time,
        //处理溢出
        None => u64::MAX,
    }
}

#[derive(Debug, PartialEq, Eq)]
pub struct TimerEntry<T> {
    time: u64,
    inner: VecDeque<T>,
}

impl<T> TimerEntry<T> {
    #[must_use]
    pub fn new(time: u64) -> Self {
        TimerEntry {
            time,
            inner: VecDeque::new(),
        }
    }

    #[must_use]
    pub fn len(&self) -> usize {
        self.inner.len()
    }

    #[must_use]
    pub fn is_empty(&self) -> bool {
        self.inner.is_empty()
    }

    #[must_use]
    pub fn get_time(&self) -> u64 {
        self.time
    }

    pub fn pop_front(&mut self) -> Option<T> {
        self.inner.pop_front()
    }

    pub fn push_back(&mut self, t: T) {
        self.inner.push_back(t);
    }

    pub fn remove(&mut self, t: &T) -> Option<T>
    where
        T: Ord,
    {
        let index = self
            .inner
            .binary_search_by(|x| x.cmp(t))
            .unwrap_or_else(|x| x);
        self.inner.remove(index)
    }

    pub fn iter_mut(&mut self) -> IterMut<'_, T> {
        self.inner.iter_mut()
    }

    #[must_use]
    pub fn iter(&self) -> Iter<'_, T> {
        self.inner.iter()
    }
}

#[repr(C)]
#[derive(Debug, PartialEq, Eq)]
pub struct TimerList<T> {
    dequeue: VecDeque<TimerEntry<T>>,
}

impl<T> TimerList<T> {
    #[must_use]
    pub fn new() -> Self {
        TimerList {
            dequeue: VecDeque::new(),
        }
    }

    #[must_use]
    pub fn len(&self) -> usize {
        self.dequeue.len()
    }

    pub fn insert(&mut self, time: u64, t: T) {
        let index = self
            .dequeue
            .binary_search_by(|x| x.time.cmp(&time))
            .unwrap_or_else(|x| x);
        if let Some(entry) = self.dequeue.get_mut(index) {
            entry.push_back(t);
        } else {
            let mut entry = TimerEntry::new(time);
            entry.push_back(t);
            self.dequeue.insert(index, entry);
        }
    }

    #[must_use]
    pub fn front(&self) -> Option<&TimerEntry<T>> {
        self.dequeue.front()
    }

    pub fn pop_front(&mut self) -> Option<TimerEntry<T>> {
        self.dequeue.pop_front()
    }

    #[must_use]
    pub fn is_empty(&self) -> bool {
        self.dequeue.is_empty()
    }

    pub fn get_entry(&mut self, time: u64) -> Option<&mut TimerEntry<T>> {
        let index = self
            .dequeue
            .binary_search_by(|x| x.time.cmp(&time))
            .unwrap_or_else(|x| x);
        self.dequeue.get_mut(index)
    }

    pub fn iter_mut(&mut self) -> IterMut<'_, TimerEntry<T>> {
        self.dequeue.iter_mut()
    }

    #[must_use]
    pub fn iter(&self) -> Iter<'_, TimerEntry<T>> {
        self.dequeue.iter()
    }
}

impl<T> Default for TimerList<T> {
    fn default() -> Self {
        Self::new()
    }
}

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

    #[test]
    fn test() {
        println!("{}", now());
    }

    #[test]
    fn timer_list() {
        let mut list = TimerList::new();
        assert_eq!(list.len(), 0);
        list.insert(1, String::from("data is typed"));
        assert_eq!(list.len(), 1);

        let mut entry = list.pop_front().unwrap();
        assert_eq!(entry.len(), 1);
        let string = entry.pop_front().unwrap();
        assert_eq!(string, String::from("data is typed"));
    }
}