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use chrono::{ DateTime, Utc };
use std::iter::Cycle;
use std::vec::IntoIter as VecIter;
use super::event::SunEvent;
use super::time_of_event;
use super::pos::GlobalPosition;
#[derive(Debug, Clone)]
enum CycleState<T> {
Next(T),
Restarting
}
fn cycled(events: &[SunEvent]) -> Cycle<VecIter<CycleState<SunEvent>>> {
assert!(!events.is_empty());
let mut events = events.to_owned();
events.sort();
events.dedup();
let mut cycled_events = vec![];
for event in events {
cycled_events.push(CycleState::Next(event));
}
cycled_events.push(CycleState::Restarting);
cycled_events.into_iter().cycle()
}
#[derive(Debug, Clone)]
pub struct SunEvents {
pos: GlobalPosition,
current_time: DateTime<Utc>,
event_whitelist_iter: Cycle<VecIter<CycleState<SunEvent>>>
}
impl SunEvents {
pub fn starting_from(start_date: DateTime<Utc>, position: GlobalPosition, event_whitelist: &[SunEvent]) -> Self {
SunEvents {
pos: position,
current_time: start_date,
event_whitelist_iter: cycled(event_whitelist)
}
}
pub fn forecast(self) -> ForecastedSunEvents {
ForecastedSunEvents(self)
}
pub fn history(self) -> HistoricSunEvents {
HistoricSunEvents(self)
}
}
pub struct ForecastedSunEvents(SunEvents);
impl Iterator for ForecastedSunEvents {
type Item = (SunEvent, DateTime<Utc>);
fn next(&mut self) -> Option<Self::Item> {
loop {
if let CycleState::Next(event) = self.0.event_whitelist_iter.next().unwrap() {
if let Some(event_time) = time_of_event(self.0.current_time.date(), &self.0.pos, event) {
if event_time > self.0.current_time {
self.0.current_time = event_time;
return Some((event, event_time));
}
}
} else {
let tomorrow = self.0.current_time.date().succ();
self.0.current_time = tomorrow.and_hms(0, 0, 0);
}
}
}
}
pub struct HistoricSunEvents(SunEvents);
impl Iterator for HistoricSunEvents {
type Item = (SunEvent, DateTime<Utc>);
fn next(&mut self) -> Option<Self::Item> {
loop {
if let CycleState::Next(event) = self.0.event_whitelist_iter.next().unwrap() {
if let Some(event_time) = time_of_event(self.0.current_time.date(), &self.0.pos, event) {
if event_time < self.0.current_time {
self.0.current_time = event_time;
return Some((event, event_time));
}
}
} else {
let yesterday = self.0.current_time.date().pred();
self.0.current_time = yesterday.and_hms(23, 59, 59);
}
}
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn should_only_produce_events_in_the_whitelist() {
let pos = GlobalPosition::at(70.0, 34.0);
let whitelist = &[SunEvent::SUNRISE, SunEvent::SUNSET];
let events = SunEvents::starting_from(Utc::now(), pos, whitelist);
for (event, _time) in events.forecast().take(500) {
assert!(event == SunEvent::SUNRISE || event == SunEvent::SUNSET);
}
}
#[test]
fn forecast_should_never_skip_a_day() {
let pos = GlobalPosition::at(40.60710285372043, -111.85515699873065);
let whitelist = &[SunEvent::SUNRISE];
let events = SunEvents::starting_from(Utc::now(), pos, whitelist);
let mut maybe_last_time: Option<DateTime<Utc>> = None;
for (_event, time) in events.forecast().take(500) {
if let Some(last_time) = maybe_last_time {
assert_eq!(last_time.date().succ(), time.date());
};
maybe_last_time = Some(time);
}
}
#[test]
fn history_should_never_skip_a_day() {
let pos = GlobalPosition::at(40.60710285372043, -111.85515699873065);
let whitelist = &[SunEvent::SUNRISE];
let events = SunEvents::starting_from(Utc::now(), pos, whitelist);
let mut maybe_last_time: Option<DateTime<Utc>> = None;
for (_event, time) in events.history().take(500) {
if let Some(last_time) = maybe_last_time {
assert_eq!(last_time.date().pred(), time.date());
};
maybe_last_time = Some(time);
}
}
}