| 1 | //! Merge windows: when a branch takes merges, by the week, with freezes and |
| 2 | //! exceptions on a calendar. |
| 3 | |
| 4 | use g1t_contracts::rules::{MergeWindowRule, Period, Weekday}; |
| 5 | use g1t_contracts::time::{parse_rfc3339, rfc3339}; |
| 6 | |
| 7 | const MINUTE: u64 = 60 * 1000; |
| 8 | const DAY_MINUTES: i64 = 24 * 60; |
| 9 | |
| 10 | /// A time zone's offset from UTC in minutes: `+02:00`, `-0530`, `UTC`. |
| 11 | pub fn offset_minutes(zone: &str) -> Option<i64> { |
| 12 | let zone = zone.trim(); |
| 13 | if zone.is_empty() || zone.eq_ignore_ascii_case("utc") || zone == "Z" { |
| 14 | return Some(0); |
| 15 | } |
| 16 | let zone = zone.strip_prefix("UTC").or_else(|| zone.strip_prefix("utc")).unwrap_or(zone); |
| 17 | let (sign, rest) = match zone.chars().next()? { |
| 18 | '+' => (1, &zone[1..]), |
| 19 | '-' => (-1, &zone[1..]), |
| 20 | _ => return None, |
| 21 | }; |
| 22 | let (hours, minutes) = match rest.split_once(':') { |
| 23 | Some((hours, minutes)) => (hours, minutes), |
| 24 | None if rest.len() == 4 => rest.split_at(2), |
| 25 | None => (rest, "0"), |
| 26 | }; |
| 27 | let (hours, minutes) = (hours.parse::<i64>().ok()?, minutes.parse::<i64>().ok()?); |
| 28 | if hours > 14 || minutes > 59 { |
| 29 | return None; |
| 30 | } |
| 31 | Some(sign * (hours * 60 + minutes)) |
| 32 | } |
| 33 | |
| 34 | /// Minutes into the day of `HH:MM`. |
| 35 | pub fn clock(text: &str) -> Option<i64> { |
| 36 | let (hours, minutes) = text.trim().split_once(':')?; |
| 37 | let (hours, minutes) = (hours.parse::<i64>().ok()?, minutes.parse::<i64>().ok()?); |
| 38 | if hours > 24 || minutes > 59 || (hours == 24 && minutes > 0) { |
| 39 | return None; |
| 40 | } |
| 41 | Some(hours * 60 + minutes) |
| 42 | } |
| 43 | |
| 44 | /// The day of the week of a count of days since 1970-01-01, a Thursday. |
| 45 | fn weekday(days: i64) -> Weekday { |
| 46 | Weekday::ALL[(days + 3).rem_euclid(7) as usize] |
| 47 | } |
| 48 | |
| 49 | fn in_period(period: &Period, now: u64) -> bool { |
| 50 | let Some(start) = parse_rfc3339(&period.start) else { return false }; |
| 51 | let end = period.end.as_deref().and_then(parse_rfc3339); |
| 52 | start <= now && end.is_none_or(|end| now < end) |
| 53 | } |
| 54 | |
| 55 | /// Why merging is closed now, or `None` when it is open. |
| 56 | #[derive(Clone, Debug, PartialEq, Eq)] |
| 57 | pub enum Closed { |
| 58 | /// A freeze covers now: its reason, and when it ends if it does. |
| 59 | Frozen { reason: String, until: Option<String> }, |
| 60 | /// Outside every weekly window: when the next one opens, RFC 3339. |
| 61 | Outside { opens: Option<String> }, |
| 62 | } |
| 63 | |
| 64 | /// Whether merging is allowed at `now` (milliseconds since the epoch). |
| 65 | pub fn closed(rule: &MergeWindowRule, now: u64) -> Option<Closed> { |
| 66 | if rule.exceptions.iter().any(|period| in_period(period, now)) { |
| 67 | return None; |
| 68 | } |
| 69 | if let Some(freeze) = rule.freezes.iter().find(|period| in_period(period, now)) { |
| 70 | return Some(Closed::Frozen { reason: freeze.reason.trim().to_owned(), until: freeze.end.clone() }); |
| 71 | } |
| 72 | if rule.windows.is_empty() { |
| 73 | return None; |
| 74 | } |
| 75 | let offset = offset_minutes(&rule.time_zone).unwrap_or(0); |
| 76 | let local = (now / MINUTE) as i64 + offset; |
| 77 | if open_at(rule, local) { |
| 78 | return None; |
| 79 | } |
| 80 | // The next minute a window opens, within a week and a day. |
| 81 | let opens = (1..=(8 * DAY_MINUTES)) |
| 82 | .map(|ahead| local + ahead) |
| 83 | .find(|minute| open_at(rule, *minute) && !open_at(rule, minute - 1)) |
| 84 | .map(|minute| rfc3339(((minute - offset) as u64) * MINUTE)); |
| 85 | Some(Closed::Outside { opens }) |
| 86 | } |
| 87 | |
| 88 | /// Whether a local minute (since the epoch) falls in a weekly window. |
| 89 | fn open_at(rule: &MergeWindowRule, local: i64) -> bool { |
| 90 | let (day, minute) = (local.div_euclid(DAY_MINUTES), local.rem_euclid(DAY_MINUTES)); |
| 91 | rule.windows.iter().any(|window| { |
| 92 | let (Some(start), Some(end)) = (clock(&window.start), clock(&window.end)) else { |
| 93 | return false; |
| 94 | }; |
| 95 | if start <= end { |
| 96 | window.days.contains(&weekday(day)) && start <= minute && minute < end |
| 97 | } else { |
| 98 | // Past midnight: the evening of a listed day, or the morning after. |
| 99 | (window.days.contains(&weekday(day)) && minute >= start) |
| 100 | || (window.days.contains(&weekday(day - 1)) && minute < end) |
| 101 | } |
| 102 | }) |
| 103 | } |
| 104 | |
| 105 | /// What a closed window tells people. |
| 106 | pub fn explain(closed: &Closed) -> String { |
| 107 | match closed { |
| 108 | Closed::Frozen { reason, until } => { |
| 109 | let why = if reason.is_empty() { String::new() } else { format!(" ({reason})") }; |
| 110 | match until { |
| 111 | Some(until) => format!("Merging is frozen{why} until {until}."), |
| 112 | None => format!("Merging is frozen{why} until the freeze is lifted."), |
| 113 | } |
| 114 | } |
| 115 | Closed::Outside { opens: Some(opens) } => format!("Merging is outside the merge window; it next opens at {opens}."), |
| 116 | Closed::Outside { opens: None } => "Merging is outside the merge window.".to_owned(), |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | #[cfg(test)] |
| 121 | mod tests { |
| 122 | use super::*; |
| 123 | use g1t_contracts::rules::WeeklyWindow; |
| 124 | |
| 125 | /// 2026-10-07 is a Wednesday. |
| 126 | fn at(text: &str) -> u64 { |
| 127 | parse_rfc3339(text).unwrap() |
| 128 | } |
| 129 | |
| 130 | fn weekdays(start: &str, end: &str) -> MergeWindowRule { |
| 131 | MergeWindowRule { |
| 132 | windows: vec![WeeklyWindow { |
| 133 | days: vec![Weekday::Mon, Weekday::Tue, Weekday::Wed, Weekday::Thu], |
| 134 | start: start.into(), |
| 135 | end: end.into(), |
| 136 | }], |
| 137 | ..MergeWindowRule::default() |
| 138 | } |
| 139 | } |
| 140 | |
| 141 | #[test] |
| 142 | fn zones_and_clocks_parse() { |
| 143 | assert_eq!(offset_minutes("UTC"), Some(0)); |
| 144 | assert_eq!(offset_minutes(""), Some(0)); |
| 145 | assert_eq!(offset_minutes("+02:00"), Some(120)); |
| 146 | assert_eq!(offset_minutes("-0530"), Some(-330)); |
| 147 | assert_eq!(offset_minutes("UTC+1"), Some(60)); |
| 148 | assert_eq!(offset_minutes("Europe/Paris"), None); |
| 149 | assert_eq!(clock("09:30"), Some(570)); |
| 150 | assert_eq!(clock("24:00"), Some(1440)); |
| 151 | assert_eq!(clock("25:00"), None); |
| 152 | } |
| 153 | |
| 154 | #[test] |
| 155 | fn days_of_the_week_are_counted_from_a_thursday() { |
| 156 | assert_eq!(weekday(0), Weekday::Thu); |
| 157 | assert_eq!(weekday(at("2026-10-07T12:00:00Z") as i64 / 86_400_000), Weekday::Wed); |
| 158 | } |
| 159 | |
| 160 | #[test] |
| 161 | fn inside_the_window_merging_is_open() { |
| 162 | let rule = weekdays("09:00", "17:00"); |
| 163 | assert_eq!(closed(&rule, at("2026-10-07T10:00:00Z")), None); |
| 164 | assert_eq!(closed(&MergeWindowRule::default(), at("2026-10-10T03:00:00Z")), None); |
| 165 | } |
| 166 | |
| 167 | #[test] |
| 168 | fn outside_it_says_when_it_opens() { |
| 169 | let rule = weekdays("09:00", "17:00"); |
| 170 | // Wednesday evening: Thursday morning. |
| 171 | assert_eq!( |
| 172 | closed(&rule, at("2026-10-07T18:00:00Z")), |
| 173 | Some(Closed::Outside { opens: Some("2026-10-08T09:00:00.000Z".into()) }) |
| 174 | ); |
| 175 | // Friday: the next Monday. |
| 176 | assert_eq!( |
| 177 | closed(&rule, at("2026-10-09T10:00:00Z")), |
| 178 | Some(Closed::Outside { opens: Some("2026-10-12T09:00:00.000Z".into()) }) |
| 179 | ); |
| 180 | } |
| 181 | |
| 182 | #[test] |
| 183 | fn the_window_is_in_its_time_zone() { |
| 184 | let rule = MergeWindowRule { time_zone: "-05:00".into(), ..weekdays("09:00", "17:00") }; |
| 185 | // 13:00 UTC is 08:00 there: not yet. |
| 186 | assert!(closed(&rule, at("2026-10-07T13:00:00Z")).is_some()); |
| 187 | assert_eq!(closed(&rule, at("2026-10-07T15:00:00Z")), None); |
| 188 | } |
| 189 | |
| 190 | #[test] |
| 191 | fn a_window_can_run_past_midnight() { |
| 192 | let rule = MergeWindowRule { |
| 193 | windows: vec![WeeklyWindow { days: vec![Weekday::Fri], start: "22:00".into(), end: "02:00".into() }], |
| 194 | ..MergeWindowRule::default() |
| 195 | }; |
| 196 | assert_eq!(closed(&rule, at("2026-10-09T23:00:00Z")), None); |
| 197 | assert_eq!(closed(&rule, at("2026-10-10T01:00:00Z")), None); |
| 198 | assert!(closed(&rule, at("2026-10-10T03:00:00Z")).is_some()); |
| 199 | } |
| 200 | |
| 201 | #[test] |
| 202 | fn freezes_close_it_and_exceptions_open_it() { |
| 203 | let mut rule = weekdays("00:00", "24:00"); |
| 204 | rule.freezes.push(Period { start: "2026-10-07T00:00:00Z".into(), end: Some("2026-10-08T00:00:00Z".into()), reason: "Release".into() }); |
| 205 | rule.freezes.push(Period { start: "2026-10-12T00:00:00Z".into(), end: None, reason: String::new() }); |
| 206 | assert_eq!( |
| 207 | explain(&closed(&rule, at("2026-10-07T10:00:00Z")).unwrap()), |
| 208 | "Merging is frozen (Release) until 2026-10-08T00:00:00Z." |
| 209 | ); |
| 210 | assert_eq!(closed(&rule, at("2026-10-08T10:00:00Z")), None); |
| 211 | assert_eq!(explain(&closed(&rule, at("2026-10-13T10:00:00Z")).unwrap()), "Merging is frozen until the freeze is lifted."); |
| 212 | rule.exceptions.push(Period { start: "2026-10-07T12:00:00Z".into(), end: Some("2026-10-07T13:00:00Z".into()), reason: "Hotfix".into() }); |
| 213 | assert_eq!(closed(&rule, at("2026-10-07T12:30:00Z")), None); |
| 214 | } |
| 215 | } |