| 1 | package calendar |
| 2 | |
| 3 | import ( |
| 4 | "regexp" |
| 5 | "strconv" |
| 6 | "strings" |
| 7 | "time" |
| 8 | ) |
| 9 | |
| 10 | // span is the day, or the RUN of days, that one sentence named. |
| 11 | // |
| 12 | // last is INCLUSIVE and equals start unless a range was read. "london |
| 13 | // tues–thurs" is three days in London: read as a single date it becomes |
| 14 | // a Tuesday with the word "thurs" stranded in the title, which is what |
| 15 | // it did before this file existed. |
| 16 | type span struct { |
| 17 | start time.Time |
| 18 | last time.Time |
| 19 | found bool |
| 20 | isRange bool |
| 21 | } |
| 22 | |
| 23 | func oneDay(t time.Time, found bool) span { |
| 24 | return span{start: t, last: t, found: found} |
| 25 | } |
| 26 | |
| 27 | // rangeSep is what people actually type between two dates. The hyphen |
| 28 | // family has three members because a keyboard gives you "-" and macOS |
| 29 | // substitutes "–" behind your back mid-sentence — the screenshot that |
| 30 | // prompted this had an en dash nobody typed. |
| 31 | const rangeSep = `(?:\s*[-–—]\s*|\s+(?:to|until|till|through|thru)\s+)` |
| 32 | |
| 33 | var ( |
| 34 | // A run of weekdays: "tues–thurs", "Monday to Wednesday". |
| 35 | reWeekdayRange = regexp.MustCompile(`(?i)\b(?:from\s+)?(?:(next|this)\s+)?(?:on\s+)?(` + |
| 36 | weekdayAlt + `)` + rangeSep + `(?:next\s+)?(` + weekdayAlt + `)\b`) |
| 37 | // Two full dates: "12 March to 14 April". |
| 38 | reDateRange = regexp.MustCompile(`(?i)\b(?:from\s+)?(?:on\s+)?(\d{1,2})(?:st|nd|rd|th)?\s+(` + |
| 39 | monthAlt + `)` + rangeSep + `(\d{1,2})(?:st|nd|rd|th)?\s+(` + monthAlt + `)\b`) |
| 40 | // Days sharing a month: "12–14 March". |
| 41 | reDayDayMonth = regexp.MustCompile(`(?i)\b(?:from\s+)?(?:on\s+)?(\d{1,2})(?:st|nd|rd|th)?` + |
| 42 | rangeSep + `(\d{1,2})(?:st|nd|rd|th)?\s+(` + monthAlt + `)\b`) |
| 43 | // The same, month first: "March 12–14". |
| 44 | reMonthDayDay = regexp.MustCompile(`(?i)\b(?:from\s+)?(?:on\s+)?(` + monthAlt + |
| 45 | `)\s+(\d{1,2})(?:st|nd|rd|th)?` + rangeSep + `(\d{1,2})(?:st|nd|rd|th)?\b`) |
| 46 | // Numeric: "12/3-14/3". |
| 47 | reNumericRange = regexp.MustCompile(`\b(?:from\s+)?(?:on\s+)?(\d{1,2})/(\d{1,2})` + |
| 48 | rangeSep + `(\d{1,2})/(\d{1,2})\b`) |
| 49 | ) |
| 50 | |
| 51 | // takeSpan reads the day or the run of days out of the sentence. |
| 52 | // |
| 53 | // Every RANGE pattern is tried before any single-date one, and that |
| 54 | // ordering is the whole fix. Run the singles first and "12–14 March" |
| 55 | // matches "14 March" — the range's own end date — leaving a "12" behind |
| 56 | // in the title and booking one day instead of three. |
| 57 | // |
| 58 | // Ranges are tried before takeTimes for the same reason a single date |
| 59 | // is: the patterns here all require a month name, a weekday name or a |
| 60 | // slash, so "Retro 3-4pm" cannot reach them. That is deliberate. A |
| 61 | // digits-only range with no calendar word in it is a time, always. |
| 62 | func takeSpan(c *consumed, now time.Time) span { |
| 63 | if m := c.take(reDateRange); m != nil { |
| 64 | d1, _ := strconv.Atoi(m[1]) |
| 65 | d2, _ := strconv.Atoi(m[3]) |
| 66 | s := onOrAfter(now, months[strings.ToLower(m[2])], d1) |
| 67 | e := time.Date(s.Year(), months[strings.ToLower(m[4])], d2, 0, 0, 0, 0, now.Location()) |
| 68 | return rangeSpan(s, e, 1, 0) |
| 69 | } |
| 70 | if m := c.take(reDayDayMonth); m != nil { |
| 71 | d1, _ := strconv.Atoi(m[1]) |
| 72 | d2, _ := strconv.Atoi(m[2]) |
| 73 | mo := months[strings.ToLower(m[3])] |
| 74 | s := onOrAfter(now, mo, d1) |
| 75 | // A month rolls rather than a year: "30–2 April" is the 30th of |
| 76 | // March only if somebody wrote it that way, but "30–2 May" read |
| 77 | // as a year later would be absurd. |
| 78 | return rangeSpan(s, time.Date(s.Year(), mo, d2, 0, 0, 0, 0, now.Location()), 0, 1) |
| 79 | } |
| 80 | if m := c.take(reMonthDayDay); m != nil { |
| 81 | d1, _ := strconv.Atoi(m[2]) |
| 82 | d2, _ := strconv.Atoi(m[3]) |
| 83 | mo := months[strings.ToLower(m[1])] |
| 84 | s := onOrAfter(now, mo, d1) |
| 85 | return rangeSpan(s, time.Date(s.Year(), mo, d2, 0, 0, 0, 0, now.Location()), 0, 1) |
| 86 | } |
| 87 | if m := c.take(reNumericRange); m != nil { |
| 88 | return rangeSpan(numericDay(now, m[1], m[2]), numericDay(now, m[3], m[4]), 1, 0) |
| 89 | } |
| 90 | if m := c.take(reWeekdayRange); m != nil { |
| 91 | s := nextWeekday(now, weekdays[strings.ToLower(m[2])], strings.EqualFold(m[1], "next")) |
| 92 | // The end is the FIRST of that weekday on or after the start, so |
| 93 | // "Sunday to Tuesday" crosses the week boundary instead of |
| 94 | // running backwards into a negative event. |
| 95 | delta := (int(weekdays[strings.ToLower(m[3])]) - int(s.Weekday()) + 7) % 7 |
| 96 | return span{start: s, last: s.AddDate(0, 0, delta), found: true, isRange: true} |
| 97 | } |
| 98 | day, found := takeDate(c, now) |
| 99 | return oneDay(day, found) |
| 100 | } |
| 101 | |
| 102 | // rangeSpan makes an end that is not before its start, rolling forward |
| 103 | // by years or months as the caller's units say. |
| 104 | func rangeSpan(s, e time.Time, years, months int) span { |
| 105 | if e.Before(s) { |
| 106 | e = e.AddDate(years, months, 0) |
| 107 | } |
| 108 | return span{start: s, last: e, found: true, isRange: true} |
| 109 | } |
| 110 | |
| 111 | func numericDay(now time.Time, dd, mm string) time.Time { |
| 112 | d, _ := strconv.Atoi(dd) |
| 113 | mo, _ := strconv.Atoi(mm) |
| 114 | return time.Date(now.Year(), time.Month(mo), d, 0, 0, 0, 0, now.Location()) |
| 115 | } |
| 116 | |
amadan