| 1 | package calendar |
| 2 | |
| 3 | import ( |
| 4 | "regexp" |
| 5 | "strings" |
| 6 | "time" |
| 7 | ) |
| 8 | |
| 9 | // QuickParse is everything one typed sentence was understood to mean. |
| 10 | // |
| 11 | // It is a plain value, and ParseQuick is a pure function of (text, now, |
| 12 | // zone). That is deliberate: this is the one piece of the app whose |
| 13 | // correctness is entirely a question of "what does this sentence mean", |
| 14 | // so it is testable as a table of sentences and nothing else has to be |
| 15 | // stood up to ask it a question. |
| 16 | type QuickParse struct { |
| 17 | Title string |
| 18 | Location string |
| 19 | |
| 20 | // StartLocal and EndLocal are wall clock in the person's own zone, |
| 21 | // "2006-01-02T15:04" — the same form the create form submits, and |
| 22 | // the record the app stores (Ruling 1). |
| 23 | StartLocal string |
| 24 | EndLocal string |
| 25 | AllDay bool |
| 26 | |
| 27 | // Repeat is one of the picker's own six values, never a rule the |
| 28 | // picker cannot offer (Ruling 4). |
| 29 | Repeat string |
| 30 | |
| 31 | // Attendees are addresses found in the text. They are RECORDED, not |
| 32 | // invited: nothing is emailed to them. See Notes. |
| 33 | Attendees []string |
| 34 | |
| 35 | // Notes are the sentences the pane shows about what was assumed. |
| 36 | // Every defaulted field names itself here, because a default the |
| 37 | // person cannot see is a guess. |
| 38 | Notes []string |
| 39 | } |
| 40 | |
| 41 | // Empty reports whether nothing usable was typed. |
| 42 | func (q QuickParse) Empty() bool { |
| 43 | return strings.TrimSpace(q.Title) == "" && len(q.Attendees) == 0 |
| 44 | } |
| 45 | |
| 46 | // consumed marks the parts of the sentence that have already been |
| 47 | // understood. |
| 48 | // |
| 49 | // A parser that deleted matches as it went would lose the positions |
| 50 | // that later patterns need — "at" means one thing before a time has |
| 51 | // been taken out of the sentence and another thing after. Overwriting |
| 52 | // with NUL instead keeps every index stable AND stops a later regex |
| 53 | // matching across a hole, which is what makes "at 3pm in McCloskeys" |
| 54 | // resolve to a time and a place rather than to two places. |
| 55 | type consumed struct { |
| 56 | src []rune |
| 57 | work []rune |
| 58 | } |
| 59 | |
| 60 | func newConsumed(s string) *consumed { |
| 61 | r := []rune(s) |
| 62 | w := make([]rune, len(r)) |
| 63 | copy(w, r) |
| 64 | return &consumed{src: r, work: w} |
| 65 | } |
| 66 | |
| 67 | func (c *consumed) String() string { return string(c.work) } |
| 68 | |
| 69 | // take finds the first match of re in what is left and blanks it, |
| 70 | // returning the submatches. group is the capture whose span survives — |
| 71 | // pass 0 to consume the whole match. |
| 72 | func (c *consumed) take(re *regexp.Regexp) []string { |
| 73 | loc := re.FindStringSubmatchIndex(string(c.work)) |
| 74 | if loc == nil { |
| 75 | return nil |
| 76 | } |
| 77 | // Indices from FindStringSubmatchIndex are byte offsets into the |
| 78 | // string form; convert once to rune offsets so the blanking lines |
| 79 | // up on a sentence containing anything non-ASCII. |
| 80 | s := string(c.work) |
| 81 | from := len([]rune(s[:loc[0]])) |
| 82 | to := len([]rune(s[:loc[1]])) |
| 83 | for i := from; i < to; i++ { |
| 84 | c.work[i] = 0 |
| 85 | } |
| 86 | return matchStrings(s, loc) |
| 87 | } |
| 88 | |
| 89 | func matchStrings(s string, loc []int) []string { |
| 90 | out := make([]string, len(loc)/2) |
| 91 | for i := range out { |
| 92 | if loc[2*i] < 0 { |
| 93 | out[i] = "" |
| 94 | continue |
| 95 | } |
| 96 | out[i] = s[loc[2*i]:loc[2*i+1]] |
| 97 | } |
| 98 | return out |
| 99 | } |
| 100 | |
| 101 | // rest is what nobody claimed: the title. |
| 102 | func (c *consumed) rest() string { |
| 103 | var b strings.Builder |
| 104 | for _, r := range c.work { |
| 105 | if r == 0 { |
| 106 | b.WriteRune(' ') |
| 107 | continue |
| 108 | } |
| 109 | b.WriteRune(r) |
| 110 | } |
| 111 | return tidy(b.String()) |
| 112 | } |
| 113 | |
| 114 | var spaces = regexp.MustCompile(`\s+`) |
| 115 | |
| 116 | // tidy collapses the whitespace that blanking leaves behind and drops |
| 117 | // the joining words that only made sense next to what was removed. |
| 118 | func tidy(s string) string { |
| 119 | s = spaces.ReplaceAllString(s, " ") |
| 120 | s = strings.TrimSpace(s) |
| 121 | // Leading and trailing connectives, e.g. "Coffee with" once the |
| 122 | // address has been lifted out of "Coffee with doc@example.com". |
| 123 | for { |
| 124 | before := s |
| 125 | for _, w := range []string{"with", "at", "in", "on", "from", "to", "and", "-", "–", ","} { |
| 126 | s = strings.TrimSpace(strings.TrimSuffix(s, " "+w)) |
| 127 | if strings.EqualFold(s, w) { |
| 128 | s = "" |
| 129 | } |
| 130 | s = strings.TrimSpace(strings.TrimPrefix(s, w+" ")) |
| 131 | } |
| 132 | s = strings.Trim(s, " ,-–") |
| 133 | if s == before { |
| 134 | return s |
| 135 | } |
| 136 | } |
| 137 | } |
| 138 | |
| 139 | // ParseQuick reads one typed sentence into an event. |
| 140 | // |
| 141 | // The ORDER of these steps is the design, not an implementation detail. |
| 142 | // Addresses go first because an address contains characters every later |
| 143 | // pattern would misread. Times are taken before places because "at" is |
| 144 | // ambiguous and time has to win it: read places first and "at 3pm in |
| 145 | // McCloskeys" books a meeting in a place called "3pm". |
| 146 | func ParseQuick(text string, now time.Time, zone string) QuickParse { |
| 147 | var q QuickParse |
| 148 | c := newConsumed(text) |
| 149 | |
| 150 | q.Attendees = takeAttendees(c) |
| 151 | q.AllDay = takeAllDay(c) |
| 152 | q.Repeat = takeRepeat(c) |
| 153 | |
| 154 | when := takeSpan(c, now) |
| 155 | start, end, timeFound := takeTimes(c) |
| 156 | dur, durFound := takeDuration(c) |
| 157 | |
| 158 | q.Location = takeLocation(c) |
| 159 | q.Title = c.rest() |
| 160 | |
| 161 | q.fill(now, zone, when, start, end, timeFound, dur, durFound) |
| 162 | return q |
| 163 | } |
| 164 | |
| 165 | // fill turns what was found into a start and an end, and writes a note |
| 166 | // for every part it had to decide on its own. |
| 167 | func (q *QuickParse) fill(now time.Time, zone string, when span, |
| 168 | start, end clockTime, timeFound bool, dur time.Duration, durFound bool) { |
| 169 | |
| 170 | day, last := when.start, when.last |
| 171 | if !when.found { |
| 172 | day, last = now, now |
| 173 | } |
| 174 | |
| 175 | // A RUN of days with no clock anywhere in the sentence is an |
| 176 | // all-day event. "london tues-thurs" is a trip, and reading it as an |
| 177 | // hour on Tuesday with a two-day tail nobody asked for would be |
| 178 | // wrong in a way the pane could not show. |
| 179 | if when.isRange && !timeFound && !q.AllDay { |
| 180 | q.AllDay = true |
| 181 | q.Notes = append(q.Notes, |
| 182 | "A run of days with no time, so this is an all-day event.") |
| 183 | } |
| 184 | |
| 185 | if q.AllDay { |
| 186 | // A DATE, never a datetime at midnight - that is what puts a |
| 187 | // birthday on the wrong day west of Greenwich. And the end is |
| 188 | // EXCLUSIVE like every other range in this app: the day AFTER |
| 189 | // the last one. Writing the same date twice makes an all-day |
| 190 | // event of zero length, which the validator refuses outright. |
| 191 | q.StartLocal = day.Format(LayoutDate) |
| 192 | q.EndLocal = last.AddDate(0, 0, 1).Format(LayoutDate) |
| 193 | q.note(when.found, len(q.Attendees) > 0) |
| 194 | return |
| 195 | } |
| 196 | |
| 197 | if !timeFound { |
| 198 | // The next half hour, said out loud rather than assumed. |
| 199 | next := nextHalfHour(now) |
| 200 | if !when.found { |
| 201 | day, last = next, next |
| 202 | } |
| 203 | start = clockTime{h: next.Hour(), m: next.Minute()} |
| 204 | q.Notes = append(q.Notes, |
| 205 | "No time found, so this starts at the next half hour.") |
| 206 | } |
| 207 | |
| 208 | startAt := time.Date(day.Year(), day.Month(), day.Day(), start.h, start.m, 0, 0, time.UTC) |
| 209 | |
| 210 | // Every end lands on the LAST day of the span, which is the same day |
| 211 | // as the start unless a range was read - so there is one rule here |
| 212 | // rather than a range case bolted onto a single-day one. |
| 213 | var endAt time.Time |
| 214 | switch { |
| 215 | case end.set: |
| 216 | endAt = time.Date(last.Year(), last.Month(), last.Day(), end.h, end.m, 0, 0, time.UTC) |
| 217 | // "9pm to 1am" crosses midnight; an end before its start is the |
| 218 | // next day rather than a negative meeting. |
| 219 | if !endAt.After(startAt) { |
| 220 | endAt = endAt.AddDate(0, 0, 1) |
| 221 | } |
| 222 | case durFound: |
| 223 | endAt = time.Date(last.Year(), last.Month(), last.Day(), start.h, start.m, 0, 0, time.UTC).Add(dur) |
| 224 | default: |
| 225 | endAt = time.Date(last.Year(), last.Month(), last.Day(), start.h, start.m, 0, 0, time.UTC).Add(time.Hour) |
| 226 | if when.isRange { |
| 227 | q.Notes = append(q.Notes, |
| 228 | "No end time found, so this ends an hour after it starts on the last day.") |
| 229 | } else { |
| 230 | q.Notes = append(q.Notes, "No end time found, so this lasts an hour.") |
| 231 | } |
| 232 | } |
| 233 | |
| 234 | q.StartLocal = startAt.Format(LayoutLocal) |
| 235 | q.EndLocal = endAt.Format(LayoutLocal) |
| 236 | q.note(when.found, len(q.Attendees) > 0) |
| 237 | } |
| 238 | |
| 239 | // note adds the two sentences every branch above owes the pane. They |
| 240 | // live here because the all-day branch returns early and used to skip |
| 241 | // the attendee one - the single line a person most needs to read. |
| 242 | func (q *QuickParse) note(dayFound, haveAttendees bool) { |
| 243 | if !dayFound { |
| 244 | q.Notes = append(q.Notes, "No date found, so this is today.") |
| 245 | } |
| 246 | if haveAttendees { |
| 247 | q.Notes = append(q.Notes, |
| 248 | "Nobody is emailed. Attendees are recorded on the event only.") |
| 249 | } |
| 250 | } |
| 251 | |
| 252 | // nextHalfHour rounds forward to the next :00 or :30. |
| 253 | func nextHalfHour(now time.Time) time.Time { |
| 254 | t := now.Truncate(time.Minute) |
| 255 | switch { |
| 256 | case t.Minute() < 30: |
| 257 | return t.Add(time.Duration(30-t.Minute()) * time.Minute) |
| 258 | default: |
| 259 | return t.Add(time.Duration(60-t.Minute()) * time.Minute) |
| 260 | } |
| 261 | } |
| 262 | |
amadan