74 lines
2 KiB
Go
74 lines
2 KiB
Go
package darwindb
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import (
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"fmt"
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"time"
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"git.lukegb.com/lukegb/depot/go/trains/darwin"
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)
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// secondsify adds :00 onto the end of a string if it's HH:MM formatted, otherwise does nothing.
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func secondsify(ts string) string {
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if len(ts) == 5 { // xx:xx (no seconds)
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return ts + ":00"
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}
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return ts
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}
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// startTime takes a train and ascertains its "start time".
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func startTime(s *darwin.Schedule) (time.Time, error) {
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// We assume these are sensibly sorted by Darwin.
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if len(s.CallingPoints) == 0 {
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return time.Time{}, fmt.Errorf("no calling points")
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}
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cp := s.CallingPoints[0]
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var ts string
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tsCandidates := []string{cp.WTD, cp.PTD, cp.WTP, cp.WTA, cp.PTA}
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for _, tsc := range tsCandidates {
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if tsc != "" {
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ts = tsc
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}
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}
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if ts == "" {
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return time.Time{}, fmt.Errorf("failed to find a suitable timestamp in first calling point")
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}
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ts = fmt.Sprintf("%v %v", s.SSD, secondsify(ts))
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t, err := time.ParseInLocation("2006-01-02 15:04:05", ts, darwin.London)
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if err != nil {
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return time.Time{}, fmt.Errorf("parsing start time %q: %w", ts, err)
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}
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return t, nil
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}
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// timeToTimestamp takes a string HH:MM and places it appropriately given the approximate 'start time' of the train.
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func timeToTimestamp(ts string, startTime time.Time) *time.Time {
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if ts == "" {
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return nil
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}
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ts = secondsify(ts)
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t, err := time.ParseInLocation("2006-01-02 15:04:05", startTime.Format("2006-01-02 ")+ts, darwin.London)
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if err != nil {
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return nil
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}
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// Follow Darwin rules for determining time skips
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// https://wiki.openraildata.com/index.php/Darwin:Schedule_Element#Ordering
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difference := t.Sub(startTime)
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switch {
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case difference > -6*time.Hour && difference < 18*time.Hour:
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return &t
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case difference <= -6*time.Hour:
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// e.g. 08:00 start time, 01:00 time "now" (-7 hrs) -- add a day
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t = t.AddDate(0, 0, 1)
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return &t
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case difference >= 18*time.Hour:
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// e.g. 01:00 start time, 22:00 time "now" (+18 hrs) -- sub a day
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t = t.AddDate(0, 0, -1)
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return &t
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}
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panic(fmt.Sprintf("unhandled difference %v", difference))
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}
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