Initial commit

calendar/calendarevent.go

@@ -0,0 +1,111 @@
+package calendar
+
+import (
+	"strings"
+	"time"
+
+	ics "github.com/arran4/golang-ical"
+)
+
+// CalendarClass is a class that represents what "class" the specified event is
+//
+// Currently, I have only observed this value as being `PUBLIC`, but other
+// values are handled as panics
+type CalendarClass byte
+
+const (
+	ClassPublic CalendarClass = iota
+)
+
+func ParseClass(raw string) CalendarClass {
+	switch raw {
+	case "PUBLIC":
+		return ClassPublic
+	}
+	panic("Unknown class: " + raw)
+}
+
+func (cc CalendarClass) String() string {
+	switch cc {
+	case ClassPublic:
+		return "PUBLIC"
+	default:
+		panic("Unknown class")
+	}
+}
+
+// CalendarEvent represents a single event in a calendar that is tied to a certain date
+type CalendarEvent struct {
+	UID string
+	// A summary of the event, including the name of the event
+	// This value is set every time as far as I can tell
+	Summary string
+	// A fescription of the event, including more specific information. Not always
+	// set, so don't rely on it
+	Description string
+	// Access class? of the event
+	Class        CalendarClass
+	LastModified time.Time
+	DateStamp    time.Time
+	StartTime    time.Time
+	EndTime      time.Time
+	// Every event comes with a category. This usually contains the name of the
+	// class, along with some other information (Semester code, CRN, sections)
+	Category struct {
+		ClassName string
+		OtherData string
+	}
+}
+
+const calendarTimeFormat = "20060102T150405Z"
+
+// FromVEvent parses an ICS VEvent's format and outputs a specific calendar event, or an error
+func FromVEvent(external *ics.VEvent) (event CalendarEvent, err error) {
+	if len(external.Components) > 0 {
+		panic("Event has unhandled components")
+	}
+
+	for _, prop := range external.Properties {
+		if len(prop.ICalParameters) > 0 {
+			panic("Property has unhandled ICalParameters")
+		}
+
+		switch prop.IANAToken {
+		case "UID":
+			event.UID = prop.Value
+		case "SUMMARY":
+			event.Summary = prop.Value
+		case "DESCRIPTION":
+			event.Description = prop.Value
+		case "CLASS":
+			event.Class = ParseClass(prop.Value)
+		case "LAST-MODIFIED":
+			event.LastModified, err = time.Parse(calendarTimeFormat, prop.Value)
+			if err != nil {
+				return event, err
+			}
+		case "DTSTAMP":
+			event.DateStamp, err = time.Parse(calendarTimeFormat, prop.Value)
+			if err != nil {
+				return event, err
+			}
+		case "DTSTART":
+			event.StartTime, err = time.Parse(calendarTimeFormat, prop.Value)
+			if err != nil {
+				return event, err
+			}
+		case "DTEND":
+			event.EndTime, err = time.Parse(calendarTimeFormat, prop.Value)
+			if err != nil {
+				return event, err
+			}
+		case "CATEGORIES":
+			dashIndex := strings.Index(prop.Value, "-")
+			event.Category.ClassName = prop.Value[:dashIndex]
+			event.Category.OtherData = prop.Value[dashIndex:]
+		default:
+			panic("Unknown token when parsing event: " + prop.IANAToken)
+		}
+	}
+	return event, nil
+}