Implemented basic CalDAV query and parsing

src/calanonsync/calanonsync.go

@@ -169,6 +169,17 @@ func main() {
 	for _, item := range items {
 		fmt.Printf("%#v\n", item)
 	}
+
+	c := NewCalDAV(s.CalDAV)
+	calDavItems, err := c.GetEvents()
+	if err != nil {
+		log.Println(err)
+		return
+	}
+	for _, item := range calDavItems {
+		fmt.Printf("%s\n  UID: %s\n  Summary: %s\n  Start: %s\n  End: %s\n",
+			item.HRef, item.UID(), item.Summary(), item.Start(), item.End())
+	}
 }
 
 const folderIdRequest = `<?xml version="1.0" encoding="utf-8"?>

src/calanonsync/caldav.go

@@ -0,0 +1,176 @@
+package main
+
+import (
+	"bufio"
+	"encoding/xml"
+	"errors"
+	"io"
+	"log"
+	"net/http"
+	"strings"
+	"time"
+)
+
+const ICAL_TIME = "20060102T150405"
+const ICAL_DATE = "20060102"
+
+type CalDAV struct {
+	ServerSettings
+	httpClient *http.Client
+}
+
+type ICal struct {
+	data      []string
+	eventData []string // sub slice
+}
+
+func (i ICal) Summary() string {
+	for _, s := range i.eventData {
+		if strings.HasPrefix(s, "SUMMARY:") {
+			return s[len("SUMMARY:"):]
+		}
+	}
+	return ""
+}
+
+func (i ICal) UID() string {
+	for _, s := range i.eventData {
+		if strings.HasPrefix(s, "UID:") {
+			return s[len("UID:"):]
+		}
+	}
+	return ""
+}
+
+func (i ICal) getTimeField(f string) time.Time {
+	for _, s := range i.eventData {
+		if strings.HasPrefix(s, f) {
+			st := s[strings.LastIndex(s, ":")+1:]
+			// BEWARE, we don't parse possible ICal timezones (yet). If it is not
+			// a UTC time, we simply assume local time.
+			zone := time.Local
+			if st[len(st)-1:] == "Z" {
+				st = st[:len(st)-1]
+				zone = time.UTC
+			}
+			t, err := time.ParseInLocation(ICAL_TIME, st, zone)
+			if err != nil {
+				log.Printf("Cannot decode %s '%s': %s", f, st, err)
+			}
+			return t
+		}
+	}
+	return time.Time{}
+}
+
+func (i ICal) Start() time.Time {
+	return i.getTimeField("DTSTART")
+}
+
+func (i ICal) End() time.Time {
+	return i.getTimeField("DTEND")
+}
+
+func (i *ICal) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+	s := ""
+	err := d.DecodeElement(&s, &start)
+	if err != nil {
+		return err
+	}
+	ical, err := ParseICal(strings.NewReader(s))
+	if err != nil {
+		return err
+	}
+
+	*i = *ical
+	return nil
+}
+
+func ParseICal(r io.Reader) (*ICal, error) {
+	var data []string
+	scanner := bufio.NewScanner(r)
+	eventStart := -1
+	eventEnd := -1
+	i := 0
+	for scanner.Scan() {
+		line := scanner.Text()
+		data = append(data, line)
+
+		if eventStart == -1 && line == "BEGIN:VEVENT" {
+			eventStart = i
+		}
+		if eventEnd == -1 && line == "END:VEVENT" {
+			eventEnd = i
+		}
+
+		i++
+	}
+	err := scanner.Err()
+	if err != nil {
+		return nil, err
+	}
+
+	// If we didn't find a start or an end, abort.
+	if eventStart < 0 || eventEnd <= eventStart {
+		return nil, errors.New("calendar item without event")
+	}
+
+	return &ICal{
+		data:      data,
+		eventData: data[eventStart+1 : eventEnd],
+	}, err
+}
+
+func NewCalDAV(settings ServerSettings) *CalDAV {
+	return &CalDAV{
+		httpClient:     http.DefaultClient,
+		ServerSettings: settings,
+	}
+}
+
+type CalDAVItem struct {
+	HRef string
+	ICal
+}
+
+func (c *CalDAV) GetEvents() ([]CalDAVItem, error) {
+	req, err := http.NewRequest("PROPFIND", c.URL, strings.NewReader(`<propfind xmlns='DAV:'><prop><calendar-data xmlns='urn:ietf:params:xml:ns:caldav'/></prop></propfind>`))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "text/xml")
+	req.SetBasicAuth(c.Username, c.Password)
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	defer resp.Body.Close()
+	ms := &MultiStatus{}
+	err = xml.NewDecoder(resp.Body).Decode(ms)
+	if err != nil {
+		return nil, err
+	}
+
+	result := make([]CalDAVItem, 0, len(ms.Response))
+	for _, p := range ms.Response {
+		item := CalDAVItem{p.HRef, p.PropStat.Prop.CalendarData}
+		result = append(result, item)
+	}
+
+	return result, nil
+}
+
+type MultiStatus struct {
+	Response []PropFindResponse `xml:"response"`
+}
+
+type PropFindResponse struct {
+	HRef     string `xml:"href"`
+	PropStat struct {
+		Prop struct {
+			CalendarData ICal `xml:"calendar-data"`
+		} `xml:"prop"`
+	} `xml:"propstat"`
+}