caldav: extend query filter types

The basic types related to queries and filtering are missing some
features specified in the RFC (as also noted in the TODO comments). This
adds several of the missing elements, working towards being able to
handle all RFC-compliant queries.

The work is not fully done, e.g. the collation for text-match is still
not handled, but it's getting pretty close.

caldav/elements.go

@@ -21,7 +21,8 @@ var (
 	calendarQueryName    = xml.Name{namespace, "calendar-query"}
 	calendarMultigetName = xml.Name{namespace, "calendar-multiget"}
 
-	calendarName = xml.Name{namespace, "calendar"}
+	calendarName     = xml.Name{namespace, "calendar"}
+	calendarDataName = xml.Name{namespace, "calendar-data"}
 )
 
 // https://tools.ietf.org/html/rfc4791#section-6.2.1
@@ -98,19 +99,49 @@ type compFilter struct {
 
 // https://tools.ietf.org/html/rfc4791#section-9.7.2
 type propFilter struct {
-	XMLName      xml.Name   `xml:"urn:ietf:params:xml:ns:caldav prop-filter"`
+	XMLName      xml.Name      `xml:"urn:ietf:params:xml:ns:caldav prop-filter"`
+	Name         string        `xml:"name,attr"`
+	IsNotDefined *struct{}     `xml:"is-not-defined,omitempty"`
+	TimeRange    *timeRange    `xml:"time-range,omitempty"`
+	TextMatch    *textMatch    `xml:"text-match,omitempty"`
+	ParamFilter  []paramFilter `xml:"param-filter,omitempty"`
+}
+
+// https://tools.ietf.org/html/rfc4791#section-9.7.3
+type paramFilter struct {
+	XMLName      xml.Name   `xml:"urn:ietf:params:xml:ns:caldav param-filter"`
 	Name         string     `xml:"name,attr"`
 	IsNotDefined *struct{}  `xml:"is-not-defined,omitempty"`
-	TimeRange    *timeRange `xml:"time-range,omitempty"`
 	TextMatch    *textMatch `xml:"text-match,omitempty"`
-	// TODO: param-filter
 }
 
 // https://tools.ietf.org/html/rfc4791#section-9.7.5
 type textMatch struct {
-	XMLName xml.Name `xml:"urn:ietf:params:xml:ns:caldav text-match"`
-	Text    string   `xml:",chardata"`
-	// TODO: collation, negate-condition
+	XMLName         xml.Name        `xml:"urn:ietf:params:xml:ns:caldav text-match"`
+	Text            string          `xml:",chardata"`
+	Collation       string          `xml:"collation,attr,omitempty"`
+	NegateCondition negateCondition `xml:"negate-condition,attr,omitempty"`
+}
+
+type negateCondition bool
+
+func (nc *negateCondition) UnmarshalText(b []byte) error {
+	switch s := string(b); s {
+	case "yes":
+		*nc = true
+	case "no":
+		*nc = false
+	default:
+		return fmt.Errorf("caldav: invalid negate-condition value: %q", s)
+	}
+	return nil
+}
+
+func (nc negateCondition) MarshalText() ([]byte, error) {
+	if nc {
+		return []byte("yes"), nil
+	}
+	return nil, nil
 }
 
 // https://tools.ietf.org/html/rfc4791#section-9.9