make notification as separate package (#5294)

* Remove old notification files

* Add net package

* Add event package

* Modify minio to take new notification system

pkg/event/targetid.go

@@ -0,0 +1,73 @@
+/*
+ * Minio Cloud Storage, (C) 2018 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package event
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+// TargetID - holds identification and name strings of notification target.
+type TargetID struct {
+	ID   string
+	Name string
+}
+
+// String - returns string representation.
+func (tid TargetID) String() string {
+	return tid.ID + ":" + tid.Name
+}
+
+// ToARN - converts to ARN.
+func (tid TargetID) ToARN(region string) ARN {
+	return ARN{TargetID: tid, region: region}
+}
+
+// MarshalJSON - encodes to JSON data.
+func (tid TargetID) MarshalJSON() ([]byte, error) {
+	return json.Marshal(tid.String())
+}
+
+// UnmarshalJSON - decodes JSON data.
+func (tid *TargetID) UnmarshalJSON(data []byte) error {
+	var s string
+	if err := json.Unmarshal(data, &s); err != nil {
+		return err
+	}
+
+	targetID, err := parseTargetID(s)
+	if err != nil {
+		return err
+	}
+
+	*tid = *targetID
+	return nil
+}
+
+// parseTargetID - parses string to TargetID.
+func parseTargetID(s string) (*TargetID, error) {
+	tokens := strings.Split(s, ":")
+	if len(tokens) != 2 {
+		return nil, fmt.Errorf("invalid TargetID format '%v'", s)
+	}
+
+	return &TargetID{
+		ID:   tokens[0],
+		Name: tokens[1],
+	}, nil
+}