Add documentation to Message and Delivery

message.go

@@ -2,22 +2,37 @@ package messenger
 
 import "time"
 
+// Message represents a Facebook messenge message.
 type Message struct {
-	Sender      Sender       `json:"-"`
-	Recipient   Recipient    `json:"-"`
-	Time        time.Time    `json:"-"`
-	Mid         string       `json:"mid"`
-	Text        string       `json:"text"`
-	Seq         int          `json:"seq"`
+	// Sender is who the message was sent from.
+	Sender Sender `json:"-"`
+	// Recipient is who the message was sent to.
+	Recipient Recipient `json:"-"`
+	// Time is when the message was sent.
+	Time time.Time `json:"-"`
+	// Mid is the ID of the message.
+	Mid string `json:"mid"`
+	// Seq is order the message was sent in relation to other messages.
+	Seq int `json:"seq"`
+	// Text is the textual contents of the message.
+	Text string `json:"text"`
+	// Attachments is the information about the attachments which were sent
+	// with the message.
 	Attachments []Attachment `json:"attachments"`
 }
 
+// Delivery represents a the event fired when a recipient reads one of Messengers sent
+// messages.
 type Delivery struct {
-	Mids         []string `json:"mids"`
-	RawWatermark int64    `json:"watermark"`
-	Seq          int      `json:"seq"`
+	// Mids are the IDs of the messages which were read.
+	Mids []string `json:"mids"`
+	// RawWatermark is the timestamp contained in the message of when the read was.
+	RawWatermark int64 `json:"watermark"`
+	// Seq is the sequence the message was sent in.
+	Seq int `json:"seq"`
 }
 
+// Watermark is the RawWatermark timestamp rendered as a time.Time.
 func (d Delivery) Watermark() time.Time {
 	return time.Unix(d.RawWatermark, 0)
 }