Support animated avatar URLs (#388)

* Methods to obtain a user's avatar URL

* Created EndpointUserAvatarAnimated and updated AvatarURL

* Fixed the size parameter

endpoints.go

@@ -54,16 +54,17 @@ var (
 	EndpointReport       = EndpointAPI + "report"
 	EndpointIntegrations = EndpointAPI + "integrations"
 
-	EndpointUser              = func(uID string) string { return EndpointUsers + uID }
-	EndpointUserAvatar        = func(uID, aID string) string { return EndpointCDNAvatars + uID + "/" + aID + ".png" }
-	EndpointUserSettings      = func(uID string) string { return EndpointUsers + uID + "/settings" }
-	EndpointUserGuilds        = func(uID string) string { return EndpointUsers + uID + "/guilds" }
-	EndpointUserGuild         = func(uID, gID string) string { return EndpointUsers + uID + "/guilds/" + gID }
-	EndpointUserGuildSettings = func(uID, gID string) string { return EndpointUsers + uID + "/guilds/" + gID + "/settings" }
-	EndpointUserChannels      = func(uID string) string { return EndpointUsers + uID + "/channels" }
-	EndpointUserDevices       = func(uID string) string { return EndpointUsers + uID + "/devices" }
-	EndpointUserConnections   = func(uID string) string { return EndpointUsers + uID + "/connections" }
-	EndpointUserNotes         = func(uID string) string { return EndpointUsers + "@me/notes/" + uID }
+	EndpointUser               = func(uID string) string { return EndpointUsers + uID }
+	EndpointUserAvatar         = func(uID, aID string) string { return EndpointCDNAvatars + uID + "/" + aID + ".png" }
+	EndpointUserAvatarAnimated = func(uID, aID string) string { return EndpointCDNAvatars + uID + "/" + aID + ".gif" }
+	EndpointUserSettings       = func(uID string) string { return EndpointUsers + uID + "/settings" }
+	EndpointUserGuilds         = func(uID string) string { return EndpointUsers + uID + "/guilds" }
+	EndpointUserGuild          = func(uID, gID string) string { return EndpointUsers + uID + "/guilds/" + gID }
+	EndpointUserGuildSettings  = func(uID, gID string) string { return EndpointUsers + uID + "/guilds/" + gID + "/settings" }
+	EndpointUserChannels       = func(uID string) string { return EndpointUsers + uID + "/channels" }
+	EndpointUserDevices        = func(uID string) string { return EndpointUsers + uID + "/devices" }
+	EndpointUserConnections    = func(uID string) string { return EndpointUsers + uID + "/connections" }
+	EndpointUserNotes          = func(uID string) string { return EndpointUsers + "@me/notes/" + uID }
 
 	EndpointGuild                = func(gID string) string { return EndpointGuilds + gID }
 	EndpointGuildInivtes         = func(gID string) string { return EndpointGuilds + gID + "/invites" }

user.go

@@ -1,6 +1,9 @@
 package discordgo
 
-import "fmt"
+import (
+	"fmt"
+	"strings"
+)
 
 // A User stores all data for an individual Discord user.
 type User struct {
@@ -24,3 +27,16 @@ func (u *User) String() string {
 func (u *User) Mention() string {
 	return fmt.Sprintf("<@%s>", u.ID)
 }
+
+// AvatarURL returns a URL to the user's avatar.
+//		size:     The size of the user's avatar as a power of two
+func (u *User) AvatarURL(size string) string {
+	var URL string
+	if strings.HasPrefix(u.Avatar, "a_") {
+		URL = EndpointUserAvatarAnimated(u.ID, u.Avatar)
+	} else {
+		URL = EndpointUserAvatar(u.ID, u.Avatar)
+	}
+
+	return URL + "?size=" + size
+}