IconURL for GuildPreview and GuildWithCounts (#885)

* Add missing field

* Helpers

* Renames

* Use helper

* Add withCounts query option to Guild()

* Move IconURL

* Add IconURL to GuildPreview

* Update comments

* Send `[]` rather than `null` on empty activities slice

* Add more robust file support for webhooks

* Add withCounts query option to Guild()

* Update comments

* Split guild func

* Update structs.go

Co-authored-by: Fedor Lapshin <fe.lap.prog@gmail.com>

* Update structs.go

Co-authored-by: Fedor Lapshin <fe.lap.prog@gmail.com>

* Revert

* Format yaml

* Add IconURL to GuildPreview

* Revert

* Revert space

* Update restapi.go

Co-authored-by: Fedor Lapshin <fe.lap.prog@gmail.com>

* Remove variadic

* Revert yamls

* Remove param

* Hardcode string

Co-authored-by: Carson Hoffman <c@rsonhoffman.com>
Co-authored-by: Fedor Lapshin <fe.lap.prog@gmail.com>

restapi.go

@@ -472,6 +472,19 @@ func (s *Session) Guild(guildID string) (st *Guild, err error) {
 	return
 }
 
+// GuildWithCounts returns a Guild structure of a specific Guild with approximate member and presence counts.
+// guildID    : The ID of a Guild
+func (s *Session) GuildWithCounts(guildID string) (st *Guild, err error) {
+
+	body, err := s.RequestWithBucketID("GET", EndpointGuild(guildID)+"?with_counts=true", nil, EndpointGuild(guildID))
+	if err != nil {
+		return
+	}
+
+	err = unmarshal(body, &st)
+	return
+}
+
 // GuildPreview returns a GuildPreview structure of a specific public Guild.
 // guildID   : The ID of a Guild
 func (s *Session) GuildPreview(guildID string) (st *GuildPreview, err error) {
@@ -515,7 +528,7 @@ func (s *Session) GuildEdit(guildID string, g GuildParams) (st *Guild, err error
 		}
 	}
 
-	//Bounds checking for regions
+	// Bounds checking for regions
 	if g.Region != "" {
 		isValid := false
 		regions, _ := s.VoiceRegions()

structs.go

@@ -757,16 +757,31 @@ type GuildPreview struct {
 	// The list of enabled guild features
 	Features []string `json:"features"`
 
-	// Approximate number of members in this guild, returned from the GET /guild/<id> endpoint when with_counts is true
+	// Approximate number of members in this guild
+	// NOTE: this field is only filled when using GuildWithCounts
 	ApproximateMemberCount int `json:"approximate_member_count"`
 
-	// Approximate number of non-offline members in this guild, returned from the GET /guild/<id> endpoint when with_counts is true
+	// Approximate number of non-offline members in this guild
+	// NOTE: this field is only filled when using GuildWithCounts
 	ApproximatePresenceCount int `json:"approximate_presence_count"`
 
 	// the description for the guild
 	Description string `json:"description"`
 }
 
+// IconURL returns a URL to the guild's icon.
+func (g *GuildPreview) IconURL() string {
+	if g.Icon == "" {
+		return ""
+	}
+
+	if strings.HasPrefix(g.Icon, "a_") {
+		return EndpointGuildIconAnimated(g.ID, g.Icon)
+	}
+
+	return EndpointGuildIcon(g.ID, g.Icon)
+}
+
 // GuildScheduledEvent is a representation of a scheduled event in a guild. Only for retrieval of the data.
 // https://discord.com/developers/docs/resources/guild-scheduled-event#guild-scheduled-event
 type GuildScheduledEvent struct {