func fetchGroupHistory(api *slack.Client, ID string) []slack.Message { historyParams := slack.NewHistoryParameters() historyParams.Count = 1000 // Fetch History history, err := api.GetGroupHistory(ID, historyParams) check(err) messages := history.Messages latest := messages[len(messages)-1].Timestamp for { if history.HasMore != true { break } historyParams.Latest = latest history, err = api.GetGroupHistory(ID, historyParams) check(err) length := len(history.Messages) if length > 0 { latest = history.Messages[length-1].Timestamp messages = append(messages, history.Messages...) } } return messages }