diff --git a/vendor/github.com/slack-go/slack/slackevents/action_events.go b/vendor/github.com/slack-go/slack/slackevents/action_events.go
new file mode 100644
index 00000000..c6016f10
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/slackevents/action_events.go
@@ -0,0 +1,36 @@
+package slackevents
+
+import (
+	"encoding/json"
+
+	"github.com/slack-go/slack"
+)
+
+type MessageActionResponse struct {
+	ResponseType    string `json:"response_type"`
+	ReplaceOriginal bool   `json:"replace_original"`
+	Text            string `json:"text"`
+}
+
+type MessageActionEntity struct {
+	ID     string `json:"id"`
+	Domain string `json:"domain"`
+	Name   string `json:"name"`
+}
+
+type MessageAction struct {
+	Type             string                   `json:"type"`
+	Actions          []slack.AttachmentAction `json:"actions"`
+	CallbackID       string                   `json:"callback_id"`
+	Team             MessageActionEntity      `json:"team"`
+	Channel          MessageActionEntity      `json:"channel"`
+	User             MessageActionEntity      `json:"user"`
+	ActionTimestamp  json.Number              `json:"action_ts"`
+	MessageTimestamp json.Number              `json:"message_ts"`
+	AttachmentID     json.Number              `json:"attachment_id"`
+	Token            string                   `json:"token"`
+	Message          slack.Message            `json:"message"`
+	OriginalMessage  slack.Message            `json:"original_message"`
+	ResponseURL      string                   `json:"response_url"`
+	TriggerID        string                   `json:"trigger_id"`
+}
diff --git a/vendor/github.com/slack-go/slack/slackevents/inner_events.go b/vendor/github.com/slack-go/slack/slackevents/inner_events.go
new file mode 100644
index 00000000..452328e8
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/slackevents/inner_events.go
@@ -0,0 +1,506 @@
+// inner_events.go provides EventsAPI particular inner events
+
+package slackevents
+
+import (
+	"encoding/json"
+
+	"github.com/slack-go/slack"
+)
+
+// EventsAPIInnerEvent the inner event of a EventsAPI event_callback Event.
+type EventsAPIInnerEvent struct {
+	Type string `json:"type"`
+	Data interface{}
+}
+
+// AppMentionEvent is an (inner) EventsAPI subscribable event.
+type AppMentionEvent struct {
+	Type            string      `json:"type"`
+	User            string      `json:"user"`
+	Text            string      `json:"text"`
+	TimeStamp       string      `json:"ts"`
+	ThreadTimeStamp string      `json:"thread_ts"`
+	Channel         string      `json:"channel"`
+	EventTimeStamp  json.Number `json:"event_ts"`
+
+	// When Message comes from a channel that is shared between workspaces
+	UserTeam   string `json:"user_team,omitempty"`
+	SourceTeam string `json:"source_team,omitempty"`
+
+	// BotID is filled out when a bot triggers the app_mention event
+	BotID string `json:"bot_id,omitempty"`
+}
+
+// AppHomeOpenedEvent Your Slack app home was opened.
+type AppHomeOpenedEvent struct {
+	Type           string      `json:"type"`
+	User           string      `json:"user"`
+	Channel        string      `json:"channel"`
+	EventTimeStamp json.Number `json:"event_ts"`
+	Tab            string      `json:"tab"`
+	View           slack.View  `json:"view"`
+}
+
+// AppUninstalledEvent Your Slack app was uninstalled.
+type AppUninstalledEvent struct {
+	Type string `json:"type"`
+}
+
+// ChannelCreatedEvent represents the Channel created event
+type ChannelCreatedEvent struct {
+	Type           string             `json:"type"`
+	Channel        ChannelCreatedInfo `json:"channel"`
+	EventTimestamp string             `json:"event_ts"`
+}
+
+// ChannelDeletedEvent represents the Channel deleted event
+type ChannelDeletedEvent struct {
+	Type    string `json:"type"`
+	Channel string `json:"channel"`
+}
+
+// ChannelArchiveEvent represents the Channel archive event
+type ChannelArchiveEvent struct {
+	Type    string `json:"type"`
+	Channel string `json:"channel"`
+	User    string `json:"user"`
+}
+
+// ChannelUnarchiveEvent represents the Channel unarchive event
+type ChannelUnarchiveEvent struct {
+	Type    string `json:"type"`
+	Channel string `json:"channel"`
+	User    string `json:"user"`
+}
+
+// ChannelLeftEvent represents the Channel left event
+type ChannelLeftEvent struct {
+	Type    string `json:"type"`
+	Channel string `json:"channel"`
+}
+
+// ChannelRenameEvent represents the Channel rename event
+type ChannelRenameEvent struct {
+	Type    string            `json:"type"`
+	Channel ChannelRenameInfo `json:"channel"`
+}
+
+// ChannelIDChangedEvent represents the Channel identifier changed event
+type ChannelIDChangedEvent struct {
+	Type           string `json:"type"`
+	OldChannelID   string `json:"old_channel_id"`
+	NewChannelID   string `json:"new_channel_id"`
+	EventTimestamp string `json:"event_ts"`
+}
+
+// ChannelCreatedInfo represents the information associated with the Channel created event
+type ChannelCreatedInfo struct {
+	ID        string `json:"id"`
+	IsChannel bool   `json:"is_channel"`
+	Name      string `json:"name"`
+	Created   int    `json:"created"`
+	Creator   string `json:"creator"`
+}
+
+// ChannelRenameInfo represents the information associated with the Channel rename event
+type ChannelRenameInfo struct {
+	ID      string `json:"id"`
+	Name    string `json:"name"`
+	Created int    `json:"created"`
+}
+
+// GroupDeletedEvent represents the Group deleted event
+type GroupDeletedEvent struct {
+	Type    string `json:"type"`
+	Channel string `json:"channel"`
+}
+
+// GroupArchiveEvent represents the Group archive event
+type GroupArchiveEvent struct {
+	Type    string `json:"type"`
+	Channel string `json:"channel"`
+}
+
+// GroupUnarchiveEvent represents the Group unarchive event
+type GroupUnarchiveEvent struct {
+	Type    string `json:"type"`
+	Channel string `json:"channel"`
+}
+
+// GroupLeftEvent represents the Group left event
+type GroupLeftEvent struct {
+	Type    string `json:"type"`
+	Channel string `json:"channel"`
+}
+
+// GroupRenameEvent represents the Group rename event
+type GroupRenameEvent struct {
+	Type    string          `json:"type"`
+	Channel GroupRenameInfo `json:"channel"`
+}
+
+// GroupRenameInfo represents the information associated with the Group rename event
+type GroupRenameInfo struct {
+	ID      string `json:"id"`
+	Name    string `json:"name"`
+	Created int    `json:"created"`
+}
+
+// GridMigrationFinishedEvent An enterprise grid migration has finished on this workspace.
+type GridMigrationFinishedEvent struct {
+	Type         string `json:"type"`
+	EnterpriseID string `json:"enterprise_id"`
+}
+
+// GridMigrationStartedEvent An enterprise grid migration has started on this workspace.
+type GridMigrationStartedEvent struct {
+	Type         string `json:"type"`
+	EnterpriseID string `json:"enterprise_id"`
+}
+
+// LinkSharedEvent A message was posted containing one or more links relevant to your application
+type LinkSharedEvent struct {
+	Type      string `json:"type"`
+	User      string `json:"user"`
+	TimeStamp string `json:"ts"`
+	Channel   string `json:"channel"`
+	// MessageTimeStamp can be both a numeric timestamp if the LinkSharedEvent corresponds to a sent
+	// message and (contrary to the field name) a uuid if the LinkSharedEvent is generated in the
+	// compose text area.
+	MessageTimeStamp string        `json:"message_ts"`
+	ThreadTimeStamp  string        `json:"thread_ts"`
+	Links            []sharedLinks `json:"links"`
+}
+
+type sharedLinks struct {
+	Domain string `json:"domain"`
+	URL    string `json:"url"`
+}
+
+// MessageEvent occurs when a variety of types of messages has been posted.
+// Parse ChannelType to see which
+// if ChannelType = "group", this is a private channel message
+// if ChannelType = "channel", this message was sent to a channel
+// if ChannelType = "im", this is a private message
+// if ChannelType = "mim", A message was posted in a multiparty direct message channel
+// TODO: Improve this so that it is not required to manually parse ChannelType
+type MessageEvent struct {
+	// Basic Message Event - https://api.slack.com/events/message
+	ClientMsgID     string      `json:"client_msg_id"`
+	Type            string      `json:"type"`
+	User            string      `json:"user"`
+	Text            string      `json:"text"`
+	ThreadTimeStamp string      `json:"thread_ts"`
+	TimeStamp       string      `json:"ts"`
+	Channel         string      `json:"channel"`
+	ChannelType     string      `json:"channel_type"`
+	EventTimeStamp  json.Number `json:"event_ts"`
+
+	// When Message comes from a channel that is shared between workspaces
+	UserTeam   string `json:"user_team,omitempty"`
+	SourceTeam string `json:"source_team,omitempty"`
+
+	// Edited Message
+	Message         *MessageEvent `json:"message,omitempty"`
+	PreviousMessage *MessageEvent `json:"previous_message,omitempty"`
+	Edited          *Edited       `json:"edited,omitempty"`
+
+	// Message Subtypes
+	SubType string `json:"subtype,omitempty"`
+
+	// bot_message (https://api.slack.com/events/message/bot_message)
+	BotID    string `json:"bot_id,omitempty"`
+	Username string `json:"username,omitempty"`
+	Icons    *Icon  `json:"icons,omitempty"`
+
+	Upload bool   `json:"upload"`
+	Files  []File `json:"files"`
+
+	Attachments []slack.Attachment `json:"attachments,omitempty"`
+
+	// Root is the message that was broadcast to the channel when the SubType is
+	// thread_broadcast. If this is not a thread_broadcast message event, this
+	// value is nil.
+	Root *MessageEvent `json:"root"`
+}
+
+// MemberJoinedChannelEvent A member joined a public or private channel
+type MemberJoinedChannelEvent struct {
+	Type        string `json:"type"`
+	User        string `json:"user"`
+	Channel     string `json:"channel"`
+	ChannelType string `json:"channel_type"`
+	Team        string `json:"team"`
+	Inviter     string `json:"inviter"`
+}
+
+// MemberLeftChannelEvent A member left a public or private channel
+type MemberLeftChannelEvent struct {
+	Type        string `json:"type"`
+	User        string `json:"user"`
+	Channel     string `json:"channel"`
+	ChannelType string `json:"channel_type"`
+	Team        string `json:"team"`
+}
+
+type pinEvent struct {
+	Type           string `json:"type"`
+	User           string `json:"user"`
+	Item           Item   `json:"item"`
+	Channel        string `json:"channel_id"`
+	EventTimestamp string `json:"event_ts"`
+	HasPins        bool   `json:"has_pins,omitempty"`
+}
+
+type reactionEvent struct {
+	Type           string `json:"type"`
+	User           string `json:"user"`
+	Reaction       string `json:"reaction"`
+	ItemUser       string `json:"item_user"`
+	Item           Item   `json:"item"`
+	EventTimestamp string `json:"event_ts"`
+}
+
+// ReactionAddedEvent An reaction was added to a message - https://api.slack.com/events/reaction_added
+type ReactionAddedEvent reactionEvent
+
+// ReactionRemovedEvent An reaction was removed from a message - https://api.slack.com/events/reaction_removed
+type ReactionRemovedEvent reactionEvent
+
+// PinAddedEvent An item was pinned to a channel - https://api.slack.com/events/pin_added
+type PinAddedEvent pinEvent
+
+// PinRemovedEvent An item was unpinned from a channel - https://api.slack.com/events/pin_removed
+type PinRemovedEvent pinEvent
+
+type tokens struct {
+	Oauth []string `json:"oauth"`
+	Bot   []string `json:"bot"`
+}
+
+// TeamJoinEvent A new member joined a workspace -  https://api.slack.com/events/team_join
+type TeamJoinEvent struct {
+	Type string      `json:"type"`
+	User *slack.User `json:"user"`
+}
+
+// TokensRevokedEvent APP's API tokes are revoked - https://api.slack.com/events/tokens_revoked
+type TokensRevokedEvent struct {
+	Type   string `json:"type"`
+	Tokens tokens `json:"tokens"`
+}
+
+// EmojiChangedEvent is the event of custom emoji has been added or changed
+type EmojiChangedEvent struct {
+	Type           string      `json:"type"`
+	Subtype        string      `json:"subtype"`
+	EventTimeStamp json.Number `json:"event_ts"`
+
+	// filled out when custom emoji added
+	Name string `json:"name,omitempty"`
+
+	// filled out when custom emoji removed
+	Names []string `json:"names,omitempty"`
+
+	// filled out when custom emoji renamed
+	OldName string `json:"old_name,omitempty"`
+	NewName string `json:"new_name,omitempty"`
+
+	// filled out when custom emoji added or renamed
+	Value string `json:"value,omitempty"`
+}
+
+// JSONTime exists so that we can have a String method converting the date
+type JSONTime int64
+
+// Comment contains all the information relative to a comment
+type Comment struct {
+	ID        string   `json:"id,omitempty"`
+	Created   JSONTime `json:"created,omitempty"`
+	Timestamp JSONTime `json:"timestamp,omitempty"`
+	User      string   `json:"user,omitempty"`
+	Comment   string   `json:"comment,omitempty"`
+}
+
+// File is a file upload
+type File struct {
+	ID                 string `json:"id"`
+	Created            int    `json:"created"`
+	Timestamp          int    `json:"timestamp"`
+	Name               string `json:"name"`
+	Title              string `json:"title"`
+	Mimetype           string `json:"mimetype"`
+	Filetype           string `json:"filetype"`
+	PrettyType         string `json:"pretty_type"`
+	User               string `json:"user"`
+	Editable           bool   `json:"editable"`
+	Size               int    `json:"size"`
+	Mode               string `json:"mode"`
+	IsExternal         bool   `json:"is_external"`
+	ExternalType       string `json:"external_type"`
+	IsPublic           bool   `json:"is_public"`
+	PublicURLShared    bool   `json:"public_url_shared"`
+	DisplayAsBot       bool   `json:"display_as_bot"`
+	Username           string `json:"username"`
+	URLPrivate         string `json:"url_private"`
+	URLPrivateDownload string `json:"url_private_download"`
+	Thumb64            string `json:"thumb_64"`
+	Thumb80            string `json:"thumb_80"`
+	Thumb360           string `json:"thumb_360"`
+	Thumb360W          int    `json:"thumb_360_w"`
+	Thumb360H          int    `json:"thumb_360_h"`
+	Thumb480           string `json:"thumb_480"`
+	Thumb480W          int    `json:"thumb_480_w"`
+	Thumb480H          int    `json:"thumb_480_h"`
+	Thumb160           string `json:"thumb_160"`
+	Thumb720           string `json:"thumb_720"`
+	Thumb720W          int    `json:"thumb_720_w"`
+	Thumb720H          int    `json:"thumb_720_h"`
+	Thumb800           string `json:"thumb_800"`
+	Thumb800W          int    `json:"thumb_800_w"`
+	Thumb800H          int    `json:"thumb_800_h"`
+	Thumb960           string `json:"thumb_960"`
+	Thumb960W          int    `json:"thumb_960_w"`
+	Thumb960H          int    `json:"thumb_960_h"`
+	Thumb1024          string `json:"thumb_1024"`
+	Thumb1024W         int    `json:"thumb_1024_w"`
+	Thumb1024H         int    `json:"thumb_1024_h"`
+	ImageExifRotation  int    `json:"image_exif_rotation"`
+	OriginalW          int    `json:"original_w"`
+	OriginalH          int    `json:"original_h"`
+	Permalink          string `json:"permalink"`
+	PermalinkPublic    string `json:"permalink_public"`
+}
+
+// Edited is included when a Message is edited
+type Edited struct {
+	User      string `json:"user"`
+	TimeStamp string `json:"ts"`
+}
+
+// Icon is used for bot messages
+type Icon struct {
+	IconURL   string `json:"icon_url,omitempty"`
+	IconEmoji string `json:"icon_emoji,omitempty"`
+}
+
+// Item is any type of slack message - message, file, or file comment.
+type Item struct {
+	Type      string       `json:"type"`
+	Channel   string       `json:"channel,omitempty"`
+	Message   *ItemMessage `json:"message,omitempty"`
+	File      *File        `json:"file,omitempty"`
+	Comment   *Comment     `json:"comment,omitempty"`
+	Timestamp string       `json:"ts,omitempty"`
+}
+
+// ItemMessage is the event message
+type ItemMessage struct {
+	Type            string   `json:"type"`
+	User            string   `json:"user"`
+	Text            string   `json:"text"`
+	Timestamp       string   `json:"ts"`
+	PinnedTo        []string `json:"pinned_to"`
+	ReplaceOriginal bool     `json:"replace_original"`
+	DeleteOriginal  bool     `json:"delete_original"`
+}
+
+// IsEdited checks if the MessageEvent is caused by an edit
+func (e MessageEvent) IsEdited() bool {
+	return e.Message != nil &&
+		e.Message.Edited != nil
+}
+
+const (
+	// AppMention is an Events API subscribable event
+	AppMention = "app_mention"
+	// AppHomeOpened Your Slack app home was opened
+	AppHomeOpened = "app_home_opened"
+	// AppUninstalled Your Slack app was uninstalled.
+	AppUninstalled = "app_uninstalled"
+	// ChannelCreated is sent when a new channel is created.
+	ChannelCreated = "channel_created"
+	// ChannelDeleted is sent when a channel is deleted.
+	ChannelDeleted = "channel_deleted"
+	// ChannelArchive is sent when a channel is archived.
+	ChannelArchive = "channel_archive"
+	// ChannelUnarchive is sent when a channel is unarchived.
+	ChannelUnarchive = "channel_unarchive"
+	// ChannelLeft is sent when a channel is left.
+	ChannelLeft = "channel_left"
+	// ChannelRename is sent when a channel is rename.
+	ChannelRename = "channel_rename"
+	// ChannelIDChanged is sent when a channel identifier is changed.
+	ChannelIDChanged = "channel_id_changed"
+	// GroupDeleted is sent when a group is deleted.
+	GroupDeleted = "group_deleted"
+	// GroupArchive is sent when a group is archived.
+	GroupArchive = "group_archive"
+	// GroupUnarchive is sent when a group is unarchived.
+	GroupUnarchive = "group_unarchive"
+	// GroupLeft is sent when a group is left.
+	GroupLeft = "group_left"
+	// GroupRename is sent when a group is renamed.
+	GroupRename = "group_rename"
+	// GridMigrationFinished An enterprise grid migration has finished on this workspace.
+	GridMigrationFinished = "grid_migration_finished"
+	// GridMigrationStarted An enterprise grid migration has started on this workspace.
+	GridMigrationStarted = "grid_migration_started"
+	// LinkShared A message was posted containing one or more links relevant to your application
+	LinkShared = "link_shared"
+	// Message A message was posted to a channel, private channel (group), im, or mim
+	Message = "message"
+	// Member Joined Channel
+	MemberJoinedChannel = "member_joined_channel"
+	// Member Left Channel
+	MemberLeftChannel = "member_left_channel"
+	// PinAdded An item was pinned to a channel
+	PinAdded = "pin_added"
+	// PinRemoved An item was unpinned from a channel
+	PinRemoved = "pin_removed"
+	// ReactionAdded An reaction was added to a message
+	ReactionAdded = "reaction_added"
+	// ReactionRemoved An reaction was removed from a message
+	ReactionRemoved = "reaction_removed"
+	// TeamJoin A new user joined the workspace
+	TeamJoin = "team_join"
+	// TokensRevoked APP's API tokes are revoked
+	TokensRevoked = "tokens_revoked"
+	// EmojiChanged A custom emoji has been added or changed
+	EmojiChanged = "emoji_changed"
+)
+
+// EventsAPIInnerEventMapping maps INNER Event API events to their corresponding struct
+// implementations. The structs should be instances of the unmarshalling
+// target for the matching event type.
+var EventsAPIInnerEventMapping = map[string]interface{}{
+	AppMention:            AppMentionEvent{},
+	AppHomeOpened:         AppHomeOpenedEvent{},
+	AppUninstalled:        AppUninstalledEvent{},
+	ChannelCreated:        ChannelCreatedEvent{},
+	ChannelDeleted:        ChannelDeletedEvent{},
+	ChannelArchive:        ChannelArchiveEvent{},
+	ChannelUnarchive:      ChannelUnarchiveEvent{},
+	ChannelLeft:           ChannelLeftEvent{},
+	ChannelRename:         ChannelRenameEvent{},
+	ChannelIDChanged:      ChannelIDChangedEvent{},
+	GroupDeleted:          GroupDeletedEvent{},
+	GroupArchive:          GroupArchiveEvent{},
+	GroupUnarchive:        GroupUnarchiveEvent{},
+	GroupLeft:             GroupLeftEvent{},
+	GroupRename:           GroupRenameEvent{},
+	GridMigrationFinished: GridMigrationFinishedEvent{},
+	GridMigrationStarted:  GridMigrationStartedEvent{},
+	LinkShared:            LinkSharedEvent{},
+	Message:               MessageEvent{},
+	MemberJoinedChannel:   MemberJoinedChannelEvent{},
+	MemberLeftChannel:     MemberLeftChannelEvent{},
+	PinAdded:              PinAddedEvent{},
+	PinRemoved:            PinRemovedEvent{},
+	ReactionAdded:         ReactionAddedEvent{},
+	ReactionRemoved:       ReactionRemovedEvent{},
+	TeamJoin:              TeamJoinEvent{},
+	TokensRevoked:         TokensRevokedEvent{},
+	EmojiChanged:          EmojiChangedEvent{},
+}
diff --git a/vendor/github.com/slack-go/slack/slackevents/outer_events.go b/vendor/github.com/slack-go/slack/slackevents/outer_events.go
new file mode 100644
index 00000000..8d682cc3
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/slackevents/outer_events.go
@@ -0,0 +1,71 @@
+// outer_events.go provides EventsAPI particular outer events
+
+package slackevents
+
+import (
+	"encoding/json"
+)
+
+// EventsAPIEvent is the base EventsAPIEvent
+type EventsAPIEvent struct {
+	Token        string `json:"token"`
+	TeamID       string `json:"team_id"`
+	Type         string `json:"type"`
+	APIAppID     string `json:"api_app_id"`
+	EnterpriseID string `json:"enterprise_id"`
+	Data         interface{}
+	InnerEvent   EventsAPIInnerEvent
+}
+
+// EventsAPIURLVerificationEvent received when configuring a EventsAPI driven app
+type EventsAPIURLVerificationEvent struct {
+	Token     string `json:"token"`
+	Challenge string `json:"challenge"`
+	Type      string `json:"type"`
+}
+
+// ChallengeResponse is a response to a EventsAPIEvent URLVerification challenge
+type ChallengeResponse struct {
+	Challenge string
+}
+
+// EventsAPICallbackEvent is the main (outer) EventsAPI event.
+type EventsAPICallbackEvent struct {
+	Type         string           `json:"type"`
+	Token        string           `json:"token"`
+	TeamID       string           `json:"team_id"`
+	APIAppID     string           `json:"api_app_id"`
+	InnerEvent   *json.RawMessage `json:"event"`
+	AuthedUsers  []string         `json:"authed_users"`
+	AuthedTeams  []string         `json:"authed_teams"`
+	EventID      string           `json:"event_id"`
+	EventTime    int              `json:"event_time"`
+	EventContext string           `json:"event_context"`
+}
+
+// EventsAPIAppRateLimited indicates your app's event subscriptions are being rate limited
+type EventsAPIAppRateLimited struct {
+	Type              string `json:"type"`
+	Token             string `json:"token"`
+	TeamID            string `json:"team_id"`
+	MinuteRateLimited int    `json:"minute_rate_limited"`
+	APIAppID          string `json:"api_app_id"`
+}
+
+const (
+	// CallbackEvent is the "outer" event of an EventsAPI event.
+	CallbackEvent = "event_callback"
+	// URLVerification is an event used when configuring your EventsAPI app
+	URLVerification = "url_verification"
+	// AppRateLimited indicates your app's event subscriptions are being rate limited
+	AppRateLimited = "app_rate_limited"
+)
+
+// EventsAPIEventMap maps OUTTER Event API events to their corresponding struct
+// implementations. The structs should be instances of the unmarshalling
+// target for the matching event type.
+var EventsAPIEventMap = map[string]interface{}{
+	CallbackEvent:   EventsAPICallbackEvent{},
+	URLVerification: EventsAPIURLVerificationEvent{},
+	AppRateLimited:  EventsAPIAppRateLimited{},
+}
diff --git a/vendor/github.com/slack-go/slack/slackevents/parsers.go b/vendor/github.com/slack-go/slack/slackevents/parsers.go
new file mode 100644
index 00000000..0cc584c7
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/slackevents/parsers.go
@@ -0,0 +1,258 @@
+package slackevents
+
+import (
+	"crypto/subtle"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"reflect"
+
+	"github.com/slack-go/slack"
+)
+
+// eventsMap checks both slack.EventsMapping and
+// and slackevents.EventsAPIInnerEventMapping. If the event
+// exists, returns the the unmarshalled struct instance of
+// target for the matching event type.
+// TODO: Consider moving all events into its own package?
+func eventsMap(t string) (interface{}, bool) {
+	// Must parse EventsAPI FIRST as both RTM and EventsAPI
+	// have a type: "Message" event.
+	// TODO: Handle these cases more explicitly.
+	v, exists := EventsAPIInnerEventMapping[t]
+	if exists {
+		return v, exists
+	}
+	v, exists = slack.EventMapping[t]
+	if exists {
+		return v, exists
+	}
+	return v, exists
+}
+
+func parseOuterEvent(rawE json.RawMessage) (EventsAPIEvent, error) {
+	e := &EventsAPIEvent{}
+	err := json.Unmarshal(rawE, e)
+	if err != nil {
+		return EventsAPIEvent{
+			"",
+			"",
+			"unmarshalling_error",
+			"",
+			"",
+			&slack.UnmarshallingErrorEvent{ErrorObj: err},
+			EventsAPIInnerEvent{},
+		}, err
+	}
+	if e.Type == CallbackEvent {
+		cbEvent := &EventsAPICallbackEvent{}
+		err = json.Unmarshal(rawE, cbEvent)
+		if err != nil {
+			return EventsAPIEvent{
+				"",
+				"",
+				"unmarshalling_error",
+				"",
+				"",
+				&slack.UnmarshallingErrorEvent{ErrorObj: err},
+				EventsAPIInnerEvent{},
+			}, err
+		}
+		return EventsAPIEvent{
+			e.Token,
+			e.TeamID,
+			e.Type,
+			e.APIAppID,
+			e.EnterpriseID,
+			cbEvent,
+			EventsAPIInnerEvent{},
+		}, nil
+	}
+	urlVE := &EventsAPIURLVerificationEvent{}
+	err = json.Unmarshal(rawE, urlVE)
+	if err != nil {
+		return EventsAPIEvent{
+			"",
+			"",
+			"unmarshalling_error",
+			"",
+			"",
+			&slack.UnmarshallingErrorEvent{ErrorObj: err},
+			EventsAPIInnerEvent{},
+		}, err
+	}
+	return EventsAPIEvent{
+		e.Token,
+		e.TeamID,
+		e.Type,
+		e.APIAppID,
+		e.EnterpriseID,
+		urlVE,
+		EventsAPIInnerEvent{},
+	}, nil
+}
+
+func parseInnerEvent(e *EventsAPICallbackEvent) (EventsAPIEvent, error) {
+	iE := &slack.Event{}
+	rawInnerJSON := e.InnerEvent
+	err := json.Unmarshal(*rawInnerJSON, iE)
+	if err != nil {
+		return EventsAPIEvent{
+			e.Token,
+			e.TeamID,
+			"unmarshalling_error",
+			e.APIAppID,
+			"",
+			&slack.UnmarshallingErrorEvent{ErrorObj: err},
+			EventsAPIInnerEvent{},
+		}, err
+	}
+	v, exists := eventsMap(iE.Type)
+	if !exists {
+		return EventsAPIEvent{
+			e.Token,
+			e.TeamID,
+			iE.Type,
+			e.APIAppID,
+			"",
+			nil,
+			EventsAPIInnerEvent{},
+		}, fmt.Errorf("Inner Event does not exist! %s", iE.Type)
+	}
+	t := reflect.TypeOf(v)
+	recvEvent := reflect.New(t).Interface()
+	err = json.Unmarshal(*rawInnerJSON, recvEvent)
+	if err != nil {
+		return EventsAPIEvent{
+			e.Token,
+			e.TeamID,
+			"unmarshalling_error",
+			e.APIAppID,
+			"",
+			&slack.UnmarshallingErrorEvent{ErrorObj: err},
+			EventsAPIInnerEvent{},
+		}, err
+	}
+	return EventsAPIEvent{
+		e.Token,
+		e.TeamID,
+		e.Type,
+		e.APIAppID,
+		"",
+		e,
+		EventsAPIInnerEvent{iE.Type, recvEvent},
+	}, nil
+}
+
+type Config struct {
+	VerificationToken string
+	TokenVerified     bool
+}
+
+type Option func(cfg *Config)
+
+type verifier interface {
+	Verify(token string) bool
+}
+
+func OptionVerifyToken(v verifier) Option {
+	return func(cfg *Config) {
+		cfg.TokenVerified = v.Verify(cfg.VerificationToken)
+	}
+}
+
+// OptionNoVerifyToken skips the check of the Slack verification token
+func OptionNoVerifyToken() Option {
+	return func(cfg *Config) {
+		cfg.TokenVerified = true
+	}
+}
+
+type TokenComparator struct {
+	VerificationToken string
+}
+
+func (c TokenComparator) Verify(t string) bool {
+	return subtle.ConstantTimeCompare([]byte(c.VerificationToken), []byte(t)) == 1
+}
+
+// ParseEvent parses the outter and inner events (if applicable) of an events
+// api event returning a EventsAPIEvent type. If the event is a url_verification event,
+// the inner event is empty.
+func ParseEvent(rawEvent json.RawMessage, opts ...Option) (EventsAPIEvent, error) {
+	e, err := parseOuterEvent(rawEvent)
+	if err != nil {
+		return EventsAPIEvent{}, err
+	}
+
+	cfg := &Config{}
+	cfg.VerificationToken = e.Token
+	for _, opt := range opts {
+		opt(cfg)
+	}
+
+	if !cfg.TokenVerified {
+		return EventsAPIEvent{}, errors.New("Invalid verification token")
+	}
+
+	if e.Type == CallbackEvent {
+		cbEvent := e.Data.(*EventsAPICallbackEvent)
+		innerEvent, err := parseInnerEvent(cbEvent)
+		if err != nil {
+			err := fmt.Errorf("EventsAPI Error parsing inner event: %s, %s", innerEvent.Type, err)
+			return EventsAPIEvent{
+				"",
+				"",
+				"unmarshalling_error",
+				"",
+				"",
+				&slack.UnmarshallingErrorEvent{ErrorObj: err},
+				EventsAPIInnerEvent{},
+			}, err
+		}
+		return innerEvent, nil
+	}
+	urlVerificationEvent := &EventsAPIURLVerificationEvent{}
+	err = json.Unmarshal(rawEvent, urlVerificationEvent)
+	if err != nil {
+		return EventsAPIEvent{
+			"",
+			"",
+			"unmarshalling_error",
+			"",
+			"",
+			&slack.UnmarshallingErrorEvent{ErrorObj: err},
+			EventsAPIInnerEvent{},
+		}, err
+	}
+	return EventsAPIEvent{
+		e.Token,
+		e.TeamID,
+		e.Type,
+		e.APIAppID,
+		e.EnterpriseID,
+		urlVerificationEvent,
+		EventsAPIInnerEvent{},
+	}, nil
+}
+
+func ParseActionEvent(payloadString string, opts ...Option) (MessageAction, error) {
+	byteString := []byte(payloadString)
+	action := MessageAction{}
+	err := json.Unmarshal(byteString, &action)
+	if err != nil {
+		return MessageAction{}, errors.New("MessageAction unmarshalling failed")
+	}
+
+	cfg := &Config{}
+	cfg.VerificationToken = action.Token
+	for _, opt := range opts {
+		opt(cfg)
+	}
+
+	if !cfg.TokenVerified {
+		return MessageAction{}, errors.New("invalid verification token")
+	} else {
+		return action, nil
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/socketmode/client.go b/vendor/github.com/slack-go/slack/socketmode/client.go
new file mode 100644
index 00000000..8fd0b987
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/socketmode/client.go
@@ -0,0 +1,63 @@
+package socketmode
+
+import (
+	"encoding/json"
+	"time"
+
+	"github.com/slack-go/slack"
+
+	"github.com/gorilla/websocket"
+)
+
+type ConnectedEvent struct {
+	ConnectionCount int // 1 = first time, 2 = second time
+	Info            *slack.SocketModeConnection
+}
+
+type DebugInfo struct {
+	// Host is the name of the host name on the Slack end, that can be something like `applink-7fc4fdbb64-4x5xq`
+	Host string `json:"host"`
+
+	// `hello` type only
+	BuildNumber               int `json:"build_number"`
+	ApproximateConnectionTime int `json:"approximate_connection_time"`
+}
+
+type ConnectionInfo struct {
+	AppID string `json:"app_id"`
+}
+
+type SocketModeMessagePayload struct {
+	Event json.RawMessage `json:"event"`
+}
+
+// Client is a Socket Mode client that allows programs to use [Events API](https://api.slack.com/events-api)
+// and [interactive components](https://api.slack.com/interactivity) over WebSocket.
+// Please see [Intro to Socket Mode](https://api.slack.com/apis/connections/socket) for more information
+// on Socket Mode.
+//
+// The implementation is highly inspired by https://www.npmjs.com/package/@slack/socket-mode,
+// but the structure and the design has been adapted as much as possible to that of our RTM client for consistency
+// within the library.
+//
+// You can instantiate the socket mode client with
+// Client's New() and call Run() to start it. Please see examples/socketmode for the usage.
+type Client struct {
+	// Client is the main API, embedded
+	slack.Client
+
+	// maxPingInterval is the maximum duration elapsed after the last WebSocket PING sent from Slack
+	// until Client considers the WebSocket connection is dead and needs to be reopened.
+	maxPingInterval time.Duration
+
+	// Connection life-cycle
+	Events              chan Event
+	socketModeResponses chan *Response
+
+	// dialer is a gorilla/websocket Dialer. If nil, use the default
+	// Dialer.
+	dialer *websocket.Dialer
+
+	debug bool
+	log   ilogger
+}
diff --git a/vendor/github.com/slack-go/slack/socketmode/deadman.go b/vendor/github.com/slack-go/slack/socketmode/deadman.go
new file mode 100644
index 00000000..7aeea760
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/socketmode/deadman.go
@@ -0,0 +1,31 @@
+package socketmode
+
+import "time"
+
+type deadmanTimer struct {
+	timeout time.Duration
+	timer   *time.Timer
+}
+
+func newDeadmanTimer(timeout time.Duration) *deadmanTimer {
+	return &deadmanTimer{
+		timeout: timeout,
+		timer:   time.NewTimer(timeout),
+	}
+}
+
+func (smc *deadmanTimer) Elapsed() <-chan time.Time {
+	return smc.timer.C
+}
+
+func (smc *deadmanTimer) Reset() {
+	// Note that this is the correct way to Reset a non-expired timer
+	if !smc.timer.Stop() {
+		select {
+		case <-smc.timer.C:
+		default:
+		}
+	}
+
+	smc.timer.Reset(smc.timeout)
+}
diff --git a/vendor/github.com/slack-go/slack/socketmode/event.go b/vendor/github.com/slack-go/slack/socketmode/event.go
new file mode 100644
index 00000000..5ae434a7
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/socketmode/event.go
@@ -0,0 +1,30 @@
+package socketmode
+
+import "encoding/json"
+
+// Event is the event sent to the consumer of Client
+type Event struct {
+	Type EventType
+	Data interface{}
+
+	// Request is the json-decoded raw WebSocket message that is received via the Slack Socket Mode
+	// WebSocket connection.
+	Request *Request
+}
+
+type ErrorBadMessage struct {
+	Cause   error
+	Message json.RawMessage
+}
+
+type ErrorWriteFailed struct {
+	Cause    error
+	Response *Response
+}
+
+type errorRequestedDisconnect struct {
+}
+
+func (e errorRequestedDisconnect) Error() string {
+	return "disconnection requested: Slack requested us to disconnect"
+}
diff --git a/vendor/github.com/slack-go/slack/socketmode/log.go b/vendor/github.com/slack-go/slack/socketmode/log.go
new file mode 100644
index 00000000..9f3b7f69
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/socketmode/log.go
@@ -0,0 +1,51 @@
+package socketmode
+
+import "fmt"
+
+// TODO merge logger, ilogger, and internalLogger with the top-level package's equivalents
+
+// logger is a logger interface compatible with both stdlib and some
+// 3rd party loggers.
+type logger interface {
+	Output(int, string) error
+}
+
+// ilogger represents the internal logging api we use.
+type ilogger interface {
+	logger
+	Print(...interface{})
+	Printf(string, ...interface{})
+	Println(...interface{})
+}
+
+// internalLog implements the additional methods used by our internal logging.
+type internalLog struct {
+	logger
+}
+
+// Println replicates the behaviour of the standard logger.
+func (t internalLog) Println(v ...interface{}) {
+	t.Output(2, fmt.Sprintln(v...))
+}
+
+// Printf replicates the behaviour of the standard logger.
+func (t internalLog) Printf(format string, v ...interface{}) {
+	t.Output(2, fmt.Sprintf(format, v...))
+}
+
+// Print replicates the behaviour of the standard logger.
+func (t internalLog) Print(v ...interface{}) {
+	t.Output(2, fmt.Sprint(v...))
+}
+
+func (smc *Client) Debugf(format string, v ...interface{}) {
+	if smc.debug {
+		smc.log.Output(2, fmt.Sprintf(format, v...))
+	}
+}
+
+func (smc *Client) Debugln(v ...interface{}) {
+	if smc.debug {
+		smc.log.Output(2, fmt.Sprintln(v...))
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/socketmode/request.go b/vendor/github.com/slack-go/slack/socketmode/request.go
new file mode 100644
index 00000000..078003a0
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/socketmode/request.go
@@ -0,0 +1,38 @@
+package socketmode
+
+import "encoding/json"
+
+// Request maps to the content of each WebSocket message received via a Socket Mode WebSocket connection
+//
+// We call this a "request" rather than e.g. a WebSocket message or an Socket Mode "event" following python-slack-sdk:
+//
+//   https://github.com/slackapi/python-slack-sdk/blob/3f1c4c6e27bf7ee8af57699b2543e6eb7848bcf9/slack_sdk/socket_mode/request.py#L6
+//
+// We know that node-slack-sdk calls it an "event", that makes it hard for us to distinguish our client's own event
+// that wraps both internal events and Socket Mode "events", vs node-slack-sdk's is for the latter only.
+//
+// https://github.com/slackapi/node-slack-sdk/blob/main/packages/socket-mode/src/SocketModeClient.ts#L537
+type Request struct {
+	Type string `json:"type"`
+
+	// `hello` type only
+	NumConnections int            `json:"num_connections"`
+	ConnectionInfo ConnectionInfo `json:"connection_info"`
+
+	// `disconnect` type only
+
+	// Reason can be "warning" or else
+	Reason string `json:"reason"`
+
+	// `hello` and `disconnect` types only
+	DebugInfo DebugInfo `json:"debug_info"`
+
+	// `events_api` type only
+	EnvelopeID string `json:"envelope_id"`
+	// TODO Can it really be a non-object type?
+	// See https://github.com/slackapi/python-slack-sdk/blob/3f1c4c6e27bf7ee8af57699b2543e6eb7848bcf9/slack_sdk/socket_mode/request.py#L26-L31
+	Payload                json.RawMessage `json:"payload"`
+	AcceptsResponsePayload bool            `json:"accepts_response_payload"`
+	RetryAttempt           int             `json:"retry_attempt"`
+	RetryReason            string          `json:"retry_reason"`
+}
diff --git a/vendor/github.com/slack-go/slack/socketmode/response.go b/vendor/github.com/slack-go/slack/socketmode/response.go
new file mode 100644
index 00000000..5c7bfabc
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/socketmode/response.go
@@ -0,0 +1,6 @@
+package socketmode
+
+type Response struct {
+	EnvelopeID string      `json:"envelope_id"`
+	Payload    interface{} `json:"payload,omitempty"`
+}
diff --git a/vendor/github.com/slack-go/slack/socketmode/socket_mode_managed_conn.go b/vendor/github.com/slack-go/slack/socketmode/socket_mode_managed_conn.go
new file mode 100644
index 00000000..9373a6be
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/socketmode/socket_mode_managed_conn.go
@@ -0,0 +1,567 @@
+package socketmode
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+	"time"
+
+	"github.com/slack-go/slack"
+	"github.com/slack-go/slack/internal/backoff"
+	"github.com/slack-go/slack/internal/misc"
+	"github.com/slack-go/slack/slackevents"
+
+	"github.com/gorilla/websocket"
+	"github.com/slack-go/slack/internal/timex"
+)
+
+// Run is a blocking function that connects the Slack Socket Mode API and handles all incoming
+// requests and outgoing responses.
+//
+// The consumer of the Client and this function should read the Client.Events channel to receive
+// `socketmode.Event`s that includes the client-specific events that may or may not wrap Socket Mode requests.
+//
+// Note that this function automatically reconnect on requested by Slack through a `disconnect` message.
+// This function exists with an error only when a reconnection is failued due to some reason.
+// If you want to retry even on reconnection failure, you'd need to write your own wrapper for this function
+// to do so.
+func (smc *Client) Run() error {
+	return smc.RunContext(context.TODO())
+}
+
+// RunContext is a blocking function that connects the Slack Socket Mode API and handles all incoming
+// requests and outgoing responses.
+//
+// The consumer of the Client and this function should read the Client.Events channel to receive
+// `socketmode.Event`s that includes the client-specific events that may or may not wrap Socket Mode requests.
+//
+// Note that this function automatically reconnect on requested by Slack through a `disconnect` message.
+// This function exists with an error only when a reconnection is failued due to some reason.
+// If you want to retry even on reconnection failure, you'd need to write your own wrapper for this function
+// to do so.
+func (smc *Client) RunContext(ctx context.Context) error {
+	for connectionCount := 0; ; connectionCount++ {
+		if err := smc.run(ctx, connectionCount); err != nil {
+			return err
+		}
+
+		// Continue and run the loop again to reconnect
+	}
+}
+
+func (smc *Client) run(ctx context.Context, connectionCount int) error {
+	messages := make(chan json.RawMessage)
+	defer close(messages)
+
+	deadmanTimer := newDeadmanTimer(smc.maxPingInterval)
+
+	pingHandler := func(_ string) error {
+		deadmanTimer.Reset()
+
+		return nil
+	}
+
+	// Start trying to connect
+	// the returned err is already passed onto the Events channel
+	//
+	// We also configures an additional ping handler for the deadmanTimer that triggers a timeout when
+	// Slack did not send us WebSocket PING for more than Client.maxPingInterval.
+	// We can use `<-smc.pingTimeout.C` to wait for the timeout.
+	info, conn, err := smc.connect(ctx, connectionCount, pingHandler)
+	if err != nil {
+		// when the connection is unsuccessful its fatal, and we need to bail out.
+		smc.Debugf("Failed to connect with Socket Mode on try %d: %s", connectionCount, err)
+
+		return err
+	}
+
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	smc.Events <- newEvent(EventTypeConnected, &ConnectedEvent{
+		ConnectionCount: connectionCount,
+		Info:            info,
+	})
+
+	smc.Debugf("WebSocket connection succeeded on try %d", connectionCount)
+
+	// We're now connected so we can set up listeners
+
+	var (
+		wg           sync.WaitGroup
+		firstErr     error
+		firstErrOnce sync.Once
+	)
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		defer cancel()
+
+		// The response sender sends Socket Mode responses over the WebSocket conn
+		if err := smc.runResponseSender(ctx, conn); err != nil {
+			firstErrOnce.Do(func() {
+				firstErr = err
+			})
+		}
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		defer cancel()
+
+		// The handler reads Socket Mode requests, and enqueues responses for sending by the response sender
+		if err := smc.runRequestHandler(ctx, messages); err != nil {
+			firstErrOnce.Do(func() {
+				firstErr = err
+			})
+		}
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		defer cancel()
+
+		// The receiver reads WebSocket messages, and enqueues parsed Socket Mode requests to be handled by
+		// the request handler
+		if err := smc.runMessageReceiver(ctx, conn, messages); err != nil {
+			firstErrOnce.Do(func() {
+				firstErr = err
+			})
+		}
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		select {
+		case <-ctx.Done():
+			// Detect when the connection is dead and try close connection.
+			if err = conn.Close(); err != nil {
+				smc.Debugf("Failed to close connection: %v", err)
+			}
+		case <-deadmanTimer.Elapsed():
+			firstErrOnce.Do(func() {
+				firstErr = errors.New("ping timeout: Slack did not send us WebSocket PING for more than Client.maxInterval")
+			})
+
+			cancel()
+		}
+	}()
+
+	wg.Wait()
+
+	if firstErr == context.Canceled {
+		return firstErr
+	}
+
+	// wg.Wait() finishes only after any of the above go routines finishes.
+	// Also, we can expect firstErr to be not nil, as goroutines can finish only on error.
+	smc.Debugf("Reconnecting due to %v", firstErr)
+
+	return nil
+}
+
+// connect attempts to connect to the slack websocket API. It handles any
+// errors that occur while connecting and will return once a connection
+// has been successfully opened.
+func (smc *Client) connect(ctx context.Context, connectionCount int, additionalPingHandler func(string) error) (*slack.SocketModeConnection, *websocket.Conn, error) {
+	const (
+		errInvalidAuth      = "invalid_auth"
+		errInactiveAccount  = "account_inactive"
+		errMissingAuthToken = "not_authed"
+		errTokenRevoked     = "token_revoked"
+	)
+
+	// used to provide exponential backoff wait time with jitter before trying
+	// to connect to slack again
+	boff := &backoff.Backoff{
+		Max: 5 * time.Minute,
+	}
+
+	for {
+		var (
+			backoff time.Duration
+		)
+
+		// send connecting event
+		smc.Events <- newEvent(EventTypeConnecting, &slack.ConnectingEvent{
+			Attempt:         boff.Attempts() + 1,
+			ConnectionCount: connectionCount,
+		})
+
+		// attempt to start the connection
+		info, conn, err := smc.openAndDial(ctx, additionalPingHandler)
+		if err == nil {
+			return info, conn, nil
+		}
+
+		// check for fatal errors
+		switch err.Error() {
+		case errInvalidAuth, errInactiveAccount, errMissingAuthToken, errTokenRevoked:
+			smc.Debugf("invalid auth when connecting with SocketMode: %s", err)
+			return nil, nil, err
+		default:
+		}
+
+		switch actual := err.(type) {
+		case misc.StatusCodeError:
+			if actual.Code == http.StatusNotFound {
+				smc.Debugf("invalid auth when connecting with Socket Mode: %s", err)
+				smc.Events <- newEvent(EventTypeInvalidAuth, &slack.InvalidAuthEvent{})
+				return nil, nil, err
+			}
+		case *slack.RateLimitedError:
+			backoff = actual.RetryAfter
+		default:
+		}
+
+		backoff = timex.Max(backoff, boff.Duration())
+		// any other errors are treated as recoverable and we try again after
+		// sending the event along the Events channel
+		smc.Events <- newEvent(EventTypeConnectionError, &slack.ConnectionErrorEvent{
+			Attempt:  boff.Attempts(),
+			Backoff:  backoff,
+			ErrorObj: err,
+		})
+
+		// get time we should wait before attempting to connect again
+		smc.Debugf("reconnection %d failed: %s reconnecting in %v\n", boff.Attempts(), err, backoff)
+
+		// wait for one of the following to occur,
+		// backoff duration has elapsed, disconnectCh is signalled, or
+		// the smc finishes disconnecting.
+		select {
+		case <-time.After(backoff): // retry after the backoff.
+		case <-ctx.Done():
+			return nil, nil, ctx.Err()
+		}
+	}
+}
+
+// openAndDial attempts to open a Socket Mode connection and dial to the connection endpoint using WebSocket.
+// It returns the  full information returned by the "apps.connections.open" method on the
+// Slack API.
+func (smc *Client) openAndDial(ctx context.Context, additionalPingHandler func(string) error) (info *slack.SocketModeConnection, _ *websocket.Conn, err error) {
+	var (
+		url string
+	)
+
+	smc.Debugf("Starting SocketMode")
+	info, url, err = smc.OpenContext(ctx)
+
+	if err != nil {
+		smc.Debugf("Failed to start or connect with SocketMode: %s", err)
+		return nil, nil, err
+	}
+
+	smc.Debugf("Dialing to websocket on url %s", url)
+	// Only use HTTPS for connections to prevent MITM attacks on the connection.
+	upgradeHeader := http.Header{}
+	upgradeHeader.Add("Origin", "https://api.slack.com")
+	dialer := websocket.DefaultDialer
+	if smc.dialer != nil {
+		dialer = smc.dialer
+	}
+	conn, _, err := dialer.DialContext(ctx, url, upgradeHeader)
+	if err != nil {
+		smc.Debugf("Failed to dial to the websocket: %s", err)
+		return nil, nil, err
+	}
+
+	conn.SetPingHandler(func(appData string) error {
+		if additionalPingHandler != nil {
+			if err := additionalPingHandler(appData); err != nil {
+				return err
+			}
+		}
+
+		smc.handlePing(conn, appData)
+
+		return nil
+	})
+
+	// We don't need to conn.SetCloseHandler because the default handler is effective enough that
+	// it sends back the CLOSE message to the server and let conn.ReadJSON() fail with CloseError.
+	// The CloseError must be handled normally in our receiveMessagesInto function.
+	//conn.SetCloseHandler(func(code int, text string) error {
+	//  ...
+	// })
+
+	return info, conn, err
+}
+
+// runResponseSender runs the handler that reads Socket Mode responses enqueued onto Client.socketModeResponses channel
+// and sends them one by one over the WebSocket connection.
+// Gorilla WebSocket is not goroutine safe hence this needs to be the single place you write to the WebSocket connection.
+func (smc *Client) runResponseSender(ctx context.Context, conn *websocket.Conn) error {
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		// 3. listen for messages that need to be sent
+		case res := <-smc.socketModeResponses:
+			smc.Debugf("Sending Socket Mode response with envelope ID %q: %v", res.EnvelopeID, res)
+
+			if err := unsafeWriteSocketModeResponse(conn, res); err != nil {
+				smc.Events <- newEvent(EventTypeErrorWriteFailed, &ErrorWriteFailed{
+					Cause:    err,
+					Response: res,
+				})
+			}
+
+			smc.Debugf("Finished sending Socket Mode response with envelope ID %q", res.EnvelopeID)
+		}
+	}
+}
+
+// runRequestHandler is a blocking function that runs the Socket Mode request receiver.
+//
+// It reads WebSocket messages sent from Slack's Socket Mode WebSocket connection,
+// parses them as Socket Mode requests, and processes them and optionally emit our own events into Client.Events channel.
+func (smc *Client) runRequestHandler(ctx context.Context, websocket chan json.RawMessage) error {
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case message := <-websocket:
+			smc.Debugf("Received WebSocket message: %s", message)
+
+			// listen for incoming messages that need to be parsed
+			evt, err := smc.parseEvent(message)
+			if err != nil {
+				smc.Events <- newEvent(EventTypeErrorBadMessage, &ErrorBadMessage{
+					Cause:   err,
+					Message: message,
+				})
+			} else if evt != nil {
+				if evt.Type == EventTypeDisconnect {
+					// We treat the `disconnect` request from Slack as an error internally,
+					// so that we can tell the consumer of this function to reopen the connection on it.
+					return errorRequestedDisconnect{}
+				}
+
+				smc.Events <- *evt
+			}
+		}
+	}
+}
+
+// runMessageReceiver monitors the Socket Mode opened WebSocket connection for any incoming
+// messages. It pushes the raw events into the channel.
+// The receiver runs until the context is closed.
+func (smc *Client) runMessageReceiver(ctx context.Context, conn *websocket.Conn, sink chan json.RawMessage) error {
+	for {
+		if err := smc.receiveMessagesInto(ctx, conn, sink); err != nil {
+			return err
+		}
+	}
+}
+
+// unsafeWriteSocketModeResponse sends a WebSocket message back to Slack.
+// WARNING: Call to this function must be serialized!
+//
+// Here's why - Gorilla WebSocket's Writes functions are not concurrency-safe.
+// That is, we must serialize all the writes to it with e.g. a goroutine or mutex.
+// We intentionally chose to use goroutine, which makes it harder to propagate write errors to the caller,
+// but is more computationally efficient.
+//
+// See the below for more information on this topic:
+// https://stackoverflow.com/questions/43225340/how-to-ensure-concurrency-in-golang-gorilla-websocket-package
+func unsafeWriteSocketModeResponse(conn *websocket.Conn, res *Response) error {
+	// set a write deadline on the connection
+	if err := conn.SetWriteDeadline(time.Now().Add(10 * time.Second)); err != nil {
+		return err
+	}
+
+	// Remove write deadline regardless of WriteJSON succeeds or not
+	defer conn.SetWriteDeadline(time.Time{})
+
+	if err := conn.WriteJSON(res); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func newEvent(tpe EventType, data interface{}, req ...*Request) Event {
+	evt := Event{Type: tpe, Data: data}
+
+	if len(req) > 0 {
+		evt.Request = req[0]
+	}
+
+	return evt
+}
+
+// Ack acknowledges the Socket Mode request with the payload.
+//
+// This tells Slack that the we have received the request denoted by the envelope ID,
+// by sending back the envelope ID over the WebSocket connection.
+func (smc *Client) Ack(req Request, payload ...interface{}) {
+	res := Response{
+		EnvelopeID: req.EnvelopeID,
+	}
+
+	if len(payload) > 0 {
+		res.Payload = payload[0]
+	}
+
+	smc.Send(res)
+}
+
+// Send sends the Socket Mode response over a WebSocket connection.
+// This is usually used for acknowledging requests, but if you need more control over Client.Ack().
+// It's normally recommended to use Client.Ack() instead of this.
+func (smc *Client) Send(res Response) {
+	js, err := json.Marshal(res)
+	if err != nil {
+		panic(err)
+	}
+
+	smc.Debugf("Scheduling Socket Mode response for envelope ID %s: %s", res.EnvelopeID, js)
+
+	smc.socketModeResponses <- &res
+}
+
+// receiveMessagesInto attempts to receive an event from the WebSocket connection for Socket Mode.
+// This will block until a frame is available from the WebSocket.
+// If the read from the WebSocket results in a fatal error, this function will return non-nil.
+func (smc *Client) receiveMessagesInto(ctx context.Context, conn *websocket.Conn, sink chan json.RawMessage) error {
+	smc.Debugf("Starting to receive message")
+	defer smc.Debugf("Finished to receive message")
+
+	event := json.RawMessage{}
+	err := conn.ReadJSON(&event)
+
+	// check if the connection was closed.
+	if websocket.IsUnexpectedCloseError(err) {
+		return err
+	}
+
+	switch {
+	case err == io.ErrUnexpectedEOF:
+		// EOF's don't seem to signify a failed connection so instead we ignore
+		// them here and detect a failed connection upon attempting to send a
+		// 'PING' message
+
+		// Unlike RTM, we don't ping from the our end as there seem to have no client ping.
+		// We just continue to the next loop so that we `smc.disconnected` should be received if
+		// this EOF error was actually due to disconnection.
+
+		return nil
+	case err != nil:
+		// All other errors from ReadJSON come from NextReader, and should
+		// kill the read loop and force a reconnect.
+		smc.Events <- newEvent(EventTypeIncomingError, &slack.IncomingEventError{
+			ErrorObj: err,
+		})
+
+		return err
+	case len(event) == 0:
+		smc.Debugln("Received empty event")
+	default:
+		if smc.debug {
+			buf := &bytes.Buffer{}
+			d := json.NewEncoder(buf)
+			d.SetIndent("", "  ")
+			if err := d.Encode(event); err != nil {
+				smc.Debugln("Failed encoding decoded json:", err)
+			}
+			reencoded := buf.String()
+
+			smc.Debugln("Incoming WebSocket message:", reencoded)
+		}
+
+		select {
+		case sink <- event:
+		case <-ctx.Done():
+			smc.Debugln("cancelled while attempting to send raw event")
+
+			return ctx.Err()
+		}
+	}
+
+	return nil
+}
+
+// parseEvent takes a raw JSON message received from the slack websocket
+// and handles the encoded event.
+// returns the our own event that wraps the socket mode request.
+func (smc *Client) parseEvent(wsMsg json.RawMessage) (*Event, error) {
+	req := &Request{}
+	err := json.Unmarshal(wsMsg, req)
+	if err != nil {
+		return nil, fmt.Errorf("unmarshalling WebSocket message: %v", err)
+	}
+
+	var evt Event
+
+	// See below two links for all the available message types.
+	// - https://github.com/slackapi/node-slack-sdk/blob/c3f4d7109062a0356fb765d53794b7b5f6b3b5ae/packages/socket-mode/src/SocketModeClient.ts#L533
+	// - https://api.slack.com/apis/connections/socket-implement
+	switch req.Type {
+	case RequestTypeHello:
+		evt = newEvent(EventTypeHello, nil, req)
+	case RequestTypeEventsAPI:
+		payloadEvent := req.Payload
+
+		eventsAPIEvent, err := slackevents.ParseEvent(payloadEvent, slackevents.OptionNoVerifyToken())
+		if err != nil {
+			return nil, fmt.Errorf("parsing Events API event: %v", err)
+		}
+
+		evt = newEvent(EventTypeEventsAPI, eventsAPIEvent, req)
+	case RequestTypeDisconnect:
+		// See https://api.slack.com/apis/connections/socket-implement#disconnect
+
+		evt = newEvent(EventTypeDisconnect, nil, req)
+	case RequestTypeSlashCommands:
+		// See https://api.slack.com/apis/connections/socket-implement#command
+		var cmd slack.SlashCommand
+
+		if err := json.Unmarshal(req.Payload, &cmd); err != nil {
+			return nil, fmt.Errorf("parsing slash command: %v", err)
+		}
+
+		evt = newEvent(EventTypeSlashCommand, cmd, req)
+	case RequestTypeInteractive:
+		// See belows:
+		// - https://api.slack.com/apis/connections/socket-implement#button
+		// - https://api.slack.com/apis/connections/socket-implement#home
+		// - https://api.slack.com/apis/connections/socket-implement#modal
+		// - https://api.slack.com/apis/connections/socket-implement#menu
+
+		var callback slack.InteractionCallback
+
+		if err := json.Unmarshal(req.Payload, &callback); err != nil {
+			return nil, fmt.Errorf("parsing interaction callback: %v", err)
+		}
+
+		evt = newEvent(EventTypeInteractive, callback, req)
+	default:
+		return nil, fmt.Errorf("processing WebSocket message: encountered unsupported type %q", req.Type)
+	}
+
+	return &evt, nil
+}
+
+// handlePing handles an incoming 'PONG' message which should be in response to
+// a previously sent 'PING' message. This is then used to compute the
+// connection's latency.
+func (smc *Client) handlePing(conn *websocket.Conn, event string) {
+	smc.Debugf("WebSocket ping message received: %s", event)
+
+	// In WebSocket, we need to respond a PING from the server with a PONG with the same payload as the PING.
+	if err := conn.WriteControl(websocket.PongMessage, []byte(event), time.Now().Add(10*time.Second)); err != nil {
+		smc.Debugf("Failed writing WebSocket PONG message: %v", err)
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/socketmode/socketmode.go b/vendor/github.com/slack-go/slack/socketmode/socketmode.go
new file mode 100644
index 00000000..d91d422b
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/socketmode/socketmode.go
@@ -0,0 +1,121 @@
+package socketmode
+
+import (
+	"context"
+	"log"
+	"os"
+	"time"
+
+	"github.com/slack-go/slack"
+
+	"github.com/gorilla/websocket"
+)
+
+// EventType is the type of events that are emitted by scoketmode.Client.
+// You receive and handle those events from a socketmode.Client.Events channel.
+// Those event types does not necessarily match 1:1 to those of Slack Events API events.
+type EventType string
+
+const (
+	// The following request types are the types of requests sent from Slack via Socket Mode WebSocket connection
+	// and handled internally by the socketmode.Client.
+	// The consumer of socketmode.Client will never see it.
+
+	RequestTypeHello         = "hello"
+	RequestTypeEventsAPI     = "events_api"
+	RequestTypeDisconnect    = "disconnect"
+	RequestTypeSlashCommands = "slash_commands"
+	RequestTypeInteractive   = "interactive"
+
+	// The following event types are for events emitted by socketmode.Client itself and
+	// does not originate from Slack.
+	EventTypeConnecting       = EventType("connecting")
+	EventTypeInvalidAuth      = EventType("invalid_auth")
+	EventTypeConnectionError  = EventType("connection_error")
+	EventTypeConnected        = EventType("connected")
+	EventTypeIncomingError    = EventType("incoming_error")
+	EventTypeErrorWriteFailed = EventType("write_error")
+	EventTypeErrorBadMessage  = EventType("error_bad_message")
+
+	//
+	// The following event types are guaranteed to not change unless Slack changes
+	//
+
+	EventTypeHello        = EventType("hello")
+	EventTypeDisconnect   = EventType("disconnect")
+	EventTypeEventsAPI    = EventType("events_api")
+	EventTypeInteractive  = EventType("interactive")
+	EventTypeSlashCommand = EventType("slash_commands")
+
+	websocketDefaultTimeout = 10 * time.Second
+	defaultMaxPingInterval  = 30 * time.Second
+)
+
+// Open calls the "apps.connections.open" endpoint and returns the provided URL and the full Info block.
+//
+// To have a fully managed Websocket connection, use `New`, and call `Run()` on it.
+func (smc *Client) Open() (info *slack.SocketModeConnection, websocketURL string, err error) {
+	ctx, cancel := context.WithTimeout(context.Background(), websocketDefaultTimeout)
+	defer cancel()
+
+	return smc.StartSocketModeContext(ctx)
+}
+
+// OpenContext calls the "apps.connections.open" endpoint and returns the provided URL and the full Info block.
+//
+// To have a fully managed Websocket connection, use `New`, and call `Run()` on it.
+func (smc *Client) OpenContext(ctx context.Context) (info *slack.SocketModeConnection, websocketURL string, err error) {
+	return smc.StartSocketModeContext(ctx)
+}
+
+// Option options for the managed Client.
+type Option func(client *Client)
+
+// OptionDialer takes a gorilla websocket Dialer and uses it as the
+// Dialer when opening the websocket for the Socket Mode connection.
+func OptionDialer(d *websocket.Dialer) Option {
+	return func(smc *Client) {
+		smc.dialer = d
+	}
+}
+
+// OptionPingInterval determines how often we expect Slack to deliver WebSocket ping to us.
+// If no ping is delivered to us within this interval after the last ping, we assumes the WebSocket connection
+// is dead and needs to be reconnected.
+func OptionPingInterval(d time.Duration) Option {
+	return func(smc *Client) {
+		smc.maxPingInterval = d
+	}
+}
+
+// OptionDebug enable debugging for the client
+func OptionDebug(b bool) func(*Client) {
+	return func(c *Client) {
+		c.debug = b
+	}
+}
+
+// OptionLog set logging for client.
+func OptionLog(l logger) func(*Client) {
+	return func(c *Client) {
+		c.log = internalLog{logger: l}
+	}
+}
+
+// New returns a Socket Mode client which provides a fully managed connection to
+// Slack's Websocket-based Socket Mode.
+func New(api *slack.Client, options ...Option) *Client {
+	result := &Client{
+		Client:              *api,
+		Events:              make(chan Event, 50),
+		socketModeResponses: make(chan *Response, 20),
+		maxPingInterval:     defaultMaxPingInterval,
+		log:                 log.New(os.Stderr, "slack-go/slack/socketmode", log.LstdFlags|log.Lshortfile),
+	}
+
+	for _, opt := range options {
+		opt(result)
+	}
+
+	return result
+}
diff --git a/vendor/modules.txt b/vendor/modules.txt
index dfc3a0b2..0d25c72f 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -371,7 +371,9 @@ github.com/slack-go/slack/internal/backoff
 github.com/slack-go/slack/internal/errorsx
 github.com/slack-go/slack/internal/misc
 github.com/slack-go/slack/internal/timex
+github.com/slack-go/slack/slackevents
 github.com/slack-go/slack/slackutilsx
+github.com/slack-go/slack/socketmode
 # github.com/spf13/afero v1.6.0
 ## explicit; go 1.13
 github.com/spf13/afero