Add plugin slash command support (#7941)

* add plugin slash command support

* remove unused string

* rebase

app/command.go

@@ -75,6 +75,13 @@ func (a *App) ListAutocompleteCommands(teamId string, T goi18n.TranslateFunc) ([
 		}
 	}
 
+	for _, cmd := range a.PluginCommandsForTeam(teamId) {
+		if cmd.AutoComplete && !seen[cmd.Trigger] {
+			seen[cmd.Trigger] = true
+			commands = append(commands, cmd)
+		}
+	}
+
 	if *a.Config().ServiceSettings.EnableCommands {
 		if result := <-a.Srv.Store.Command().GetByTeam(teamId); result.Err != nil {
 			return nil, result.Err
@@ -111,7 +118,7 @@ func (a *App) ListAllCommands(teamId string, T goi18n.TranslateFunc) ([]*model.C
 	for _, value := range commandProviders {
 		if cmd := value.GetCommand(a, T); cmd != nil {
 			cpy := *cmd
-			if cpy.AutoComplete && !seen[cpy.Id] {
+			if cpy.AutoComplete && !seen[cpy.Trigger] {
 				cpy.Sanitize()
 				seen[cpy.Trigger] = true
 				commands = append(commands, &cpy)
@@ -119,13 +126,20 @@ func (a *App) ListAllCommands(teamId string, T goi18n.TranslateFunc) ([]*model.C
 		}
 	}
 
+	for _, cmd := range a.PluginCommandsForTeam(teamId) {
+		if !seen[cmd.Trigger] {
+			seen[cmd.Trigger] = true
+			commands = append(commands, cmd)
+		}
+	}
+
 	if *a.Config().ServiceSettings.EnableCommands {
 		if result := <-a.Srv.Store.Command().GetByTeam(teamId); result.Err != nil {
 			return nil, result.Err
 		} else {
 			teamCmds := result.Data.([]*model.Command)
 			for _, cmd := range teamCmds {
-				if !seen[cmd.Id] {
+				if !seen[cmd.Trigger] {
 					cmd.Sanitize()
 					seen[cmd.Trigger] = true
 					commands = append(commands, cmd)
@@ -151,6 +165,12 @@ func (a *App) ExecuteCommand(args *model.CommandArgs) (*model.CommandResponse, *
 		}
 	}
 
+	if cmd, response, err := a.ExecutePluginCommand(args); err != nil {
+		return nil, err
+	} else if cmd != nil {
+		return a.HandleCommandResponse(cmd, args, response, true)
+	}
+
 	if !*a.Config().ServiceSettings.EnableCommands {
 		return nil, model.NewAppError("ExecuteCommand", "api.command.disabled.app_error", nil, "", http.StatusNotImplemented)
 	}