Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/channels/app/slashcommands/command_join.go

@@ -0,0 +1,79 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package slashcommands
+
+import (
+	"strings"
+
+	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/server/channels/app"
+	"github.com/mattermost/mattermost-server/v6/server/channels/app/request"
+	"github.com/mattermost/mattermost-server/v6/server/platform/shared/i18n"
+)
+
+type JoinProvider struct {
+}
+
+const (
+	CmdJoin = "join"
+)
+
+func init() {
+	app.RegisterCommandProvider(&JoinProvider{})
+}
+
+func (*JoinProvider) GetTrigger() string {
+	return CmdJoin
+}
+
+func (*JoinProvider) GetCommand(a *app.App, T i18n.TranslateFunc) *model.Command {
+	return &model.Command{
+		Trigger:          CmdJoin,
+		AutoComplete:     true,
+		AutoCompleteDesc: T("api.command_join.desc"),
+		AutoCompleteHint: T("api.command_join.hint"),
+		DisplayName:      T("api.command_join.name"),
+	}
+}
+
+func (*JoinProvider) DoCommand(a *app.App, c request.CTX, args *model.CommandArgs, message string) *model.CommandResponse {
+	channelName := strings.ToLower(message)
+
+	if strings.HasPrefix(message, "~") {
+		channelName = message[1:]
+	}
+
+	channel, err := a.Srv().Store().Channel().GetByName(args.TeamId, channelName, true)
+	if err != nil {
+		return &model.CommandResponse{Text: args.T("api.command_join.list.app_error"), ResponseType: model.CommandResponseTypeEphemeral}
+	}
+
+	if channel.Name != channelName {
+		return &model.CommandResponse{ResponseType: model.CommandResponseTypeEphemeral, Text: args.T("api.command_join.missing.app_error")}
+	}
+
+	switch channel.Type {
+	case model.ChannelTypeOpen:
+		if !a.HasPermissionToChannel(c, args.UserId, channel.Id, model.PermissionJoinPublicChannels) {
+			return &model.CommandResponse{Text: args.T("api.command_join.fail.app_error"), ResponseType: model.CommandResponseTypeEphemeral}
+		}
+	case model.ChannelTypePrivate:
+		if !a.HasPermissionToChannel(c, args.UserId, channel.Id, model.PermissionReadChannel) {
+			return &model.CommandResponse{Text: args.T("api.command_join.fail.app_error"), ResponseType: model.CommandResponseTypeEphemeral}
+		}
+	default:
+		return &model.CommandResponse{Text: args.T("api.command_join.fail.app_error"), ResponseType: model.CommandResponseTypeEphemeral}
+	}
+
+	if appErr := a.JoinChannel(c, channel, args.UserId); appErr != nil {
+		return &model.CommandResponse{Text: args.T("api.command_join.fail.app_error"), ResponseType: model.CommandResponseTypeEphemeral}
+	}
+
+	team, appErr := a.GetTeam(channel.TeamId)
+	if appErr != nil {
+		return &model.CommandResponse{Text: args.T("api.command_join.fail.app_error"), ResponseType: model.CommandResponseTypeEphemeral}
+	}
+
+	return &model.CommandResponse{GotoLocation: args.SiteURL + "/" + team.Name + "/channels/" + channel.Name}
+}