<#
        ESM.ps1 - Exchange Service Monitor
        This script will connect to all the Exchange servers in the organization
        It Will then Test Critical services based on server roles
        Services that are not running will be restarted
        Written by David Sankovsky, Version 1.0 August 29th, 2017
    #>

    #Set Up Critical Services based on server roles
    $MBXservices="IISAdmin","MSExchangeADTopology","MSExchangeDelivery","MSExchangeIS","MSExchangeMailboxAssistants","MSExchangeRepl","MSExchangeRPC","MSExchangeServiceHost","MSExchangeSubmission","MSExchangeThrottling","MSExchangeTransportLogSearch","W3Svc","WinRM" #MBX Services
    $CASServices="Spooler","MSExchangeIMAP4","MSExchangeMailboxReplication","MSExchangeEdgeSync","MSExchangeTransport" #CAS Specific Services
    $CAS7Services="MSExchangeADTopology","MSExchangeDiagnostics","MSExchangeFrontEndTransport","MSExchangeHM","MSExchangeServiceHost","MSExchangeUMCR"

    $LOGFILE="C:\Monitoring\log.txt" #Log File location

    <#
        The Telegram function receives a service name and a server as parameters,
        if invoked, the function will send a message through the telegram APP using a specific bot opened by HNF.
        All the recipients are configured in the "targets" array the script runs on each target separately so that if one causes an error, it won't break the script.
    #>

    function Telegram {
        Param ([String]$Service,[String]$Server)
        $URI = "https://api.telegram.org/bot###:***/sendMessage"
        $targets = "###","###","###","###"
        $text = "$service could not be restarted on $server! Critical service is down!"
        Foreach ($target in $targets){
            $querystring = $URI+"?chat_id=$target&text="+$text.Replace(' ','+')
            WriteLog "Sending $text to TelegramID $target"
            Invoke-WebRequest -Uri $querystring
        }
    }

    <#
        WriteLog Function Writes log messages to the Log File and appends the TimeStamp before the actual log entry.
        The Time Stamp is re-evaluated every time the function is called to allow for a more granular log search
        Time Stamp format is [DD\MM\YYYY HH: mm]
    #>
    function WriteLog {
        Param ([String] $Message)
        $tStamp=Get-Date
        $Day=$($tStamp).Day
        $Month=$($tStamp).Month
        $Year=$($tStamp).Year
        $Hour=$($tStamp).Hour
        $Minute=$($tStamp).Minute

        echo "[$Day\$Month\$Year $Hour`:$Minute] $Message" >> $LOGFILE
    }

    <#
        SendMail Function receives a service name, a Server name and a status
        The function then sends a mail to sticket based on the received status
            if the status is "failed": The system will inform that the service is down and that the system will attempt to restart the service on its own
            if the status is "restarted": The system will inform that the service was successfully restarted and that no further action is required.
            if the status is neither of the above (default is ERR): The system will inform that it was unable to automatically restart the service and that a sysadmins intervention is required, the system will also attempt to send an SMS
    #>
    function SendMail {
        Param ([String]$Service,[String]$Server,[String]$Status)
        echo "$Service on $Server"
        if ($Status.Equals("Failed")) {
            #echo "$Service failed on $Server"
            Send-MailMessage -From "ExchangeMonitor@domain.com" -To "sticket@domain.com" -Subject "Detected Service Failure on $Server! $Service is down!" -SmtpServer "server"
        }
        elseif ($Status.Equals("Restarted")){
            Send-MailMessage -From "ExchangeMonitor@domain.com" -To "sticket@domain.com" -Subject "The $Service Service was succesfully restarted on $Server!" -SmtpServer "server"
        }
        else{
            Send-MailMessage -From "ExchangeMonitor@domain.com" -To "sticket@domain.com" -Subject "Could not restart $Service on $Server!  Critical Service is down!" -SmtpServer "server"
            Telegram $Service $Server
        }
    }

    #Add PowerShell Exchange commands Snap-in (Depending on which server is running this script, this command could be omitted
    Add-PSSnapin Microsoft.Exchange.Management.PowerShell.Snapin

    do{ #monitoring script logic starts here
        $servers=$(Get-ExchangeServer)#Get all available Exchange servers
        Foreach ($server in $servers){ #Run through one server at a time
            $FailedService=0 #Count the number of Failed services per serer
            if ($($server.ServerRole.ToString()).Contains("Client") -and -not ($($server.name.ToString().Contains("CAS7")))){ #Check the server Roles, if contains the string "Client", the server is CAS
                    ForEach ($CASService in $CASServices){ #Run through all the services listed in CASServices
                    $ServiceStatus=Get-Service -Name $CASService -ComputerName $($server.Name) #Remotely ascertain the status of the service in question.
                    if ($ServiceStatus.Status -ne "Running"){ #If the service is not running as it should
                        WriteLog "The Service $((Get-Service -Name $CASService).DisplayName.ToString()) is down on $server"
                        SendMail $((Get-Service -Name $CASService).DisplayName.ToString()) ($($server.Name)).ToString() "Failed"
                        Start-Service -Name $CASService #Attempt to restart the service.
                        Start-Sleep -Seconds 120 #wait for 2 minutes
                        $ServiceStatus=Get-Service -Name $CASService -ComputerName $($server.Name) #retest said service
                        if ($ServiceStatus.Status -ne "Running"){
                            $FailedService+=1 # if service did not start properly after 2 minutes, Increase the failed service counter
                            WriteLog "Coiuld not recover $((Get-Service -Name $CASService).DisplayName.ToString()) on $server!"
                            SendMail $((Get-Service -Name $CASService).DisplayName.ToString()) ($($server.Name)).ToString() "ERR"
                        }
                        else {
                            WriteLog "The Service $((Get-Service -Name $CASService).DisplayName.ToString()) recovered on $server!"
                            SendMail $((Get-Service -Name $CASService).DisplayName.ToString()) ($($server.Name)).ToString() "Restarted"
                        }
                    }
                }
            }
            if(-not ($($server.name.ToString().Contains("CAS7")))){
                ForEach ($MBXService in $MBXServices){
                    $ServiceStatus=Get-Service -Name $MBXService -ComputerName $($server.Name)
                    if ($ServiceStatus.Status -ne "Running"){
                        sendMail $((Get-Service -Name $MBXService).DisplayName.ToString()) ($($server.Name)).ToString() "Failed"
                        Start-Service -Name $MBXService #Attempt to restart the service
                        Start-Sleep -Seconds 120 #Wait for 2 minutes
                        $ServiceStatus=Get-Service -Name $MBXService -ComputerName $($server.Name) #retest the service
                        if ($ServiceStatus.Status -ne "Running"){
                            $FailedService+=1
                            SendMail $((Get-Service -Name $MBXService).DisplayName.ToString()) ($($server.Name)).ToString() "ERR"
                        }
                        else{
                            SendMail $((Get-Service -Name $MBXService).DisplayName.ToString()) ($($server.Name)).ToString() "Restarted"
                        }
                    }
                }
            }
            if ($($server.name.ToString().Contains("Cas7"))){
                ForEach ($CAS7Service in $CAS7Services){ #Run through all the services listed in CASServices
                    $ServiceStatus=Get-Service -Name $CAS7Service -ComputerName $($server.Name) #Remotely ascertain the status of the service in question.
                    if ($ServiceStatus.Status -ne "Running"){ #If the service is not running as it should
                        WriteLog "The Service $((Get-Service -Name $CAS7Service).DisplayName.ToString()) is down on $server"
                        SendMail $((Get-Service -Name $CAS7Service).DisplayName.ToString()) ($($server.Name)).ToString() "Failed"
                        Start-Service -Name $CAS7Service #Attempt to restart the service.
                        Start-Sleep -Seconds 120 #wait for 2 minutes
                        $ServiceStatus=Get-Service -Name $CAS7Service -ComputerName $($server.Name) #retest said service
                        if ($ServiceStatus.Status -ne "Running"){
                            $FailedService+=1 # if service did not start properly after 2 minutes, Increase the failed service counter
                            WriteLog "Coiuld not recover $((Get-Service -Name $CAS7Service).DisplayName.ToString()) on $server!"
                            SendMail $((Get-Service -Name $CAS7Service).DisplayName.ToString()) ($($server.Name)).ToString() "ERR"
                        }
                        else {
                            WriteLog "The Service $((Get-Service -Name $CAS7Service).DisplayName.ToString()) recovered on $server!"
                            SendMail $((Get-Service -Name $CAS7Service).DisplayName.ToString()) ($($server.Name)).ToString() "Restarted"
                        }
                    }
                }
            }
        }
        WriteLog "Finished a full run, Waiting 10 minutes"
        Start-Sleep -Seconds 600 #Run script every 10 minutes
    }until($infinity)