$smtp_sender = 'vcenter@domain.com'
$smtp_recipients = 'support@domain.com'
$smtp_server = 'smtp.domain.com'
$smtp_user = ''
$smtp_password = ''
$smtp_port = '25'
$vcenter = $global:defaultviservers.Name
$alarms = @(
    @{
        alarm_definition = 'Datastore usage on disk'
        subject = 'Datastore Usage on Disk Alert'
        transitions = @(
            @{
                start_state = 'green'
                final_state = 'yellow'
            },
            @{
                start_state = 'yellow'
                final_state = 'red'
            }
        )
    },
    @{
        alarm_definition = 'Host CPU usage'
        subject = 'Host CPU Usage Alert'
        transitions = @(
            @{
                start_state = 'green'
                final_state = 'yellow'
            },
            @{
                start_state = 'yellow'
                final_state = 'red'
            }
        )
    },
    @{
        alarm_definition = 'Host connection and power state'
        subject = 'Host Connection and Power State Alert'
        transitions = @(
            @{
                start_state = 'green'
                final_state = 'yellow'
            },
            @{
                start_state = 'yellow'
                final_state = 'red'
            }
        )
    },@{
        alarm_definition = 'Host memory usage'
        subject = 'Host Memory Usage Alert'
        transitions = @(
            @{
                start_state = 'green'
                final_state = 'yellow'
            },
            @{
                start_state = 'yellow'
                final_state = 'red'
            }
        )
    }
)

# Configure SMTP
Get-AdvancedSetting -Entity $vcenter -Name mail.smtp.server | Set-AdvancedSetting -Value $smtp_server -Confirm:$false | Out-Null
Get-AdvancedSetting -Entity $vcenter -Name mail.smtp.port | Set-AdvancedSetting -Value $smtp_port -Confirm:$false | Out-Null
Get-AdvancedSetting -Entity $vcenter -Name mail.sender | Set-AdvancedSetting  -Value $smtp_sender -Confirm:$false | Out-Null
if ($smtp_user -and $smtp_password) {
    Get-AdvancedSetting -Entity $vcenter -Name mail.smtp.username | Set-AdvancedSetting -Entity $vcenter -Value $smtp_user -Confirm:$false | Out-Null
    Get-AdvancedSetting -Entity $vcenter -Name mail.smtp.password | Set-AdvancedSetting -Entity $vcenter -Value $smtp_password -Confirm:$false | Out-Null
}

Get-AdvancedSetting -Entity $vcenter -Name mail.smtp.server, mail.smtp.port, mail.sender, mail.smtp.username, mail.smtp.password

# Configure alarm actions
foreach ($a in $alarms) {
    # Remove existing alarm actions
    Get-AlarmAction -AlarmDefinition $a.alarm_definition | Remove-AlarmAction -Confirm:$false

    # Add send email alarm action
    $action = New-AlarmAction -AlarmDefinition $a.alarm_definition -Email -To $smtp_recipients -Subject $a.subject

    # Define transitions
    foreach ($trans in $a.transitions) {
        # Skip default transition
        if ($trans.start_state -eq 'yellow' -and $trans.final_state -eq 'red') {
            continue
        }

        New-AlarmActionTrigger -AlarmAction $action -StartStatus $trans.start_state -EndStatus $trans.final_state | Out-Null
    }

    Write-Host "$($a.alarm_definition) action triggers:"
    Get-AlarmActionTrigger -AlarmAction $action | Out-String
}