param (
	[string] $Server,
	[string] $Database,
	[string] $BackupPath
)

## Path and name used to invoke script
$CUR_SCRIPT = $myinvocation.InvocationName

## Load SMO assemblies
[Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.ConnectionInfo")|out-null
[Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.SmoEnum")|out-null
[Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.Smo")|out-null
$SMO = [Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.Smo")
## Parse out the internal version number
$SMOVer = $SMO.FullName.Split(",")[1].Split("=")[1].Split(".")[0]
## Load SMOExtended if not SQL Server 2005 (9)
if ($SMOVer -ne 9) {
	[Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.SMOExtended")|out-null
}

## Check user input, prompt for each value not provided as parameters
if(!$Server) { $Server = read-host "Enter Server Name" }
if(!$Database) { $Database = read-host "Enter Database Name" }
if(!$BackupPath) { $BackupPath = read-host "Enter Backup Path (optional)" }

## Return Help and exit if any required input is missing
if(!$Server -or !$Database) {
	write-host "Usage: $CUR_SCRIPT options:
	string SQL Server Instance
	string Database Name
	string Backup Path (optional)" -f red
	exit
}

## Function to raise error
Function RaisError ([string]$ErrMsg){
	write-host $ErrMsg -f red
	$error.clear()
}

## Create server object
$Srv = New-Object "Microsoft.SqlServer.Management.Smo.Server" $Server

## Get default backup path if not provided
if (!$BackupPath) {
	$BackupPath = $Srv.BackupDirectory
}

## Make sure backup path exists
if ($BackupPath) {
	$BackupPath = [System.IO.Path]::Combine($BackupPath, $Database)
	[System.IO.Directory]::CreateDirectory($BackupPath) | out-null
} else {
	RaisError "`tUnable to find a backup path"
}

## Connect to database
$DBase = $Srv.Databases[$Database]


## Create backup name
$BkDate = Get-Date -Format yyyyMMddHHmmss
$BkName = $Database + "_backup_$BkDate.bak"

## Backup the Principal database
$Backup = new-object "Microsoft.SqlServer.Management.Smo.Backup"
$BkFile = new-object "Microsoft.SqlServer.Management.Smo.BackupDeviceItem"
$BkFile.DeviceType = 'File'
$BkFile.Name = [System.IO.Path]::Combine($BackupPath, $BkName)
$BKFileName = $BkFile.Name
$Backup.Devices.Add($BkFile)
$Backup.Database = $Database
$Backup.Action = 'Database'
$Backup.Initialize = 1
$Backup.BackupSetDescription = "Backup of database $Database"
$Backup.BackupSetName = "$Database Backup"
$Backup.PercentCompleteNotification = 5
$Backup.SqlBackup($Srv)
if (!$error){
	write-host "`tDatabase $Database backed up to $BkFileName" -f green
	return $BkFileName
} else {
	RaisError "`tDatabase $Database backup returned an error."
}