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

## 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) { $Database = read-host "Enter Database Name" }
if(!$Backup) { $Backup = read-host "Enter Backup Path\Name" }

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

## Make sure backup file exists
$BackupExists = Test-Path $Backup
if (!$BackupExists) {
	RaisError "`tBackup file does not exist or is not accessible."
	Exit
}

## If database exists, delete it
$DBExists = $Srv.Databases[$Database]
if ($DBExists) {
	if ($DBExists.status -eq "online") {
		$Srv.KillDatabase($Database)
	} else {
		$DBExists.drop()
	}
	if ($error){
		RaisError "`tDrop of existing database returned an error."
		Exit
	}
}

## Restore the database
$Restore = new-object "Microsoft.SqlServer.Management.Smo.Restore"
$Restore.Database = $Database
$Restore.Action = 'Database'
$BkFile = new-object "Microsoft.SqlServer.Management.Smo.BackupDeviceItem"
$BkFile.DeviceType = 'File'
$BkFile.Name = $Backup
$Restore.Devices.Add($BkFile)
$Restore.ReplaceDatabase = $false

## Check file list and generate new file names if files already exists
$DateSerial = Get-Date -Format yyyyMMddHHmmss
$DataFiles = $Restore.ReadFileList($Server)
ForEach ($DataRow in $DataFiles) {
	$LogicalName = $DataRow.LogicalName
	$PhysicalName = $DataRow.PhysicalName
	$FileExists = Test-Path $PhysicalName
	if ($FileExists) {
		$PhysicalName = $PhysicalName -replace(".mdf", "_$DateSerial.mdf")
		$PhysicalName = $PhysicalName -replace(".ldf", "_$DateSerial.ldf")
		$PhysicalName = $PhysicalName -replace(".ndf", "_$DateSerial.ndf")
		$Restore.RelocateFiles.Add((new-object microsoft.sqlserver.management.smo.relocatefile -ArgumentList $LogicalName, $PhysicalName)) | out-null;
	}
}
$Restore.NoRecovery = $false
$Restore.PercentCompleteNotification = 5
$Restore.SqlRestore($Server)
if (!$error){
	write-host "`tDatabase $Database restored from $Backup" -f green
} else {
	RaisError "`tRestore of database $Database returned an error."
	Exit
}