Param ([switch]$help = $false,[switch]$enable_tracing = $false,[String]$AlertName,[String]$ResolutionStateName,[String]$Severity,[String]$ManagedEntityFullName,[String]$source, [String]$AlertDescription)

# v3.0 only, several features used will not work with 2.0
Set-StrictMode -Version 3.0

# Send XML payload to NRDP processor.
function send_alert_to_nagios([String]$xmlPost, [Hashtable]$aryNagVars) {
   $webAgent = New-Object System.Net.WebClient
   $nvcWebData = New-Object System.Collections.Specialized.NameValueCollection
   $nvcWebData.Add('token', $aryNagVars['nrdptoken'])
   $nvcWebData.Add('cmd', 'submitcheck')
   $nvcWebData.Add('XMLDATA', $xmlPost)
   if ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
      logger( "Sending NRDP check: `n$xmlPost")
   }
   $strWebResponse = $webAgent.UploadValues($aryNagVars['nrdpurl'], 'POST', $nvcWebData)
   $strReturn = [System.Text.Encoding]::ASCII.GetString($strWebResponse)
   if ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
      logger( "NRDP replied: `n$strReturn")
   }
   if ($strReturn.Contains("<message>OK</message>")) {
       if ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
          logger("SUCCESS - SCOM checks succesfully sent")
       }
       return $true
   } else {
       logger("ERROR - SCOM checks failed to send")
       return $false
   }
}

# Generate XML information for NRDP. Probably should change this to a bulk submission in the future instead of sending every alert individually.
function generate_alert_xml([Hashtable]$aryNagVars) {
    $aryNagVars['output'] = [System.Web.HttpUtility]::HtmlEncode($aryNagVars['output'])
    $xmlBuilder = "<?xml version='1.0'?>`n<checkresults>"
    $xmlBuilder += "`n`t<checkresult type='service' checktype='" + $aryNagVars['activecheck'] + "'>"
    $xmlBuilder += "`n`t`t<hostname>" + $aryNagVars['hostname'] + "</hostname>"
    $xmlBuilder += "`n`t`t<servicename>" + $aryNagVars['service'] + "</servicename>"
    $xmlBuilder += "`n`t`t<state>" + $aryNagVars['state'] + "</state>"
    $xmlBuilder += "`n`t`t<output>" + $aryNagVars['output'] + "</output>"
    $xmlBuilder += "`n`t</checkresult>"
    $xmlBuilder += "`n</checkresults>"
    return $xmlBuilder
}


# Log writing mechanism.
function logger([String]$strMessage) {
    $dtTime = Get-Date
    $strMessage = $dtTime.ToString() + " " + $strMessage
    Write-Host $strMessage
    if ($aryMainConf['logging']['log_enable'] -eq 1) {
        $strLogFile = $aryMainConf['logging']['log_full_path']
        $strMessage | Out-File $strLogFile -Encoding ascii -Append
    }
}


# Import scombag main configuration file.
function import_main_config([String]$strExecutingPath) {
    $strConfigFile = $strExecutingPath + "scomnagios.ini"

    if (Test-Path $strConfigFile) {
		# PS has no INI import function :( this is a simple INI import mechanism.
        $aryIniContents = @{}
        switch -regex -file $strConfigFile {
            "^\[(.+)\]\s*$" {
                $strHeading = $Matches[1]
                $aryIniContents[$strHeading] = @{}
            }
            "^\s*(\S.*?)\s*=\s*(\S.*?)\s*$" {
                $strKey = $Matches[1]
                $strValue = $Matches[2]
                $aryIniContents[$strHeading][$strKey] = $strValue
            }
        }
    } else {
        Write-Host "Unable to find main config file at path: $strConfigFile"
        exit 2
    }

    return $aryIniContents
}


function help {
    $strVersion = "v0.1"
    $strNRDPVersion = "1.2"
    Write-Host "SCOM-Nagios version: $strVersion for NRDP version: $strNRDPVersion"
    Write-Host "GNU GPL License"
    Write-Host "Usage: scomnagios.ps1 alertname resolutionstate severity managedentityname description `n"
    Write-Host @'
-help
	Display this help text.
-enable_tracing
    Enable a verbose tracing execution. Used for testing changes to the map file.

'@
    exit 0
}

##########################################
### BEGIN MAIN
##########################################
if ($help) {
    help   
}
Add-Type -Assembly System.Web

# Set the script home directory
if( $PSCommandPath ) {
  $strExecutingPath = Split-Path -parent $PSCommandPath
  Set-Location -Path $strExecutingPath

  if (!("\" -eq $strExecutingPath.Substring($strExecutingPath.Length - 1, 1))) {
    $strExecutingPath = $strExecutingPath + "\"
  }
} else {
    $strExecutingPath = "\"
}

#Import-Module OperationsManager -ErrorVariable strImportError
#if ($strImportError) {
#    logger("Error loading one or more module(s): " + $strImportError)
#    logger("Unable to continue.")
#    exit 2
#}

# Import and validate the main configuration file
$aryMainConf = import_main_config($strExecutingPath)
Set-Variable -Name $aryMainConf -Scope Global

if ($enable_tracing) {
    $aryMainConf['main']['trace_mode_enabled'] = 1
}

# Roll over logs and initialize logging.
if ($aryMainConf['logging']['log_enable'] -eq 1) {
    if (!("\" -eq $aryMainConf['logging']['log_dir'].Substring($aryMainConf['logging']['log_dir'].Length - 1, 1))) {
        $aryMainConf['logging']['log_dir'] = $aryMainConf['logging']['log_dir'] + "\"
    }

    if (Test-Path $aryMainConf['logging']['log_dir']) {
        $aryMainConf['logging']['log_full_path'] = $aryMainConf['logging']['log_dir'] + $aryMainConf['logging']['log_name']
    } elseif (Test-Path $strExecutingPath + $aryMainConf['logging']['log_dir']) {
        $aryMainConf['logging']['log_full_path'] = $strExecutingPath + $aryMainConf['logging']['log_dir'] + $aryMainConf['logging']['log_name']
    } else {
        Write-Host "Can't find log directory. Unable to continue."
        exit 2
    }

    $dtStartTime = Get-Date

    $bLogExists = Test-Path $aryMainConf['logging']['log_full_path']

    if ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
        Add-Content $aryMainConf['logging']['log_full_path'] "`r`n############################################################" 
    }
    Add-Content $aryMainConf['logging']['log_full_path'] "Nagios relay running at: $dtStartTime"
}

if ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
    logger("Trace mode enabled. This is a tracing run.")
}

# process parameters
# activecheck hostname service state output
# nrdptoken nrdpurl
if ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
    logger("ManagedEntityFullName = $ManagedEntityFullName")
    logger("AlertName             = $AlertName")
    logger("ResolutionStateName   = $ResolutionStateName")
    logger("Severity              = $Severity")
    logger("Source                = $Source")
}
$nagvars = @{}
$nagvars['nrdptoken'] = $aryMainConf['nrdp']['token']
$nagvars['nrdpurl'] = $aryMainConf['nrdp']['url']
$nagvars['activecheck'] = 0
# Remember these are string comparisons!
if ( $ResolutionStateName -eq "Closed" ) {
    $nagvars['state'] = 0
} elseif ( $Severity -eq 2 ) {
    $nagvars['state'] = 2
} else {
    $nagvars['state'] = 1
}
if( ! $AlertDescription ) {
    $AlertDescription = $Source 
}
if( $AlertDescription ) {
    if( $nagvars['state'] -gt 0 ) {
      $nagvars['output'] = "["+$ResolutionStateName+"] "+$AlertName + '\n' + ( $AlertDescription -replace '<','&amp;lt;' -replace '>','&amp;gt;')
    } else {
      $nagvars['output'] = "["+$ResolutionStateName+"] "+$AlertName
    }
} else {
    $nagvars['output'] = "["+$ResolutionStateName+"] "+$AlertName + ": Status "+$nagvars['state']
}
if( $aryMainConf['main']['handle_links'] -eq 1 ) {
    $nagvars['output'] = $nagvars['output'] -replace '((https?|ftp|mailto)://\S+)','&lt;A HREF="${1}"&gt;${1}&lt;/A&gt;'
}
if( $aryMainConf['main']['force_error_status'] -gt 0 -and $nagvars['state'] -gt 0 ) {
  if ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
    logger("Forcing status to "+$aryMainConf['main']['force_error_status'])
  }
  $nagvars['state'] = $aryMainConf['main']['force_error_status']
}

# This is something like objectname:fqdn[;netbios][;otherdata]
# note otherdata may contain a colon, objectname is [a-zA-z0-9\.]+
# Set to lower case and trim off domain though
if( $ManagedEntityFullName -ne "" ) {
    $nagvars['hostname'] = $ManagedEntityFullName
    $nagvars['hostname'] = $nagvars['hostname'] -replace '^.*?:'
    $nagvars['hostname'] = $nagvars['hostname'] -replace ';.*$'
    if( $aryMainConf['hostname']['lower_case'] ) {
         $nagvars['hostname'] = $nagvars['hostname'].ToLower()
    }
    if( $aryMainConf['hostname']['domain'] ) {
        $nagvars['hostname'] = $nagvars['hostname'] -replace ('.'+$aryMainConf['hostname']['domain']+'$')
    }
} elseif( $aryMainConf['hostname']['domain'] -and ( $Source -match ("([a-zA-Z0-9\.\-]+)\."+$aryMainConf['hostname']['domain'])) ) {
    $nagvars['hostname'] = $Matches[1]
    if( $aryMainConf['hostname']['lower_case'] ) {
         $nagvars['hostname'] = $nagvars['hostname'].ToLower()
    }
} else {
    $nagvars['hostname'] = "SCOM"
}

# Override Service settings based on $AlertName matches
$nagvars['service'] = "SCOM: Unknown"
if( $aryMainConf['service_desc']['default'] ) {
    $nagvars['service'] = $aryMainConf['service_desc']['default']
}
if( $ManagedEntityFullName -match "^.*?;([-a-zA-Z0-9:]+)" ) {
    $tag = $Matches[1]
    if( $tag -and $nagvars['hostname'] -notmatch $tag.ToLower() ) {
	    $nagvars['service'] = "SCOM: "+$Matches[1]
        if ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
            logger("Overriding service default name with data from tag [$tag]")
        }
    }
}
if ($aryMainConf['service_desc']['max'] -gt 0) {
    for($rule = 1;$rule -le $aryMainConf['service_desc']['max']; $rule++) {
        if ($aryMainConf['service_desc']["desc$rule"]) {
          if ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
              logger("Processing match rule $rule")
          }        
          if($aryMainConf['service_desc']["name$rule"] -and ( $AlertName -cmatch $aryMainConf['service_desc']["name$rule"] )) {
              $nagvars['service'] = $aryMainConf['service_desc']["desc$rule"]
              break
          }
          if($aryMainConf['service_desc']["entity$rule"] -and ( $ManagedEntityFullName -cmatch $aryMainConf['service_desc']["entity$rule"] )) {
              $nagvars['service'] = $aryMainConf['service_desc']["desc$rule"]
              break
          }
          if($aryMainConf['service_desc']["source$rule"] -and ( $Source -cmatch $aryMainConf['service_desc']["source$rule"] )) {
              $nagvars['service'] = $aryMainConf['service_desc']["desc$rule"]
              break
          }
          if($aryMainConf['service_desc']["alert$rule"] -and ( $AlertDescription -cmatch $aryMainConf['service_desc']["alert$rule"] )) {
              $nagvars['service'] = $aryMainConf['service_desc']["desc$rule"]
              break
          }
        }
    }
}

# Trace logging
if ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
    logger("hostname     = "+$nagvars['hostname'])
    logger("service_desc = "+$nagvars['service'])
    logger("state        = "+$nagvars['state'])
}

if( $nagvars['service'] -eq 'IGNORE' ) {
	# We dont log this
	if ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
	   logger("Not sending to Nagios due to IGNORE configuration")
	}
	exit 0
}


if( $nagvars['hostname'] -eq 'microsoft.systemcenter.agentwatchersgroup' ) {
	# We dont log this
	logger("Not sending to Nagios due to invalid hostname")
	exit 0
}

# Send alert to Nagios
if( $nagvars['state'] -gt 0 -or $aryMainConf['main']['errors_only'] -ne 1  ) {
  # Verify
  if( (!$nagvars['nrdpurl']) -or (!$nagvars['nrdptoken']) ) {
    logger( "No NRDP URL and Token provided in ini file." )
    exit 2
  }
  # Build XML
  $xmlPost = generate_alert_xml $nagvars 
  # Send
  $rv = send_alert_to_nagios $xmlPost $nagvars 
} elseif ($aryMainConf['main']['trace_mode_enabled'] -eq 1) {
  logger("Not sending to Nagios as errors_only=1 and this is status 0")
}

exit 0