# Modify the path variable
$path = "C:\Documents and Settings\BLAHBLAHBLAHUSERNAME\Desktop\HL7Messages"
$src = (Get-ChildItem $path)[1].FullName

# take hl7 message as string, convert to posh obj
function hl7-to-object {
    param($src)
    # go from hl7 to powershell array of objects
    $msg = @()
    $cursorCount = 0
    $src | Foreach {
        $split = $_.Split("|")

        $nodeName = $split[0]

        $properties = @()
        $split | select -skip 1 | foreach {
            $properties += $_
        }

        $object = New-Object psobject
        $object | Add-Member –membertype noteproperty –Name HL7Pos –Value $cursorCount
        $object | Add-Member –membertype noteproperty –Name Segment –Value $nodeName
        $object | Add-Member –membertype noteproperty –Name Fields –Value $properties

        $msg += $object

        $cursorCount += 1
    }
    return $msg
}

# take posh object formed from hl7 and convert to hl7 string
function object-to-hl7 {
    param($msgObj)
    # convert back to HL7
    $msgSrc = @()
    $msgObj | foreach {
        $msgSrc += $_.Segment + "|" + ($_.Fields -join "|")
    }
    return ($msgSrc -join "`r`n")
}

# --------
# EXAMPLES
# --------

#read hl7 file
$msg = hl7-to-object((get-content $src))
#reading and writing
# grab
$MSH = ($msg | where {$_.Segment -eq "MSH"} | select -First 1)

$IN1_B = ($msg | where {$_.Segment -eq "IN1"} | select -Skip 1)

#$IN1_B.HL7Pos
($msg | where {$_.HL7Pos -eq $IN1_B.HL7Pos} | select -First 1)

# set field
$MSH.Fields[4] = "TEST"
# ensure its set to our value
write-host (($msg | where {$_.Segment -eq "MSH"} | select -First 1).Fields[4])
#print back out to console with our changes
write-host (object-to-hl7($msg))

# search all hl7s and return whether the patient name has a john in it

(Get-ChildItem $path) | foreach {
    $msg = hl7-to-object((get-content $_))
    $isRightPatient = ($msg | where {($_.Segment -eq "PID") -and ($_.Fields[4] -like "*JOHN*")} | select -First 1)
    if($isRightPatient -eq $null) {
        write-host "No"
    } else {
        write-host "Yes"
    }
}