<#
#>

[CmdletBinding()]
param
(
# Array of strings listing computer name(s) to wake up. Names will be matched using RegEx
    [Alias("Computer")]
    [String[]]
    $TargetComputer = "",
# XML database file containing computer details (Default: WOLDatabase.xml)
    [Alias("List", "Database")]
    [String]
    $WolDatabase = "WOLDatabase.xml",
# Skip connectivity check
    [Alias("NoCheck", "NoReadiness")]
    [Switch]
    $NoConnectivityCheck,
# Delay before running first connectivity check (Default: 10)
    [Alias("Delay")]
    [Int]
    $ConnectivityCheckDelay = 10,
# Seconds before aborting connectivity check (Default: 300)
    [Alias("Timeout")]
    [Int]
    $ConnectivityCheckTimeout = 300,
# Seconds between connectivity checks (Default: 30)
    [Alias("Interval")]
    [Int]
    $ConnectivityCheckInterval = 30,
# Port to use for connectivity check (Default: 3389-RDP)
    [Alias("CheckPort")]
    [Int]
    $ConnectivityCheckPort = 3389
)

function exitError($errMessage, $PSItem, $exitCode = 1)
{
    if ( [String]::IsNullOrEmpty($errMessage))
    {
        Write-Host -ForegroundColor Red "`n`rABNORMAL EXIT: exitError function called without exit message!`n`r"
        exit 99
    }
    Write-Host -ForegroundColor Red "`r`nERROR: ${errMessage}."
    if ($PSItem)
    {
        Write-Host -ForegroundColor Red "`r`nAdditional information:`r`n$PSItem"
    }
    Write-Host
    Exit $exitCode
}

function exitGracefully()
{
    Write-Host -ForegroundColor Green "`r`nFinished.`r`n"
    Exit 0
}

# constants
Set-Variable -Name wolModuleName -Value "wol-magicPacket" -Option Constant

# exit on error if Send-MagicPacket module is not loaded
if (!(Get-Module -Name $wolModuleName))
{
    try
    {
        Import-Module -Name $wolModuleName -ErrorAction Stop
    }
    catch
    {
        $errMessage = "Unable to load '$wolModuleName'"
        exitError $errMessage $PSItem
    }
}

# exit if database cannot be found/read
if (!(Test-Path -Path $WolDatabase -PathType Leaf))
{
    $errMessage = "Unable to find or read Wake-On-LAN database file ($WolDatabase)"
    exitError $errMessage
}

# get target computer name if not already specified
if ( [String]::IsNullOrWhiteSpace($TargetComputer))
{
    do
    {
        $TargetComputer = Read-Host -Prompt 'Computer to wake-up'
    } while ( [String]::IsNullOrWhiteSpace($TargetComputer))
}
Write-Host

# read database and assemble list of target computers
[xml]$wolDb = Get-Content -Path $WolDatabase
$broadcastIP = $wolDb.WOLDatabase.Configuration.BroadcastAddress
$port = $wolDb.WOLDatabase.Configuration.Port
$dnsSuffix = $wolDb.WOLDatabase.Configuration.DnsSuffix
$targetComputers = [System.Collections.Generic.List[PSObject]]::new()
$TargetComputer | ForEach-Object {
    $tgt = $_
    $wolDb.WOLDatabase.Computers.Computer | Where-Object { $_.name -match $tgt } | ForEach-Object { $targetComputers.Add($_) }
}
$removeFromTargetComputers = [System.Collections.Generic.List[String]]::new()

# exit if nothing to do (i.e. empty targetComputers list)
if ($targetComputers.Count -eq 0)
{
    Write-Host -ForegroundColor Yellow "No computers found matching '$TargetComputer'. Nothing to do.`r`n"
    exit 0
}

# send WOL magic packets
$targetComputers | ForEach-Object {
    $wolError = @()
    $name = $_.name
    $friendlyName = $_.friendlyName
    if ( [String]::IsNullOrWhiteSpace($friendlyName))
    {
        Write-Host "Processing request to wake-up '$name'... " -NoNewline
    }
    else
    {
        Write-Host "Processing request to wake-up '$friendlyName'... " -NoNewline
    }

    # send magic packet
    $_.mac | Send-MagicPacket -BroadcastIP $broadcastIP -Port $port -ErrorAction SilentlyContinue -ErrorVariable +wolError
    if ($wolError.Count -eq 0)
    {
        Write-Host -ForegroundColor Green "[OK]"
    }
    else
    {
        Write-Host -ForegroundColor Red "[ERROR]"
        # queue for removal from computers on which to run a connectivity check
        $removeFromTargetComputers.Add($name)
    }
}

# remove computers from targetComputers if WOL packet was not successfully sent
$removeFromTargetComputers | ForEach-Object {
    $removeName = $_
    $targetComputers.Remove(($targetComputers | Where-Object { $_.name -eq $removeName })) | Out-Null
}

# exit if connectivity check skipped or if no computers to test
if ($NoConnectivityCheck)
{
    Write-Host "`r`nSkipping connectivity checks."
    exitGracefully
}
elseif ($targetComputers.Count -eq 0)
{
    exitError "No wake-up packets sent successfully" -exitCode 5
}

# wait for initial delay seconds to let computer(s) wake up
for ($i = $ConnectivityCheckDelay; $i -gt 0; $i--) {
    Write-Progress -Activity "Waiting for computer(s) to wake-up..." -SecondsRemaining $i
    Start-Sleep 1
}
Write-Progress -Activity "Waiting for computer(s) to wake-up..." -Completed

# iterate computers and test connectivity
# TODO: run connectivity test as background job
$connCheckTotalTime = 0
$removeFromTargetComputers.Clear()
do
{
    $targetComputers | ForEach-Object {
        $name = $_.name
        $friendlyName = $_.friendlyName
        $fqdn = -join ($name, $dnsSuffix)
        $connectionError = @()

        if ( [String]::IsNullOrWhiteSpace($friendlyName))
        {
            Write-Host "Testing connection readiness of '$name'... " -NoNewline
        }
        else
        {
            Write-Host "Testing connection readiness of '$friendlyName'... " -NoNewline
        }
        if (!(Test-NetConnection -ComputerName $fqdn -Port $ConnectivityCheckPort -InformationLevel Quiet -WarningAction SilentlyContinue -ErrorAction SilentlyContinue -ErrorVariable +connectionError))
        {
            if (($connCheckTotalTime + $ConnectivityCheckInterval) -gt $ConnectivityCheckTimeout)
            {
                # last iteration, display 'error'
                Write-Host -ForegroundColor Red "[ERROR]"
                $connectionError | ForEach-Object {
                    $errMsg = $_.ToString()
                    Write-Verbose "`t(Additional information: $errMsg)"
                }
            }
            else
            {
                # more iterations pending, display 'retrying'
                Write-Host -ForegroundColor Yellow "[RETRYING]"
            }
        }
        else
        {
            Write-Host -ForegroundColor Green "[OK]"
            # queue for removal from computers to check next round
            $removeFromTargetComputers.Add($name)
        }
    }

    # remove computers from targetComputers if connectivity check already successful
    $removeFromTargetComputers | ForEach-Object {
        $removeName = $_
        $targetComputers.Remove(($targetComputers | Where-Object { $_.name -eq $removeName })) | Out-Null
    }

    # sleep until next test interval and increase time counter
    $connCheckTotalTime += $ConnectivityCheckInterval
    if ($connCheckTotalTime -le $ConnectivityCheckTimeout -and $targetComputers.Count -gt 0)
    {
        for ($i = $ConnectivityCheckInterval; $i -gt 0; $i--) {
            Write-Progress -Activity "Waiting for next connectivity check..." -SecondsRemaining $i
            Start-Sleep 1
        }
        Write-Progress -Activity "Waiting for next connectivity check..." -Completed
    }
} while ($connCheckTotalTime -le $ConnectivityCheckTimeout -and $targetComputers.Count -gt 0)

# exit gracefully
exitGracefully