<#
.SYNOPSIS
  Monitor disk space and alert when below threshold

.DESCRIPTION
  Checks all fixed drives for available space and alerts when below threshold.
  Can be scheduled as a task for proactive monitoring.

.PARAMETER ThresholdPercent
  Alert when free space falls below this percentage (default: 15)

.PARAMETER ThresholdGB
  Alternative: alert when free space falls below this many GB (default: not used)

.PARAMETER LogPath
  Path to log file for alerts (default: C:\Temp\DiskSpace-Monitor.log)

.PARAMETER SendEmail
  Send email alerts (requires email parameters, default: $false)

.PARAMETER SmtpServer
  SMTP server for email alerts

.PARAMETER EmailFrom
  From address for email alerts

.PARAMETER EmailTo
  To address(es) for email alerts (comma-separated)

.NOTES
  ⚠️  AI-GENERATED SCRIPT - UNTESTED
  This script was generated by Claude AI and has not been tested in production.
  Review and test thoroughly in a non-production environment before use.

  - Suitable for scheduled task execution
  - Exit codes: 0=OK, 1=Warning (below threshold), 2=Error
  - Email functionality requires SMTP access

.EXAMPLE
  .\Monitor-DiskSpace.ps1

.EXAMPLE
  .\Monitor-DiskSpace.ps1 -ThresholdPercent 20 -LogPath "D:\Logs\DiskMonitor.log"

.EXAMPLE
  .\Monitor-DiskSpace.ps1 -SendEmail $true -SmtpServer "smtp.domain.com" -EmailFrom "alerts@domain.com" -EmailTo "admin@domain.com"
#>

[CmdletBinding()]
param(
    [int]$ThresholdPercent = 15,
    [int]$ThresholdGB = 0,
    [string]$LogPath = "C:\Temp\DiskSpace-Monitor.log",
    [bool]$SendEmail = $false,
    [string]$SmtpServer = "",
    [string]$EmailFrom = "",
    [string]$EmailTo = ""
)

function Write-Log {
    param([string]$Message, [string]$Level = "INFO")
    $stamp = (Get-Date).ToString('yyyy-MM-dd HH:mm:ss')
    $line = "[$stamp] [$Level] $Message"
    Write-Output $line

    # Ensure log directory exists
    $logDir = Split-Path -Path $LogPath -Parent
    if ($logDir -and -not (Test-Path -Path $logDir)) {
        try {
            New-Item -ItemType Directory -Path $logDir -Force | Out-Null
        } catch {}
    }

    try {
        Add-Content -Path $LogPath -Value $line -Encoding UTF8 -ErrorAction SilentlyContinue
    } catch {}
}

Write-Log "⚠️  AI-GENERATED SCRIPT - UNTESTED" "WARNING"
Write-Log "Starting disk space monitoring on $env:COMPUTERNAME"

# Get all fixed drives
$disks = Get-CimInstance -ClassName Win32_LogicalDisk -Filter "DriveType=3" -ErrorAction SilentlyContinue

if (-not $disks) {
    Write-Log "ERROR: Could not retrieve disk information" "ERROR"
    exit 2
}

$alerts = @()
$allDisksOK = $true

foreach ($disk in $disks) {
    $drive = $disk.DeviceID
    $sizeGB = [math]::Round($disk.Size / 1GB, 2)
    $freeGB = [math]::Round($disk.FreeSpace / 1GB, 2)
    $usedGB = [math]::Round(($disk.Size - $disk.FreeSpace) / 1GB, 2)
    $percentFree = [math]::Round(($disk.FreeSpace / $disk.Size) * 100, 2)

    Write-Log "Drive $drive - Size: $sizeGB GB, Free: $freeGB GB ($percentFree%)"

    # Check thresholds
    $alertTriggered = $false
    $alertReason = ""

    if ($ThresholdGB -gt 0 -and $freeGB -lt $ThresholdGB) {
        $alertTriggered = $true
        $alertReason = "Free space ($freeGB GB) below threshold ($ThresholdGB GB)"
    } elseif ($percentFree -lt $ThresholdPercent) {
        $alertTriggered = $true
        $alertReason = "Free space ($percentFree%) below threshold ($ThresholdPercent%)"
    }

    if ($alertTriggered) {
        $allDisksOK = $false
        $alertMsg = "ALERT: Drive $drive - $alertReason"
        Write-Log $alertMsg "ALERT"

        $alerts += [PSCustomObject]@{
            Drive       = $drive
            SizeGB      = $sizeGB
            FreeGB      = $freeGB
            UsedGB      = $usedGB
            PercentFree = $percentFree
            Reason      = $alertReason
        }
    }
}

# Send email if configured and alerts exist
if ($SendEmail -and $alerts.Count -gt 0) {
    if (-not $SmtpServer -or -not $EmailFrom -or -not $EmailTo) {
        Write-Log "Email alerts enabled but SMTP parameters incomplete" "WARNING"
    } else {
        Write-Log "Sending email alert to $EmailTo via $SmtpServer"

        $subject = "DISK SPACE ALERT: $env:COMPUTERNAME"
        $body = @"
Disk Space Alert on $env:COMPUTERNAME
Generated: $(Get-Date)

The following drives have triggered disk space alerts:

"@

        foreach ($alert in $alerts) {
            $body += @"

Drive: $($alert.Drive)
  Size: $($alert.SizeGB) GB
  Free: $($alert.FreeGB) GB ($($alert.PercentFree)%)
  Used: $($alert.UsedGB) GB
  Alert: $($alert.Reason)
"@
        }

        $body += @"


Threshold Settings:
  Percent Threshold: $ThresholdPercent%
  GB Threshold: $ThresholdGB GB

Please investigate and free up disk space as needed.
"@

        try {
            Send-MailMessage -To $EmailTo.Split(',') -From $EmailFrom -Subject $subject -Body $body -SmtpServer $SmtpServer -ErrorAction Stop
            Write-Log "Email sent successfully"
        } catch {
            Write-Log "ERROR sending email: $($_.Exception.Message)" "ERROR"
        }
    }
}

# Exit with appropriate code
if ($allDisksOK) {
    Write-Log "All disks have sufficient free space"
    exit 0
} else {
    Write-Log "$($alerts.Count) disk(s) below threshold"
    exit 1
}