#Requires -Version 5.1
<#
.SYNOPSIS
    eDNC Special Character Fix - Real-time file watcher to strip invalid characters from DNC files.

.DESCRIPTION
    Monitors a specified folder for DNC program files (.pun, .nc, etc.) and automatically
    removes special characters (0xFF and others) that cause issues with CNC machines.

    Some legacy DNC systems and communication protocols add padding or termination bytes
    that modern CNC controllers cannot process correctly.

.PARAMETER WatchFolder
    The folder to monitor for DNC files. Default: C:\Dnc_Files\Q

.PARAMETER FileFilter
    File pattern to watch. Default: *.pun

.PARAMETER IncludeSubfolders
    Whether to watch subfolders. Default: $true

.PARAMETER CharactersToRemove
    Array of byte values to strip from files. Default: @(255) for 0xFF

.EXAMPLE
    .\eDNC-SpecialCharFix.ps1
    Runs with default settings, watching C:\Dnc_Files\Q for *.pun files

.EXAMPLE
    .\eDNC-SpecialCharFix.ps1 -WatchFolder "D:\DNC\Programs" -FileFilter "*.nc"
    Watches D:\DNC\Programs for .nc files

.EXAMPLE
    .\eDNC-SpecialCharFix.ps1 -CharactersToRemove @(255, 0, 26)
    Removes 0xFF, NULL, and SUB (Ctrl+Z) characters

.NOTES
    Author: GE Aerospace - Rutland
    Version: 1.4.0
    Date: 2025-12-12

    v1.4.0 - Auto-update:
    - Checks S:\DT\cameron\eDNC-Fix\version.ini every 5 minutes
    - Auto-downloads and restarts if newer version found

    v1.3.0 - Fixed header UI:
    - GE Aerospace ASCII banner stays at top
    - Live status updates in header (Processing, Cleaned, Failed)
    - Live stats counter (Cleaned/Failed count)
    - Auto-elevate to Administrator via batch file

    v1.2.0 - Immediate processing:
    - Process file immediately when eDNC releases it (50ms initial delay)
    - Aggressive retry: 100ms -> 200ms -> 400ms -> 800ms (15 attempts)
    - Debouncing to prevent duplicate processing
    - Exclusive file lock for atomic read/write

    Common problematic characters:
    - 0xFF (255) - Padding/fill character
    - 0x00 (0)   - NULL character
    - 0x1A (26)  - SUB/Ctrl+Z (EOF marker in some systems)
    - 0x7F (127) - DEL character
#>

[CmdletBinding()]
param(
    [Parameter()]
    [string]$WatchFolder = "C:\Dnc_Files\Q",

    [Parameter()]
    [string]$FileFilter = "*.pun",

    [Parameter()]
    [bool]$IncludeSubfolders = $true,

    [Parameter()]
    [int[]]$CharactersToRemove = @(255)
)

# Script info
$ScriptVersion = "1.4.0"
$ScriptName = "eDNC Special Character Fix"

# Auto-update settings
$UpdateSource = "S:\DT\cameron\eDNC-Fix"
$LocalPath = "C:\eDNC-Fix"
$UpdateCheckInterval = 300  # Check every 5 minutes (in seconds)
$script:LastUpdateCheck = [DateTime]::MinValue

# Header display function
function Show-Header {
    param([int]$Cleaned = 0, [int]$Failed = 0, [string]$Status = "Watching...")

    $headerLines = @(
        ""
        "  ____  ____                                                  "
        " / ___|| ___|     / \   ___ _ __ ___  ___ _ __   __ _  ___ ___ "
        "| |  _ |  _|     / _ \ / _ \ '__/ _ \/ __| '_ \ / _`` |/ __/ _ \"
        "| |_| || |___   / ___ \  __/ | | (_) \__ \ |_) | (_| | (_|  __/"
        " \____||_____| /_/   \_\___|_|  \___/|___/ .__/ \__,_|\___\___|"
        "                                         |_|                   "
        ""
        "  $ScriptName"
        "  by Cam P. | v$ScriptVersion"
        ""
        "  Folder: $WatchFolder"
        "  Filter: $FileFilter | Cleaned: $Cleaned | Failed: $Failed"
        ""
        "  Status: $Status"
        "================================================================"
    )

    # Save cursor, go to top, draw header
    [Console]::SetCursorPosition(0, 0)

    for ($i = 0; $i -lt $headerLines.Count; $i++) {
        $line = $headerLines[$i]
        # Clear line and write
        Write-Host ("`r" + $line.PadRight([Console]::WindowWidth - 1)) -NoNewline

        # Apply colors
        [Console]::SetCursorPosition(0, $i)
        if ($i -ge 1 -and $i -le 6) {
            Write-Host $line -ForegroundColor Cyan
        } elseif ($i -eq 8) {
            Write-Host $line -ForegroundColor White
        } elseif ($i -eq 9) {
            Write-Host $line -ForegroundColor Gray
        } elseif ($i -eq 14) {
            if ($Status -like "*ERROR*" -or $Status -like "*FAILED*") {
                Write-Host $line -ForegroundColor Red
            } elseif ($Status -like "*CLEANED*") {
                Write-Host $line -ForegroundColor Green
            } else {
                Write-Host $line -ForegroundColor Yellow
            }
        } elseif ($i -eq 15) {
            Write-Host $line -ForegroundColor DarkGray
        } else {
            Write-Host $line
        }
    }

    return $headerLines.Count
}

# Auto-update function
function Check-ForUpdate {
    $versionFile = Join-Path $UpdateSource "version.ini"

    # Skip if source not available
    if (-not (Test-Path $versionFile)) {
        return $false
    }

    try {
        # Read version from INI file
        $content = Get-Content $versionFile -Raw
        if ($content -match 'Version=(\d+\.\d+\.\d+)') {
            $remoteVersion = [version]$matches[1]
            $localVersion = [version]$ScriptVersion

            if ($remoteVersion -gt $localVersion) {
                return $remoteVersion.ToString()
            }
        }
    }
    catch {
        # Silently fail if can't read
    }

    return $false
}

function Invoke-Update {
    param([string]$NewVersion)

    Write-Host ""
    Write-Host "  [UPDATE] New version $NewVersion available!" -ForegroundColor Magenta
    Write-Host "  [UPDATE] Downloading update..." -ForegroundColor Magenta

    try {
        # Copy new files
        $files = @("eDNC-SpecialCharFix.ps1", "Run-eDNCFix.bat", "Install-ScheduledTask.ps1", "version.ini")
        foreach ($file in $files) {
            $src = Join-Path $UpdateSource $file
            $dst = Join-Path $LocalPath $file
            if (Test-Path $src) {
                Copy-Item -Path $src -Destination $dst -Force
            }
        }

        Write-Host "  [UPDATE] Update complete! Restarting..." -ForegroundColor Magenta
        Start-Sleep -Seconds 2

        # Restart the script
        $scriptPath = Join-Path $LocalPath "eDNC-SpecialCharFix.ps1"
        Start-Process powershell.exe -ArgumentList "-NoProfile -ExecutionPolicy Bypass -File `"$scriptPath`"" -WindowStyle Normal

        # Exit current instance
        exit 0
    }
    catch {
        Write-Host "  [UPDATE] Update failed: $($_.Exception.Message)" -ForegroundColor Red
    }
}

# Initialize console
Clear-Host
$script:HeaderHeight = Show-Header -Status "Initializing..."

# Validate watch folder exists
if (-not (Test-Path $WatchFolder)) {
    Show-Header -Status "ERROR: Watch folder does not exist!"
    [Console]::SetCursorPosition(0, $script:HeaderHeight + 1)
    Write-Host "Please create the folder or specify a different path." -ForegroundColor Yellow
    exit 1
}

# Update header with ready status
Show-Header -Status "Watching for files... (Ctrl+C to stop)" | Out-Null
[Console]::SetCursorPosition(0, $script:HeaderHeight + 1)
Write-Host "Removing bytes: $($CharactersToRemove -join ', ') (0x$($CharactersToRemove | ForEach-Object { '{0:X2}' -f $_ } | Join-String -Separator ', 0x'))" -ForegroundColor DarkGray
Write-Host ""

# Statistics
$script:FilesProcessed = 0
$script:BytesRemoved = 0
$script:FailedFiles = 0

# Debounce tracking - prevent processing same file multiple times
$script:RecentlyProcessed = @{}
$script:DebounceSeconds = 5

# Create file system watcher
$watcher = New-Object System.IO.FileSystemWatcher
$watcher.Path = $WatchFolder
$watcher.Filter = $FileFilter
$watcher.IncludeSubdirectories = $IncludeSubfolders
$watcher.EnableRaisingEvents = $true

# Define the cleanup action
$action = {
    $path = $Event.SourceEventArgs.FullPath
    $changeType = $Event.SourceEventArgs.ChangeType
    $fileName = Split-Path $path -Leaf

    # Get parameters from message data
    $charsToRemove = $Event.MessageData.CharsToRemove
    $debounceSeconds = $Event.MessageData.DebounceSeconds
    $statusLine = $Event.MessageData.StatusLine

    # Helper to update status line in header
    $updateStatus = {
        param($msg, $color = "Yellow")
        $savedPos = [Console]::CursorTop
        [Console]::SetCursorPosition(0, $statusLine)
        Write-Host ("  Status: " + $msg).PadRight([Console]::WindowWidth - 1) -ForegroundColor $color
        [Console]::SetCursorPosition(0, $savedPos)
    }

    # Helper to update stats line in header
    $updateStats = {
        $savedPos = [Console]::CursorTop
        [Console]::SetCursorPosition(0, 12)
        Write-Host ("  Filter: $($Event.MessageData.FileFilter) | Cleaned: $($script:FilesProcessed) | Failed: $($script:FailedFiles)").PadRight([Console]::WindowWidth - 1) -ForegroundColor White
        [Console]::SetCursorPosition(0, $savedPos)
    }

    # Debounce check - skip if we processed this file recently
    $now = Get-Date
    if ($script:RecentlyProcessed.ContainsKey($path)) {
        $lastProcessed = $script:RecentlyProcessed[$path]
        if (($now - $lastProcessed).TotalSeconds -lt $debounceSeconds) {
            return  # Skip duplicate event
        }
    }

    & $updateStatus "Processing: $fileName" "Yellow"
    Write-Host "$(Get-Date -Format 'yyyy-MM-dd HH:mm:ss') | $changeType | $fileName" -ForegroundColor White

    # Brief initial delay to let eDNC finish (50ms)
    Start-Sleep -Milliseconds 50

    # Try to acquire exclusive access - process immediately when available
    $maxRetries = 15
    $retryCount = 0
    $baseDelay = 100  # Start with 100ms, doubles each retry (100, 200, 400, 800...)

    while ($retryCount -lt $maxRetries) {
        $fileStream = $null
        try {
            # Try to open file with exclusive access - this confirms it's available
            $fileStream = [System.IO.File]::Open(
                $path,
                [System.IO.FileMode]::Open,
                [System.IO.FileAccess]::ReadWrite,
                [System.IO.FileShare]::None
            )

            # Read all bytes while we have exclusive lock
            $fileStream.Position = 0
            $bytes = New-Object byte[] $fileStream.Length
            $null = $fileStream.Read($bytes, 0, $bytes.Length)
            $originalCount = $bytes.Length

            # Remove specified bytes
            $cleaned = [System.Collections.Generic.List[byte]]::new()
            foreach ($b in $bytes) {
                if ($b -notin $charsToRemove) {
                    $cleaned.Add($b)
                }
            }
            $newCount = $cleaned.Count

            # Only rewrite if we found characters to remove
            if ($originalCount -ne $newCount) {
                # Truncate and rewrite
                $fileStream.Position = 0
                $fileStream.SetLength(0)
                $cleanedArray = $cleaned.ToArray()
                $fileStream.Write($cleanedArray, 0, $cleanedArray.Length)
                $fileStream.Flush()

                $removed = $originalCount - $newCount
                Write-Host "  [CLEANED] Removed $removed byte(s)" -ForegroundColor Green
                $script:FilesProcessed++
                $script:BytesRemoved += $removed
                & $updateStatus "CLEANED: $fileName ($removed bytes)" "Green"
                & $updateStats
            } else {
                Write-Host "  [OK] No special characters found" -ForegroundColor Gray
                & $updateStatus "OK: $fileName (no changes)" "Gray"
            }

            # Mark as recently processed
            $script:RecentlyProcessed[$path] = Get-Date
            break
        }
        catch [System.IO.IOException] {
            $retryCount++
            if ($retryCount -lt $maxRetries) {
                # Exponential backoff: 100ms, 200ms, 400ms, 800ms...
                $delay = [math]::Min($baseDelay * [math]::Pow(2, $retryCount - 1), 16000)
                Write-Host "  [RETRY] File locked, waiting $([math]::Round($delay/1000, 1))s... ($retryCount/$maxRetries)" -ForegroundColor Yellow
                & $updateStatus "RETRY: $fileName ($retryCount/$maxRetries)" "Yellow"
                Start-Sleep -Milliseconds $delay
            } else {
                Write-Host "  [FAILED] Could not access file after $maxRetries attempts" -ForegroundColor Red
                $script:FailedFiles++
                & $updateStatus "FAILED: $fileName" "Red"
                & $updateStats
            }
        }
        catch {
            Write-Host "  [ERROR] $($_.Exception.Message)" -ForegroundColor Red
            $script:FailedFiles++
            & $updateStatus "ERROR: $fileName" "Red"
            & $updateStats
            break
        }
        finally {
            if ($fileStream) {
                $fileStream.Close()
                $fileStream.Dispose()
            }
        }
    }
}

# Create message data object to pass parameters to the action
$messageData = @{
    CharsToRemove = $CharactersToRemove
    DebounceSeconds = $script:DebounceSeconds
    StatusLine = 14  # Line number for status updates
    FileFilter = $FileFilter
}

# Register event handlers
$null = Register-ObjectEvent -InputObject $watcher -EventName Created -Action $action -MessageData $messageData
$null = Register-ObjectEvent -InputObject $watcher -EventName Changed -Action $action -MessageData $messageData

# Keep script running
try {
    while ($true) {
        Start-Sleep -Seconds 1

        # Periodic update check
        $now = Get-Date
        if (($now - $script:LastUpdateCheck).TotalSeconds -ge $UpdateCheckInterval) {
            $script:LastUpdateCheck = $now
            $newVersion = Check-ForUpdate
            if ($newVersion) {
                Invoke-Update -NewVersion $newVersion
            }
        }
    }
}
finally {
    # Cleanup on exit
    $watcher.EnableRaisingEvents = $false
    $watcher.Dispose()
    Get-EventSubscriber | Unregister-Event

    Write-Host ""
    Write-Host "========================================" -ForegroundColor Cyan
    Write-Host " Session Summary" -ForegroundColor Cyan
    Write-Host "========================================" -ForegroundColor Cyan
    Write-Host "  Files Cleaned:  $script:FilesProcessed"
    Write-Host "  Bytes Removed:  $script:BytesRemoved"
    if ($script:FailedFiles -gt 0) {
        Write-Host "  Failed Files:   $script:FailedFiles" -ForegroundColor Red
    }
    Write-Host ""
    Write-Host "Stopped watching folder" -ForegroundColor Yellow
}