$logFile = "C:\ProgramData\Microsoft\IntuneManagementExtension\Logs\EPMregistration.txt"

function Write-Log {
    param (
        [string]$Message,
        [string]$Level = "INFO"
    )
    $timestamp = Get-Date -Format "dd-MM-yyyy HH:mm:ss"
    $logMessage = "$timestamp [$Level] $Message"
    Add-Content -Path $logFile -Value $logMessage
    Write-Host $logMessage
}

function Check-EPMStatus {
    $appxPackage = Get-AppxPackage -Name "Microsoft.EpmShellExtension"
    $service = Get-Service -Name "MEMEPMSvc" -ErrorAction SilentlyContinue
    $dllPath = "C:\Program Files\Microsoft EPM Agent\EPMShellExtension\EpmShellExtension.dll"

    if ($null -eq $appxPackage) {
        Write-Log "EPM Shell Extension is not installed." -Level "ERROR"
        return $false
    }
    Write-Log "EPM Shell Extension is installed." -Level "INFO"

    if ($null -eq $service) {
        Write-Log "MEMEPMSvc service is not installed." -Level "ERROR"
        return $false
    }
    Write-Log "MEMEPMSvc service is installed." -Level "INFO"

    if (-not (Test-Path $dllPath)) {
        Write-Log "EpmShellExtension.dll not found at expected location: $dllPath" -Level "ERROR"
        return $false
    }
    Write-Log "EpmShellExtension.dll is present at the expected location." -Level "INFO"

    Write-Log "All required components are present. Proceeding with registry modifications." -Level "INFO"
    return $true
}

# Check EPM status before proceeding
if (-not (Check-EPMStatus)) {
    Write-Log "Exiting script due to missing EPM components." -Level "ERROR"
    exit
}

# Mount the HKCR drive
try {
    New-PSDrive -Name HKCR -PSProvider Registry -Root HKEY_CLASSES_ROOT -ErrorAction Stop | Out-Null
    Write-Log "HKCR drive mounted successfully." -Level "INFO"
} catch {
    Write-Log "Failed to mount HKCR drive: $($_.Exception.Message)" -Level "ERROR"
    exit
}

# Function to check and add registry key/value
function Ensure-RegistryValue {
    param (
        [string]$Path,
        [string]$Name,
        [object]$Value,
        [string]$Type
    )

    try {
        if (!(Test-Path $Path)) {
            New-Item -Path $Path -Force | Out-Null
        }

        $existingValue = Get-ItemProperty -Path $Path -Name $Name -ErrorAction SilentlyContinue

        if ($null -eq $existingValue -or $existingValue.$Name -ne $Value) {
            Set-ItemProperty -Path $Path -Name $Name -Value $Value -Type $Type -Force
            Write-Log "Added/Updated: $Path\$Name" -Level "INFO"
        } else {
            Write-Log "Already exists and correct: $Path\$Name" -Level "INFO"
        }

        # Verify the value after setting
        $verifiedValue = Get-ItemPropertyValue -Path $Path -Name $Name -ErrorAction Stop
        if ($verifiedValue -ne $Value) {
            throw "Verification failed: $Path\$Name. Expected '$Value', but got '$verifiedValue'"
        }
    }
    catch {
        Write-Log "Error processing $Path\$Name`: $($_.Exception.Message)" -Level "ERROR"
    }
}

# Array of registry entries to check/add
$registryEntries = @(
    @{Path="HKCR:\CLSID\{02D0A1D6-0F3A-4534-BE54-5178737324E0}"; Name="(Default)"; Value=""; Type="String"},
    @{Path="HKCR:\CLSID\{02D0A1D6-0F3A-4534-BE54-5178737324E0}\InprocServer32"; Name="(Default)"; Value="C:\Program Files\Microsoft EPM Agent\EPMShellExtension\EpmShellExtension.dll"; Type="String"},
    @{Path="HKCR:\CLSID\{02D0A1D6-0F3A-4534-BE54-5178737324E0}\InprocServer32"; Name="ThreadingModel"; Value="Apartment"; Type="String"},
    @{Path="HKCR:\exefile\shellex\ContextMenuHandlers\MEMEPMShExt"; Name="(Default)"; Value="{02D0A1D6-0F3A-4534-BE54-5178737324E0}"; Type="String"},
    @{Path="HKCR:\PackagedCom\ClassIndex\{02D0A1D6-0F3A-4534-BE54-5178737324E0}\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe"; Name="(Default)"; Value=""; Type="String"},
    @{Path="HKCR:\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Class\{02D0A1D6-0F3A-4534-BE54-5178737324E0}"; Name="ServerId"; Value=0; Type="DWord"},
    @{Path="HKCR:\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Class\{02D0A1D6-0F3A-4534-BE54-5178737324E0}"; Name="DllPath"; Value="EpmShellExtension.dll"; Type="String"},
    @{Path="HKCR:\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Class\{02D0A1D6-0F3A-4534-BE54-5178737324E0}"; Name="Threading"; Value=0; Type="DWord"},
    @{Path="HKCR:\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Server\0"; Name="ApplicationId"; Value="EpmShellIdentity"; Type="String"},
    @{Path="HKCR:\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Server\0"; Name="ApplicationDisplayName"; Value="EpmShellIdentity"; Type="String"},
    @{Path="HKCR:\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Server\0"; Name="DisplayName"; Value="Microsoft EPM Agent"; Type="String"},
    @{Path="HKCR:\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Server\0"; Name="SurrogateAppId"; Value="{02D0A1D6-0F3A-4534-BE54-5178737324E0}"; Type="String"},
    @{Path="HKLM:\SOFTWARE\Classes\PackagedCom\ClassIndex\{02D0A1D6-0F3A-4534-BE54-5178737324E0}\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe"; Name="(Default)"; Value=""; Type="String"},
    @{Path="HKLM:\SOFTWARE\Classes\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Class\{02D0A1D6-0F3A-4534-BE54-5178737324E0}"; Name="ServerId"; Value=0; Type="DWord"},
    @{Path="HKLM:\SOFTWARE\Classes\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Class\{02D0A1D6-0F3A-4534-BE54-5178737324E0}"; Name="DllPath"; Value="EpmShellExtension.dll"; Type="String"},
    @{Path="HKLM:\SOFTWARE\Classes\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Class\{02D0A1D6-0F3A-4534-BE54-5178737324E0}"; Name="Threading"; Value=0; Type="DWord"},
    @{Path="HKLM:\SOFTWARE\Classes\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Server\0"; Name="ApplicationId"; Value="EpmShellIdentity"; Type="String"},
    @{Path="HKLM:\SOFTWARE\Classes\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Server\0"; Name="ApplicationDisplayName"; Value="EpmShellIdentity"; Type="String"},
    @{Path="HKLM:\SOFTWARE\Classes\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Server\0"; Name="DisplayName"; Value="Microsoft EPM Agent"; Type="String"},
    @{Path="HKLM:\SOFTWARE\Classes\PackagedCom\Package\Microsoft.EpmShellExtension_1.0.0.0_neutral__8wekyb3d8bbwe\Server\0"; Name="SurrogateAppId"; Value="{02D0A1D6-0F3A-4534-BE54-5178737324E0}"; Type="String"}
)

# Process each registry entry
foreach ($entry in $registryEntries) {
    Ensure-RegistryValue @entry
}

# Final verification
$allSuccessful = $true
foreach ($entry in $registryEntries) {
    try {
        $value = Get-ItemPropertyValue -Path $entry.Path -Name $entry.Name -ErrorAction Stop
        if ($value -eq $entry.Value) {
            Write-Log "Verified: $($entry.Path)\$($entry.Name)" -Level "INFO"
        } else {
            Write-Log "Verification failed: $($entry.Path)\$($entry.Name). Expected '$($entry.Value)', but got '$value'" -Level "ERROR"
            $allSuccessful = $false
        }
    }
    catch {
        Write-Log "Verification failed: $($entry.Path)\$($entry.Name). Error: $($_.Exception.Message)" -Level "ERROR"
        $allSuccessful = $false
    }
}

if ($allSuccessful) {
    Write-Log "All registry entries were successfully added and verified." -Level "INFO"
} else {
    Write-Log "Some registry entries could not be added or verified. Please check the log for details." -Level "WARN"
}

# Remove the HKCR drive
Remove-PSDrive -Name HKCR
Write-Log "HKCR drive removed." -Level "INFO"

Write-Log "Script execution completed." -Level "INFO"