<#
.TITLE
    Get Compliance Policy Coverage

.SYNOPSIS
    Finds device platforms in the tenant that no assigned compliance policy covers.

.DESCRIPTION
    This script compares the platforms of all enrolled Intune devices against the
    platforms targeted by assigned compliance policies. Platforms with enrolled
    devices but no assigned compliance policy are a real gap: those devices report
    as compliant by default (or fall to the built-in policy) and can slip through
    Conditional Access checks. The report also lists compliance policies that exist
    but are not assigned to anything, and the device count per platform so gaps can
    be prioritized.

.TAGS
    Security,Compliance

.MINROLE
    Intune Administrator

.PERMISSIONS
    DeviceManagementConfiguration.Read.All,DeviceManagementManagedDevices.Read.All

.AUTHOR
    Ugur Koc

.VERSION
    1.2

.CHANGELOG
    1.2 - Added Azure Automation contract validation, portal-safe boolean parameters, beta Graph endpoints, and terminating paging errors
    1.1 - Azure Automation now records script progress, outcomes, and summaries in job history
    1.0 - Initial release

.LASTUPDATE
    2026-07-30

.EXAMPLE
    .\get-compliance-policy-coverage.ps1
    Shows the platform coverage matrix and any gaps

.EXAMPLE
    .\get-compliance-policy-coverage.ps1 -ExportToCsv "true"
    Exports the coverage report to a timestamped CSV file

.NOTES
    - Requires Microsoft.Graph.Authentication module
    - Policy platform is derived from the policy's OData type (windows10CompliancePolicy targets Windows, etc.)
    - A platform counts as covered when at least one policy for it has at least one assignment; group scoping within the platform is not evaluated
    - Check the tenant's "Mark devices with no compliance policy assigned as" setting: if it is set to Compliant, uncovered platforms silently pass Conditional Access
    - Uses beta Graph endpoints for consistency with the rest of the library
    - Local interactive sign-in uses the MgGraphCommunity module to avoid the Graph SDK's mandatory WAM broker on Windows
#>

[CmdletBinding()]
param(
    [Parameter(Mandatory = $false, HelpMessage = "Export results to CSV")]
    [ValidateSet("true", "false", "1", "0", '$true', '$false')]
    [string]$ExportToCsv,

    [Parameter(Mandatory = $false, HelpMessage = "Output path for exports")]
    [string]$OutputPath = ".",

    [Parameter(Mandatory = $false, HelpMessage = "Force module installation without prompting")]
    [ValidateSet("true", "false", "1", "0", '$true', '$false')]
    [string]$ForceModuleInstall
)

# Normalize the local module-install override for Azure Automation parameter binding.
$forceModuleInstallRaw = [string]$ForceModuleInstall
Remove-Variable -Name ForceModuleInstall
if ([string]::IsNullOrWhiteSpace($forceModuleInstallRaw)) {
    $ForceModuleInstall = $false
}
elseif ($forceModuleInstallRaw.Trim().ToLowerInvariant() -in @("true", "1", '$true')) {
    $ForceModuleInstall = $true
}
elseif ($forceModuleInstallRaw.Trim().ToLowerInvariant() -in @("false", "0", '$false')) {
    $ForceModuleInstall = $false
}
else {
    throw "Parameter 'ForceModuleInstall' accepts only true, false, 1, 0, $true, or $false."
}

# Azure Automation supplies portal parameter values as strings. Normalize the
# public boolean parameters once so local and runbook execution use real booleans.
foreach ($runbookBooleanParameter in @('ExportToCsv')) {
    $runbookBooleanRaw = [string](Get-Variable -Name $runbookBooleanParameter -ValueOnly)
    Remove-Variable -Name $runbookBooleanParameter

    if ([string]::IsNullOrWhiteSpace($runbookBooleanRaw)) {
        Set-Variable -Name $runbookBooleanParameter -Value $false
        continue
    }

    switch ($runbookBooleanRaw.Trim().ToLowerInvariant()) {
        { $_ -in @("true", "1", '$true') } {
            Set-Variable -Name $runbookBooleanParameter -Value $true
        }
        { $_ -in @("false", "0", '$false') } {
            Set-Variable -Name $runbookBooleanParameter -Value $false
        }
        default {
            throw "Parameter '$runbookBooleanParameter' accepts only true, false, 1, 0, $true, or $false."
        }
    }
}

# ============================================================================
# ENVIRONMENT DETECTION AND SETUP
# ============================================================================

function Initialize-RequiredModule {
    param(
        [string[]]$ModuleNames,
        [bool]$IsAutomationEnvironment,
        [bool]$ForceInstall = $false
    )

    foreach ($ModuleName in $ModuleNames) {
        Write-Verbose "Checking module: $ModuleName"

        $module = Get-Module -ListAvailable -Name $ModuleName | Select-Object -First 1

        if (-not $module) {
            if ($IsAutomationEnvironment) {
                throw "Module '$ModuleName' is not available in Azure Automation"
            }
            else {
                Write-Information "Module '$ModuleName' not found. Installing..." -InformationAction Continue

                if (-not $ForceInstall) {
                    $response = Read-Host "Install module '$ModuleName'? (Y/N)"
                    if ($response -notmatch '^[Yy]') {
                        throw "Module '$ModuleName' is required but installation was declined."
                    }
                }

                try {
                    $isAdmin = ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator")
                    $scope = if ($isAdmin) { "AllUsers" } else { "CurrentUser" }

                    Install-Module -Name $ModuleName -Scope $scope -Force -AllowClobber -Repository PSGallery
                    Write-Information "✓ Successfully installed '$ModuleName'" -InformationAction Continue
                }
                catch {
                    throw "Failed to install module '$ModuleName': $($_.Exception.Message)"
                }
            }
        }

        Import-Module -Name $ModuleName -Force -ErrorAction Stop
    }
}

# Detect execution environment
$IsAzureAutomation = $null -ne $PSPrivateMetadata.JobId.Guid

# Initialize required modules
$RequiredModules = @("Microsoft.Graph.Authentication")

# MgGraphCommunity gives WAM-free interactive sign-in for local runs
if (-not $IsAzureAutomation) {
    $RequiredModules += "MgGraphCommunity"
}

try {
    Initialize-RequiredModule -ModuleNames $RequiredModules -IsAutomationEnvironment $IsAzureAutomation -ForceInstall $ForceModuleInstall
    Write-Verbose "✓ All required modules are available"
}
catch {
    Write-Error "Module initialization failed: $_"
    exit 1
}

# ============================================================================
# AUTHENTICATION
# ============================================================================

try {
    if ($IsAzureAutomation) {
        Write-Output "Connecting to Microsoft Graph using Managed Identity..."
        Connect-MgGraph -Identity -NoWelcome -ErrorAction Stop
    }
    else {
        Write-Output "Connecting to Microsoft Graph..."
        $Scopes = @(
            "DeviceManagementConfiguration.Read.All",
            "DeviceManagementManagedDevices.Read.All"
        )
        Connect-MgGraphCommunity -Scopes $Scopes -NoWelcome -ErrorAction Stop
    }
    Write-Output "✓ Successfully connected to Microsoft Graph"
}
catch {
    Write-Error "Failed to connect to Microsoft Graph: $($_.Exception.Message)"
    exit 1
}

# ============================================================================
# HELPER FUNCTIONS
# ============================================================================

function Get-MgGraphAllPage {
    param(
        [string]$Uri,
        [int]$DelayMs = 100
    )

    $allResults = @()
    $nextLink = $Uri

    do {
        try {
            if ($allResults.Count -gt 0) {
                Start-Sleep -Milliseconds $DelayMs
            }

            $response = Invoke-MgGraphRequest -Uri $nextLink -Method GET

            if ($null -ne $response.value) {
                $allResults += $response.value
            }
            else {
                $allResults += $response
            }

            $nextLink = $response.'@odata.nextLink'
        }
        catch {
            if ($_.Exception.Message -like "*429*") {
                Write-Information "Rate limit hit, waiting 60 seconds..." -InformationAction Continue
                Start-Sleep -Seconds 60
                continue
            }
            throw "Error fetching data: $($_.Exception.Message)"
        }
    } while ($nextLink)

    return $allResults
}

function Get-PolicyPlatform {
    param([string]$ODataType)

    # Compliance policy types map 1:1 to platforms
    switch -Wildcard ($ODataType) {
        "*windows10CompliancePolicy" { "Windows" }
        "*windows81CompliancePolicy" { "Windows" }
        "*macOSCompliancePolicy" { "macOS" }
        "*iosCompliancePolicy" { "iOS/iPadOS" }
        "*androidCompliancePolicy" { "Android" }
        "*androidWorkProfileCompliancePolicy" { "Android" }
        "*androidDeviceOwnerCompliancePolicy" { "Android" }
        "*aospDeviceOwnerCompliancePolicy" { "Android" }
        "*linuxCompliancePolicy" { "Linux" }
        default { ($ODataType -replace "#microsoft.graph.", "") -replace "CompliancePolicy", "" }
    }
}

function Get-DevicePlatform {
    param([string]$OperatingSystem)

    switch -Wildcard ($OperatingSystem) {
        "Windows*" { "Windows" }
        "macOS*" { "macOS" }
        "iOS*" { "iOS/iPadOS" }
        "iPadOS*" { "iOS/iPadOS" }
        "Android*" { "Android" }
        "Linux*" { "Linux" }
        default { $OperatingSystem }
    }
}

# ============================================================================
# MAIN SCRIPT LOGIC
# ============================================================================

try {
    Write-Output "Retrieving compliance policies with assignments..."
    $policies = Get-MgGraphAllPage -Uri "https://graph.microsoft.com/beta/deviceManagement/deviceCompliancePolicies?`$expand=assignments"
    Write-Output "✓ Found $(@($policies).Count) compliance policies"

    Write-Output "Retrieving managed devices..."
    $devices = Get-MgGraphAllPage -Uri "https://graph.microsoft.com/beta/deviceManagement/managedDevices?`$select=id,operatingSystem,complianceState"
    Write-Output "✓ Found $(@($devices).Count) managed devices"

    # Device counts per platform
    $devicePlatforms = @{}
    foreach ($device in $devices) {
        $platform = Get-DevicePlatform -OperatingSystem ([string]$device.operatingSystem)
        if (-not $devicePlatforms.ContainsKey($platform)) { $devicePlatforms[$platform] = 0 }
        $devicePlatforms[$platform]++
    }

    # Assigned policy counts per platform
    $platformPolicies = @{}
    [System.Collections.Generic.List[Object]]$unassignedPolicies = @()

    foreach ($policy in $policies) {
        $platform = Get-PolicyPlatform -ODataType ([string]$policy.'@odata.type')
        $isAssigned = (@($policy.assignments).Count -gt 0)

        if ($isAssigned) {
            if (-not $platformPolicies.ContainsKey($platform)) {
                $platformPolicies[$platform] = [System.Collections.Generic.List[string]]::new()
            }
            $platformPolicies[$platform].Add($policy.displayName)
        }
        else {
            $unassignedPolicies.Add([PSCustomObject]@{
                    PolicyName = $policy.displayName
                    Platform   = $platform
                })
        }
    }

    # Build coverage matrix
    [System.Collections.Generic.List[Object]]$report = @()
    foreach ($platform in ($devicePlatforms.Keys | Sort-Object)) {
        $assignedPolicyNames = if ($platformPolicies.ContainsKey($platform)) { @($platformPolicies[$platform]) } else { @() }
        $noncompliantCount = @($devices | Where-Object { (Get-DevicePlatform -OperatingSystem ([string]$_.operatingSystem)) -eq $platform -and $_.complianceState -eq "noncompliant" }).Count

        $report.Add([PSCustomObject]@{
                Platform           = $platform
                DeviceCount        = $devicePlatforms[$platform]
                NoncompliantCount  = $noncompliantCount
                AssignedPolicies   = $assignedPolicyNames.Count
                PolicyNames        = ($assignedPolicyNames -join "; ")
                CoverageStatus     = if ($assignedPolicyNames.Count -gt 0) { "Covered" } else { "NOT COVERED" }
            })
    }

    # ----- Display results -----
    Write-Output "`nCOMPLIANCE POLICY COVERAGE"
    Write-Output ("=" * 50)
    Write-Output "Generated: $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss')"
    Write-Output ("=" * 50)

    foreach ($row in $report) {
        Write-Output "`n[$($row.CoverageStatus)] $($row.Platform)"
        Write-Output "  Devices: $($row.DeviceCount) ($($row.NoncompliantCount) noncompliant)"
        if ($row.AssignedPolicies -gt 0) {
            Write-Output "  Assigned policies: $($row.PolicyNames)"
        }
        else {
            Write-Output "  No assigned compliance policy targets this platform"
        }
    }

    if ($unassignedPolicies.Count -gt 0) {
        Write-Output "`nUnassigned compliance policies:"
        foreach ($row in ($unassignedPolicies | Sort-Object Platform, PolicyName)) {
            Write-Output "  $($row.PolicyName) [$($row.Platform)]"
        }
    }

    # Summary
    $gapPlatforms = @($report | Where-Object { $_.CoverageStatus -eq "NOT COVERED" })
    Write-Output "`n"
    Write-Output ("=" * 50)
    Write-Output "Summary: $($report.Count) platforms with devices, $($gapPlatforms.Count) without compliance coverage, $($unassignedPolicies.Count) unassigned policies"
    if ($gapPlatforms.Count -gt 0) {
        Write-Output "Gap platforms: $(($gapPlatforms | ForEach-Object { $_.Platform }) -join ', ')"
    }
    Write-Output ("=" * 50)

    # Export to CSV if requested
    if ($ExportToCsv) {
        $timestamp = Get-Date -Format "yyyy-MM-dd_HH-mm-ss"
        $csvPath = Join-Path $OutputPath "Compliance_Coverage_$timestamp.csv"
        $report | Export-Csv -Path $csvPath -NoTypeInformation -Encoding UTF8
        Write-Output "✓ CSV report saved: $csvPath"
    }
}
catch {
    Write-Error "Script execution failed: $($_.Exception.Message)"
    exit 1
}
finally {
    try {
        $null = Disconnect-MgGraph
        Write-Output "✓ Disconnected from Microsoft Graph"
    }
    catch {
        Write-Verbose "Graph disconnection completed"
    }
}

# Copia sin cambios de https://github.com/ugurkocde/IntuneAutomation (commit 797bb2e).
# MIT License
#
# Copyright (c) 2025 Ugur Koc | Microsoft MVP
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.