<#
.SYNOPSIS
    Reports what a Microsoft Entra ID group is and what it's wired to: members, owners,
    group-based licenses, app assignments and Intune policy assignments.
.DESCRIPTION
    Read-only. Looks the group up by name or object ID, then returns one row per finding
    with Section, Name and Detail columns, so the output sorts, filters and exports to CSV
    cleanly. Intune assignments cover device configuration profiles, compliance policies
    and (unless -SkipSettingsCatalog) Settings catalog policies.
.PARAMETER Identity
    The group's display name or object ID.
.PARAMETER SkipIntune
    Don't look at Intune assignments. Handy if you don't have Intune read rights.
.PARAMETER SkipSettingsCatalog
    Skip Settings catalog policies, which are only exposed on the Graph beta endpoint.
.EXAMPLE
    .\Get-EntraGroupReport.ps1 -Identity 'Sales Team'
.EXAMPLE
    .\Get-EntraGroupReport.ps1 -Identity 'Sales Team' | Export-Csv .\sales-team.csv -NoTypeInformation
#>
[CmdletBinding()]
param(
    [Parameter(Mandatory, ValueFromPipeline)]
    [string]$Identity,
    [switch]$SkipIntune,
    [switch]$SkipSettingsCatalog
)

$ErrorActionPreference = 'Stop'
$scopes = 'Directory.Read.All', 'DeviceManagementConfiguration.Read.All'
if (-not (Get-MgContext)) { Connect-MgGraph -Scopes $scopes -NoWelcome }

function New-Row([string]$Section, [string]$Name, [string]$Detail = '') {
    [pscustomobject]@{ Section = $Section; Name = $Name; Detail = $Detail }
}

# --- Find the group (by ID if it looks like a GUID, otherwise by exact display name)
$props = 'Id,DisplayName,Description,GroupTypes,MailEnabled,SecurityEnabled,Mail,MembershipRule,OnPremisesSyncEnabled,AssignedLicenses,CreatedDateTime'
if ($Identity -as [guid]) {
    $group = Get-MgGroup -GroupId $Identity -Property $props
}
else {
    $found = @(Get-MgGroup -Filter "displayName eq '$($Identity -replace "'", "''")'" -Property $props -All)
    if ($found.Count -eq 0) { throw "No group named '$Identity'." }
    if ($found.Count -gt 1) { throw "$($found.Count) groups are named '$Identity'. Use the object ID instead: $($found.Id -join ', ')" }
    $group = $found[0]
}

$kind = if ($group.GroupTypes -contains 'Unified') { 'Microsoft 365' } elseif ($group.MailEnabled) { 'Mail-enabled security / distribution' } else { 'Security' }
New-Row 'Group' $group.DisplayName "$kind group, ID $($group.Id), created $($group.CreatedDateTime)"
if ($group.MembershipRule) { New-Row 'Group' 'Dynamic rule' $group.MembershipRule }
if ($group.OnPremisesSyncEnabled) { New-Row 'Group' 'Source' 'Synced from on-premises AD' }

# --- Owners and members
foreach ($o in Get-MgGroupOwner -GroupId $group.Id -All) {
    New-Row 'Owner' $o.AdditionalProperties['displayName'] $o.AdditionalProperties['userPrincipalName']
}
foreach ($m in Get-MgGroupMember -GroupId $group.Id -All) {
    $type = ($m.AdditionalProperties['@odata.type'] -replace '#microsoft.graph.', '')
    $upn  = $m.AdditionalProperties['userPrincipalName']
    $detail = if ($upn) { "$type, $upn" } else { $type }
    New-Row 'Member' $m.AdditionalProperties['displayName'] $detail
}

# --- Licenses assigned through this group
if ($group.AssignedLicenses) {
    $skuNames = @{}
    Get-MgSubscribedSku -All | ForEach-Object { $skuNames[[string]$_.SkuId] = $_.SkuPartNumber }
    foreach ($lic in $group.AssignedLicenses) {
        $disabled = if ($lic.DisabledPlans) { "$($lic.DisabledPlans.Count) service plan(s) disabled" } else { 'All service plans' }
        $name = if ($skuNames[[string]$lic.SkuId]) { $skuNames[[string]$lic.SkuId] } else { [string]$lic.SkuId }
        New-Row 'License' $name $disabled
    }
}

# --- Enterprise apps the group is assigned to
foreach ($a in Get-MgGroupAppRoleAssignment -GroupId $group.Id -All) {
    $role = if ($a.AppRoleId -eq [guid]::Empty) { 'Default access' } else { "App role $($a.AppRoleId)" }
    New-Row 'App' $a.ResourceDisplayName $role
}

# --- Intune policies that target the group
if (-not $SkipIntune) {
    $sources = [ordered]@{
        'Configuration profile' = 'v1.0/deviceManagement/deviceConfigurations?$expand=assignments&$select=id,displayName'
        'Compliance policy'     = 'v1.0/deviceManagement/deviceCompliancePolicies?$expand=assignments&$select=id,displayName'
    }
    if (-not $SkipSettingsCatalog) { $sources['Settings catalog'] = 'beta/deviceManagement/configurationPolicies?$expand=assignments&$select=id,name' }

    foreach ($label in $sources.Keys) {
        $uri = $sources[$label]
        try {
            while ($uri) {
                $page = Invoke-MgGraphRequest -Method GET -Uri $uri
                foreach ($policy in $page.value) {
                    foreach ($assignment in $policy.assignments) {
                        if ($assignment.target.groupId -ne $group.Id) { continue }
                        $mode = if ($assignment.target.'@odata.type' -like '*exclusion*') { 'Excluded' } else { 'Included' }
                        $policyName = if ($policy.displayName) { $policy.displayName } else { $policy.name }
                        New-Row $label $policyName $mode
                    }
                }
                $uri = $page.'@odata.nextLink'
            }
        }
        catch { Write-Warning "Couldn't read $label assignments: $($_.Exception.Message)" }
    }
}