<#
.SYNOPSIS
    Export all active memberships in privileged Microsoft Entra roles,
    including expansion of group-assigned roles to transitive group members.

.NOTES
    - Uses Microsoft Graph PowerShell only (no Microsoft.Graph.Beta module import)
    - Uses Invoke-MgGraphRequest against the beta endpoint only for role definition discovery
    - Exports CSV to .\Entra-PrivilegedRoleMemberships.csv

.REQUIREMENTS
    Install-Module Microsoft.Graph -Scope CurrentUser

.PERMISSIONS
    Suggested delegated scopes:
      RoleManagement.Read.Directory
      Directory.Read.All
      GroupMember.Read.All
#>

param(
    [string]$CsvPath = ".\Entra-PrivilegedRoleMemberships.csv"
)

$ErrorActionPreference = "Stop"

function Get-ObjectType {
    param([object]$Object)

    if ($null -eq $Object.AdditionalProperties.'@odata.type') {
        return $Object.GetType().Name
    }

    return ($Object.AdditionalProperties.'@odata.type' -replace '^#microsoft.graph\.', '')
}

function Get-DisplayNameSafe {
    param([object]$Object)

    if ($Object.PSObject.Properties.Name -contains 'DisplayName' -and $Object.DisplayName) {
        return $Object.DisplayName
    }

    if ($Object.AdditionalProperties -and $Object.AdditionalProperties.ContainsKey('displayName')) {
        return $Object.AdditionalProperties['displayName']
    }

    return $null
}

function Get-UpnSafe {
    param([object]$Object)

    if ($Object.PSObject.Properties.Name -contains 'UserPrincipalName' -and $Object.UserPrincipalName) {
        return $Object.UserPrincipalName
    }

    if ($Object.AdditionalProperties -and $Object.AdditionalProperties.ContainsKey('userPrincipalName')) {
        return $Object.AdditionalProperties['userPrincipalName']
    }

    return $null
}

function Get-MailSafe {
    param([object]$Object)

    if ($Object.PSObject.Properties.Name -contains 'Mail' -and $Object.Mail) {
        return $Object.Mail
    }

    if ($Object.AdditionalProperties -and $Object.AdditionalProperties.ContainsKey('mail')) {
        return $Object.AdditionalProperties['mail']
    }

    return $null
}

function Invoke-GraphGetAllPages {
    param(
        [Parameter(Mandatory)]
        [string]$Uri
    )

    $items = @()
    $nextLink = $Uri

    while ($nextLink) {
        $response = Invoke-MgGraphRequest -Method GET -Uri $nextLink -OutputType PSObject

        if ($response.value) {
            $items += $response.value
        }
        else {
            $items += $response
            break
        }

        $nextLink = $response.'@odata.nextLink'
    }

    return $items
}

Write-Host "Connecting to Microsoft Graph..." -ForegroundColor Cyan

Import-Module Microsoft.Graph.Authentication
Import-Module Microsoft.Graph.Identity.Governance
Import-Module Microsoft.Graph.DirectoryObjects
Import-Module Microsoft.Graph.Groups

Connect-MgGraph -Scopes @(
    "RoleManagement.Read.Directory",
    "Directory.Read.All",
    "GroupMember.Read.All"
) -NoWelcome

Write-Host "Getting privileged role definitions from Graph beta endpoint..." -ForegroundColor Cyan

$roleDefsUri = "https://graph.microsoft.com/beta/roleManagement/directory/roleDefinitions?`$filter=isPrivileged eq true"
$privilegedRoles = Invoke-GraphGetAllPages -Uri $roleDefsUri

if (-not $privilegedRoles) {
    Write-Warning "No privileged roles were returned."
    return
}

Write-Host "Getting active role assignments..." -ForegroundColor Cyan
$assignments = Get-MgRoleManagementDirectoryRoleAssignment -All

$privilegedRoleIds = @($privilegedRoles | ForEach-Object { $_.id })
$privilegedAssignments = $assignments | Where-Object { $_.RoleDefinitionId -in $privilegedRoleIds }

if (-not $privilegedAssignments) {
    Write-Warning "No active assignments found for privileged roles."
    return
}

$roleMap = @{}
foreach ($role in $privilegedRoles) {
    $roleMap[$role.id] = $role.displayName
}

$principalCache = @{}
$groupMemberCache = @{}
$results = New-Object System.Collections.Generic.List[object]

foreach ($assignment in $privilegedAssignments) {
    $roleName = $roleMap[$assignment.RoleDefinitionId]
    $principalId = $assignment.PrincipalId
    $directoryScopeId = $assignment.DirectoryScopeId

    if (-not $principalCache.ContainsKey($principalId)) {
        try {
            $principalCache[$principalId] = Get-MgDirectoryObjectById -Ids $principalId
        }
        catch {
            Write-Warning "Failed to resolve principal $principalId"
            continue
        }
    }

    $principal = $principalCache[$principalId]
    $principalType = Get-ObjectType -Object $principal
    $principalName = Get-DisplayNameSafe -Object $principal

    switch ($principalType.ToLower()) {
        "group" {
            if (-not $groupMemberCache.ContainsKey($principalId)) {
                try {
                    $groupMemberCache[$principalId] = Get-MgGroupTransitiveMember -GroupId $principalId -All
                }
                catch {
                    Write-Warning "Failed to expand group members for group $principalName ($principalId)"
                    $groupMemberCache[$principalId] = @()
                }
            }

            $members = $groupMemberCache[$principalId]

            if (-not $members -or $members.Count -eq 0) {
                $results.Add([pscustomobject]@{
                    RoleName                = $roleName
                    AssignmentType          = "GroupAssignment"
                    AssignmentPrincipalType = $principalType
                    AssignmentPrincipal     = $principalName
                    AssignmentPrincipalId   = $principalId
                    ExpandedMemberType      = $null
                    ExpandedMemberName      = $null
                    ExpandedMemberUPN       = $null
                    ExpandedMemberMail      = $null
                    ExpandedMemberId        = $null
                    DirectoryScopeId        = $directoryScopeId
                    Notes                   = "Group assigned, but no transitive members returned"
                })
            }
            else {
                foreach ($member in $members) {
                    $memberType = Get-ObjectType -Object $member
                    $memberName = Get-DisplayNameSafe -Object $member
                    $memberUpn  = Get-UpnSafe -Object $member
                    $memberMail = Get-MailSafe -Object $member

                    $results.Add([pscustomobject]@{
                        RoleName                = $roleName
                        AssignmentType          = "GroupAssignmentExpanded"
                        AssignmentPrincipalType = $principalType
                        AssignmentPrincipal     = $principalName
                        AssignmentPrincipalId   = $principalId
                        ExpandedMemberType      = $memberType
                        ExpandedMemberName      = $memberName
                        ExpandedMemberUPN       = $memberUpn
                        ExpandedMemberMail      = $memberMail
                        ExpandedMemberId        = $member.Id
                        DirectoryScopeId        = $directoryScopeId
                        Notes                   = "Expanded from group assignment"
                    })
                }
            }
        }

        default {
            $results.Add([pscustomobject]@{
                RoleName                = $roleName
                AssignmentType          = "DirectAssignment"
                AssignmentPrincipalType = $principalType
                AssignmentPrincipal     = $principalName
                AssignmentPrincipalId   = $principalId
                ExpandedMemberType      = $principalType
                ExpandedMemberName      = $principalName
                ExpandedMemberUPN       = Get-UpnSafe -Object $principal
                ExpandedMemberMail      = Get-MailSafe -Object $principal
                ExpandedMemberId        = $principalId
                DirectoryScopeId        = $directoryScopeId
                Notes                   = "Direct role assignment"
            })
        }
    }
}

$results |
    Sort-Object RoleName, AssignmentType, ExpandedMemberName |
    Export-Csv -Path $CsvPath -NoTypeInformation -Encoding UTF8

Write-Host ""
Write-Host "Exported to: $CsvPath" -ForegroundColor Green
Write-Host ""

$results |
    Sort-Object RoleName, ExpandedMemberName |
    Format-Table RoleName, AssignmentType, AssignmentPrincipal, ExpandedMemberName, ExpandedMemberUPN, ExpandedMemberType -AutoSize