# Install the Microsoft Graph PowerShell module if not already installed
# Install-Module Microsoft.Graph -Scope CurrentUser

Import-Module Microsoft.Graph

# Connect to Microsoft Graph with the required scopes
Connect-MgGraph -Scopes "Group.ReadWrite.All", "User.Read.All", "Device.Read.All", "Directory.Read.All"

# Function to convert a group and include associated devices or users
function Convert-Group {
    param (
        [Parameter(Mandatory = $true)]
        [string]$SourceGroupId,
        [Parameter(Mandatory = $true)]
        [ValidateSet("User", "Device")]
        [string]$TargetMembershipType,
        [Parameter(Mandatory = $false)]
        [string]$NewGroupName
    )

    # Get the source group
    $sourceGroup = Get-MgGroup -GroupId $SourceGroupId

    # Get all members of the source group
    $members = Get-MgGroupMember -GroupId $SourceGroupId -All

    # Initialize an array to hold the target members
    $targetMembers = @()

    if ($TargetMembershipType -eq "User") {
        # For each device, get the assigned user
        foreach ($member in $members) {
            if ($member.'@odata.type' -eq '#microsoft.graph.device') {
                $deviceId = $member.Id
                # Get the registered user of the device
                $device = Get-MgDevice -DeviceId $deviceId -ExpandProperty registeredOwners
                $assignedUsers = $device.RegisteredOwners | Where-Object { $_.'@odata.type' -eq '#microsoft.graph.user' }
                foreach ($user in $assignedUsers) {
                    if (-not $targetMembers.Contains($user.Id)) {
                        $targetMembers += $user.Id
                    }
                }
            }
        }
    } elseif ($TargetMembershipType -eq "Device") {
        # For each user, get all devices assigned to them
        foreach ($member in $members) {
            if ($member.'@odata.type' -eq '#microsoft.graph.user') {
                $userId = $member.Id
                # Get devices registered to the user
                $userDevices = Get-MgUserRegisteredDevice -UserId $userId -All
                foreach ($device in $userDevices) {
                    if (-not $targetMembers.Contains($device.Id)) {
                        $targetMembers += $device.Id
                    }
                }
            }
        }
    }

    # Set the new group name
    if (-not $NewGroupName) {
        $NewGroupName = "$($sourceGroup.DisplayName) - Converted to $TargetMembershipType Group"
    }

    # Create a new security group
    $newGroupParams = @{
        DisplayName     = $NewGroupName
        MailEnabled     = $false
        MailNickname    = $NewGroupName -replace ' ', ''
        SecurityEnabled = $true
        GroupTypes      = @()
    }

    $newGroup = New-MgGroup @newGroupParams

    # Add members to the new group
    foreach ($memberId in $targetMembers) {
        try {
            New-MgGroupMemberByRef -GroupId $newGroup.Id -DirectoryObjectId $memberId
        } catch {
            Write-Warning "Failed to add member with ID $memberId to the group."
        }
    }

    Write-Host "New group created with ID: $($newGroup.Id)"
}

# Example usage:
# Convert a device group to a user group
Convert-Group -SourceGroupId "<SourceGroupId>" -TargetMembershipType "User"

# Convert a user group to a device group
# Convert-Group -SourceGroupId "<SourceGroupId>" -TargetMembershipType "Device"