`Get-MatrixJoinedMembers` (#1)

* add `Get-MatrixJoinedMembers`

* add Get-Help section

PSMatrix.psd1

@@ -72,7 +72,8 @@ PowerShellVersion = '7.0'
 FunctionsToExport = @(
     'New-MatrixAccessToken',
     'Remove-MatrixAccessToken',
-    'Get-MatrixJoinedRooms'
+    'Get-MatrixJoinedRooms',
+    'Get-MatrixJoinedMembers'
 )
 
 # Cmdlets to export from this module, for best performance, do not use wildcards and do not delete the entry, use an empty array if there are no cmdlets to export.

public/Get-MatrixJoinedMembers.ps1

@@ -0,0 +1,55 @@
+<#
+    .Synopsis
+    Get all joined members for a given Room ID.
+
+    .Description
+    Get all joined members for a given Room ID from _matrix/client/v3/rooms/{roomId}/joined_members. See https://spec.matrix.org/v1.2/client-server-api/#get_matrixclientv3roomsroomidjoined_members.
+
+    .Parameter ServerUrl
+    URL for the Matrix server to log into, for example "https://matrix.example.com".
+
+    .Parameter AccessToken
+    A SecureString containing the Matrix access token.
+
+    .Parameter RoomId
+    The Matrix room ID to retrieve joined members for.
+
+    .Example
+    Get-MatrixJoinedMembers -ServerUrl $server -AccessToken $token -RoomId "!ehXvUhWNASUkSLvAGP:matrix.org"
+#>
+function Get-MatrixJoinedMembers {
+    param(
+        [Parameter(Mandatory)]
+        [string]$ServerUrl,
+
+        [Parameter(Mandatory)]
+        [SecureString]$AccessToken,
+
+        [Parameter(Mandatory)]
+        [string]$RoomId
+    )
+
+    $url = New-MatrixUrl -ServerUrl $ServerUrl -ApiPath "_matrix/client/v3/rooms/$RoomId/joined_members"
+    Write-Debug "URL: $url"
+    $headers = Get-MatrixAuthHeaders -AccessToken $AccessToken
+
+    try {
+        $res = Invoke-RestMethod -Uri $url -Headers $headers
+        $joinedObject = $res.joined
+        $members = @()
+
+        $joinedObject.PSObject.Properties | ForEach-Object {
+            $member = [PSCustomObject]@{
+                MatrixId = $_.Name
+                DisplayName = $_.Value.display_name
+                AvatarUrl = $_.Value.avatar_url
+            }
+
+            $members += $member
+        }
+
+        return $members
+    } catch {
+        Write-Error $_
+    }
+}