Allow referencing component schemas in component schemas

src/Pode.psd1

@@ -220,6 +220,7 @@
         'New-PodeOAStringProperty',
         'New-PodeOABoolProperty',
         'New-PodeOAObjectProperty',
+        'New-PodeOASchemaProperty',
         'ConvertTo-PodeOAParameter',
         'Set-PodeOARouteInfo',
         'Enable-PodeOpenApiViewer',

src/Private/OpenApi.ps1

@@ -130,6 +130,13 @@ function ConvertTo-PodeOASchemaProperty
         format = $Property.format
     }
 
+    # schema refs
+    if($Property.type -ieq 'schema') {
+        $schema = @{ 
+            '$ref' = "#components/schemas/$($Property['schema'])"
+        }
+    }
+
     # are we using an array?
     if ($Property.array) {
         $Property.array = $false

src/Public/OpenApi.ps1

@@ -1219,6 +1219,63 @@ function New-PodeOAObjectProperty
     return $param
 }
 
+<#
+.SYNOPSIS
+Creates a OpenAPI schema reference property.
+
+.DESCRIPTION
+Creates a new OpenAPI schema reference from another OpenAPI schema.
+
+.PARAMETER Name
+The Name of the property.
+
+.PARAMETER Reference
+An component schema name.
+
+.PARAMETER Description
+A Description of the property.
+
+.PARAMETER Array
+If supplied, the schema reference will be treated as an array.
+
+.EXAMPLE
+New-PodeOASchemaProperty -Name 'Config' -ComponentSchema "MyConfigSchema"
+#>
+function New-PodeOASchemaProperty
+{
+    [CmdletBinding()]
+    param(
+        [Parameter()]
+        [string]
+        $Name,
+
+        [Parameter(Mandatory=$true)]
+        [string]
+        $Reference,
+
+        [Parameter()]
+        [string]
+        $Description,
+
+        [switch]
+        $Array
+    )
+
+    if(!(Test-PodeOAComponentSchema -Name $Reference)) {
+        throw "The OpenApi component schema doesn't exist: $($Reference)"
+    }
+
+    $param = @{
+        name = $Name
+        type = 'schema'
+        schema = $Reference
+        array = $Array.IsPresent
+        description = $Description
+    }
+
+    return $param
+}
+
 <#
 .SYNOPSIS
 Converts an OpenAPI property into a Request Parameter.