Functions/GenXdev.Windows/Get-KnownFolderPath.ps1

###############################################################################
<#
.SYNOPSIS
Gets the path of a Windows known folder using the Windows Shell32 API.

.DESCRIPTION
Retrieves the path of a specified Windows known folder using the Shell32 API's
SHGetKnownFolderPath function. This method is more reliable than using
environment variables as it works consistently across different Windows versions
and language settings. Supports all standard Windows known folders like
Documents, Downloads, AppData etc.

For OneDrive, the path is read from the environment variable set by the
OneDrive sync client, with a registry and default-location fallback.

.LICENSE
Copyright (C) 2026 René Vaessen / GenXdev

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.

.PARAMETER KnownFolder
Specifies the name of the Windows known folder to retrieve. Must be one of the
predefined folder names like 'Documents', 'Downloads', etc. The function will
return the full path to this folder.

.EXAMPLE
Get-KnownFolderPath -KnownFolder 'Documents'
Returns: C:\Users\Username\Documents

.EXAMPLE
folder Downloads
Returns: C:\Users\Username\Downloads using the alias

.EXAMPLE
cd (folder Desktop)
Changes to the Desktop folder using the alias

.EXAMPLE
folder OneDrive
Returns the OneDrive folder path from the env var, registry, or default
location
#>

function Get-KnownFolderPath {

    [CmdletBinding()]
    [Alias('folder')]

    param (
        ########################################################################
        [Parameter(
            Mandatory = $true,
            Position = 0,
            HelpMessage = 'The Windows known folder name to get the path for'
        )]
        [ValidateSet('3DObjects', 'AddNewPrograms', 'AdminTools', 'AppUpdates',
            'CDBurning', 'ChangeRemovePrograms', 'CommonAdminTools',
            'CommonOEMLinks', 'CommonPrograms', 'CommonStartMenu',
            'CommonStartup', 'CommonTemplates', 'ComputerFolder',
            'ConflictFolder', 'ConnectionsFolder', 'Contacts',
            'ControlPanelFolder', 'Cookies', 'Desktop', 'Documents', 'Downloads',
            'Favorites', 'Fonts', 'Games', 'GameTasks', 'History',
            'InternetCache', 'InternetFolder', 'Links', 'LocalAppData',
            'LocalAppDataLow', 'LocalizedResourcesDir', 'Music', 'NetHood',
            'NetworkFolder', 'OriginalImages', 'PhotoAlbums', 'Pictures',
            'Playlists', 'PrintersFolder', 'PrintHood', 'Profile',
            'ProgramData', 'ProgramFiles', 'ProgramFilesX64', 'ProgramFilesX86',
            'ProgramFilesCommon', 'ProgramFilesCommonX64',
            'ProgramFilesCommonX86', 'Programs', 'Public', 'PublicDesktop',
            'PublicDocuments', 'PublicDownloads', 'PublicGameTasks',
            'PublicMusic', 'PublicPictures', 'PublicVideos', 'QuickLaunch',
            'Recent', 'RecycleBinFolder', 'ResourceDir', 'RoamingAppData',
            'SampleMusic', 'SamplePictures', 'SamplePlaylists', 'SampleVideos',
            'SavedGames', 'SavedSearches', 'SEARCH_CSC', 'SEARCH_MAPI',
            'SearchHome', 'SendTo', 'SidebarDefaultParts', 'SidebarParts',
            'StartMenu', 'Startup', 'SyncManagerFolder', 'SyncResultsFolder',
            'SyncSetupFolder', 'System', 'SystemX86', 'Templates',
            'TreeProperties', 'UserProfiles', 'UsersFiles', 'Videos',
            'Windows',
            'OneDrive')]
        [string]$KnownFolder
        ########################################################################
    )

    begin {

        # define known folder guids for windows shell32 api
        $knownFolders = @{
            '3DObjects'             = '31C0DD25-9439-4F12-BF41-7FF4EDA38722';
            'AddNewPrograms'        = 'de61d971-5ebc-4f02-a3a9-6c82895e5c04';
            'AdminTools'            = '724EF170-A42D-4FEF-9F26-B60E846FBA4F';
            'AppUpdates'            = 'a305ce99-f527-492b-8b1a-7e76fa98d6e4';
            'CDBurning'             = '9E52AB10-F80D-49DF-ACB8-4330F5687855';
            'ChangeRemovePrograms'  = 'df7266ac-9274-4867-8d55-3bd661de872d';
            'CommonAdminTools'      = 'D0384E7D-BAC3-4797-8F14-CBA229B392B5';
            'CommonOEMLinks'        = 'C1BAE2D0-10DF-4334-BEDD-7AA20B227A9D';
            'CommonPrograms'        = '0139D44E-6AFE-49F2-8690-3DAFCAE6FFB8';
            'CommonStartMenu'       = 'A4115719-D62E-491D-AA7C-E74B8BE3B067';
            'CommonStartup'         = '82A5EA35-D9CD-47C5-9629-E15D2F714E6E';
            'CommonTemplates'       = 'B94237E7-57AC-4347-9151-B08C6C32D1F7';
            'ComputerFolder'        = '0AC0837C-BBF8-452A-850D-79D08E667CA7';
            'ConflictFolder'        = '4bfefb45-347d-4006-a5be-ac0cb0567192';
            'ConnectionsFolder'     = '6F0CD92B-2E97-45D1-88FF-B0D186B8DEDD';
            'Contacts'              = '56784854-C6CB-462b-8169-88E350ACB882';
            'ControlPanelFolder'    = '82A74AEB-AEB4-465C-A014-D097EE346D63';
            'Cookies'               = '2B0F765D-C0E9-4171-908E-08A611B84FF6';
            'Desktop'               = 'B4BFCC3A-DB2C-424C-B029-7FE99A87C641';
            'Documents'             = 'FDD39AD0-238F-46AF-ADB4-6C85480369C7';
            'Downloads'             = '374DE290-123F-4565-9164-39C4925E467B';
            'Favorites'             = '1777F761-68AD-4D8A-87BD-30B759FA33DD';
            'Fonts'                 = 'FD228CB7-AE11-4AE3-864C-16F3910AB8FE';
            'Games'                 = 'CAC52C1A-B53D-4edc-92D7-6B2E8AC19434';
            'GameTasks'             = '054FAE61-4DD8-4787-80B6-090220C4B700';
            'History'               = 'D9DC8A3B-B784-432E-A781-5A1130A75963';
            'InternetCache'         = '352481E8-33BE-4251-BA85-6007CAEDCF9D';
            'InternetFolder'        = '4D9F7874-4E0C-4904-967B-40B0D20C3E4B';
            'Links'                 = 'bfb9d5e0-c6a9-404c-b2b2-ae6db6af4968';
            'LocalAppData'          = 'F1B32785-6FBA-4FCF-9D55-7B8E7F157091';
            'LocalAppDataLow'       = 'A520A1A4-1780-4FF6-BD18-167343C5AF16';
            'LocalizedResourcesDir' = '2A00375E-224C-49DE-B8D1-440DF7EF3DDC';
            'Music'                 = '4BD8D571-6D19-48D3-BE97-422220080E43';
            'NetHood'               = 'C5ABBF53-E17F-4121-8900-86626FC2C973';
            'NetworkFolder'         = 'D20BEEC4-5CA8-4905-AE3B-BF251EA09B53';
            'OriginalImages'        = '2C36C0AA-5812-4b87-BFD0-4CD0DFB19B39';
            'PhotoAlbums'           = '69D2CF90-FC33-4FB7-9A0C-EBB0F0FCB43C';
            'Pictures'              = '33E28130-4E1E-4676-835A-98395C3BC3BB';
            'Playlists'             = 'DE92C1C7-837F-4F69-A3BB-86E631204A23';
            'PrintersFolder'        = '76FC4E2D-D6AD-4519-A663-37BD56068185';
            'PrintHood'             = '9274BD8D-CFD1-41C3-B35E-B13F55A758F4';
            'Profile'               = '5E6C858F-0E22-4760-9AFE-EA3317B67173';
            'ProgramData'           = '62AB5D82-FDC1-4DC3-A9DD-070D1D495D97';
            'ProgramFiles'          = '905e63b6-c1bf-494e-b29c-65b732d3d21a';
            'ProgramFilesX64'       = '6D809377-6AF0-444b-8957-A3773F02200E';
            'ProgramFilesX86'       = '7C5A40EF-A0FB-4BFC-874A-C0F2E0B9FA8E';
            'ProgramFilesCommon'    = 'F7F1ED05-9F6D-47A2-AAAE-29D317C6F066';
            'ProgramFilesCommonX64' = '6365D5A7-0F0D-45E5-87F6-0DA56B6A4F7D';
            'ProgramFilesCommonX86' = 'DE974D24-D9C6-4D3E-BF91-F4455120B917';
            'Programs'              = 'A77F5D77-2E2B-44C3-A6A2-ABA601054A51';
            'Public'                = 'DFDF76A2-C82A-4D63-906A-5644AC457385';
            'PublicDesktop'         = 'C4AA340D-F20F-4863-AFEF-F87EF2E6BA25';
            'PublicDocuments'       = 'ED4824AF-DCE4-45A8-81E2-FC7965083634';
            'PublicDownloads'       = '3D644C9B-1FB8-4f30-9B45-F670235F79C0';
            'PublicGameTasks'       = 'DEBF2536-E1A8-4c59-B6A2-414586476AEA';
            'PublicMusic'           = '3214FAB5-9757-4298-BB61-92A9DEAA44FF';
            'PublicPictures'        = 'B6EBFB86-6907-413C-9AF7-4FC2ABF07CC5';
            'PublicVideos'          = '2400183A-6185-49FB-A2D8-4A392A602BA3';
            'QuickLaunch'           = '52a4f021-7b75-48a9-9f6b-4b87a210bc8f';
            'Recent'                = 'AE50C081-EBD2-438A-8655-8A092E34987A';
            'RecycleBinFolder'      = 'B7534046-3ECB-4C18-BE4E-64CD4CB7D6AC';
            'ResourceDir'           = '8AD10C31-2ADB-4296-A8F7-E4701232C972';
            'RoamingAppData'        = '3EB685DB-65F9-4CF6-A03A-E3EF65729F3D';
            'SampleMusic'           = 'B250C668-F57D-4EE1-A63C-290EE7D1AA1F';
            'SamplePictures'        = 'C4900540-2379-4C75-844B-64E6FAF8716B';
            'SamplePlaylists'       = '15CA69B3-30EE-49C1-ACE1-6B5EC372AFB5';
            'SampleVideos'          = '859EAD94-2E85-48AD-A71A-0969CB56A6CD';
            'SavedGames'            = '4C5C32FF-BB9D-43b0-B5B4-2D72E54EAAA4';
            'SavedSearches'         = '7d1d3a04-debb-4115-95cf-2f29da2920da';
            'SEARCH_CSC'            = 'ee32e446-31ca-4aba-814f-a5ebd2fd6d5e';
            'SEARCH_MAPI'           = '98ec0e18-2098-4d44-8644-66979315a281';
            'SearchHome'            = '190337d1-b8ca-4121-a639-6d472d16972a';
            'SendTo'                = '8983036C-27C0-404B-8F08-102D10DCFD74';
            'SidebarDefaultParts'   = '7B396E54-9EC5-4300-BE0A-2482EBAE1A26';
            'SidebarParts'          = 'A75D362E-50FC-4fb7-AC2C-A8BEAA314493';
            'StartMenu'             = '625B53C3-AB48-4EC1-BA1F-A1EF4146FC19';
            'Startup'               = 'B97D20BB-F46A-4C97-BA10-5E3608430854';
            'SyncManagerFolder'     = '43668BF8-C14E-49B2-97C9-747784D784B7';
            'SyncResultsFolder'     = '289a9a43-be44-4057-a41b-587a76d7e7f9';
            'SyncSetupFolder'       = '0F214138-B1D3-4a90-BBA9-27CBC0C5389A';
            'System'                = '1AC14E77-02E7-4E5D-B744-2EB1AE5198B7';
            'SystemX86'             = 'D65231B0-B2F1-4857-A4CE-A8E7C6EA7D27';
            'Templates'             = 'A63293E8-664E-48DB-A079-DF759E0509F7';
            'TreeProperties'        = '5b3749ad-b49f-49c1-83eb-15370fbd4882';
            'UserProfiles'          = '0762D272-C50A-4BB0-A382-697DCD729B80';
            'UsersFiles'            = 'f3ce0f7c-4901-4acc-8648-d5d44b04ef8f';
            'Videos'                = '18989B1D-99B5-455B-841C-AB7C74E4DDFC';
            'Windows'               = 'F38BF404-1D43-42F2-9305-67DE0B28FC23';
        }

        # check if the windows api type is already defined in the current session
        $type = ([System.Management.Automation.PSTypeName]'Win32.Shell32API').Type

        if (-not $type) {

            Microsoft.PowerShell.Utility\Write-Verbose (
                'Defining Windows Shell32 API function'
            )

            # define the p/invoke signature for shgetknownfolderpath
            $signature = @'
[DllImport("shell32.dll")]
public extern static int SHGetKnownFolderPath(
    ref Guid folderId,
    uint flags,
    IntPtr token,
    [MarshalAs(UnmanagedType.LPWStr)] out string pszPath);
'@

            # add the shell32 api function definition as a new .net type
            $type = Microsoft.PowerShell.Utility\Add-Type `
                -MemberDefinition $signature `
                -Namespace 'Win32' `
                -Name 'Shell32API' `
                -PassThru
        }
    }

    process {

        # OneDrive is not a standard SHGetKnownFolderPath folder;
        # resolve it via env var, registry, or default location
        if ($KnownFolder -eq 'OneDrive') {

            if ([PSGenXdevCmdlet]::IsRunningUnderPester()) {

                return (GenXdev\Expand-Path "$($ENV:TEMP)\GenXdev.PowerShell\OneDrive\" -CreateDirectory)
            }

            # 1) Try the environment variable set by the OneDrive client
            $oneDrivePath = [System.Environment]::GetEnvironmentVariable(
                'OneDrive',
                [System.EnvironmentVariableTarget]::User
            )

            if ($oneDrivePath -and (Microsoft.PowerShell.Management\Test-Path -LiteralPath $oneDrivePath)) {
                return $oneDrivePath
            }

            # 2) Try registry: HKCU\Software\Microsoft\OneDrive\Accounts\Personal\UserFolder
            try {
                $regPath = Microsoft.PowerShell.Management\Get-ItemProperty `
                    -LiteralPath 'HKCU:\Software\Microsoft\OneDrive\Accounts\Personal' `
                    -Name 'UserFolder' `
                    -ErrorAction SilentlyContinue

                if ($regPath -and $regPath.UserFolder -and (Microsoft.PowerShell.Management\Test-Path -LiteralPath $regPath.UserFolder)) {
                    return $regPath.UserFolder
                }
            }
            catch { }

            # 3) Fallback to default location
            $defaultPath = GenXdev\Expand-Path '~\OneDrive'
            if (Microsoft.PowerShell.Management\Test-Path -LiteralPath $defaultPath) {
                return $defaultPath
            }

            Microsoft.PowerShell.Utility\Write-Warning (
                'OneDrive folder not found. Returning default path.'
            )
            return $defaultPath
        }

        Microsoft.PowerShell.Utility\Write-Verbose (
            "Getting path for known folder: $KnownFolder"
        )

        # convert the guid string to a guid object
        $folderGuid = Microsoft.PowerShell.Utility\New-Object Guid `
            $KnownFolders[$KnownFolder]

        # create a reference variable to store the output path
        [string]$path = $null

        # call the windows api to retrieve the folder path
        $code = $type::SHGetKnownFolderPath([ref]$folderGuid, 0, 0, [ref]$path)

        # check if the api call was successful and return the path
        if ($code -eq 0) {

            return $path
        }

        Microsoft.PowerShell.Utility\Write-Verbose (
            "Failed to get path for: $KnownFolder (code: $code)"
        )

        return $null
    }

    end {
    }
}