param(
    [Parameter(Mandatory = $true)]
    [Alias('WebUrl')]
    [string]$SiteUrl,

    [string]$TermSetName = '',

    [string]$TermSetId = '',

    [ValidateRange(1, 1440)]
    [int]$CacheMinutes = 15,

    [switch]$EnableDebug,

    [string]$Description = 'MSFT-Custom-Solution:MegaMenu'
)

if (-not (Get-Command -Name Get-SPSite -ErrorAction SilentlyContinue)) {
    if (Get-Module -ListAvailable -Name Microsoft.SharePoint.PowerShell) {
        Import-Module Microsoft.SharePoint.PowerShell -DisableNameChecking
    }
    elseif (Get-PSSnapin -Registered -Name Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue) {
        Add-PSSnapin Microsoft.SharePoint.PowerShell
    }
    else {
        throw 'Die SharePoint PowerShell-Komponenten wurden nicht gefunden. Bitte in der SharePoint Management Shell ausfuehren.'
    }
}

$componentId = [Guid]'c0abbffb-355d-4d4e-bd38-9e15fb811506'
$legacyComponentId = [Guid]'abc3361f-bb2d-491f-aba3-cd51c19a299b'
$location = 'ClientSideExtension.ApplicationCustomizer'
$configurationProperty = 'PortalSettings.MegaMenu.Configuration'

$properties = [string](@{
    termSetName = $TermSetName
    termSetId = $TermSetId
    cacheMinutes = $CacheMinutes
    debug = [bool]$EnableDebug.IsPresent
} | ConvertTo-Json -Depth 10 -Compress)

$site = Get-SPSite -Identity $SiteUrl

try {
    $rootWeb = $site.RootWeb
    $rootWeb.AllProperties[$configurationProperty] = [string]$properties
    $rootWeb.Update()

    $siteActions = @(
        $site.UserCustomActions |
            Where-Object {
                $_.ClientSideComponentId -eq $componentId -or
                $_.ClientSideComponentId -eq $legacyComponentId
            }
    )

    foreach ($siteAction in $siteActions) {
        $siteAction.Delete()
    }

    $created = 0
    $updated = 0
    $removedLegacy = 0

    foreach ($web in $site.AllWebs) {
        try {
            $actions = @(
                $web.UserCustomActions |
                    Where-Object {
                        $_.ClientSideComponentId -eq $componentId -or
                        $_.ClientSideComponentId -eq $legacyComponentId
                    }
            )

            $currentAction = $actions |
                Where-Object {
                    $_.ClientSideComponentId -eq $componentId
                } |
                Select-Object -First 1

            foreach ($existingAction in $actions) {
                if ($currentAction -and $existingAction.Id -eq $currentAction.Id) {
                    continue
                }

                $existingAction.Delete()
                $removedLegacy++
            }

            if (-not $currentAction) {
                $currentAction = $web.UserCustomActions.Add()
                $currentAction.Name = [Guid]::NewGuid().ToString('B')
                $created++
            }
            else {
                $updated++
            }

            $currentAction.Title = 'MegaMenu Application Customizer'
            $currentAction.Description = $Description
            $currentAction.Location = $location
            $currentAction.ClientSideComponentId = $componentId
            $currentAction.ClientSideComponentProperties = $properties
            $currentAction.Sequence = 100
            $currentAction.Update()
            $web.Update()

            Write-Host ('MegaMenu synchronisiert: ' + $web.Url) -ForegroundColor Green
        }
        finally {
            $web.Dispose()
        }
    }

    Write-Host ''
    Write-Host 'MegaMenu wurde fuer die gesamte Site Collection konfiguriert.' -ForegroundColor Green
    Write-Host ('Zentrale Konfiguration: ' + $configurationProperty)
    Write-Host ('Neu registrierte Webs: ' + $created)
    Write-Host ('Aktualisierte Webs: ' + $updated)
    Write-Host ('Entfernte alte oder doppelte Registrierungen: ' + $removedLegacy)
    Write-Host ('Properties: ' + $properties)
    Write-Host 'Neue Unterwebs koennen durch erneutes Ausfuehren idempotent synchronisiert werden.' -ForegroundColor Yellow
}
finally {
    if ($site) {
        $site.Dispose()
    }
}