param(
    [Parameter(Mandatory=$true,Position=0)]
    [string]$BaseUrl,
    
    [ValidateRange(1,1000)]
    [int]$MaxDepth = 5,
    
    [string]$OutputPath = "sitemap.xml"
)

function Resolve-Url {
    param(
        [string]$Base,
        [string]$Reference
    )
    try {
        $uriBase = [System.Uri]::new($Base)
        $resolved = [System.Uri]::new($uriBase, $Reference)
        return $resolved.AbsoluteUri
    } catch {
        return $null
    }
}

function Get-InternalLinks {
    param(
        [string]$PageUrl,
        [string]$RootHost
    )
    try {
        $response = Invoke-WebRequest -Uri $PageUrl -UseBasicParsing -ErrorAction Stop
    } catch {
        return @()
    }

    $links = @()
    foreach ($a in $response.ParsedHtml.getElementsByTagName('a')) {
        $href = $a.href
        if ([string]::IsNullOrWhiteSpace($href)) { continue }

        $abs = Resolve-Url -Base $PageUrl -Reference $href
        if ($null -eq $abs) { continue }

        $uri = [System.Uri]::new($abs)
        if ($uri.Host -eq $RootHost -and $uri.Scheme -match 'https?') {
            $clean = $uri.GetLeftPart('PathAndQuery').TrimEnd('#')
            $links += $clean
        }
    }
    return $links | Sort-Object -Unique
}

$rootUri = [System.Uri]::new($BaseUrl)
$rootHost = $rootUri.Host

$queue = New-Object System.Collections.Generic.Queue[PSObject]
$visited = [System.Collections.Generic.HashSet[string]]::new()
$queue.Enqueue([pscustomobject]@{ Url = $BaseUrl; Depth = 0 })
$visited.Add($BaseUrl) | Out-Null

$collected = @()

while ($queue.Count -gt 0) {
    $item = $queue.Dequeue()
    $url  = $item.Url
    $depth = $item.Depth

    $collected += $url

    if ($depth -ge $MaxDepth) { continue }

    $links = Get-InternalLinks -PageUrl $url -RootHost $rootHost
    foreach ($link in $links) {
        if (-not $visited.Contains($link)) {
            $visited.Add($link) | Out-Null
            $queue.Enqueue([pscustomobject]@{ Url = $link; Depth = $depth + 1 })
        }
    }
}

# Build XML
[xml]$xmlDoc = New-Object System.Xml.XmlDocument
$xmlDeclaration = $xmlDoc.CreateXmlDeclaration("1.0","UTF-8",$null)
$xmlDoc.AppendChild($xmlDeclaration) | Out-Null

$ns = "http://www.sitemaps.org/schemas/sitemap/0.9"
$urlset = $xmlDoc.CreateElement("urlset", $ns)
$xmlDoc.AppendChild($urlset) | Out-Null

foreach ($loc in $collected | Sort-Object -Unique) {
    $urlElem = $xmlDoc.CreateElement("url", $ns)

    $locElem = $xmlDoc.CreateElement("loc", $ns)
    $locElem.InnerText = $loc
    $urlElem.AppendChild($locElem) | Out-Null

    $lastmodElem = $xmlDoc.CreateElement("lastmod", $ns)
    $lastmodElem.InnerText = (Get-Date).ToString("yyyy-MM-ddTHH:mm:sszzz")
    $urlElem.AppendChild($lastmodElem) | Out-Null

    $urlset.AppendChild($urlElem) | Out-Null
}

$xmlDoc.Save($OutputPath)

Write-Output "Sitemap generated: $OutputPath"
Write-Output "Total URLs: $($collected.Count)"