param(
    [Parameter(Mandatory=$true)]
    [string]$RootPath,

    [Parameter(Mandatory=$true)]
    [string]$BaseUrl,

    [string]$OutputFile = "sitemap.xml",

    [ValidateSet('html','htm','aspx','php','jsp','cfm')]
    [string[]]$IncludeExtensions = @('html','htm','aspx','php')
)

# Ensure root path ends without trailing backslash
$RootPath = (Resolve-Path -Path $RootPath).Path.TrimEnd('\')

# Normalize BaseUrl to end with slash
if (-not $BaseUrl.EndsWith('/')) { $BaseUrl += '/' }

# Prepare list of files
$searchPattern = "*.*"
$files = Get-ChildItem -Path $RootPath -Recurse -File -Include $IncludeExtensions | ForEach-Object {
    $_
}

if ($files.Count -eq 0) {
    Write-Warning "No files with the specified extensions were found under '$RootPath'."
    exit 1
}

# Create the XML writer settings
$settings = New-Object System.Xml.XmlWriterSettings
$settings.Indent = $true
$settings.Encoding = [System.Text.Encoding]::UTF8

$writer = [System.Xml.XmlWriter]::Create($OutputFile, $settings)

try {
    $writer.WriteStartDocument()
    $writer.WriteStartElement("urlset")
    $writer.WriteAttributeString("xmlns", "http://www.sitemaps.org/schemas/sitemap/0.9")

    foreach ($file in $files) {
        # Build relative path
        $relativePath = $file.FullName.Substring($RootPath.Length).TrimStart('\','/').Replace('\','/')

        # URL encode special characters in the path
        $encodedPath = [System.Web.HttpUtility]::UrlPathEncode($relativePath)

        $loc = $BaseUrl + $encodedPath

        $writer.WriteStartElement("url")
        $writer.WriteElementString("loc", $loc)

        # Optional elements: lastmod, changefreq, priority
        $lastMod = $file.LastWriteTimeUtc.ToString("yyyy-MM-ddTHH:mm:ssZ")
        $writer.WriteElementString("lastmod", $lastMod)

        # You can customize these defaults as needed
        $writer.WriteElementString("changefreq", "weekly")
        $writer.WriteElementString("priority", "0.5")

        $writer.WriteEndElement() # </url>
    }

    $writer.WriteEndElement() # </urlset>
    $writer.WriteEndDocument()
}
finally {
    $writer.Flush()
    $writer.Close()
}

Write-Host "Sitemap generated at: $(Resolve-Path -Path $OutputFile).Path"