param(
    [Parameter(Mandatory=$true, Position=0)]
    [string]$RootPath,

    [Parameter(Mandatory=$true, Position=1)]
    [ValidatePattern('^https?://')]
    [string]$BaseUrl,

    [Parameter(Position=2)]
    [string]$OutputPath = (Join-Path -Path $RootPath -ChildPath 'sitemap.xml')
)

function Convert-PathToUrl {
    param(
        [string]$FilePath,
        [string]$RootPath,
        [string]$BaseUrl
    )
    $relative = Resolve-Path -Path $FilePath -Relative -RelativeBasePath $RootPath
    $relative = $relative -replace '\\','/'
    $url = $BaseUrl.TrimEnd('/') + '/' + $relative.TrimStart('/')
    return $url
}

# Ensure root path exists
if (-not (Test-Path -LiteralPath $RootPath -PathType Container)) {
    Write-Error "RootPath '$RootPath' does not exist or is not a directory."
    exit 1
}

# Gather files to include in the sitemap
$extensions = '.html', '.htm', '.php', '.asp', '.aspx', '.jsp'
$files = Get-ChildItem -Path $RootPath -Recurse -File | Where-Object { $extensions -contains $_.Extension.ToLower() }

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

$urlset = $xmlDoc.CreateElement('urlset')
$xmlnsAttr = $xmlDoc.CreateAttribute('xmlns')
$xmlnsAttr.Value = 'http://www.sitemaps.org/schemas/sitemap/0.9'
$urlset.Attributes.Append($xmlnsAttr) | Out-Null
$xmlDoc.AppendChild($urlset) | Out-Null

foreach ($file in $files) {
    $urlElem = $xmlDoc.CreateElement('url')
    
    $locElem = $xmlDoc.CreateElement('loc')
    $locElem.InnerText = Convert-PathToUrl -FilePath $file.FullName -RootPath $RootPath -BaseUrl $BaseUrl
    $urlElem.AppendChild($locElem) | Out-Null

    $lastModElem = $xmlDoc.CreateElement('lastmod')
    $lastModElem.InnerText = $file.LastWriteTimeUtc.ToString('yyyy-MM-ddTHH:mm:ssZ')
    $urlElem.AppendChild($lastModElem) | Out-Null

    # Optional: changefreq and priority (static defaults, can be adjusted later)
    $changeFreqElem = $xmlDoc.CreateElement('changefreq')
    $changeFreqElem.InnerText = 'monthly'
    $urlElem.AppendChild($changeFreqElem) | Out-Null

    $priorityElem = $xmlDoc.CreateElement('priority')
    $priorityElem.InnerText = '0.5'
    $urlElem.AppendChild($priorityElem) | Out-Null

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

# Save XML with indentation
$settings = New-Object System.Xml.XmlWriterSettings
$settings.Indent = $true
$settings.Encoding = [System.Text.Encoding]::UTF8

$writer = [System.Xml.XmlWriter]::Create($OutputPath, $settings)
$xmlDoc.WriteContentTo($writer)
$writer.Flush()
$writer.Close()

Write-Host "Sitemap generated at: $OutputPath" -ForegroundColor Green