enum HeaderElement {
    case css(FileResource)
    case js(file: FileResource, defer: Bool)
    case jsModule(FileResource)
    case title(String)
    case description(String)
    case charset
    case viewport
}

extension HeaderElement {

    var content: String {
        switch self {
        case .css(let file):
            return "<link rel='stylesheet' href='\(file.assetUrl)' />"
        case .js(let file, let deferred):
            let deferText = deferred ? " defer" : ""
            return "<script src='\(file.assetUrl)'\(deferText)></script>"
        case .jsModule(let file):
            return "<script type='module' src='\(file.assetUrl)'></script>"
        case .title(let title):
            return "<title>\(title)</title>"
        case .description(let description):
            return "<meta name='description' content='\(description)'>"
        case .charset:
            return "<meta charset='utf-8' />"
        case .viewport:
            return "<meta name='viewport' content='width=device-width, initial-scale=1, minimum-scale=1, maximum-scale=1' />"
        }
    }
}