struct LabelsCommandProcessor: CommandProcessor {

    let commandType: ShorthandMarkdownKey = .labels

    let content: Content

    let results: PageGenerationResults

    init(content: Content, results: PageGenerationResults) {
        self.content = content
        self.results = results
    }

    func process(_ arguments: [String], markdown: Substring) -> String {
        let labels: [ContentLabel] = arguments.compactMap { arg in
            let parts = arg.components(separatedBy: "=")
            guard parts.count == 2 else {
                results.invalid(command: .labels, markdown)
                return nil
            }
            guard let icon = PageIcon(rawValue: parts[0].trimmed) else {
                results.invalid(command: .labels, markdown)
                return nil
            }
            results.requiredIcons.insert(icon)
            return .init(icon: icon, value: parts[1])
        }
        return ContentLabels(labels: labels).content
    }
}