enum PageContentAnomaly {
    case failedToLoadContent(Error)
    case missingFile(String)
    case missingPage(String)
    case missingTag(String)
    case unknownCommand(String)
    case invalidCommandArguments(command: ShorthandMarkdownKey, arguments: [String])
}

extension PageContentAnomaly: Identifiable {

    var id: String {
        switch self {
        case .failedToLoadContent:
            return "load-failed"
        case .missingFile(let string):
            return "missing-file-\(string)"
        case .missingPage(let string):
            return "missing-page-\(string)"
        case .missingTag(let string):
            return "missing-tag-\(string)"
        case .unknownCommand(let string):
            return "unknown-command-\(string)"
        case .invalidCommandArguments(let command, let arguments):
            return "invalid-arguments-\(command)-\(arguments.joined(separator: "-"))"
        }
    }
}

extension PageContentAnomaly {

    enum Severity: String, CaseIterable {
        case warning
        case error
    }

    var severity: Severity {
        switch self {
        case .failedToLoadContent:
            return .error
        case .missingFile, .missingPage, .missingTag, .unknownCommand, .invalidCommandArguments:
            return .warning
        }
    }
}

extension PageContentAnomaly: CustomStringConvertible {

    var description: String {
        switch self {
        case .failedToLoadContent(let error):
            return "Failed to load content: \(error)"
        case .missingFile(let string):
            return "Missing file \(string)"
        case .missingPage(let string):
            return "Missing page \(string)"
        case .missingTag(let string):
            return "Missing tag \(string)"
        case .unknownCommand(let string):
            return "Unknown command \(string)"
        case .invalidCommandArguments(let command, let arguments):
            return "Invalid command arguments for \(command): \(arguments)"
        }
    }
}