import Hummingbird

/// A controller type that provides information about the *DocC* archives containers.
struct ArchiveController<Context: RequestContext> {
    
    // MARK: Properties
    
    private let archivesPath: String
    private let fileService: any FileServicing

    // MARK: Initialisers
    
    /// Initialises this controller.
    /// - Parameters:
    ///   - archivesPath: A path in the local file system where the *DocC* archive contained are located.
    ///   - fileService: A service that interfaces with the local file system.
    init(
        _ archivesPath: String,
        fileService: any FileServicing = FileService()
    ) {
        self.archivesPath = archivesPath
        self.fileService = fileService
    }
    
    // MARK: Functions
    
    /// Registers the controller to a given router.
    /// - Parameter router: A router to register this controller to.
    func register(to router: Router<Context>) {
        router.get(.archives, use: listArchives)
    }
    
}

// MARK: - Helpers

private extension ArchiveController {
    
    // MARK: Functions
    
    @Sendable func listArchives(
        _ request: Request,
        context: Context
    ) async throws (HTTPError) -> ArchiveList {
        do {
            let nameArchives = try await fileService
                .listItems(in: archivesPath)
                .filter { $0.hasSuffix(.suffixArchive) }
                .map { $0.dropLast(String.suffixArchive.count) }
                .map(String.init)
                .sorted { $0 < $1 }
            
            return .init(nameArchives)
        } catch .folderNotFound {
            throw .init(.notFound)
        } catch .folderPathEmpty, .folderNotDirectory {
            throw .init(.unprocessableContent)
        } catch {
            throw .init(.badRequest)
        }
    }
    
}

// MARK: - RouterPath+Constants

private extension RouterPath {
    static let archives: RouterPath = .init("archives")
}

// MARK: - String+Constants

private extension String {
    static let suffixArchive: String = ".doccarchive"
}