import AppKit
import Foundation
import Observation
import PromptGarageCore
import UniformTypeIdentifiers

enum SidebarDestination: String, CaseIterable, Identifiable, Hashable, Sendable {
    case all
    case favorites
    case mostUsed
    case byDay
    case byTopic
    case importCenter
    case statistics

    var id: String { rawValue }
}

enum AppLaunchState: Equatable, Sendable {
    case checking
    case needsDatabase
    case validating(String)
    case ready
    case invalid(String)
    case readOnly(String)
    case failed(String)
}

struct AppErrorPresentation: Equatable, Sendable {
    let title: String
    let message: String
    let diagnostic: String
}

struct PromptEditorPresentation: Identifiable, Equatable, Sendable {
    enum Mode: Equatable, Sendable {
        case create
        case edit(Int64)
    }

    let id = UUID()
    let mode: Mode
    let initialDraft: PromptDraft

    var title: String {
        switch mode {
        case .create: "Neuer Prompt"
        case .edit: "Prompt bearbeiten"
        }
    }
}

struct LibraryQueryKey: Hashable, Sendable {
    let destination: SidebarDestination
    let text: String
    let tag: String?
    let sourceFamily: String?
    let selectedDay: String?
    let selectedTopic: PromptTopicSummary?
    let sort: PromptQuery.Sort
    let reloadToken: Int
}

@Observable
@MainActor
final class AppModel {
    var launchState: AppLaunchState = .checking
    var selectedBootstrapURL: URL?

    var destination: SidebarDestination = .all
    var searchText = ""
    var selectedTag: String?
    var selectedSourceFamily: String?
    var sort: PromptQuery.Sort = .updatedDescending
    var prompts: [PromptRecord] = []
    var totalResults = 0
    var selectedPromptID: Int64?
    var availableTags: [CountedValue] = []
    var availableSourceFamilies: [CountedValue] = []
    var dayGroups: [CountedValue] = []
    var legacyUndatedCount = 0
    var topicGroups: [PromptTopicSummary] = []
    var selectedDay: String?
    var selectedTopic: PromptTopicSummary?
    var statistics: PromptStatistics = .empty
    var isLoadingLibrary = false
    var isLoadingMoreLibrary = false
    var isLoadingStatistics = false

    var selectedImportProvider: ImportProvider = .claude
    var selectedImportFormat: ImportFormat = .claudeJSONL
    var importSourceURL: URL?
    var importPreview: ImportPreview?
    var lastImportReport: ImportReport?
    var isAnalyzingImport = false
    var isCommittingImport = false

    var editor: PromptEditorPresentation?
    var promptPendingDeletion: PromptRecord?
    var isSavingEditor = false
    var errorPresentation: AppErrorPresentation?
    var successMessage: String?

    private var bootstrapService: DatabaseBootstrapService?
    private var repository: PromptRepository?
    private let importEngine = ImportEngine()
    private static let libraryPageSize = 500
    private var didStart = false
    private var reloadToken = 0
    private var libraryGeneration = 0
    private var loadedLibraryOffset = 0
    private var loadedLibraryQueryKey: LibraryQueryKey?
    private var activeLibraryRefreshID: UUID?
    private var activeLibraryLoadMoreID: UUID?
    private var bootstrapFailure: AppErrorPresentation?
    private var toastTask: Task<Void, Never>?

    init() {
        do {
            bootstrapService = try DatabaseBootstrapService()
        } catch {
            let presentation = Self.errorPresentation(for: error, context: "App-Speicher vorbereiten")
            bootstrapFailure = presentation
            launchState = .failed(presentation.message)
            errorPresentation = presentation
        }
    }

    var selectedPrompt: PromptRecord? {
        guard let selectedPromptID else { return nil }
        return prompts.first { $0.id == selectedPromptID }
    }

    var isReadOnly: Bool {
        if case .readOnly = launchState { return true }
        return false
    }

    var canMutatePrompts: Bool {
        repository != nil && !isReadOnly && !isCommittingImport
    }

    var isBootstrapAvailable: Bool {
        bootstrapService != nil
    }

    var requiresManualDatabaseRecovery: Bool {
        guard let databaseURL = bootstrapService?.databaseURL,
              FileManager.default.fileExists(atPath: databaseURL.path)
        else {
            return false
        }
        switch launchState {
        case .invalid, .failed:
            return true
        default:
            return false
        }
    }

    var bootstrapFailureMessage: String? {
        switch launchState {
        case let .invalid(message), let .failed(message):
            message
        default:
            nil
        }
    }

    var canChooseBootstrapDatabase: Bool {
        guard isBootstrapAvailable else { return false }
        switch launchState {
        case .needsDatabase:
            return true
        case .invalid:
            return !requiresManualDatabaseRecovery
        default:
            return false
        }
    }

    var canCreateEmptyDatabase: Bool {
        canChooseBootstrapDatabase
    }

    var canInstallSelectedBootstrapDatabase: Bool {
        canChooseBootstrapDatabase && selectedBootstrapURL != nil
    }

    var hasMoreLibraryResults: Bool {
        loadedLibraryOffset < totalResults
    }

    var canLoadMoreLibraryResults: Bool {
        repository != nil
            && !isLoadingLibrary
            && !isLoadingMoreLibrary
            && hasMoreLibraryResults
            && loadedLibraryQueryKey == libraryQueryKey
    }

    var nextLibraryPageCount: Int {
        min(Self.libraryPageSize, max(0, totalResults - loadedLibraryOffset))
    }

    var databaseDisplayName: String? {
        repository?.databaseURL?.lastPathComponent
    }

    var applicationDatabasePath: String {
        bootstrapService?.databaseURL.path(percentEncoded: false)
            ?? "~/Library/Application Support/PromptGarage/prompts.db"
    }

    var footerStatus: String {
        if isCommittingImport { return "Import wird atomar geschrieben …" }
        if isAnalyzingImport { return "Importquelle wird analysiert …" }
        if isLoadingLibrary || isLoadingMoreLibrary || isLoadingStatistics {
            return "Lokale Daten werden geladen …"
        }
        return "Bereit"
    }

    var libraryQueryKey: LibraryQueryKey {
        LibraryQueryKey(
            destination: destination,
            text: searchText,
            tag: selectedTag,
            sourceFamily: selectedSourceFamily,
            selectedDay: selectedDay,
            selectedTopic: selectedTopic,
            sort: sort,
            reloadToken: reloadToken
        )
    }

    func start() async {
        guard !didStart else { return }
        didStart = true

        guard let service = requireBootstrapService(context: "App-Speicher prüfen") else { return }
        let state: DatabaseBootstrapState
        do {
            state = try await runDetached { service.inspect() }
        } catch {
            launchState = .failed(error.localizedDescription)
            showError(error, context: "Lokale Datenbank prüfen")
            return
        }

        switch state {
        case .needsDatabase:
            launchState = .needsDatabase
        case .validating:
            launchState = .needsDatabase
        case .ready:
            await openExisting(using: service, readOnlyMessage: nil)
        case let .invalid(error):
            launchState = .invalid(error.localizedDescription)
        case let .readOnly(report):
            await openExisting(
                using: service,
                readOnlyMessage: "Datenbank ist schreibgeschützt (\(report.promptCount) Prompts)."
            )
        case let .failed(message):
            launchState = .failed(message)
        }
    }

    func chooseBootstrapDatabase() {
        guard requireBootstrapService(context: "Datenbank auswählen") != nil else { return }
        guard canChooseBootstrapDatabase else {
            showManualDatabaseRecoveryError(context: "Datenbank auswählen")
            return
        }

        let panel = NSOpenPanel()
        panel.title = "Vorhandene prompts.db auswählen"
        panel.message = "Die Quelle wird geprüft und anschließend kopiert. Das Original bleibt unverändert."
        panel.prompt = "Auswählen"
        panel.canChooseFiles = true
        panel.canChooseDirectories = false
        panel.allowsMultipleSelection = false
        panel.allowedContentTypes = [UTType(filenameExtension: "db") ?? .data]

        guard panel.runModal() == .OK, let url = panel.url else { return }
        selectedBootstrapURL = url
    }

    func importSelectedBootstrapDatabase() async {
        guard let service = requireBootstrapService(context: "Datenbank übernehmen") else { return }
        guard canChooseBootstrapDatabase else {
            showManualDatabaseRecoveryError(context: "Datenbank übernehmen")
            return
        }
        guard let sourceURL = selectedBootstrapURL else {
            showErrorMessage(
                "Wähle zuerst eine prompts.db aus.",
                context: "Datenbank übernehmen"
            )
            return
        }
        launchState = .validating(sourceURL.lastPathComponent)
        dismissError()

        do {
            let openedRepository = try await runDetached {
                try service.installDatabase(from: sourceURL)
            }
            repository = openedRepository
            launchState = .ready
            await refreshAll()
            showSuccess("Sammlung wurde lokal übernommen.")
        } catch {
            launchState = .invalid(error.localizedDescription)
            showError(error, context: "Datenbank übernehmen")
        }
    }

    func startWithEmptyDatabase() async {
        guard let service = requireBootstrapService(context: "Leere Sammlung erstellen") else { return }
        guard canCreateEmptyDatabase else {
            showManualDatabaseRecoveryError(context: "Leere Sammlung erstellen")
            return
        }
        launchState = .validating("Neue Datenbank")
        dismissError()

        do {
            let openedRepository = try await runDetached {
                try service.startEmpty()
            }
            repository = openedRepository
            launchState = .ready
            await refreshAll()
            showSuccess("Leere lokale Sammlung ist bereit.")
        } catch {
            launchState = .failed(error.localizedDescription)
            showError(error, context: "Leere Sammlung erstellen")
        }
    }

    func refreshLibrary() async {
        libraryGeneration &+= 1
        let generation = libraryGeneration
        let queryKey = libraryQueryKey
        activeLibraryLoadMoreID = nil
        isLoadingMoreLibrary = false
        loadedLibraryQueryKey = nil

        guard let repository else {
            activeLibraryRefreshID = nil
            isLoadingLibrary = false
            prompts = []
            totalResults = 0
            loadedLibraryOffset = 0
            selectedPromptID = nil
            return
        }
        if destination == .byDay && selectedDay == nil {
            activeLibraryRefreshID = nil
            isLoadingLibrary = false
            prompts = []
            totalResults = 0
            loadedLibraryOffset = 0
            selectedPromptID = nil
            return
        }
        if destination == .byTopic && selectedTopic == nil {
            activeLibraryRefreshID = nil
            isLoadingLibrary = false
            prompts = []
            totalResults = 0
            loadedLibraryOffset = 0
            selectedPromptID = nil
            return
        }

        let query = makePromptQuery(limit: Self.libraryPageSize, offset: 0)
        let requestID = UUID()
        activeLibraryRefreshID = requestID
        isLoadingLibrary = true
        defer {
            if activeLibraryRefreshID == requestID {
                activeLibraryRefreshID = nil
                isLoadingLibrary = false
            }
        }

        do {
            let page = try await runDetached {
                try repository.page(matching: query)
            }
            guard generation == libraryGeneration,
                  queryKey == libraryQueryKey,
                  query == makePromptQuery(limit: Self.libraryPageSize, offset: 0)
            else {
                return
            }
            prompts = page.prompts
            totalResults = page.total
            loadedLibraryOffset = page.prompts.count
            loadedLibraryQueryKey = queryKey
            retainValidSelection()
        } catch is CancellationError {
            // A newer query owns the visible result.
        } catch {
            guard generation == libraryGeneration, queryKey == libraryQueryKey else { return }
            showError(error, context: "Bibliothek laden")
        }
    }

    func loadMoreLibraryResults() async {
        guard let repository, canLoadMoreLibraryResults else { return }

        let generation = libraryGeneration
        let queryKey = libraryQueryKey
        let offset = loadedLibraryOffset
        let limit = min(Self.libraryPageSize, totalResults - offset)
        guard limit > 0 else { return }

        let query = makePromptQuery(limit: limit, offset: offset)
        let requestID = UUID()
        activeLibraryLoadMoreID = requestID
        isLoadingMoreLibrary = true
        defer {
            if activeLibraryLoadMoreID == requestID {
                activeLibraryLoadMoreID = nil
                isLoadingMoreLibrary = false
            }
        }

        do {
            let page = try await runDetached {
                try repository.page(matching: query)
            }
            guard generation == libraryGeneration,
                  queryKey == libraryQueryKey,
                  offset == loadedLibraryOffset,
                  query == makePromptQuery(limit: limit, offset: offset)
            else {
                return
            }

            var knownIDs = Set(prompts.map(\.id))
            prompts.append(contentsOf: page.prompts.filter { knownIDs.insert($0.id).inserted })
            loadedLibraryOffset = offset + page.prompts.count
            totalResults = page.total
            retainValidSelection()
        } catch is CancellationError {
            // A full refresh or a newer query owns the visible result.
        } catch {
            guard generation == libraryGeneration, queryKey == libraryQueryKey else { return }
            showError(error, context: "Weitere Prompts laden")
        }
    }

    func refreshStatistics() async {
        guard let repository else { return }
        isLoadingStatistics = true
        defer { isLoadingStatistics = false }
        do {
            statistics = try await runDetached {
                try repository.statistics()
            }
        } catch {
            showError(error, context: "Statistik laden")
        }
    }

    func clearLibraryFilters() {
        searchText = ""
        selectedTag = nil
        selectedSourceFamily = nil
        sort = destination == .mostUsed ? .mostUsed : .updatedDescending
    }

    func presentCreatePrompt() {
        guard canMutatePrompts else { return }
        editor = PromptEditorPresentation(mode: .create, initialDraft: PromptDraft())
    }

    func presentEditPrompt(_ prompt: PromptRecord) {
        guard canMutatePrompts else { return }
        editor = PromptEditorPresentation(mode: .edit(prompt.id), initialDraft: PromptDraft(prompt: prompt))
    }

    func saveEditor(_ draft: PromptDraft, presentation: PromptEditorPresentation) async -> Bool {
        guard let repository, canMutatePrompts else { return false }
        if let message = draft.validationMessage {
            showErrorMessage(message, context: "Prompt prüfen")
            return false
        }
        isSavingEditor = true
        defer { isSavingEditor = false }

        do {
            let previousSelection = selectedPromptID
            let savedPrompt = try await runDetached {
                switch presentation.mode {
                case .create:
                    try repository.create(draft)
                case let .edit(id):
                    try repository.update(id: id, with: draft)
                }
            }
            editor = nil
            reloadToken += 1
            await refreshMetadataAndStatistics()
            await refreshLibrary()
            retainValidSelection(preferredID: savedPrompt.id, fallbackID: previousSelection)
            showSuccess(presentation.mode == .create ? "Prompt wurde erstellt." : "Änderungen wurden gespeichert.")
            return true
        } catch {
            showError(error, context: "Prompt speichern")
            return false
        }
    }

    func toggleStar(_ prompt: PromptRecord) async {
        guard let repository, canMutatePrompts else { return }
        do {
            let updated = try await runDetached {
                try repository.toggleStar(id: prompt.id)
            }
            replacePrompt(updated)
            if destination == .favorites && !updated.isStarred {
                reloadToken += 1
                await refreshLibrary()
            }
            await refreshStatistics()
        } catch {
            showError(error, context: "Favorit ändern")
        }
    }

    func setRating(_ rating: Int?, for prompt: PromptRecord) async {
        guard let repository, canMutatePrompts else { return }
        do {
            let updated = try await runDetached {
                try repository.setRating(rating, for: prompt.id)
            }
            replacePrompt(updated)
            await refreshStatistics()
        } catch {
            showError(error, context: "Bewertung speichern")
        }
    }

    func copy(_ prompt: PromptRecord, countAsUse: Bool) async {
        let pasteboard = NSPasteboard.general
        pasteboard.clearContents()
        pasteboard.setString(prompt.content, forType: .string)

        guard countAsUse else {
            showSuccess("Prompt wurde kopiert.")
            return
        }
        guard let repository, canMutatePrompts else {
            showSuccess("Prompt wurde kopiert; Nutzungszähler blieb unverändert.")
            return
        }

        do {
            let updated = try await runDetached {
                try repository.markUsed(id: prompt.id)
            }
            replacePrompt(updated)
            await refreshStatistics()
            showSuccess("Kopiert und als verwendet gezählt.")
        } catch {
            showError(error, context: "Nutzung zählen")
        }
    }

    func requestDelete(_ prompt: PromptRecord) {
        guard canMutatePrompts else { return }
        promptPendingDeletion = prompt
    }

    func confirmDelete() async {
        guard let repository, let prompt = promptPendingDeletion, canMutatePrompts else { return }
        promptPendingDeletion = nil
        do {
            _ = try await runDetached {
                try repository.delete(id: prompt.id)
            }
            selectedPromptID = nil
            reloadToken += 1
            await refreshAll()
            showSuccess("Prompt wurde gelöscht.")
        } catch {
            showError(error, context: "Prompt löschen")
        }
    }

    func selectImportProvider(_ provider: ImportProvider) {
        selectedImportProvider = provider
        selectedImportFormat = provider.formats.first ?? .claudeJSONL
        resetImportPreview()
    }

    func selectImportFormat(_ format: ImportFormat) {
        selectedImportFormat = format
        selectedImportProvider = format.provider
        resetImportPreview()
    }

    func chooseAndPreviewImportSource() async {
        guard let repository else { return }
        let format = selectedImportFormat
        let panel = NSOpenPanel()
        panel.title = "Quelle für \(format.displayName) auswählen"
        panel.prompt = "Analysieren"
        panel.canChooseFiles = true
        panel.canChooseDirectories = format.allowsDirectory
        panel.allowsMultipleSelection = false
        panel.allowedContentTypes = allowedContentTypes(for: format)

        guard panel.runModal() == .OK, let url = panel.url else { return }
        importSourceURL = url
        importPreview = nil
        lastImportReport = nil
        isAnalyzingImport = true
        dismissError()
        defer { isAnalyzingImport = false }

        let engine = importEngine
        do {
            let preview = try await runDetached {
                let dedupIndex = try repository.makeDedupIndex()
                return try engine.preview(format: format, sourceURL: url, dedupIndex: dedupIndex)
            }
            importPreview = preview
            if preview.candidates.isEmpty {
                showSuccess("Analyse abgeschlossen: keine neuen Prompts.")
            }
        } catch {
            showError(error, context: "Importquelle analysieren")
        }
    }

    func commitImport() async {
        guard let repository, let preview = importPreview, canMutatePrompts else { return }
        isCommittingImport = true
        dismissError()
        defer { isCommittingImport = false }

        do {
            let finalStatistics = try await runDetached {
                try repository.importCandidates(
                    preview.candidates,
                    baseStatistics: preview.statistics
                )
            }
            lastImportReport = ImportReport(preview: preview, statistics: finalStatistics)
            importPreview = nil
            importSourceURL = nil
            reloadToken += 1
            await refreshAll()
            showSuccess("\(finalStatistics.imported) Prompts wurden importiert.")
        } catch {
            showErrorMessage(
                "Keine Änderungen übernommen. \(error.localizedDescription)",
                context: "Import zurückgerollt"
            )
        }
    }

    func resetImportPreview() {
        importSourceURL = nil
        importPreview = nil
        lastImportReport = nil
    }

    func dismissError() {
        errorPresentation = nil
    }

    func copyErrorDiagnostic() {
        guard let diagnostic = errorPresentation?.diagnostic else { return }
        let pasteboard = NSPasteboard.general
        pasteboard.clearContents()
        pasteboard.setString(diagnostic, forType: .string)
        showSuccess("Diagnose wurde kopiert.")
    }

    private func openExisting(
        using service: DatabaseBootstrapService,
        readOnlyMessage: String?
    ) async {
        do {
            guard let openedRepository = try await runDetached({ try service.openExisting() }) else {
                launchState = .needsDatabase
                return
            }
            repository = openedRepository
            launchState = readOnlyMessage.map(AppLaunchState.readOnly) ?? .ready
            await refreshAll()
        } catch {
            launchState = .failed(error.localizedDescription)
            showError(error, context: "Lokale Datenbank öffnen")
        }
    }

    private func refreshAll() async {
        await refreshMetadataAndStatistics()
        await refreshLibrary()
    }

    private func refreshMetadataAndStatistics() async {
        guard let repository else { return }
        isLoadingStatistics = true
        defer { isLoadingStatistics = false }
        do {
            let result = try await runDetached {
                (
                    try repository.allTags(),
                    try repository.sourceFamilies(),
                    try repository.statistics(),
                    try repository.dayGroups(),
                    try repository.legacyUndatedCount(),
                    try repository.browsingTopicGroups()
                )
            }
            availableTags = result.0
            availableSourceFamilies = result.1
            statistics = result.2
            dayGroups = result.3
            legacyUndatedCount = result.4
            topicGroups = result.5
            let selectedDayStillExists = self.selectedDay.map { selected in
                dayGroups.contains(where: { $0.name == selected })
            } ?? false
            if !selectedDayStillExists {
                self.selectedDay = dayGroups.first?.name
            }

            if let selectedTopicID = selectedTopic?.id {
                selectedTopic = topicGroups.first(where: { $0.id == selectedTopicID })
                    ?? topicGroups.first
            } else {
                selectedTopic = topicGroups.first
            }
        } catch {
            showError(error, context: "Filter und Statistik laden")
        }
    }

    private func makePromptQuery(limit: Int = AppModel.libraryPageSize, offset: Int = 0) -> PromptQuery {
        PromptQuery(
            text: searchText,
            tag: destination == .byTopic ? selectedTopic?.topic : selectedTag,
            sourceFamily: selectedSourceFamily,
            promptedDay: destination == .byDay ? selectedDay : nil,
            untaggedOnly: destination == .byTopic && selectedTopic?.isUntagged == true,
            starredOnly: destination == .favorites,
            usedOnly: destination == .mostUsed,
            sort: destination == .mostUsed ? .mostUsed : sort,
            limit: limit,
            offset: offset
        )
    }

    private func retainValidSelection(preferredID: Int64? = nil, fallbackID: Int64? = nil) {
        if let preferredID, prompts.contains(where: { $0.id == preferredID }) {
            selectedPromptID = preferredID
            return
        }
        if let fallbackID, prompts.contains(where: { $0.id == fallbackID }) {
            selectedPromptID = fallbackID
            return
        }
        if let selectedPromptID, prompts.contains(where: { $0.id == selectedPromptID }) {
            return
        }
        selectedPromptID = prompts.first?.id
    }

    private func replacePrompt(_ prompt: PromptRecord) {
        guard let index = prompts.firstIndex(where: { $0.id == prompt.id }) else { return }
        prompts[index] = prompt
    }

    private func allowedContentTypes(for format: ImportFormat) -> [UTType] {
        switch format {
        case .claudeJSONL, .codexHistoryJSONL, .geminiJSONL:
            return [UTType(filenameExtension: "jsonl") ?? .json, .json]
        case .hermesStateDatabase:
            return [UTType(filenameExtension: "db") ?? .data]
        case .chatGPTAnalysisJSON, .chatGPTRawConversationsJSON:
            return [.json]
        case .geminiMarkdown:
            if let markdown = UTType(filenameExtension: "md") {
                return [markdown, .plainText]
            }
            return [.plainText]
        }
    }

    private func showError(_ error: Error, context: String) {
        errorPresentation = Self.errorPresentation(for: error, context: context)
    }

    private func requireBootstrapService(context: String) -> DatabaseBootstrapService? {
        guard let bootstrapService else {
            let presentation = bootstrapFailure ?? AppErrorPresentation(
                title: context,
                message: "Der lokale App-Speicher ist nicht verfügbar.",
                diagnostic: "PromptGarage | \(context)\nDatabaseBootstrapService unavailable"
            )
            launchState = .failed(presentation.message)
            errorPresentation = presentation
            return nil
        }
        return bootstrapService
    }

    private func showErrorMessage(_ message: String, context: String) {
        errorPresentation = AppErrorPresentation(
            title: context,
            message: message,
            diagnostic: "PromptGarage | \(context)\n\(message)"
        )
    }

    private func showManualDatabaseRecoveryError(context: String) {
        showErrorMessage(
            "Die vorhandene App-Datenbank wird niemals automatisch ersetzt. Beende PromptGarage, verschiebe oder benenne \(applicationDatabasePath) manuell um und starte die App danach erneut.",
            context: context
        )
    }

    private static func errorPresentation(for error: Error, context: String) -> AppErrorPresentation {
        AppErrorPresentation(
            title: context,
            message: error.localizedDescription,
            diagnostic: "PromptGarage | \(context)\n\(String(reflecting: error))"
        )
    }

    private func showSuccess(_ message: String) {
        toastTask?.cancel()
        successMessage = message
        toastTask = Task { [weak self] in
            try? await Task.sleep(for: .seconds(3))
            guard !Task.isCancelled else { return }
            self?.successMessage = nil
        }
    }
}

private func runDetached<Value: Sendable>(
    _ operation: @escaping @Sendable () throws -> Value
) async throws -> Value {
    try await Task.detached(priority: .userInitiated, operation: operation).value
}