// AppGroupConfiguration.swift
// OSGKeyboard · Shared
//
// Single source of truth for App Group UserDefaults keys (`config.*`).
// Both `ProviderConfig` (main app) and `AppGroupStore` (keyboard ext)
// should read/write through this type so keys and defaults stay aligned.

import Foundation

public struct AppGroupConfiguration: Sendable, Equatable {
    // MARK: - Keys

    public enum Keys {
        public static let providerId = "config.providerId"
        public static let baseURL = "config.baseURL"
        /// Legacy plaintext slot — migrated to Keychain on first read.
        public static let apiKeyLegacy = "config.apiKey"
        public static let model = "config.model"
        public static let modeId = "config.modeId"
        public static let localeId = "config.localeId"
        public static let engineMode = "config.engineMode"
        public static let hasCompletedOnboarding = "config.hasCompletedOnboarding"
        public static let onboardingPage = "config.onboardingPage"
        public static let hasAcknowledgedCloudSharing = "config.hasAcknowledgedCloudSharing"
        public static let uiLanguage = "config.uiLanguage"
        public static let translationTargetLocaleId = "config.translationTargetLocaleId"
        public static let handednessPreference = "config.handednessPreference"
        public static let cursorDragNavigationEnabled = "config.cursorDragNavigationEnabled"
        public static let polishIntensity = "config.polishIntensity"
        public static let detectedAppContext = "config.detectedAppContext"
        public static let detectedAppContextAt = "config.detectedAppContextAt"
        public static let personalDictionary = "config.personalDictionary.v1"
        /// When true, the main app mirrors the personal dictionary via iCloud KVS.
        public static let personalDictionaryICloudSyncEnabled = "config.personalDictionary.iCloudSyncEnabled"
        /// When true, the host app auto-returns to the source app after a cold-start handoff.
        public static let flowSkipAppSwitch = "config.flowSkipAppSwitch"
        /// Raw `FlowInactivityDuration` value; session expires after this idle window.
        public static let flowInactivityDuration = "config.flowInactivityDuration"
    }

    // MARK: - Stored fields

    public var providerId: String
    public var baseURL: String
    public var model: String
    public var modeId: String
    public var localeId: String
    public var engineMode: String
    public var hasCompletedOnboarding: Bool
    public var onboardingPage: Int
    public var hasAcknowledgedCloudSharing: Bool
    public var uiLanguage: AppUILanguage
    public var translationTargetLocaleId: String
    public var handednessPreference: HandednessPreference
    public var cursorDragNavigationEnabled: Bool
    public var polishIntensity: PolishIntensity
    public var personalDictionary: PersonalDictionary
    /// Opt-in iCloud KVS sync for the personal dictionary (main app only).
    public var personalDictionaryICloudSyncEnabled: Bool
    /// Auto-return to the host app after `startflow` cold start (default on).
    public var flowSkipAppSwitch: Bool
    /// Idle timeout before the Flow session ends; resets on each utterance.
    public var flowInactivityDuration: FlowInactivityDuration

    // MARK: - Derived

    /// Translation is on iff a target locale other than `offLocaleId` is selected.
    public var translationEnabled: Bool {
        translationTargetLocaleId != TranslationLanguageCatalog.offLocaleId
    }

    public var isTranslationEffective: Bool {
        translationEnabled
    }

    public var isLocalEngine: Bool {
        engineMode == "local"
    }

    public var polishModeForPipeline: PolishingService.PolishMode {
        isTranslationEffective
            ? .translate(targetLocaleId: translationTargetLocaleId)
            : .polish
    }

    /// Local engine pins the LLM step to DeepSeek; cloud uses the user's provider.
    public var polishProviderIdOverride: String? {
        engineMode == "local" ? "deepseek" : nil
    }

    public var isCloudAPIKeyMissingForVoiceInput: Bool {
        guard engineMode == "cloud" else { return false }
        return apiKey.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
    }

    /// API key lives in the Keychain (cross-process, encrypted at rest).
    public var apiKey: String {
        Keychain.apiKey(for: providerId) ?? ""
    }

    public func makeClient() -> LLMClient {
        OpenAICompatibleClient(
            baseURL: baseURL,
            apiKey: apiKey,
            model: model
        )
    }

    // MARK: - Detected app context

    public func detectedAppContext(from defaults: UserDefaults) -> (context: AppContext, observedAt: Date)? {
        guard let raw = defaults.string(forKey: Keys.detectedAppContext),
              let value = AppContext(rawValue: raw)
        else { return nil }
        let timestamp = defaults.object(forKey: Keys.detectedAppContextAt) as? Date ?? .distantPast
        return (value, timestamp)
    }

    public mutating func setDetectedAppContext(_ context: AppContext, at date: Date = Date(), to defaults: UserDefaults) {
        defaults.set(context.rawValue, forKey: Keys.detectedAppContext)
        defaults.set(date, forKey: Keys.detectedAppContextAt)
    }

    // MARK: - Load / save

    /// Loads configuration from App Group defaults. Returns `nil` when the suite is unavailable.
    public static func load(from defaults: UserDefaults? = nil) -> AppGroupConfiguration? {
        guard let store = defaults ?? AppGroup.defaultsIfAvailable else { return nil }
        return load(fromAvailable: store)
    }

    /// Loads configuration from a known-available UserDefaults suite.
    public static func load(fromAvailable defaults: UserDefaults) -> AppGroupConfiguration {
        var config = AppGroupConfiguration(
            providerId: defaults.string(forKey: Keys.providerId) ?? "openai",
            baseURL: "",
            model: "",
            modeId: defaults.string(forKey: Keys.modeId) ?? "polish",
            localeId: defaults.string(forKey: Keys.localeId) ?? "auto",
            engineMode: defaults.string(forKey: Keys.engineMode) ?? "cloud",
            hasCompletedOnboarding: defaults.bool(forKey: Keys.hasCompletedOnboarding),
            onboardingPage: {
                let saved = defaults.integer(forKey: Keys.onboardingPage)
                return saved > 0 ? saved : 0
            }(),
            hasAcknowledgedCloudSharing: defaults.bool(forKey: Keys.hasAcknowledgedCloudSharing),
            uiLanguage: AppUILanguage.fromStored(defaults.string(forKey: Keys.uiLanguage)),
            translationTargetLocaleId: defaults.string(forKey: Keys.translationTargetLocaleId)
                ?? TranslationLanguageCatalog.offLocaleId,
            handednessPreference: HandednessPreference.fromStored(
                defaults.string(forKey: Keys.handednessPreference)
            ),
            cursorDragNavigationEnabled: {
                if defaults.object(forKey: Keys.cursorDragNavigationEnabled) == nil {
                    return true
                }
                return defaults.bool(forKey: Keys.cursorDragNavigationEnabled)
            }(),
            polishIntensity: resolvePolishIntensity(from: defaults),
            personalDictionary: decodePersonalDictionary(from: defaults),
            personalDictionaryICloudSyncEnabled: {
                if defaults.object(forKey: Keys.personalDictionaryICloudSyncEnabled) == nil {
                    return true
                }
                return defaults.bool(forKey: Keys.personalDictionaryICloudSyncEnabled)
            }(),
            flowSkipAppSwitch: {
                if defaults.object(forKey: Keys.flowSkipAppSwitch) == nil {
                    return true
                }
                return defaults.bool(forKey: Keys.flowSkipAppSwitch)
            }(),
            flowInactivityDuration: FlowInactivityDuration.fromStored(
                defaults.string(forKey: Keys.flowInactivityDuration)
            )
        )

        let preset = LLMProvider.provider(id: config.providerId)
        if config.baseURL.isEmpty {
            config.baseURL = defaults.string(forKey: Keys.baseURL) ?? preset.defaultBaseURL
        }
        if config.model.isEmpty {
            config.model = defaults.string(forKey: Keys.model) ?? preset.defaultModel
        }

        // One-shot legacy migration: plaintext apiKey in UserDefaults → Keychain.
        _ = resolveAPIKey(defaults: defaults, providerId: config.providerId)

        // Cloud no longer exposes off/transcribe; migrate legacy values.
        if config.engineMode == "cloud", config.modeId != "polish" {
            config.modeId = "polish"
            defaults.set("polish", forKey: Keys.modeId)
        }
        // DeepSeek is local-engine only — never a cloud picker choice.
        if config.engineMode == "cloud", config.providerId == "deepseek" {
            let openAI = LLMProvider.provider(id: "openai")
            config.providerId = openAI.id
            config.baseURL = openAI.defaultBaseURL
            config.model = openAI.defaultModel
            defaults.set(openAI.id, forKey: Keys.providerId)
            defaults.set(openAI.defaultBaseURL, forKey: Keys.baseURL)
            defaults.set(openAI.defaultModel, forKey: Keys.model)
        }

        return config
    }

    public func save(to defaults: UserDefaults) {
        defaults.set(providerId, forKey: Keys.providerId)
        defaults.set(baseURL, forKey: Keys.baseURL)
        defaults.set(model, forKey: Keys.model)
        defaults.set(modeId, forKey: Keys.modeId)
        defaults.set(localeId, forKey: Keys.localeId)
        defaults.set(engineMode, forKey: Keys.engineMode)
        defaults.set(hasCompletedOnboarding, forKey: Keys.hasCompletedOnboarding)
        defaults.set(onboardingPage, forKey: Keys.onboardingPage)
        defaults.set(hasAcknowledgedCloudSharing, forKey: Keys.hasAcknowledgedCloudSharing)
        defaults.set(uiLanguage.rawValue, forKey: Keys.uiLanguage)
        defaults.set(translationTargetLocaleId, forKey: Keys.translationTargetLocaleId)
        defaults.set(handednessPreference.rawValue, forKey: Keys.handednessPreference)
        defaults.set(cursorDragNavigationEnabled, forKey: Keys.cursorDragNavigationEnabled)
        defaults.set(polishIntensity.rawValue, forKey: Keys.polishIntensity)
        defaults.set(flowSkipAppSwitch, forKey: Keys.flowSkipAppSwitch)
        defaults.set(flowInactivityDuration.rawValue, forKey: Keys.flowInactivityDuration)
        defaults.set(personalDictionaryICloudSyncEnabled, forKey: Keys.personalDictionaryICloudSyncEnabled)
        Self.encodePersonalDictionary(personalDictionary, to: defaults)
    }

    // MARK: - Private helpers

    private static func resolvePolishIntensity(from defaults: UserDefaults) -> PolishIntensity {
        guard let raw = defaults.string(forKey: Keys.polishIntensity) else {
            return .default
        }
        let resolved = PolishIntensity.resolve(storedRawValue: raw)
        if raw == PolishIntensity.legacyOffRawValue {
            defaults.set(resolved.rawValue, forKey: Keys.polishIntensity)
        }
        return resolved
    }

    private static func decodePersonalDictionary(from defaults: UserDefaults) -> PersonalDictionary {
        guard let data = defaults.data(forKey: Keys.personalDictionary) else {
            return .empty
        }
        do {
            var dictionary = try JSONDecoder().decode(PersonalDictionary.self, from: data)
            if dictionary.entries.contains(where: { $0.source == .history }) {
                for index in dictionary.entries.indices where dictionary.entries[index].source == .history {
                    dictionary.entries[index].source = .manual
                }
                dictionary.version += 1
                if let migrated = try? JSONEncoder().encode(dictionary) {
                    defaults.set(migrated, forKey: Keys.personalDictionary)
                }
            }
            return dictionary
        } catch {
            OSGLog.config.warning("personalDictionary decode failed: \(error.localizedDescription, privacy: .public)")
            return .empty
        }
    }

    private static func encodePersonalDictionary(_ dictionary: PersonalDictionary, to defaults: UserDefaults) {
        do {
            let data = try JSONEncoder().encode(dictionary)
            defaults.set(data, forKey: Keys.personalDictionary)
        } catch {
            OSGLog.config.warning("personalDictionary encode failed: \(error.localizedDescription, privacy: .public)")
        }
    }

    /// Read the API key from the Keychain, falling back to a one-time migration from UserDefaults.
    static func resolveAPIKey(defaults: UserDefaults?, providerId: String) -> String {
        if let stored = Keychain.apiKey(for: providerId), !stored.isEmpty {
            return stored
        }
        if let legacyKeychain = Keychain.legacyAPIKey(), !legacyKeychain.isEmpty {
            try? Keychain.setAPIKey(legacyKeychain, for: providerId)
            try? Keychain.deleteLegacyAPIKey()
            return legacyKeychain
        }
        if let defaults,
           let legacy = defaults.string(forKey: Keys.apiKeyLegacy),
           !legacy.isEmpty {
            try? Keychain.setAPIKey(legacy, for: providerId)
            defaults.removeObject(forKey: Keys.apiKeyLegacy)
            return legacy
        }
        return ""
    }
}