// AppGroupPersistor.swift
// OSGKeyboard · Keyboard Extension
//
// Extracted from KeyboardViewController so the view controller doesn't
// have to know about App Group availability checks, AppGroupStore
// reads/writes, or how to render the locale / mode into the State
// view model.

import Foundation
import OSGKeyboardShared

/// Outcome of `load()` — distinguishes "everything fine" from "the
/// App Group isn't configured so we can't read anything". The view
/// controller flips its `phase` accordingly.
public enum AppGroupLoadResult: Equatable {
    case loaded
    case unavailable
}

@MainActor
public struct AppGroupPersistor {

    public init() {}

    /// Hydrate `state` from the App Group. Returns `loaded` on success
    /// or `unavailable` if the App Group suite can't be opened (which
    /// in DEBUG `fatalError`s inside `AppGroup.isAvailable`).
    public func load(into state: KeyboardViewController.State) -> AppGroupLoadResult {
        guard AppGroup.isAvailable else {
            return .unavailable
        }
        let store = AppGroupStore()
        state.localeId         = store.localeId
        // Both engines always polish; ignore legacy off/transcribe modeId.
        state.mode             = .polish
        state.engineMode       = store.engineMode
        // v0.2.1 follow-up: only the target locale is persisted —
        // `translationEnabled` is derived from it. Hydrate once at
        // startup; `refreshRuntimeFlags` keeps the chip in sync while
        // the keyboard stays open.
        state.translationTargetLocaleId = store.translationTargetLocaleId
        state.handednessPreference = store.handednessPreference
        state.cursorDragNavigationEnabled = store.cursorDragNavigationEnabled
        state.micDisabled = store.isCloudAPIKeyMissingForVoiceInput
        state.micDisabledHint = store.isCloudAPIKeyMissingForVoiceInput
            ? ExtL10n.string("keyboard.mic.disabled.missingApiKey")
            : ""

        #if DEBUG
        // Print a masked view of the live App Group config so we can see
        // from the device console exactly what the keyboard extension
        // actually sees (and whether it agrees with the main App).
        let key = store.apiKey
        let masked: String
        if key.count > 8 {
            masked = "\(key.prefix(4))…\(key.suffix(4)) (\(key.count) chars)"
        } else if key.isEmpty {
            masked = "<empty>"
        } else {
            masked = "<\(key.count) chars>"
        }
        print("""
        🔍 [AppGroupPersistor.load]
           providerId      = \(store.providerId)
           baseURL         = \(store.baseURL)
           apiKey          = \(masked)
           model           = \(store.model)
           modeId          = \(store.modeId)
           localeId        = \(store.localeId)
        """)
        #endif
        return .loaded
    }

    /// Lightweight refresh for flags the host app may update while the
    /// keyboard stays open (model downloads, engine switches).
    ///
    /// When `protectTranslationUntil` is in the future, the translation
    /// target locale is not overwritten — avoids the 1 Hz poll clobbering
    /// a chip selection the user just wrote to the App Group.
    public func refreshRuntimeFlags(
        into state: KeyboardViewController.State,
        protectTranslationUntil: Date? = nil
    ) {
        guard AppGroup.isAvailable else { return }
        let store = AppGroupStore()
        state.engineMode = store.engineMode
        let shouldProtectTranslation = protectTranslationUntil.map { Date() < $0 } ?? false
        if !shouldProtectTranslation {
            state.translationTargetLocaleId = store.translationTargetLocaleId
        }
        state.handednessPreference = store.handednessPreference
        state.cursorDragNavigationEnabled = store.cursorDragNavigationEnabled
        state.micDisabled = store.isCloudAPIKeyMissingForVoiceInput
        state.micDisabledHint = store.isCloudAPIKeyMissingForVoiceInput
            ? ExtL10n.string("keyboard.mic.disabled.missingApiKey")
            : ""
    }

    /// Persist `mode` to the App Group store.
    public func persist(mode: KeyboardViewController.State.InputMode) {
        guard AppGroup.isAvailable else { return }
        AppGroupStore().setModeId(mode.rawValue)
    }

    /// Persist `localeId` to the App Group store.
    public func persist(localeId: String) {
        guard AppGroup.isAvailable else { return }
        AppGroupStore().setLocaleId(localeId)
    }

    /// Persist `engineMode` to the App Group store.
    public func persist(engineMode: String) {
        guard AppGroup.isAvailable else { return }
        AppGroupStore().setEngineMode(engineMode)
    }

    /// v0.2.1: persist translation target locale id (e.g. `"en"`,
    /// `"ja"`, or `TranslationLanguageCatalog.offLocaleId`). The
    /// chip / picker call this through `KeyboardState.setTranslationTargetLocaleId`.
    ///
    /// v0.2.1 follow-up: removed `persist(translationEnabled:)` — the
    /// enabled state is derived from the locale id, so callers only
    /// need to write the locale. Keeping the legacy Bool overload
    /// around would have implied that there's a separate on/off
    /// switch to persist, which is no longer the model.
    public func persist(translationTargetLocaleId: String) {
        guard AppGroup.isAvailable else { return }
        AppGroupStore().setTranslationTargetLocaleId(translationTargetLocaleId)
    }
}