import Foundation
import SwiftData

/// Lokales Cache-Model für Decks. Spiegelt das Server-DTO + zwei
/// computed Werte (cardCount, dueCount), die Web pro Deck als zusätzliche
/// API-Calls holt.
///
/// Offline-Read: Liste sichtbar ohne Netz. Server bleibt Wahrheit —
/// alle Edits laufen über die API, der Cache wird nur beim Re-Fetch
/// aktualisiert.
@Model
final class CachedDeck {
    @Attribute(.unique) var id: String
    var userId: String
    var name: String
    var deckDescription: String?
    var color: String?
    var categoryRaw: String?
    var visibilityRaw: String
    var contentHash: String?
    var forkedFromMarketplaceDeckId: String?
    var forkedFromMarketplaceVersionId: String?
    var archivedAt: Date?
    var createdAt: Date
    var updatedAt: Date

    /// Anzahl Karten im Deck (über `/api/v1/cards?deck_id=...`).
    var cardCount: Int = 0

    /// Anzahl fälliger Reviews (über `/api/v1/reviews/due?deck_id=...`).
    var dueCount: Int = 0

    /// Zeitpunkt des letzten erfolgreichen Server-Pulls für dieses Deck.
    var lastFetchedAt: Date

    init(deck: Deck, cardCount: Int = 0, dueCount: Int = 0) {
        id = deck.id
        userId = deck.userId
        name = deck.name
        deckDescription = deck.description
        color = deck.color
        categoryRaw = deck.category?.rawValue
        visibilityRaw = deck.visibility.rawValue
        contentHash = deck.contentHash
        forkedFromMarketplaceDeckId = deck.forkedFromMarketplaceDeckId
        forkedFromMarketplaceVersionId = deck.forkedFromMarketplaceVersionId
        archivedAt = deck.archivedAt
        createdAt = deck.createdAt
        updatedAt = deck.updatedAt
        self.cardCount = cardCount
        self.dueCount = dueCount
        lastFetchedAt = .now
    }

    /// Übernimmt aktualisierte Felder vom Server-DTO.
    func update(from deck: Deck, cardCount: Int, dueCount: Int) {
        name = deck.name
        deckDescription = deck.description
        color = deck.color
        categoryRaw = deck.category?.rawValue
        visibilityRaw = deck.visibility.rawValue
        contentHash = deck.contentHash
        forkedFromMarketplaceDeckId = deck.forkedFromMarketplaceDeckId
        forkedFromMarketplaceVersionId = deck.forkedFromMarketplaceVersionId
        archivedAt = deck.archivedAt
        updatedAt = deck.updatedAt
        self.cardCount = cardCount
        self.dueCount = dueCount
        lastFetchedAt = .now
    }

    var category: DeckCategory? {
        categoryRaw.flatMap(DeckCategory.init(rawValue:))
    }

    var isFromMarketplace: Bool {
        forkedFromMarketplaceDeckId != nil
    }
}