import Foundation

/// Deck-DTO. Wire-Format aus `cards/apps/api/src/lib/dto.ts:toDeckDto`.
/// snake_case-Felder via `CodingKeys`, Optionals explizit nullable.
struct Deck: Codable, Identifiable, Hashable, Sendable {
    let id: String
    let userId: String
    let name: String
    let description: String?
    let color: String?
    let category: DeckCategory?
    let visibility: DeckVisibility
    let fsrsSettings: FsrsSettings
    let contentHash: String?
    let forkedFromMarketplaceDeckId: String?
    let forkedFromMarketplaceVersionId: String?
    let archivedAt: Date?
    let createdAt: Date
    let updatedAt: Date

    enum CodingKeys: String, CodingKey {
        case id
        case userId = "user_id"
        case name
        case description
        case color
        case category
        case visibility
        case fsrsSettings = "fsrs_settings"
        case contentHash = "content_hash"
        case forkedFromMarketplaceDeckId = "forked_from_marketplace_deck_id"
        case forkedFromMarketplaceVersionId = "forked_from_marketplace_version_id"
        case archivedAt = "archived_at"
        case createdAt = "created_at"
        case updatedAt = "updated_at"
    }

    /// Geforkt aus dem Cardecky-Marketplace?
    var isFromMarketplace: Bool {
        forkedFromMarketplaceDeckId != nil
    }
}

enum DeckVisibility: String, Codable, Sendable {
    case `private`
    case space
    case `public`
}

/// Aus `cards/packages/cards-domain/src/schemas/deck.ts:DECK_CATEGORY_IDS`.
enum DeckCategory: String, Codable, Sendable, CaseIterable {
    case language
    case medicine
    case science
    case math
    case history
    case law
    case technology
    case arts
    case music
    case sport
    case other

    /// Deutsche Labels aus `DECK_CATEGORY_LABELS`.
    var label: String {
        switch self {
        case .language: "Sprache"
        case .medicine: "Medizin"
        case .science: "Wissenschaft"
        case .math: "Mathematik"
        case .history: "Geschichte"
        case .law: "Recht"
        case .technology: "Technik"
        case .arts: "Kunst"
        case .music: "Musik"
        case .sport: "Sport"
        case .other: "Sonstiges"
        }
    }
}

/// FSRS-Settings — Native bleibt schematisch agnostisch, FSRS rechnet
/// nur der Server. Wir behalten die Felder als roh-JSON, damit eine
/// neue Setting auf dem Server uns nicht bricht.
struct FsrsSettings: Codable, Sendable, Hashable {
    let requestRetention: Double?
    let maximumInterval: Int?
    let enableFuzz: Bool?

    enum CodingKeys: String, CodingKey {
        case requestRetention = "request_retention"
        case maximumInterval = "maximum_interval"
        case enableFuzz = "enable_fuzz"
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        requestRetention = try container.decodeIfPresent(Double.self, forKey: .requestRetention)
        maximumInterval = try container.decodeIfPresent(Int.self, forKey: .maximumInterval)
        enableFuzz = try container.decodeIfPresent(Bool.self, forKey: .enableFuzz)
    }

    static let empty = FsrsSettings()

    private init(
        requestRetention: Double? = nil,
        maximumInterval: Int? = nil,
        enableFuzz: Bool? = nil
    ) {
        self.requestRetention = requestRetention
        self.maximumInterval = maximumInterval
        self.enableFuzz = enableFuzz
    }
}

/// Server-Response von `GET /api/v1/decks`.
struct DeckListResponse: Decodable, Sendable {
    let decks: [Deck]
    let total: Int
}

/// Server-Response von `GET /api/v1/cards?deck_id=...`.
struct CardListResponse: Decodable, Sendable {
    let cards: [Card]
    let total: Int
}

/// Server-Response von `GET /api/v1/reviews/due?deck_id=...`.
struct DueReviewsResponse: Decodable, Sendable {
    let total: Int
}