import Foundation

/// Rating-Werte für `POST /reviews/:cardId/:subIndex/grade`.
/// Aus `cards/packages/cards-domain/src/schemas/review.ts:RatingSchema`.
enum Rating: String, Codable, CaseIterable {
    case again
    case hard
    case good
    case easy

    /// Anzeige-Label auf dem Rating-Button.
    var label: String {
        switch self {
        case .again: "Nochmal"
        case .hard: "Schwer"
        case .good: "Gut"
        case .easy: "Leicht"
        }
    }

    /// Kurz-Symbol für minimalistische UI.
    var shortcut: String {
        switch self {
        case .again: "1"
        case .hard: "2"
        case .good: "3"
        case .easy: "4"
        }
    }
}

/// FSRS-Review-State. Aus `ReviewStateSchema`.
enum ReviewState: String, Codable {
    case new
    case learning
    case review
    case relearning
}

/// Review-DTO. Wire-Format aus `cards/apps/api/src/routes/reviews.ts:toReviewDto`.
struct Review: Codable, Hashable {
    let cardId: String
    let subIndex: Int
    let userId: String
    let due: Date
    let stability: Double
    let difficulty: Double
    let elapsedDays: Double
    let scheduledDays: Double
    let learningSteps: Int
    let reps: Int
    let lapses: Int
    let state: ReviewState
    let lastReview: Date?

    enum CodingKeys: String, CodingKey {
        case cardId = "card_id"
        case subIndex = "sub_index"
        case userId = "user_id"
        case due
        case stability
        case difficulty
        case elapsedDays = "elapsed_days"
        case scheduledDays = "scheduled_days"
        case learningSteps = "learning_steps"
        case reps
        case lapses
        case state
        case lastReview = "last_review"
    }
}

/// Eintrag aus `/reviews/due?deck_id=X` — Review + zugehörige Card.
struct DueReview: Codable, Hashable, Identifiable {
    let review: Review
    let card: ReviewCard

    var id: String {
        "\(review.cardId)-\(review.subIndex)"
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        // Flat-Decoding: Review-Felder + card-Objekt im selben JSON-Objekt
        review = try Review(from: decoder)
        card = try container.decode(ReviewCard.self, forKey: .card)
    }

    func encode(to encoder: Encoder) throws {
        try review.encode(to: encoder)
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(card, forKey: .card)
    }

    enum CodingKeys: String, CodingKey {
        case card
    }
}

/// Wrapper-Response von `GET /api/v1/reviews/due?deck_id=X`.
struct DueReviewsListResponse: Decodable {
    let reviews: [DueReview]
    let total: Int
}

/// Body für `POST /reviews/:cardId/:subIndex/grade`.
struct GradeReviewBody: Encodable {
    let rating: Rating
    let reviewedAt: Date

    enum CodingKeys: String, CodingKey {
        case rating
        case reviewedAt = "reviewed_at"
    }
}