import Foundation

/// Body für `POST /api/v1/cards`. Aus `CardCreateSchema`.
///
/// `fields` ist type-abhängig — Server validiert via
/// `validateFieldsForType()`. Pflicht-Keys pro Type:
/// - basic, basic-reverse: `front`, `back`
/// - cloze: `text` (mit `{{cN::...}}`-Clustern)
/// - typing: `front`, `answer`
/// - multiple-choice: `front`, `answer`
/// - image-occlusion: `image_ref`, `mask_regions` (β-4)
/// - audio-front: `audio_ref`, `back` (β-4)
struct CardCreateBody: Encodable {
    let deckId: String
    let type: CardType
    let fields: [String: String]
    let mediaRefs: [String]?

    enum CodingKeys: String, CodingKey {
        case deckId = "deck_id"
        case type
        case fields
        case mediaRefs = "media_refs"
    }
}

/// Body für `PATCH /api/v1/cards/:id`. Nur `fields` und `media_refs` —
/// Type und deck_id sind immutable (Server-Schema).
struct CardUpdateBody: Encodable {
    var fields: [String: String]?
    var mediaRefs: [String]?

    enum CodingKeys: String, CodingKey {
        case fields
        case mediaRefs = "media_refs"
    }
}

/// Hilfs-Builder für Card-Type-spezifische `fields`-Dictionaries.
enum CardFieldsBuilder {
    static func basic(front: String, back: String) -> [String: String] {
        ["front": front, "back": back]
    }

    static func cloze(text: String) -> [String: String] {
        ["text": text]
    }

    static func typing(front: String, answer: String) -> [String: String] {
        ["front": front, "answer": answer]
    }

    static func multipleChoice(front: String, answer: String) -> [String: String] {
        ["front": front, "answer": answer]
    }
}