import Foundation

/// Response von `POST /api/v1/media/upload`.
struct MediaUploadResponse: Decodable {
    let id: String
    let url: String
    let mimeType: String
    let kind: MediaKind
    let sizeBytes: Int
    let originalFilename: String?

    enum CodingKeys: String, CodingKey {
        case id
        case url
        case mimeType = "mime_type"
        case kind
        case sizeBytes = "size_bytes"
        case originalFilename = "original_filename"
    }
}

enum MediaKind: String, Codable {
    case image
    case audio
    case video
    case other
}

/// Image-Occlusion-Mask-Region.
/// `mask_regions`-Feld ist ein JSON-Array-**String** in `fields`,
/// nicht ein Object — Server-Schema-Constraint (`fields: Record<string,string>`).
struct MaskRegion: Codable, Hashable, Identifiable {
    let id: String
    let x: Double // 0..1 relativ
    let y: Double
    let w: Double
    let h: Double
    let label: String?

    init(id: String, x: Double, y: Double, w: Double, h: Double, label: String? = nil) {
        self.id = id
        self.x = x
        self.y = y
        self.w = w
        self.h = h
        self.label = label
    }
}

/// Helpers zum Parsen/Serialisieren von `mask_regions` als JSON-String.
enum MaskRegions {
    /// 1:1-Port aus `cards-domain/image-occlusion.ts:parseMaskRegions`.
    /// Bei Parse- oder Schema-Fehler: leere Liste. Sortiert nach ID
    /// (lexikographisch, gleich wie Server-Sortierung).
    static func parse(_ json: String) -> [MaskRegion] {
        let data = Data(json.utf8)
        guard let regions = try? JSONDecoder().decode([MaskRegion].self, from: data) else { return [] }
        return regions.sorted { $0.id < $1.id }
    }

    /// Sub-Index → Region (Sortier-Reihenfolge).
    static func region(for json: String, subIndex: Int) -> MaskRegion? {
        let all = parse(json)
        return all.indices.contains(subIndex) ? all[subIndex] : nil
    }

    /// Anzahl Regionen → Anzahl Sub-Index-Reviews.
    static func count(_ json: String) -> Int {
        parse(json).count
    }

    /// Serialisiert eine Liste zu einem JSON-Array-String fürs `fields`-Feld.
    static func encode(_ regions: [MaskRegion]) -> String {
        let encoder = JSONEncoder()
        encoder.outputFormatting = [.sortedKeys]
        guard let data = try? encoder.encode(regions),
              let json = String(bytes: data, encoding: .utf8)
        else { return "[]" }
        return json
    }
}

extension CardFieldsBuilder {
    /// `image-occlusion`-Fields: `image_ref` (media_id) +
    /// `mask_regions` (stringified JSON-Array) + optional `note`.
    static func imageOcclusion(
        imageRef: String,
        regions: [MaskRegion],
        note: String? = nil
    ) -> [String: String] {
        var fields: [String: String] = [
            "image_ref": imageRef,
            "mask_regions": MaskRegions.encode(regions)
        ]
        if let note, !note.isEmpty {
            fields["note"] = note
        }
        return fields
    }

    /// `audio-front`-Fields: `audio_ref` (media_id) + `back` (Antwort-Text).
    static func audioFront(audioRef: String, back: String) -> [String: String] {
        ["audio_ref": audioRef, "back": back]
    }
}