mana-swift-core/Sources/ManaCore/Credits/ManaCredits.swift

import Foundation

/// Mana-Guthaben eines Nutzers — alle Werte in Mana (1 Mana = 1 Cent).
/// Wire-Mirror von `GET /api/v1/credits/balance` (mana-credits). Das
/// Guthaben ist EIN Wert pro Nutzer, app-übergreifend — die ökosystemweite
/// „Gesamt-Mana-Anzeige".
public struct ManaCreditBalance: Decodable, Sendable, Equatable {
    public let balance: Int
    public let totalEarned: Int
    public let totalSpent: Int

    public init(balance: Int, totalEarned: Int, totalSpent: Int) {
        self.balance = balance
        self.totalEarned = totalEarned
        self.totalSpent = totalSpent
    }
}

/// Eine Mana-Bewegung. Wire-Mirror von `GET /api/v1/credits/transactions`.
/// `amount` ist vorzeichenbehaftet (Gutschrift positiv, Ausgabe negativ).
public struct ManaCreditTransaction: Decodable, Sendable, Identifiable {
    public let id: String
    public let type: String
    public let status: String
    public let amount: Int
    public let balanceBefore: Int
    public let balanceAfter: Int
    public let appId: String
    public let description: String
    public let createdAt: String
    public let completedAt: String?
}

/// Fehler des Credits-Clients.
public enum ManaCreditsError: Error, LocalizedError {
    case http(Int)

    public var errorDescription: String? {
        switch self {
        case let .http(code): "mana-credits antwortete mit HTTP \(code)."
        }
    }
}

/// Client für das ökosystemweite Mana-Guthaben (mana-credits-Service).
///
/// Spricht standardmäßig `credits.mana.how` mit dem mana-auth-JWT — genau
/// wie das Web-Pendant `@mana/mana-credits-client`. Das Guthaben gilt
/// app-übergreifend; jede native mana-App kann es so anzeigen.
///
/// `baseURL` ist überschreibbar (App-Config / Tests); die Endpoint-Pfade
/// (`/api/v1/credits/*`) sind Verein-Plattform-Konstanten.
public struct ManaCreditsClient: Sendable {
    private let transport: AuthenticatedTransport

    public init(
        auth: AuthClient,
        baseURL: URL = URL(string: "https://credits.mana.how")!
    ) {
        transport = AuthenticatedTransport(baseURL: baseURL, auth: auth)
    }

    /// `GET /api/v1/credits/balance` — aktuelles Mana-Guthaben.
    public func balance() async throws -> ManaCreditBalance {
        try await get("/api/v1/credits/balance")
    }

    /// `GET /api/v1/credits/transactions` — letzte Mana-Bewegungen.
    public func transactions(limit: Int = 25, offset: Int = 0) async throws -> [ManaCreditTransaction] {
        try await get("/api/v1/credits/transactions?limit=\(limit)&offset=\(offset)")
    }

    private func get<T: Decodable>(_ path: String) async throws -> T {
        let (data, http) = try await transport.request(path: path)
        guard (200 ..< 300).contains(http.statusCode) else {
            throw ManaCreditsError.http(http.statusCode)
        }
        // JSONDecoder lokal erzeugen — hält den Client `Sendable`.
        return try JSONDecoder().decode(T.self, from: data)
    }
}