class ScLoan {
  constructor({ gatewayName }) {}

  // LOS — triggers a new loan origination journey
  apply({ interactionToken }) {}

  // LMS — opens the repayment flow
  pay({ interactionToken }) {}

  // LMS — opens the principal withdrawal flow
  withdraw({ interactionToken }) {}

  // LMS — renders the loan dashboard inside a target DOM element
  // Returns { close: () => Promise, task: Promise }
  // `target` is the DOM element ID to inject the iframe into
  service({ interactionToken, target }) {}
}

class ScLoan {
    /**
     * @typedef {Object} ScLoanConfig
     * @property {String} gatewayName
     * @property {'production' | 'staging'} environment
     */

    /**
     * Setup ScLoans
     * @param {ScLoanConfig} config
     * @returns {Promise<ScLoanSuccess>}
     * @throws {ScLoanError}
     */
    const setup = async (config) => {};

    /**
     * @typedef {Object} ScLoanInfo
     * @property {String} interactionToken
     */

    /**
     * Triggers the loan interaction. The flow is determined by the interactionToken.
     * @param {ScLoanInfo} loanInfo
     * @returns {Promise<ScLoanSuccess>}
     * @throws {ScLoanError}
     */
    const triggerInteraction = async (loanInfo) => {};


    // ─── Deprecated ───────────────────────────────────────────────────────────
    // Use triggerInteraction() instead.

    /** @deprecated */
    const apply = async (loanInfo) => {};

    /** @deprecated */
    const pay = async (loanInfo) => {};

    /** @deprecated */
    const withdraw = async (loanInfo) => {};

    /** @deprecated */
    const service = async (loanInfo) => {};
}

object ScLoan {
    // Setup the ScLoan SDK
    fun setup(config: ScLoanConfig, listener: ScLoanResult)

    // Triggers the loan interaction. The flow is determined by the interactionToken.
    fun triggerInteraction(activity: Activity, config: ScLoanInfo, listener: ScLoanResult)
}

// Callback interface for every SDK method
interface ScLoanResult {
    fun onSuccess(response: ScLoanSuccess)
    fun onFailure(error: ScLoanError)
}

// Success callback returns
data class ScLoanSuccess(val data: String?, val code: Int, val message: String)

// Failure callback returns
data class ScLoanError(val code: Int, val message: String, val data: String?)

// Config object required for setup
data class ScLoanConfig(
    val gatewayName: String,
    val environment: ScLoanEnvironment = ScLoanEnvironment.PRODUCTION
)

// LoanInfo object required for triggerInteraction
class ScLoanInfo(val interactionToken: String)


// ─── Deprecated ───────────────────────────────────────────────────────────────
// Use triggerInteraction() instead.

@Deprecated fun apply(activity: Activity, config: ScLoanInfo, listener: ScLoanResult)
@Deprecated fun pay(activity: Activity, config: ScLoanInfo, listener: ScLoanResult)
@Deprecated fun withdraw(activity: Activity, config: ScLoanInfo, listener: ScLoanResult)
@Deprecated fun service(activity: Activity, config: ScLoanInfo, listener: ScLoanResult)

public class ScLoan: NSObject {
    public static let instance = ScLoan()

    // Setup the ScLoan SDK
    public func setup(
        config: ScLoanConfig,
        completion: @escaping (ScLoanResult<ScLoanSuccess>) -> Void
    )

    // Triggers the loan interaction. The flow is determined by the interactionToken.
    public func triggerInteraction(
        presentingController: UIViewController,
        loanInfo: ScLoanInfo,
        completion: @escaping (ScLoanResult<ScLoanSuccess>) -> Void
    )
}

// typealias ScLoanResult<T> = Result<T, ScLoanError>

// Config object required for setup
public class ScLoanConfig: NSObject {
    public init(gatewayName: String, environment: SCLoanEnvironment? = .production)
}

// LoanInfo object required for triggerInteraction
public class ScLoanInfo: NSObject {
    public init(interactionToken: String)
}

// Success callback — isSuccess is always true
public class ScLoanSuccess: NSObject {
    public let isSuccess: Bool  // always true
    public let data: String?
}

// Failure callback
public class ScLoanError: NSError {
    public let errorCode: Int
    public let errorMessage: String
    public let data: String?
}


// ─── Deprecated ───────────────────────────────────────────────────────────────
// Use triggerInteraction() instead.

@available(*, deprecated, message: "Use triggerInteraction() instead.")
public func apply(presentingController: UIViewController, loanInfo: ScLoanInfo, completion: ...)

@available(*, deprecated, message: "Use triggerInteraction() instead.")
public func pay(presentingController: UIViewController, loanInfo: ScLoanInfo, completion: ...)

@available(*, deprecated, message: "Use triggerInteraction() instead.")
public func withdraw(presentingController: UIViewController, loanInfo: ScLoanInfo, completion: ...)

@available(*, deprecated, message: "Use triggerInteraction() instead.")
public func service(presentingController: UIViewController, loanInfo: ScLoanInfo, completion: ...)

class ScLoan {
    // Setup the ScLoan SDK
    static Future<ScLoanSuccess> setup(ScLoanConfig config) async {}

    // Triggers the loan interaction. The flow is determined by the interactionToken.
    static Future<ScLoanSuccess> triggerInteraction(ScLoanInfo loanInfo) async {}


    // Deprecated — use triggerInteraction() for all new integrations.

    static Future<ScLoanSuccess> apply(ScLoanInfo loanInfo) async {}    // @deprecated
    static Future<ScLoanSuccess> pay(ScLoanInfo loanInfo) async {}      // @deprecated
    static Future<ScLoanSuccess> withdraw(ScLoanInfo loanInfo) async {} // @deprecated
    static Future<ScLoanSuccess> service(ScLoanInfo loanInfo) async {}  // @deprecated
}

// Config object required for setup
// Note: positional constructor — environment first, then gateway name
class ScLoanConfig {
    final ScLoanEnvironment environment;
    final String gateway;

    const ScLoanConfig(this.environment, this.gateway);
}

// LoanInfo object required for triggerInteraction
class ScLoanInfo {
    final String interactionToken;

    const ScLoanInfo(this.interactionToken);
}

enum ScLoanEnvironment { PRODUCTION, STAGING }