feature: Components - breaking the ice

Sources/PrimerSDK/Classes/Components/Core/DefaultPaymentMethodContentScope.swift

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+//
+//  DefaultPaymentMethodContentScope.swift
+//
+//
+//  Created by Boris on 6.2.25..
+//
+
+import Foundation
+#if canImport(SwiftUI)
+import SwiftUI
+#endif
+
+/// The default implementation of PaymentMethodContentScope for any payment method.
+struct DefaultPaymentMethodContentScope: PaymentMethodContentScope {
+    let method: PaymentMethod
+
+    // Simulated state; in a real system, this state would be derived from backend/network updates.
+    var simulatedState = PaymentMethodState(
+        isLoading: false,
+        validationState: PaymentValidationState(isValid: true)
+    )
+
+    /// Returns the current simulated state.
+    func getState() async -> PaymentMethodState {
+        // TODO: Replace simulated state with actual state mapping from your processing logic.
+        return simulatedState
+    }
+
+    /// Simulate payment submission.
+    func submit() async -> Result<PaymentResult, Error> {
+        // TODO: Replace with real payment submission logic.
+        try? await Task.sleep(nanoseconds: 2 * 1_000_000_000) // simulate a 2-second delay
+        return .success(PaymentResult(success: true, message: "Payment processed successfully"))
+    }
+
+    #if canImport(SwiftUI)
+    /// Provides default SwiftUI UI for the payment method.
+    @ViewBuilder
+    func defaultContent() -> AnyView {
+        // Wrap your view in AnyView to satisfy the return type.
+        AnyView(
+            VStack {
+                Text("Default UI for \(method.name)")
+                    .font(.headline)
+                    .padding()
+                // TODO: Add form fields, validations, and error messaging as needed.
+            }
+        )
+    }
+    #endif
+}

Sources/PrimerSDK/Classes/Components/Core/PaymentFlow.swift

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+//
+//  PaymentFlow.swift
+//
+//
+//  Created by Boris on 6.2.25..
+//
+
+import Foundation
+#if canImport(SwiftUI)
+import SwiftUI
+#endif
+
+/// The headless core component that encapsulates payment processing logic and state.
+/// This actor leverages Swift Concurrency (async/await) as per Apple's guidelines.
+actor PaymentFlow: PaymentFlowScope {
+
+    // MARK: Internal State
+
+    private var _paymentMethods: [PaymentMethod] = []
+    private var _selectedMethod: PaymentMethod?
+
+    // AsyncStream continuations to emit updates.
+    private var paymentMethodsContinuation: AsyncStream<[PaymentMethod]>.Continuation?
+    private var selectedMethodContinuation: AsyncStream<PaymentMethod?>.Continuation?
+
+    /// Initialize with default payment methods.
+    init() {
+        // TODO: In a production system, fetch or update available payment methods dynamically.
+        _paymentMethods = [
+            CardPaymentMethod(id: "card", name: "Credit Card"),
+            PayPalPaymentMethod(id: "paypal", name: "PayPal"),
+            ApplePayPaymentMethod(id: "applePay", name: "Apple Pay")
+        ]
+    }
+
+    // MARK: AsyncStream Providers
+
+    /// Provides an `AsyncStream` for payment methods.
+    func getPaymentMethods() async -> AsyncStream<[PaymentMethod]> {
+        return AsyncStream { continuation in
+            self.paymentMethodsContinuation = continuation
+            continuation.yield(self._paymentMethods)
+            // TODO: Implement dynamic updates if payment methods change.
+        }
+    }
+
+    /// Provides an `AsyncStream` for the currently selected payment method.
+    func getSelectedMethod() async -> AsyncStream<PaymentMethod?> {
+        return AsyncStream { continuation in
+            self.selectedMethodContinuation = continuation
+            continuation.yield(self._selectedMethod)
+            // TODO: Implement dynamic updates if the selection changes.
+        }
+    }
+
+    // MARK: Internal Update Helpers
+
+    private func updatePaymentMethods() {
+        paymentMethodsContinuation?.yield(_paymentMethods)
+    }
+
+    private func updateSelectedMethod() {
+        selectedMethodContinuation?.yield(_selectedMethod)
+    }
+
+    // MARK: PaymentFlowScope Implementation
+
+    func selectPaymentMethod(_ method: PaymentMethod?) async {
+        _selectedMethod = method
+        updateSelectedMethod()
+    }
+
+    #if canImport(SwiftUI)
+    nonisolated func paymentMethodContent<Content: View>(
+        for method: PaymentMethod,
+        @ViewBuilder content: @escaping (any PaymentMethodContentScope) -> Content
+    ) -> AnyView {
+        // Wrap the helper view in AnyView for type erasure.
+        AnyView(PaymentMethodContentView(method: method, content: content))
+    }
+    #endif
+}

Sources/PrimerSDK/Classes/Components/Core/PaymentFlowScope.swift

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+//
+//  PaymentFlowScope.swift
+//
+//
+//  Created by Boris on 6.2.25..
+//
+
+import Foundation
+#if canImport(SwiftUI)
+import SwiftUI
+#endif
+
+/// The main integration interface (similar to PaymentFlowScope on Android).
+protocol PaymentFlowScope {
+    /// Retrieves the list of available payment methods as an `AsyncStream`.
+    func getPaymentMethods() async -> AsyncStream<[PaymentMethod]>
+
+    /// Retrieves the currently selected payment method as an `AsyncStream`.
+    func getSelectedMethod() async -> AsyncStream<PaymentMethod?>
+
+    /// Asynchronously select a payment method.
+    func selectPaymentMethod(_ method: PaymentMethod?) async
+
+    #if canImport(SwiftUI)
+    /// SwiftUI helper to render payment method content.
+    @ViewBuilder
+    func paymentMethodContent<Content: View>(
+        for method: PaymentMethod,
+        @ViewBuilder content: @escaping (any PaymentMethodContentScope) -> Content
+    ) -> AnyView
+    #endif
+}

Sources/PrimerSDK/Classes/Components/Core/PaymentFlowViewModel.swift

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+//
+//  PaymentFlowViewModel.swift
+//
+//
+//  Created by Boris on 6.2.25..
+//
+
+import SwiftUI
+
+/// A view model that bridges the PaymentFlow actor with SwiftUI state.
+@MainActor
+class PaymentFlowViewModel: ObservableObject {
+    /// The underlying PaymentFlow actor.
+    let paymentFlow = PaymentFlow()
+
+    @Published var paymentMethods: [PaymentMethod] = []
+    @Published var selectedMethod: PaymentMethod?
+
+    /// Load payment methods from the PaymentFlow actor.
+    func loadPaymentMethods() async {
+        for await methods in await paymentFlow.getPaymentMethods() {
+            self.paymentMethods = methods
+        }
+    }
+
+    func loadSelectedMethod() async {
+        for await method in await paymentFlow.getSelectedMethod() {
+            self.selectedMethod = method
+        }
+    }
+
+    /// Select a payment method.
+    func selectMethod(_ method: PaymentMethod) async {
+        await paymentFlow.selectPaymentMethod(method)
+        self.selectedMethod = method
+    }
+}

Sources/PrimerSDK/Classes/Components/Core/PaymentMethod.swift

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+//
+//  PaymentMethod.swift
+//
+//
+//  Created by Boris on 6.2.25..
+//
+
+/// Protocol representing a payment method.
+protocol PaymentMethod {
+    var id: String { get }
+    var name: String { get }
+    var methodType: PaymentMethodType { get }
+    // TODO: Add additional properties (e.g., icon, configuration) if needed.
+}
+
+/// Enumeration for different payment method types.
+enum PaymentMethodType {
+    case card
+    case paypal
+    case applePay
+    // TODO: Add more types as needed.
+}
+
+/// Represents the validation state of a payment method.
+struct PaymentValidationState {
+    let isValid: Bool
+    // TODO: Add more validation info if needed (e.g., error messages).
+}
+
+/// Represents the overall state for a payment method.
+struct PaymentMethodState {
+    let isLoading: Bool
+    let validationState: PaymentValidationState
+    // TODO: Extend with additional state properties as needed.
+}

Sources/PrimerSDK/Classes/Components/Core/PaymentMethodContentScope.swift

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+//
+//  PaymentMethodContentScope.swift
+//
+//
+//  Created by Boris on 6.2.25..
+//
+
+import Foundation
+#if canImport(SwiftUI)
+import SwiftUI
+#endif
+
+/// Scope that handles behavior and UI for an individual payment method.
+protocol PaymentMethodContentScope {
+    /// The payment method for which this scope applies.
+    var method: PaymentMethod { get }
+
+    /// Retrieve the current state asynchronously.
+    func getState() async -> PaymentMethodState
+
+    /// Asynchronously submit the payment.
+    func submit() async -> Result<PaymentResult, Error>
+
+    #if canImport(SwiftUI)
+    /// Provides default SwiftUI UI for this payment method.
+    @ViewBuilder
+    func defaultContent() -> AnyView
+    #endif
+}

Sources/PrimerSDK/Classes/Components/Core/PaymentMethodContentView.swift

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+//
+//  PaymentMethodContentView.swift
+//
+//
+//  Created by Boris on 6.2.25..
+//
+
+import SwiftUI
+
+// PaymentMethodContentView.swift
+
+/// A helper view that instantiates the appropriate PaymentMethodContentScope and passes it to the provided content builder.
+struct PaymentMethodContentView<Content: View>: View {
+    let method: PaymentMethod
+    let content: (any PaymentMethodContentScope) -> Content
+
+    var body: some View {
+        // Decide which scope to use based on the payment method type.
+        let scope: any PaymentMethodContentScope
+        switch method.methodType {
+        case .card:
+            scope = DefaultPaymentMethodContentScope(method: method)
+        case .paypal:
+            scope = PayPalPaymentContentScope(method: method)
+        case .applePay:
+            scope = ApplePayPaymentContentScope(method: method)
+        }
+        return content(scope)
+    }
+}

Sources/PrimerSDK/Classes/Components/Core/PaymentResult.swift

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+//
+//  PaymentResult.swift
+//
+//
+//  Created by Boris on 6.2.25..
+//
+
+/// The result returned when a payment is processed.
+struct PaymentResult {
+    let success: Bool
+    let message: String?
+    // TODO: Add error codes or more detailed response if required.
+}