Mobile apps

import android.content.Context
import android.net.Uri
import androidx.browser.customtabs.CustomTabsIntent
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.withContext
import org.json.JSONObject
import java.net.HttpURLConnection
import java.net.URL

// Calls YOUR backend, which creates the order with its API key.
suspend fun startPayment(context: Context, cartId: String) {
    val payment = withContext(Dispatchers.IO) {
        val connection = URL("https://www.example.com/payments").openConnection() as HttpURLConnection
        connection.requestMethod = "POST"
        connection.setRequestProperty("Content-Type", "application/json")
        connection.doOutput = true
        connection.outputStream.use { it.write(JSONObject().put("cartId", cartId).toString().toByteArray()) }
        check(connection.responseCode == 200) { "Payment request failed: ${connection.responseCode}" }
        JSONObject(connection.inputStream.bufferedReader().use { it.readText() })
    }

    CustomTabsIntent.Builder().build()
        .launchUrl(context, Uri.parse(payment.getString("orderUrl")))
}

import AuthenticationServices

struct Payment: Decodable {
    let orderId: String
    let orderUrl: URL
}

// Calls YOUR backend, which creates the order with its API key.
func createPayment(cartId: String) async throws -> Payment {
    var request = URLRequest(url: URL(string: "https://www.example.com/payments")!)
    request.httpMethod = "POST"
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")
    request.httpBody = try JSONEncoder().encode(["cartId": cartId])

    let (data, response) = try await URLSession.shared.data(for: request)
    guard (response as? HTTPURLResponse)?.statusCode == 200 else {
        throw URLError(.badServerResponse)
    }
    return try JSONDecoder().decode(Payment.self, from: data)
}

@MainActor
func startPayment(cartId: String, presenter: ASWebAuthenticationPresentationContextProviding) async throws {
    let payment = try await createPayment(cartId: cartId)

    let session = ASWebAuthenticationSession(
        url: payment.orderUrl,
        callback: .https(host: "www.example.com", path: "/app")
    ) { _, _ in
        // The browser view is closed: ask your backend for the order status.
    }
    session.presentationContextProvider = presenter
    session.start()
}