Refactor payment code to make it easier to extend

1 files changed, 108 insertions, 0 deletions

diff --git a/app/src/main/java/net/taler/wallet/payment/PaymentManager.kt b/app/src/main/java/net/taler/wallet/payment/PaymentManager.kt
new file mode 100644
index 0000000..2e40250
--- /dev/null
+++ b/app/src/main/java/net/taler/wallet/payment/PaymentManager.kt
@@ -0,0 +1,108 @@
+package net.taler.wallet.payment
+
+import android.util.Log
+import androidx.annotation.UiThread
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import net.taler.wallet.Amount
+import net.taler.wallet.TAG
+import net.taler.wallet.backend.WalletBackendApi
+import org.json.JSONObject
+
+class PaymentManager(private val walletBackendApi: WalletBackendApi) {
+
+    private val mPayStatus = MutableLiveData<PayStatus>(PayStatus.None)
+    internal val payStatus: LiveData<PayStatus> = mPayStatus
+
+    private var currentPayRequestId = 0
+
+    @UiThread
+    fun preparePay(url: String) {
+        mPayStatus.value = PayStatus.Loading
+
+        val args = JSONObject(mapOf("url" to url))
+
+        currentPayRequestId += 1
+        val payRequestId = currentPayRequestId
+
+        walletBackendApi.sendRequest("preparePay", args) { isError, result ->
+            when {
+                isError -> {
+                    Log.v(TAG, "got preparePay error result")
+                    mPayStatus.value = PayStatus.Error(result.toString())
+                }
+                payRequestId != this.currentPayRequestId -> {
+                    Log.v(TAG, "preparePay result was for old request")
+                }
+                else -> {
+                    val status = result.getString("status")
+                    mPayStatus.postValue(getPayStatusUpdate(status, result))
+                }
+            }
+        }
+    }
+
+    private fun getPayStatusUpdate(status: String, json: JSONObject) = when (status) {
+        "payment-possible" -> PayStatus.Prepared(
+            contractTerms = getContractTerms(json),
+            proposalId = json.getString("proposalId"),
+            totalFees = Amount.fromJson(json.getJSONObject("totalFees"))
+        )
+        "paid" -> PayStatus.AlreadyPaid(getContractTerms(json))
+        "insufficient-balance" -> PayStatus.InsufficientBalance(getContractTerms(json))
+        "error" -> PayStatus.Error("got some error")
+        else -> PayStatus.Error("unknown status")
+    }
+
+    private fun getContractTerms(json: JSONObject): ContractTerms {
+        val ctJson = JSONObject(json.getString("contractTermsRaw"))
+        val amount = Amount.fromString(ctJson.getString("amount"))
+        val summary = ctJson.getString("summary")
+        return ContractTerms(summary, amount)
+    }
+
+    fun confirmPay(proposalId: String) {
+        val args = JSONObject(mapOf("proposalId" to proposalId))
+
+        walletBackendApi.sendRequest("confirmPay", args) { _, _ ->
+            mPayStatus.postValue(PayStatus.Success)
+        }
+    }
+
+    fun abortProposal(proposalId: String) {
+        val args = JSONObject(mapOf("proposalId" to proposalId))
+
+        Log.i(TAG, "aborting proposal")
+
+        walletBackendApi.sendRequest("abortProposal", args) { isError, _ ->
+            if (isError) {
+                Log.e(TAG, "received error response to abortProposal")
+                return@sendRequest
+            }
+            mPayStatus.postValue(PayStatus.None)
+        }
+    }
+
+    @UiThread
+    fun resetPayStatus() {
+        mPayStatus.value = PayStatus.None
+    }
+
+}
+
+sealed class PayStatus {
+    object None : PayStatus()
+    object Loading : PayStatus()
+    data class Prepared(
+        val contractTerms: ContractTerms,
+        val proposalId: String,
+        val totalFees: Amount
+    ) : PayStatus()
+
+    data class InsufficientBalance(val contractTerms: ContractTerms) : PayStatus()
+    data class AlreadyPaid(val contractTerms: ContractTerms) : PayStatus()
+    data class Error(val error: String) : PayStatus()
+    object Success : PayStatus()
+}
+
+data class ContractTerms(val summary: String, val amount: Amount)