Initial pseudo draft of the billing protocol

.idea/misc.xml

@@ -24,7 +24,7 @@
       </value>
     </option>
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_7" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" project-jdk-name="1.8" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/build/classes" />
   </component>
   <component name="ProjectType">

app/src/main/java/com/flashwifi/wifip2p/billing/Accountant.java

@@ -0,0 +1,88 @@
+package com.flashwifi.wifip2p.billing;
+
+
+import java.util.ArrayList;
+
+public class Accountant {
+    private static final Accountant ourInstance = new Accountant();
+
+
+    private ArrayList<Bill> bills;
+    private int totalMegabytes;
+    private int totalIotaPrice;
+    private int totalDurance;
+    private int bookedMegabytes;
+    private int timeoutMinutes;
+
+    private FlashChannelHelper flashChannelHelper;
+
+    private boolean closed = true;
+
+    static Accountant getInstance() {
+        return ourInstance;
+    }
+
+    private Accountant() {
+    }
+
+    public void start(int bookedMegabytes, int timeoutMinutes){
+        if (closed) {
+            bills = new ArrayList<Bill>();
+            this.bookedMegabytes = bookedMegabytes;
+            this.timeoutMinutes = timeoutMinutes;
+            totalMegabytes = 0;
+            totalIotaPrice = 0;
+            totalDurance = 0;
+            flashChannelHelper = new FlashChannelHelper();
+            closed = false;
+        }
+    }
+
+    public int getNextBillNumber() {
+        return bills.size() + 1;
+    }
+
+    private void appendBill(Bill b) {
+        bills.add(b);
+    }
+
+    private void applyTransferToFlashChannel(int iota) {
+
+    }
+
+    public Bill createBill(int megaByte, int priceInIota, int duranceMinutes){
+        if (!closed) {
+            Bill b = new Bill(getNextBillNumber(), totalDurance, duranceMinutes, megaByte, priceInIota);
+
+            totalMegabytes += megaByte;
+            totalIotaPrice += priceInIota;
+            totalDurance += duranceMinutes;
+
+            // 1) modify flash channel
+            applyTransferToFlashChannel(priceInIota);
+
+            appendBill(b);
+            return b;
+        }
+        return null;
+    }
+
+    public void close() {
+        if (!closed) {
+            closed = true;
+        }
+    }
+
+    public void markAcceptance(int index, boolean accepted) {
+        bills.get(index).setAcceptedByPeer(accepted);
+    }
+
+    public boolean billsNotAccepted() {
+        for (Bill b: bills) {
+            if (!b.isAcceptedByPeer()) {
+                return true;
+            }
+        }
+        return false;
+    }
+}

app/src/main/java/com/flashwifi/wifip2p/billing/Bill.java

@@ -0,0 +1,28 @@
+package com.flashwifi.wifip2p.billing;
+
+
+public class Bill {
+    private int index;
+    private int minuteStart;
+    private int duranceInMinutes = 1;
+    private int megabytesUsed;
+    private int priceInIota;
+
+    private boolean acceptedByPeer;
+
+    public Bill(int index, int minuteStart, int duranceInMinutes, int megabytesUsed, int priceInIota) {
+        this.index = index;
+        this.minuteStart = minuteStart;
+        this.duranceInMinutes = duranceInMinutes;
+        this.megabytesUsed = megabytesUsed;
+        this.priceInIota = priceInIota;
+    }
+
+    public boolean isAcceptedByPeer() {
+        return acceptedByPeer;
+    }
+
+    public void setAcceptedByPeer(boolean acceptedByPeer) {
+        this.acceptedByPeer = acceptedByPeer;
+    }
+}

app/src/main/java/com/flashwifi/wifip2p/billing/BillingClient.java

@@ -0,0 +1,23 @@
+package com.flashwifi.wifip2p.billing;
+
+/**
+ * 1) This class keeps the socket connection alive.
+ * 2) It tracks the state of the communication.
+ * 3) It receives new bills and flash objects sent by the server
+ * 4) It approves the changes
+ * 5) It watches the connectivity (no internet -> no money)
+ */
+
+public class BillingClient {
+    private State state = State.NOT_PAIRED;
+
+    public BillingClient(){}
+
+    enum State {
+        NOT_PAIRED,
+        INITIAL,
+        ROAMING,
+        CLOSED,
+        FULLY_ATTACHED
+    }
+}

app/src/main/java/com/flashwifi/wifip2p/billing/BillingServer.java

@@ -0,0 +1,60 @@
+package com.flashwifi.wifip2p.billing;
+
+/**
+ * 1) This class keeps the socket connection alive.
+ * 2) It tracks the state of the communication.
+ * 3) It triggers the creation of bills
+ * 4) It sends the bills and flash objects to the peer
+ * 5) It watches the time and deadlines
+ * 6)
+ */
+
+public class BillingServer {
+    private State state = State.NOT_PAIRED;
+
+    public BillingServer(int bookedMegabytes, int timeoutMinutes){
+        Accountant.getInstance().start(bookedMegabytes,timeoutMinutes);
+    }
+
+    public void start() {
+        // 0) create deadline guard
+        createDeadlineGuard();
+        // 1) create a socket
+
+        while (state != State.ERROR || state != State.FULLY_ATTACHED) {
+            // 2) accept a connection
+            if (state == State.NOT_PAIRED) {
+                // 3) pair client and hotspot and synchronize states
+            }
+            while (state == State.ROAMING) {
+                // 4) sleep(60)
+                // 5) createNewBill
+                // 6) send the bill and the signed flash object
+            }
+            if (state == State.CLOSED) {
+                // 7) close the channel and sign the final settlement
+                // 8) receive the signed settlement from client
+            }
+            while (state == State.CLOSED) {
+                // 9) reattach and rebroadcast the final transaction
+            }
+            if (state == State.FULLY_ATTACHED) {
+                // DONE!
+            }
+        }
+    }
+
+    private void createDeadlineGuard() {
+        // this method measures the time and stops the connection if
+        // nothing happened after <timeoutMinutes>
+    }
+
+    enum State {
+        NOT_PAIRED,
+        INITIAL,
+        ROAMING,
+        CLOSED,
+        FULLY_ATTACHED,
+        ERROR
+    }
+}

app/src/main/java/com/flashwifi/wifip2p/billing/FlashChannelHelper.java

@@ -0,0 +1,60 @@
+package com.flashwifi.wifip2p.billing;
+
+/**
+ * This class takes care of flash channels and their states on the tangle.
+ * It starts new threads which check the iota APIs and takes wrape the
+ * flash channel
+ */
+
+public class FlashChannelHelper {
+    // ToDo: replace this by real flash channel
+    private String flashChannel;
+
+    private boolean flashChannelRootAttached;
+    private boolean flashChannelFundedByHotspot;
+    private boolean flashChannelFundedByConsumer;
+    private boolean flashChannelSettlementAttached;
+
+    public FlashChannelHelper() {
+        flashChannelRootAttached = false;
+        flashChannelFundedByHotspot = false;
+        flashChannelFundedByConsumer = false;
+        flashChannelSettlementAttached = false;
+    }
+
+    public boolean checkRootAttached() {
+        if (flashChannelRootAttached) {
+            return true;
+        } else {
+            // ToDo: make an API call to check this
+            return false;
+        }
+    }
+
+    public boolean checkFundedByHotspot() {
+        if (flashChannelFundedByHotspot) {
+            return true;
+        } else {
+            // ToDo: make an API call to check this
+            return false;
+        }
+    }
+
+    public boolean checkFundedByConsumer() {
+        if (flashChannelFundedByConsumer) {
+            return true;
+        } else {
+            // ToDo: make an API call to check this
+            return false;
+        }
+    }
+
+    public boolean checkSettlementAttached() {
+        if (flashChannelSettlementAttached) {
+            return true;
+        } else {
+            // ToDo: make an API call to check this
+            return false;
+        }
+    }
+}