Add flow support to the Polatis SNMP driver

Change-Id: I150e174acd54c945c95ca9a1885f1f6313d44ce9
diff --git a/drivers/polatis/snmp/src/main/java/org/onosproject/drivers/polatis/snmp/PolatisFlowRuleProgrammable.java b/drivers/polatis/snmp/src/main/java/org/onosproject/drivers/polatis/snmp/PolatisFlowRuleProgrammable.java
new file mode 100644
index 0000000..e195dc3
--- /dev/null
+++ b/drivers/polatis/snmp/src/main/java/org/onosproject/drivers/polatis/snmp/PolatisFlowRuleProgrammable.java
@@ -0,0 +1,133 @@
+/*
+ * Copyright 2018 Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.drivers.polatis.snmp;
+
+import com.google.common.collect.ImmutableList;
+
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.driver.AbstractHandlerBehaviour;
+import org.onosproject.net.flow.DefaultFlowEntry;
+import org.onosproject.net.flow.FlowEntry;
+import org.onosproject.net.flow.FlowRule;
+import org.onosproject.net.flow.FlowRuleProgrammable;
+
+import org.snmp4j.smi.OID;
+import org.snmp4j.smi.VariableBinding;
+import org.snmp4j.util.TableEvent;
+
+import org.slf4j.Logger;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static org.onosproject.drivers.polatis.snmp.PolatisOpticalUtility.fromFlowRule;
+import static org.onosproject.drivers.polatis.snmp.PolatisSnmpUtility.getTable;
+import static org.onosproject.drivers.polatis.snmp.PolatisSnmpUtility.set;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Flow rule programmable behaviour for Polatis optical snmp devices.
+ */
+public class PolatisFlowRuleProgrammable
+    extends AbstractHandlerBehaviour implements FlowRuleProgrammable {
+
+    private static final String PORT_ENTRY_OID = ".1.3.6.1.4.1.26592.2.2.2.1.2";
+    private static final String PORT_PATCH_OID = PORT_ENTRY_OID + ".1.2";
+
+    private final Logger log = getLogger(getClass());
+
+    @Override
+    public Collection<FlowEntry> getFlowEntries() {
+        List<TableEvent> events;
+        DeviceId deviceId = handler().data().deviceId();
+        ImmutableList.Builder<FlowEntry> connectionsBuilder = ImmutableList.builder();
+
+        try {
+            OID[] columnOIDs = {new OID(PORT_PATCH_OID)};
+            events = getTable(handler(), columnOIDs);
+        } catch (IOException e) {
+            log.error("Error reading ports table for device {} exception {}", deviceId, e);
+            return connectionsBuilder.build();
+        }
+
+        if (events == null) {
+            log.error("Error reading ports table for device {}", deviceId);
+            return connectionsBuilder.build();
+        }
+
+        for (TableEvent event : events) {
+            if (event == null) {
+                log.error("Error reading event for device {}", deviceId);
+                continue;
+            }
+            VariableBinding[] columns = event.getColumns();
+            if (columns == null) {
+                log.error("Error reading columns for device {}", deviceId);
+                continue;
+            }
+
+            VariableBinding patchColumn = columns[0];
+            if (patchColumn == null) {
+                continue;
+            }
+
+            int port = event.getIndex().last();
+            int patch = patchColumn.getVariable().toInt();
+            if (patch == 0) {
+                continue;
+            }
+
+            FlowRule flowRule = PolatisOpticalUtility.toFlowRule(this,
+                PortNumber.portNumber(port), PortNumber.portNumber(patch));
+            connectionsBuilder.add(new DefaultFlowEntry(flowRule, FlowEntry.FlowEntryState.ADDED));
+        }
+
+        return connectionsBuilder.build();
+    }
+
+    private boolean editConnection(FlowRule rule, boolean delete) {
+        List<VariableBinding> vbs = new ArrayList<>();
+        vbs.add(fromFlowRule(rule, delete));
+        DeviceId deviceId = handler().data().deviceId();
+        try {
+            set(handler(), vbs);
+        } catch (IOException e) {
+            log.error("Error writing ports table for device {} exception {}", deviceId, e);
+            return false;
+        }
+        // TODO: check for errors
+        return true;
+    }
+
+    @Override
+    public Collection<FlowRule> applyFlowRules(Collection<FlowRule> rules) {
+        return rules.stream()
+                .filter(c -> editConnection(c, false))
+                .collect(Collectors.toList());
+    }
+
+    @Override
+    public Collection<FlowRule> removeFlowRules(Collection<FlowRule> rules) {
+        return rules.stream()
+                .filter(c -> editConnection(c, true))
+                .collect(Collectors.toList());
+    }
+}