control: Add interfacesRemoved signal support

Subscribe to and handle interfacesRemoved signals to trigger event
actions.

Change-Id: I270dc02bfa78c1801c545712710b27a3d2ba2180
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/control/json/triggers/handlers.hpp b/control/json/triggers/handlers.hpp
index 102a214..d33d00d 100644
--- a/control/json/triggers/handlers.hpp
+++ b/control/json/triggers/handlers.hpp
@@ -91,6 +91,39 @@
                         std::get<Prop>(obj), itProp->second);
         return true;
     }
+
+    /**
+     * @brief Processes an interfaces removed signal and removes the interface
+     * (including its properties) from the object cache on the manager
+     *
+     * @param[in] msg - The sdbusplus signal message
+     * @param[in] obj - Object data associated with the signal
+     * @param[in] mgr - Manager that stores the object cache
+     */
+    static bool interfacesRemoved(message& msg, const SignalObject& obj,
+                                  Manager& mgr)
+    {
+        sdbusplus::message::object_path op;
+        msg.read(op);
+        if (static_cast<const std::string&>(op) != std::get<Path>(obj))
+        {
+            // Path name does not match object's path
+            return false;
+        }
+
+        std::vector<std::string> intfs;
+        msg.read(intfs);
+        auto itIntf =
+            std::find(intfs.begin(), intfs.end(), std::get<Intf>(obj));
+        if (itIntf == intfs.cend())
+        {
+            // Object's interface not in list of interfaces removed
+            return false;
+        }
+
+        mgr.removeInterface(std::get<Path>(obj), std::get<Intf>(obj));
+        return true;
+    }
 };
 
 } // namespace phosphor::fan::control::json::trigger::signal
diff --git a/control/json/triggers/signal.cpp b/control/json/triggers/signal.cpp
index 375ec0f..683acc3 100644
--- a/control/json/triggers/signal.cpp
+++ b/control/json/triggers/signal.cpp
@@ -143,6 +143,32 @@
     }
 }
 
+void interfacesRemoved(Manager* mgr, const std::string& eventName,
+                       std::unique_ptr<ActionBase>& action)
+{
+    // Groups are optional, but a signal triggered event with no groups
+    // will do nothing since signals require a group
+    for (const auto& group : action->getGroups())
+    {
+        for (const auto& member : group.getMembers())
+        {
+            // Setup interfaces added signal handler on the group member
+            const auto match = rules::interfacesRemoved(member);
+            SignalPkg signalPkg = {Handlers::interfacesRemoved,
+                                   SignalObject(std::cref(member),
+                                                std::cref(group.getInterface()),
+                                                std::cref(group.getProperty())),
+                                   SignalActions({action})};
+            auto isSameSig = [&intf = group.getInterface()](SignalPkg& pkg) {
+                auto& obj = std::get<SignalObject>(pkg);
+                return intf == std::get<Intf>(obj);
+            };
+
+            subscribe(match, std::move(signalPkg), isSameSig, mgr);
+        }
+    }
+}
+
 void triggerSignal(const json& jsonObj, const std::string& eventName,
                    Manager* mgr,
                    std::vector<std::unique_ptr<ActionBase>>& actions)
diff --git a/control/json/triggers/signal.hpp b/control/json/triggers/signal.hpp
index 32a9021..f382828 100644
--- a/control/json/triggers/signal.hpp
+++ b/control/json/triggers/signal.hpp
@@ -61,6 +61,16 @@
 void interfacesAdded(Manager* mgr, const std::string& eventName,
                      std::unique_ptr<ActionBase>& action);
 
+/**
+ * @brief Subscribes to an interfacesRemoved signal
+ *
+ * @param[in] mgr - Pointer to manager of the trigger
+ * @param[in] eventName - Name of event associated to the signal
+ * @param[in] action - Action to be run when signal is received
+ */
+void interfacesRemoved(Manager* mgr, const std::string& eventName,
+                       std::unique_ptr<ActionBase>& action);
+
 // Match setup function for signals
 using SignalMatch = std::function<void(Manager*, const std::string&,
                                        std::unique_ptr<ActionBase>& action)>;
@@ -68,7 +78,8 @@
 /* Supported signals to their corresponding match setup functions */
 static const std::unordered_map<std::string, SignalMatch> signals = {
     {"properties_changed", propertiesChanged},
-    {"interfaces_added", interfacesAdded}};
+    {"interfaces_added", interfacesAdded},
+    {"interfaces_removed", interfacesRemoved}};
 
 /**
  * @brief Trigger to process an event after a signal is received