Canned Messages via InkHUD menu (#7096)

* Allow observers to respond to AdminMessage requests
Ground work for CannedMessage getters and setters

* Enable CannedMessage config in apps for InkHUD devices

* Migrate the InkHUD::Events AdminModule observer
Use the new AdminModule_ObserverData struct

* Bare-bones NicheGraphics util to access canned messages
Handles loading and parsing. Handle admin messages for setting and getting.

* Send canned messages via on-screen menu

* Change ThreadedMessageApplet from Observer to Module API
Allows us to intercept locally generated packets ('loopbackOK = true'), to handle outgoing canned messages.

* Fix: crash getting empty canned message string via Client API

* Move file into Utils subdir

* Move an include statement from .cpp to .h

* Limit strncpy size of dest, not source
Wasn't critical in ths specific case, but definitely a mistake.

src/graphics/niche/Utils/CannedMessageStore.cpp

@@ -0,0 +1,163 @@
+#ifdef MESHTASTIC_INCLUDE_NICHE_GRAPHICS
+
+#include "./CannedMessageStore.h"
+
+#include "FSCommon.h"
+#include "NodeDB.h"
+#include "SPILock.h"
+#include "generated/meshtastic/cannedmessages.pb.h"
+
+using namespace NicheGraphics;
+
+// Location of the file which stores the canned messages on flash
+static const char *cannedMessagesConfigFile = "/prefs/cannedConf.proto";
+
+CannedMessageStore::CannedMessageStore()
+{
+#if !MESHTASTIC_EXCLUDE_ADMIN
+    adminMessageObserver.observe(adminModule);
+#endif
+
+    // Load & parse messages from flash
+    load();
+}
+
+// Get access to (or create) the singleton instance of this class
+CannedMessageStore *CannedMessageStore::getInstance()
+{
+    // Instantiate the class the first time this method is called
+    static CannedMessageStore *const singletonInstance = new CannedMessageStore;
+
+    return singletonInstance;
+}
+
+// Access canned messages by index
+// Consumer should check CannedMessageStore::size to avoid accessing out of bounds
+const std::string &CannedMessageStore::at(uint8_t i)
+{
+    assert(i < messages.size());
+    return messages.at(i);
+}
+
+// Number of canned message strings available
+uint8_t CannedMessageStore::size()
+{
+    return messages.size();
+}
+
+// Load canned message data from flash, and parse into the individual strings
+void CannedMessageStore::load()
+{
+    // In case we're reloading
+    messages.clear();
+
+    // Attempt to load the bulk canned message data from flash
+    meshtastic_CannedMessageModuleConfig cannedMessageModuleConfig;
+    LoadFileResult result = nodeDB->loadProto("/prefs/cannedConf.proto", meshtastic_CannedMessageModuleConfig_size,
+                                              sizeof(meshtastic_CannedMessageModuleConfig),
+                                              &meshtastic_CannedMessageModuleConfig_msg, &cannedMessageModuleConfig);
+
+    // Abort if nothing to load
+    if (result != LoadFileResult::LOAD_SUCCESS || strlen(cannedMessageModuleConfig.messages) == 0)
+        return;
+
+    // Split into individual canned messages
+    // These are concatenated when stored in flash, using '|' as a delimiter
+    std::string s;
+    for (char c : cannedMessageModuleConfig.messages) { // Character by character
+
+        // If found end of a string
+        if (c == '|' || c == '\0') {
+            // Copy into the vector (if non-empty)
+            if (!s.empty())
+                messages.push_back(s);
+
+            // Reset the string builder
+            s.clear();
+
+            // End of data, all strings processed
+            if (c == 0)
+                break;
+        }
+
+        // Otherwise, append char (continue building string)
+        else
+            s.push_back(c);
+    }
+}
+
+// Handle incoming admin messages
+// We get these as an observer of AdminModule
+// It's our responsibility to handle setting and getting of canned messages via the client API
+// Ordinarily, this would be handled by the CannedMessageModule, but it is bound to Screen.cpp, so not suitable for NicheGraphics
+int CannedMessageStore::onAdminMessage(AdminModule_ObserverData *data)
+{
+    switch (data->request->which_payload_variant) {
+
+    // Client API changing the canned messages
+    case meshtastic_AdminMessage_set_canned_message_module_messages_tag:
+        handleSet(data->request);
+        *data->result = AdminMessageHandleResult::HANDLED;
+        break;
+
+    // Client API wants to know the current canned messages
+    case meshtastic_AdminMessage_get_canned_message_module_messages_request_tag:
+        handleGet(data->response);
+        *data->result = AdminMessageHandleResult::HANDLED_WITH_RESPONSE;
+        break;
+
+    default:
+        break;
+    }
+
+    return 0; // Tell caller to continue notifying other observers. (No reason to abort this event)
+}
+
+// Client API changing the canned messages
+void CannedMessageStore::handleSet(const meshtastic_AdminMessage *request)
+{
+    // Copy into the correct struct (for writing to flash as protobuf)
+    meshtastic_CannedMessageModuleConfig cannedMessageModuleConfig;
+    strncpy(cannedMessageModuleConfig.messages, request->set_canned_message_module_messages,
+            sizeof(cannedMessageModuleConfig.messages));
+
+    // Ensure the directory exists
+#ifdef FSCom
+    spiLock->lock();
+    FSCom.mkdir("/prefs");
+    spiLock->unlock();
+#endif
+
+    // Write to flash
+    nodeDB->saveProto(cannedMessagesConfigFile, meshtastic_CannedMessageModuleConfig_size,
+                      &meshtastic_CannedMessageModuleConfig_msg, &cannedMessageModuleConfig);
+
+    // Reload from flash, to update the canned messages in RAM
+    // (This is a lazy way to handle it)
+    load();
+}
+
+// Client API wants to know the current canned messages
+// We're reconstructing the monolithic canned message string from our copy of the messages in RAM
+// Lazy, but more convenient that reloading the monolithic string from flash just for this
+void CannedMessageStore::handleGet(meshtastic_AdminMessage *response)
+{
+    // Merge the canned messages back into the delimited format expected
+    std::string merged;
+    if (!messages.empty()) { // Don't run if no messages: error on pop_back with size=0
+        merged.reserve(201);
+        for (std::string &s : messages) {
+            merged += s;
+            merged += '|';
+        }
+        merged.pop_back(); // Drop the final delimiter (loop added one too many)
+    }
+
+    // Place the data into the response
+    // This response is scoped to AdminModule::handleReceivedProtobuf
+    // We were passed reference to it via the observable
+    response->which_payload_variant = meshtastic_AdminMessage_get_canned_message_module_messages_response_tag;
+    strncpy(response->get_canned_message_module_messages_response, merged.c_str(), strlen(merged.c_str()) + 1);
+}
+
+#endif