add MqttLogger

lib/MqttLogger/src/MqttLogger.h

@@ -0,0 +1,51 @@
+/*
+  MqttLogger - offer print() interface like Serial but by publishing to a given mqtt topic. 
+               Uses Serial as a fallback when no mqtt connection is available.
+
+  Claus Denk
+  https://androbi.com
+*/
+
+#ifndef MqttLogger_h
+#define MqttLogger_h
+
+#include <Arduino.h>
+#include <Print.h>
+#include <PubSubClient.h>
+
+enum MqttLoggerMode {
+    MqttAndSerialFallback = 0,
+    SerialOnly = 1,
+    MqttOnly = 2,
+    MqttAndSerial = 3,
+};
+
+class MqttLogger : public Print
+{
+private:
+    const char* topic;
+    uint8_t* buffer;
+    uint8_t* bufferEnd;
+    uint16_t bufferCnt = 0, bufferSize = 0;
+    PubSubClient* client;
+    MqttLoggerMode mode;
+    void sendBuffer();
+
+public:
+    MqttLogger(MqttLoggerMode mode=MqttLoggerMode::MqttAndSerialFallback);
+    MqttLogger(PubSubClient& client, const char* topic, MqttLoggerMode mode=MqttLoggerMode::MqttAndSerialFallback);
+    ~MqttLogger();
+
+    void setClient(PubSubClient& client);
+    void setTopic(const char* topic);
+    void setMode(MqttLoggerMode mode);
+    void setRetained(boolean retained);
+    
+    virtual size_t write(uint8_t);
+    using Print::write;
+    
+    uint16_t getBufferSize();
+    boolean setBufferSize(uint16_t size);
+};
+
+#endif