fixed some naming conventions, error catching with opening json file, read all json in, append to array, overwrite file

src/main.c

@@ -115,11 +115,11 @@ int8_t save_data_to_json_file(struct bme280_data *sensor_readings_data)
 
     timeinfo = localtime(&rawtime);
     strftime(dateString, 32, "%F", timeinfo);
-    strftime(timeString, 32, "%H_%M_%S", timeinfo);
+    strftime(timeString, 32, "%H:%M:%S", timeinfo);
     //puts(dateString);
     //time(&rawtime);
 
-    snprintf(filename, sizeof(filename), "readings_%s.json", dateString);
+    snprintf(filename, sizeof(filename), "%s.json", dateString);
 
     if (!check_file_exists(filename))
     {
@@ -132,7 +132,7 @@ int8_t save_data_to_json_file(struct bme280_data *sensor_readings_data)
     jsonFilePtr = fopen(filename, "r+");
     if (jsonFilePtr == NULL)
     {
-        sprintf("Failed to open %s", filename);
+        fprintf(stderr, "Failed to open %s\n", filename);
         exit(1);
     }
     fread(jsonBuffer, 1024, 1, jsonFilePtr);
@@ -183,7 +183,8 @@ int8_t save_data_to_json_file(struct bme280_data *sensor_readings_data)
 #endif
 
     json_object_object_add(parsed_json, timeString, latest_reading_object);
-    //fprintf(jsonFilePtr, json_object_to_json_string(parsed_json));
+    fseek(jsonFilePtr, 0, SEEK_SET);
+    ftruncate(fileno(jsonFilePtr), 0);
     fputs(json_object_to_json_string(parsed_json), jsonFilePtr);
 printf("json to write out: %s \n", json_object_to_json_string(latest_reading_object));
 printf("new json to write out: %s \n", json_object_to_json_string(parsed_json));
@@ -214,7 +215,7 @@ int8_t read_sensor_data_normal_mode(struct bme280_dev *dev)
     dev->delay_ms(200); // wait for first measurement
     readings_result = bme280_get_sensor_data(BME280_ALL, &sensor_readings_data, dev);
     print_sensor_data(&sensor_readings_data);
-    //save_data_to_json_file(&sensor_readings_data);
+    save_data_to_json_file(&sensor_readings_data);
 
     return readings_result;
 }