offer chart data as json via api /api/chart/

include/CanGrow_Webserver.h

@@ -29,6 +29,7 @@
  * include Api header files
  */
 #include "Webserver/Api_sensor.h"
+#include "Webserver/Api_chartdata.h"
 
 AsyncWebServer webserver(80);
 // load requestLogger middleware
@@ -103,6 +104,8 @@ void Webserver_Init() {
   webserver.on("/api/sensor/raw", HTTP_GET, Api_sensor_data_raw);
   webserver.on("/api/sensor/driver", HTTP_GET, Api_sensor_driver);
   
+  webserver.on("/api/chart/", HTTP_GET, Api_chart_data);
+  
   
   /* DEBUG only - offer config for direct download */
   #ifdef DEBUG

include/Webserver/Api_chartdata.h

@@ -0,0 +1,78 @@
+/*
+ * 
+ * include/Webserver/Api_chartdata.h - Chart Data API header file
+ * 
+ * 
+ *
+ */
+
+void Api_chart_data(AsyncWebServerRequest* request) {
+  AsyncJsonResponse* response = new AsyncJsonResponse();
+  JsonObject root = response->getRoot().to<JsonObject>();
+  //root["hello"] = "world";
+  for(byte i = 0 ; i < Max_Dashboard_Chart ; i++) {
+    if(config.grow.dashboard.chartConfigured[i] == true) {
+
+      JsonObject objChart = root["chart"].add<JsonObject>();
+      objChart["id"] = i;
+      //objSensor["unit"] = Sensor_Read_unit[SensorIndex[config.system.sensor.type[config.grow.dashboard.chartSensor[i]]].read[config.grow.dashboard.chartRead[i]]];
+      
+      objChart["name"] = config.system.sensor.name[config.grow.dashboard.chartSensor[i]];
+      /* when for a RAW reading rawConvert is set, return the converted description and unit */
+      if((SensorIndex[config.system.sensor.type[config.grow.dashboard.chartSensor[i]]].read[config.grow.dashboard.chartRead[i]] == SENSOR_READ_TYPE_RAW) && (config.system.sensor.rawConvert[config.grow.dashboard.chartSensor[i]][config.grow.dashboard.chartRead[i]] > 0)) {
+        objChart["descr"] = FPSTR(Sensor_Convert_Raw_descr[config.system.sensor.rawConvert[config.grow.dashboard.chartSensor[i]][config.grow.dashboard.chartRead[i]]]);
+        objChart["unit"] = FPSTR(Sensor_Convert_Raw_unit[config.system.sensor.rawConvert[config.grow.dashboard.chartSensor[i]][config.grow.dashboard.chartRead[i]]]);
+      } else {
+        objChart["descr"] = FPSTR(Sensor_Read_descr[SensorIndex[config.system.sensor.type[config.grow.dashboard.chartSensor[i]]].read[config.grow.dashboard.chartRead[i]]]);
+        objChart["unit"] = FPSTR(Sensor_Read_unit[SensorIndex[config.system.sensor.type[config.grow.dashboard.chartSensor[i]]].read[config.grow.dashboard.chartRead[i]]]);
+      }
+      
+      /* build path to chart data dir */
+      char chartDirPath[10];
+      snprintf(chartDirPath, sizeof(chartDirPath), "%s%d", CHART_BASE_PATH, i);
+      /* count number of datasets stored */
+      unsigned short dataIndex = 0;
+      
+      //Serial.println(chartDirPath);
+      
+      /* https://github.com/cotestatnt/async-esp-fs-webserver/blob/master/src/AsyncFsWebServer.cpp */
+      File rootDir = LittleFS.open(chartDirPath, "r");
+      File file = rootDir.openNextFile();
+      //float previousData = 0;
+      /* iterate through all files in chart directory */
+      while (file) { 
+        if (!file.isDirectory()) {
+          
+          /* absolute path to the file we want to read */
+          char chartFilePath[32];
+          snprintf(chartFilePath, sizeof(chartFilePath), "%s/%s", chartDirPath, file.name());
+          //Serial.println(chartFilePath);
+          /* the actual file we are reading */
+          File fileRead = LittleFS.open(chartFilePath, "r");
+          
+          while(fileRead.available()) {
+            /* convert timestamp to unsigned long */
+            unsigned long timestamp = strtoul(fileRead.readStringUntil(';').c_str(), NULL, 0);
+            /* convert the data point to float*/
+            float dataPoint = fileRead.readStringUntil('\n').toFloat();
+            
+            objChart["data"][dataIndex] = dataPoint;
+            objChart["timestamp"][dataIndex] = timestamp;
+            
+            /* increment datacount */
+            dataIndex++;
+          }
+          fileRead.close();
+          
+        } 
+        file = rootDir.openNextFile();
+      }
+      
+      objChart["datapoints"] = dataIndex;
+    
+      
+    }
+  }
+  response->setLength();
+  request->send(response);
+}