added function to get BPM graph data

Server/SaveData.cs

@@ -2,12 +2,16 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Text;
+using System.Threading;
 
 namespace Server
 {
     class SaveData
     {
         private string path;
+        private const string jsonFilename = "/json.txt";
+        private const string rawBikeFilename = "/rawBike.bin";
+        private const string rawBPMFilename = "/rawBPM.bin";
         public SaveData(string path)
         {
             this.path = path;
@@ -23,7 +27,7 @@ namespace Server
 
         public void WriteDataJSON(string data)
         {
-            using (StreamWriter sw = File.AppendText(this.path + "/json" + ".txt"))
+            using (StreamWriter sw = File.AppendText(this.path + jsonFilename))
             {
                 sw.WriteLine(data);
             }
@@ -35,7 +39,7 @@ namespace Server
             {
                 throw new ArgumentException("data should have length of 2");
             }
-            WriteRawData(data, this.path + "/rawBPM" + ".bin");
+            WriteRawData(data, this.path + rawBPMFilename);
         }
 
         public void WriteDataRAWBike(byte[] data)
@@ -44,7 +48,7 @@ namespace Server
             {
                 throw new ArgumentException("data should have length of 8");
             }
-            WriteRawData(data, this.path + "/rawBike" + ".bin");
+            WriteRawData(data, this.path + rawBikeFilename);
         }
 
         private void WriteRawData(byte[] data, string fileLocation)
@@ -67,6 +71,56 @@ namespace Server
             }
         }
 
+        /// <summary>
+        /// gets BPM graph data out of file.
+        /// if you want 100 datapoints but here are onlny 50, de last 50 datapoint will be 0
+        /// if you want 100 datapoints where it takes the average of 2, the last 75 will be 0
+        /// if the file isn't created yet it will retun null
+        /// </summary>
+        /// <param name="outputSize">the amount of data points for the output</param>
+        /// <param name="averageOver">the amount of data points form the file for one data point in the output</param>
+        /// <returns>byte array with data points from file</returns>
+        public byte[] getBPMgraphData(int outputSize, int averageOver)
+        {
+            if (File.Exists(this.path + rawBPMFilename))
+            {
+                FileInfo fi = new FileInfo(this.path + rawBPMFilename);
+                int length = (int)fi.Length;
+
+                byte[] output = new byte[outputSize];
+
+                int messageSize = 2;
+                int readSize = messageSize * averageOver;
+                byte[] readBuffer = new byte[readSize];
+
+                using (FileStream fileStream = new FileStream(this.path + rawBPMFilename, FileMode.Open, FileAccess.Read))
+                {
+                    for (int i = 1; i >= outputSize; i++)
+                    {
+                        if (length - (i * readSize) < 0)
+                        {
+                            break;
+                        }
+                        fileStream.Read(readBuffer, length - (i * readSize), readSize);
+
+                        //handling data
+                        int total = 0;
+                        for (int j = 0; j < averageOver; j++)
+                        {
+                            total += readBuffer[j * messageSize + 1];
+                        }
+                        output[i - 1] = (byte)(total / averageOver);
+                    }
+                }
+
+                return output;
+            }
+            else
+            {
+                return null;
+            }
+        }
+
 
     }
 }