91 lines
1.9 KiB
Go
91 lines
1.9 KiB
Go
package main
|
|
|
|
import (
|
|
"encoding/json"
|
|
"fmt"
|
|
"io"
|
|
"log"
|
|
"net/http"
|
|
"os"
|
|
"path/filepath"
|
|
"time"
|
|
)
|
|
|
|
var dataFile *os.File
|
|
var startTime time.Time
|
|
|
|
type VoltageData struct {
|
|
Voltage float64 `json:"voltage"`
|
|
}
|
|
|
|
func initDataFile() {
|
|
// Ensure the data/ directory exists
|
|
if err := os.MkdirAll("data", os.ModePerm); err != nil {
|
|
log.Fatalf("Failed to create data directory: %v", err)
|
|
}
|
|
|
|
// Generate a filename with timestamp
|
|
filename := filepath.Join("data", fmt.Sprintf("voltages_%s.csv", time.Now().Format("20060102_150405")))
|
|
file, err := os.OpenFile(filename, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
|
|
if err != nil {
|
|
log.Fatalf("Failed to open data file: %v", err)
|
|
}
|
|
|
|
dataFile = file
|
|
log.Printf("Logging voltage data to %s\n", filename)
|
|
|
|
// Write CSV header
|
|
_, _ = dataFile.WriteString("time_s,voltage\n")
|
|
|
|
startTime = time.Now()
|
|
}
|
|
|
|
func handler(w http.ResponseWriter, r *http.Request) {
|
|
if r.Method != http.MethodPost {
|
|
http.Error(w, "POST only", http.StatusMethodNotAllowed)
|
|
return
|
|
}
|
|
|
|
body, err := io.ReadAll(r.Body)
|
|
if err != nil {
|
|
http.Error(w, "read error", http.StatusBadRequest)
|
|
return
|
|
}
|
|
defer r.Body.Close()
|
|
|
|
// Parse JSON
|
|
var v VoltageData
|
|
if err := json.Unmarshal(body, &v); err != nil {
|
|
http.Error(w, "invalid JSON", http.StatusBadRequest)
|
|
return
|
|
}
|
|
|
|
// Compute relative time
|
|
relTime := time.Since(startTime).Seconds()
|
|
|
|
// Print voltage to console
|
|
fmt.Printf("Received voltage: %f at time %.3f s\n", v.Voltage, relTime)
|
|
|
|
// Append CSV line to file
|
|
if dataFile != nil {
|
|
if _, err := dataFile.WriteString(fmt.Sprintf("%.3f,%.6f\n", relTime, v.Voltage)); err != nil {
|
|
log.Printf("Failed to write to file: %v", err)
|
|
}
|
|
}
|
|
|
|
w.WriteHeader(http.StatusOK)
|
|
w.Write([]byte("ok"))
|
|
}
|
|
|
|
func main() {
|
|
initDataFile()
|
|
defer dataFile.Close()
|
|
|
|
http.HandleFunc("/data", handler)
|
|
|
|
addr := ":8080"
|
|
log.Println("Listening on", addr)
|
|
log.Fatal(http.ListenAndServe(addr, nil))
|
|
}
|
|
|