92 lines
1.6 KiB
Go
92 lines
1.6 KiB
Go
package main
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import (
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"encoding/json"
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"fmt"
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"io"
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"log"
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"net/http"
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"os"
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"path/filepath"
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"time"
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)
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type VoltageBatch struct {
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Voltages []float64 `json:"voltages"`
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}
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var dataFile *os.File
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var berlinTZ *time.Location
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func init() {
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var err error
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berlinTZ, err = time.LoadLocation("Europe/Berlin")
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if err != nil {
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log.Fatal(err)
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}
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}
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func initDataFile() {
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_ = os.MkdirAll("data", 0755)
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filename := filepath.Join(
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"data",
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fmt.Sprintf("voltages_%s.csv",
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time.Now().In(berlinTZ).Format("20060102_150405")),
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)
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f, err := os.OpenFile(filename,
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os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
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if err != nil {
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log.Fatal(err)
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}
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dataFile = f
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dataFile.WriteString("timestamp,voltage\n")
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}
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func handler(w http.ResponseWriter, r *http.Request) {
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if r.Method != http.MethodPost {
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http.Error(w, "POST only", http.StatusMethodNotAllowed)
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return
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}
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body, err := io.ReadAll(r.Body)
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if err != nil {
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http.Error(w, "read error", http.StatusBadRequest)
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return
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}
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defer r.Body.Close()
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var batch VoltageBatch
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if err := json.Unmarshal(body, &batch); err != nil {
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http.Error(w, "invalid JSON", http.StatusBadRequest)
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return
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}
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start := time.Now().In(berlinTZ)
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for i, v := range batch.Voltages {
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ts := start.Add(time.Duration(i) * 33 * time.Millisecond)
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dataFile.WriteString(
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fmt.Sprintf("%s,%.6f\n",
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ts.Format("2006-01-02 15:04:05.000"), v),
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)
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}
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log.Println("Got batch!")
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w.WriteHeader(http.StatusOK)
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w.Write([]byte("ok"))
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}
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func main() {
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initDataFile()
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defer dataFile.Close()
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http.HandleFunc("/data", handler)
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log.Fatal(http.ListenAndServe(":8080", nil))
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}
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