timelapse.go

package main

import (
    "flag"
    "fmt"
    "io"
    "io/ioutil"
    "log"
    "net/http"
    "os"
    "time"
)

func grabPicture(url, user, password, fname string) error {
    req, err := http.NewRequest("GET", url, nil)
    if err != nil {
        return err
    }
    req.SetBasicAuth(user, password)

    resp, err := http.DefaultClient.Do(req)
    if err != nil {
        return err
    }
    defer resp.Body.Close()
    if resp.StatusCode != 200 {
        val, exists := resp.Header["Content-Type"]
        if exists && val[0] == "text/html" {
            b, err := ioutil.ReadAll(resp.Body)
            if err != nil {
                return err
            }
            log.Fatal(string(b))
        }
        log.Println("not a 200 response")
    }

    f, err := os.Create(fname)
    if err != nil {
        return err
    }

    written, err := io.Copy(f, resp.Body)
    if err != nil {
        return err
    }
    log.Printf("Wrote %s (%d bytes)\n", fname, written)
    return nil
}

func watcher(host, user, password string, interval, duration time.Duration) error {

    url := "http://" + host + "/snapshot.cgi"
    log.Printf("watching(\"%s\", \"%s\", \"%s\")\n", url, user, password)

    ticker := time.Tick(interval)
    done   := time.After(duration)
    i := 0
    for {
        select{
        case <-ticker:
            fname := fmt.Sprintf("out_%05d.jpg", i)
            err := grabPicture(url, user, password, fname)
            if err != nil{
                return err
            }
            i += 1
        case <-done:
            return nil
        }
    }
}

func main() {
    host := flag.String("h", "ipcam_000000000000_0", "host")
    user := flag.String("u", "admin", "user name")
    password := flag.String("p", "admin", "password")
    interval := flag.Duration("i", 24*time.Second, "interval")
    duration := flag.Duration("d", 12*time.Hour  , "duration")
    flag.Parse()
    err := watcher(*host, *user, *password, *interval, *duration)
    if err != nil{
        log.Fatal(err)
    }
}