package main

import (
    "fmt"
    "io/ioutil"
    "os"
    "io"
    "strings"
    "net/http"
    "net/http/httputil"
    "bufio"
)

func main() {
    res, err := http.Get("http://net.cs.uni-bonn.de/wg/cs/teaching/wt-201415/sysprog/")
    if err != nil {
        panic(err)
    }
    website, err := ioutil.ReadAll(res.Body)
    res.Body.Close()
    if err != nil {
        panic(err)
    }
    dump, err := httputil.DumpResponse(res, false)  //get http header
    if err != nil{
        panic (err)
    }
    fmt.Printf("%s", dump)  //print http header

    /* write to file */
    f, err := os.Create("zettel.html") //create file
    if err != nil {
        panic(err)
    }
    defer f.Close()
    size, err := f.Write(website) //write
    if err != nil && size < 0 {
        panic (err)
    }
    /* worst solution ever inbound */
    file, err := os.Open("zettel.html") //open freshly written file
    if (err != nil){
        panic(err)
    }
    defer file.Close()
    reader := bufio.NewReader(file)
    line, err := reader.ReadString('\n')
    var zettel int = 0
    for err == nil {
        if (strings.Contains(line, "Uebungsblatt")){
            zettel += strings.Count(line, "Uebungsblatt")
        }
        line, err = reader.ReadString('\n')
    }
    if err != io.EOF {
        panic(err)
    }
    file.Close()
    fmt.Println("Verfügbare Übungszettel:")
    for i := 1; i<= zettel; i++ {
        fmt.Printf("Uebungsblatt%.2d.pdf\n",i)
    }
}