package main

import (
	"io/ioutil"
	"fmt"
	"bufio"
	"os"
	"github.com/pkg/errors"
	"bytes"
)

type Container interface {
	FindCgroupPaths(path string)(cgroupPaths []string, err error)
}

func FindCgroupPaths(paths []string)(cgroupPaths []string, err error){
	var auxCgroupPaths []string
	for _, path := range paths {
		auxCgroupPaths, _ = FindCgroupPath(path)
		for _, auxCgroupPath := range auxCgroupPaths{
			cgroupPaths = append(cgroupPaths, auxCgroupPath)
		}
	}
	return
}

func FindCgroupPath(path string)(cgroupPaths []string, err error){
	dir, err := ioutil.ReadDir(path)
	if err != nil {
		fmt.Printf("ERROR - FindCgroupPaths - root path is not present - %v \n", err)
	}
	for _, f := range dir {
		if f.IsDir(){
			fmt.Printf("INFO - FindCgroupPaths - Add new cgroup path - %v \n", fmt.Sprint(cgroupFreezerMesosPath, f.Name()))
			cgroupPaths = append(cgroupPaths, fmt.Sprint(cgroupFreezerMesosPath, f.Name()))
		}
	}
	return
}

func GetProcessFromCgroupPaths(paths []string)(cgroupPaths []string, err error){
	var auxProcessContainer []string
	for _, path := range paths {
		auxProcessContainer, _ = GetProcessFromCgroupPath(path)
		ppidCOnatiner, _ := PpidOfContainer(auxProcessContainer)
		cgroupPaths = append(cgroupPaths, ppidCOnatiner)
	}
	return
}

func GetProcessFromCgroupPath(path string)(process []string, err error){
	fmt.Printf("INFO - GetProcessFromCgroupPaths - Path: %v \n", path)
	file, err := os.Open(path + "/cgroup.procs")
	if err != nil {
		fmt.Printf("ERROR - GetProcessFromCgroupPath - %v \n", err)
		return
	}
	defer file.Close()
	scanner := bufio.NewScanner(file)
	scanner.Split(bufio.ScanLines)
	for scanner.Scan() {
		err = scanner.Err()
		if err == nil {
			fmt.Printf("INFO - GetProcessFromCgroupPath - Container Pid: %v \n", scanner.Text())
			process = append(process, scanner.Text())
		}
	}
	return
}

func PpidOfContainer(tasksContainer []string)(ppidCOntainer string, err error){
	for _, task := range tasksContainer {
		ppid, err := getPPID(task)
		if err == nil {
			if isPpidContainer(ppid, tasksContainer) {
				fmt.Printf("INFO - isPpidContainer - Ppid of container: %v \n", task)
				return task, err
			}
		}
	}
	fmt.Printf("ERROR - PpidOfContainer- Not find Ppid in container with process: %v \n", tasksContainer)
	return "", errors.New("Not find Ppid")
}

func isPpidContainer(pid string, tasks []string)(bool){
	for _, task := range tasks {
		if pid == task {
			return false
		}
	}
	return true
}

func getPPID(task string)(ppid string, err error){
	file, err := os.Open(fmt.Sprintf("/proc/%s/stat", task))
	if err != nil {
		fmt.Printf("ERROR - getPPID - %v \n", err)
		return ppid, err
	}
	defer file.Close()
	data, err := ioutil.ReadAll(file)
	if err != nil {
		fmt.Printf("ERROR - getPPID - %v \n", err)
		return ppid, err
	}
	_, err = fmt.Fscan(bytes.NewBuffer(data),  &ppid, &ppid, &ppid, &ppid)
	fmt.Printf("INFO - getPPID - Ppid of task: %v PPid: %v \n", task, ppid)
	return ppid, err
}