package debug

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
	"strings"
)

// Smaps prints the smaps to a file
func Smaps(note, file string) error {
	smaps, err := getMaps(os.Getpid())
	if err != nil {
		return err
	}
	f, err := os.OpenFile(file, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
	if err != nil {
		return err
	}
	defer f.Close()
	fmt.Fprintf(f, "%s: rss %d\n", note, smaps["rss"])
	fmt.Fprintf(f, "%s: pss %d\n", note, smaps["pss"])
	return nil
}

func getMaps(pid int) (map[string]int, error) {
	f, err := os.Open(fmt.Sprintf("/proc/%d/smaps", pid))
	if err != nil {
		return nil, err
	}
	defer f.Close()
	var (
		smaps = make(map[string]int)
		s     = bufio.NewScanner(f)
	)
	for s.Scan() {
		var (
			fields = strings.Fields(s.Text())
			name   = fields[0]
		)
		name = strings.TrimSuffix(strings.ToLower(name), ":")
		if len(fields) < 2 {
			continue
		}
		n, err := strconv.Atoi(fields[1])
		if err != nil {
			continue
		}
		smaps[name] += n
	}
	if err := s.Err(); err != nil {
		return nil, err
	}
	return smaps, nil
}

func keys(smaps map[string]int) []string {
	var o []string
	for k := range smaps {
		o = append(o, k)
	}
	sort.Strings(o)
	return o
}