handlemail.go

package main

import (
	"bufio"
	"bytes"
	"io"
	"os"
	"strings"
)

var (
	pattern = []byte{'-', '-', ' '}
)

func errExit(err error) {
	if err != nil {
		panic(err)
	}
}

func reCreate(arg string, byts []byte) {
	f, err := os.Create(arg)
	defer f.Close()
	errExit(err)
	bffw := bufio.NewWriter(f)
	bffw.Write(byts[:len(byts)])
	bffw.Flush()

}

func readMail(arg string) (bs []byte, needSync bool) {
	f, err := os.Open(arg)
	defer f.Close()
	errExit(err)
	bufr := bufio.NewReader(f)
	bffbyts := bytes.Buffer{}
	bffbyts.ReadFrom(bufr)
	bs = make([]byte, 0)
	var prefix []byte
	for {
		l, err := bffbyts.ReadBytes(byte('\n'))
		if err == io.EOF {
			return
		}
		bs = append(bs, l...)
		if len(l) == 1 && l[0] == '\n' {
			break
		}
	}
	for {
		l, err := bffbyts.ReadBytes(byte('\n'))
		if err == io.EOF {
			break
		}
		if len(l) > 3 {
			prefix = l[:3]
			if bytes.Equal(prefix, pattern) {
				needSync = true
				break

			} else {
				bs = append(bs, l...)
			}

		} else {
			bs = append(bs, l...)
		}

	}

	return

}

func handleMail(arg string) {
	bs, needSync := readMail(arg)
	if needSync {
		reCreate(arg, bs)
	}

}

func main() {
	args := os.Args
	args = args[1:]
	pwd := os.Getenv("PWD") + "/"
	for _, arg := range args {
		if !strings.HasPrefix(arg, "/") {
			arg = pwd + arg
		}
		handleMail(arg)
	}

}