package main

import (
	"bufio"
	"bytes"
	"flag"
	"io"
	"os"

	"github.com/golang/glog"
)

func writeMailderFile(b []byte) error { return nil }

func parse(r io.Reader, writeMessage func(b []byte) error) error {
	from := []byte("From ")
	scanner := bufio.NewScanner(r)
	buf := new(bytes.Buffer)
	for scanner.Scan() {
		b := scanner.Bytes()
		if bytes.HasPrefix(b, from) {
			// New message
			if buf.Len() > 0 {
				msg := buf.Bytes()
				// Trim empty line from end of mbox message
				msg = msg[:len(msg)-1]
				if err := writeMessage(msg); err != nil {
					return err
				}
			}
			buf.Reset()
		}
		buf.Write(b)
		buf.Write([]byte("\n"))
	}
	if buf.Len() > 0 {
		if err := writeMessage(buf.Bytes()); err != nil {
			return err
		}
	}
	return scanner.Err()
}

func parseFile(p string) error {
	r, err := os.Open(p)
	if err != nil {
		return err
	}
	defer r.Close()

	if err := parse(r, writeMailderFile); err != nil {
		return err
	}

	return nil
}
func main() {
	flag.Parse()
	defer glog.Flush()
	for _, path := range flag.Args() {
		if err := parseFile(path); err != nil {
			glog.Errorf("Failed to parse %q: %v", err)
		}
	}
}