package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"os"
	"path/filepath"

	"xinu.tv/email"

	"github.com/golang/glog"
)

var (
	saveFile = flag.String("save", "", "filename to store unread status.")
	loadFile = flag.String("load", "", "filename to load unread status.")
	maildir  = flag.String("maildir", "", "Maildir root")
)

type Status struct {
	Hash   string `json:"hash"`
	Path   string `json:"path,omitempthashy"`
	Unread bool   `json:"unread,omitempty"`
}

type Messages []Status

func (m *Messages) hashMail(path string, info os.FileInfo, err error) error {
	if info.IsDir() {
		return nil
	}
	r, err := os.Open(path)
	if err != nil {
		glog.Fatal(err)
	}
	headers := []string{"to", "from", "cc", "date", "subject"}
	h, err := email.Hash(r, headers)
	if err != nil {
		glog.Errorln(path, err)
		return nil
	}
	md := email.NewInfo(path)
	//fmt.Printf("%x %s\n", h.Sum(nil), path)
	*m = append(*m, Status{
		Path:   path,
		Hash:   fmt.Sprintf("%x", h.Sum(nil)),
		Unread: !md.Seen,
	})
	return nil
}

func (m *Messages) SaveStatus(maildir, saveFile string) error {
	if err := filepath.Walk(maildir, m.hashMail); err != nil {
		return err
	}

	b, err := json.MarshalIndent(m, "", "  ")
	if err != nil {
		return err
	}

	f, err := os.Create(saveFile)
	if err != nil {
		return err
	}
	defer f.Close()

	n, err := f.Write(b)
	if err != nil {
		return err
	}
	if n != len(b) {
		return fmt.Errorf("Short write of save status: wrote %d of %d", n,
			len(b))
	}
	return nil
}

func main() {
	defer glog.Flush()
	flag.Parse()
	m := Messages{}

	if *maildir == "" {
		glog.Fatal("Must specify Maildir with -maildir")
	}

	if *saveFile != "" {
		if err := m.SaveStatus(*maildir, *saveFile); err != nil {
			glog.Fatal(err)
		}
	}
}