package maildir

import (
	"bufio"
	"fmt"
	"io"
	"mime"
	"net/mail"

	"github.com/emersion/go-maildir"
)

// A lot of this code was borrowed from aerc/worker/maildir/message.go

type Message struct {
	Dir maildir.Dir
	Key string
}

func (m Message) NewReader() (io.Reader, error) {
	f, err := m.Dir.Open(m.Key)
	if err != nil {
		return nil, err
	}
	return bufio.NewReader(f), nil
}

// Flags fetches the set of flags currently applied to the message.
func (m Message) Flags() ([]maildir.Flag, error) {
	return m.Dir.Flags(m.Key)
}

// SetFlags replaces the message's flags with a new set.
func (m Message) SetFlags(flags []maildir.Flag) error {
	return m.Dir.SetFlags(m.Key, flags)
}

// SetOneFlag enables or disables a single message flag on the message.
func (m Message) SetOneFlag(flag maildir.Flag, enable bool) error {
	flags, err := m.Flags()
	if err != nil {
		return fmt.Errorf("error: could not read previous flags: %v", err)
	}
	if enable {
		flags = append(flags, flag)
		return m.SetFlags(flags)
	}
	var newFlags []maildir.Flag
	for _, oldFlag := range flags {
		if oldFlag != flag {
			newFlags = append(newFlags, oldFlag)
		}
	}
	return m.SetFlags(newFlags)
}

// MarkReplied either adds or removes the maildir.FlagReplied flag from the
// message.
func (m Message) MarkReplied(answered bool) error {
	return m.SetOneFlag(maildir.FlagReplied, answered)
}

// Remove deletes the email immediately.
func (m Message) Remove() error {
	return m.Dir.Remove(m.Key)
}

func decodeMime(str string) (string, error) {
	dec := new(mime.WordDecoder)
	return dec.DecodeHeader(str)
}

func (m Message) GetHeader(h string) (string, error) {
	r, err := m.NewReader()
	msg, err := mail.ReadMessage(r)
	if err != nil {
		return "", err
	}

	decodedHeader, err := decodeMime(msg.Header.Get(h))
	return decodedHeader, err
}