package store

import (
	"errors"
	"net/mail"
	"os"
	"path/filepath"

	"github.com/luksen/maildir"

	"ur.gs/crockery/internal/imap/uidlist"
)

type MaildirInterface interface {
	CreateMaildir(*Maildir) error
	FindMaildir(account Account, name string) (Maildir, error)
	FindMaildirs(account Account) ([]Maildir, error)
	FindMessagesInRange(m Maildir, start, end uint64) ([]Message, error)
}

type Maildir struct {
	Account Account
	Name    string

	directory string

	filesystem maildir.Dir
	uids       *uidlist.List
}

func (m *Maildir) Rel() string {
	return filepath.Join(m.Account.Username, m.Name)
}

func (m *Maildir) Directory() string {
	return m.directory
}

func (m *Maildir) Header(key string) (mail.Header, error) {
	return m.filesystem.Header(key)
}

func (c *concrete) CreateMaildir(m *Maildir) error {
	if m.directory == "" {
		m.directory = c.buildMaildirPath(m.Account, m.Name)
	}

	if string(m.filesystem) == "" {
		m.filesystem = maildir.Dir(m.directory)
	}

	err := m.filesystem.Create()
	if err != nil {
		return err
	}

	if m.uids == nil {
		uids, err := uidlist.Create(m.directory)
		if err != nil {
			// FIXME: this leaves a dangling Maildir
			return err
		}

		m.uids = uids
	}

	return nil
}

func (c *concrete) FindMaildir(account Account, name string) (Maildir, error) {
	// FIXME: multiple IMAP sessions get different Maildir instances, so breaking
	// any hope at locking (sigh)
	m := Maildir{
		Account:   account,
		Name:      name,
		directory: c.buildMaildirPath(account, name),
	}
	m.filesystem = maildir.Dir(m.directory)

	if _, err := os.Stat(m.Directory()); os.IsNotExist(err) {
		return Maildir{}, errors.New("not found")
	}

	uids, err := uidlist.Open(m.directory)
	if err != nil {
		return Maildir{}, err
	}
	m.uids = uids

	return m, nil
}

func (c *concrete) FindMaildirs(account Account) ([]Maildir, error) {
	// TODO: iterate through the maildir looking for submaildirs
	defaultMaildir, err := c.FindMaildir(account, "")
	if err != nil {
		return nil, err
	}

	return []Maildir{defaultMaildir}, nil
}

func (c *concrete) buildMaildirPath(account Account, parts ...string) string {
	bits := append([]string{BuildMailboxesPath(c.home), account.Username}, parts...)

	return filepath.Join(bits...)
}

func (c *concrete) FindMessagesInRange(m Maildir, start, end uint64) ([]Message, error) {
	var out []Message
	entries := m.uids.EntriesInRange(start, end)

	for _, entry := range entries {
		msg := Message{
			UID:     entry.UID,
			Maildir: m,
			Key:     entry.Key(),
		}

		out = append(out, msg)
	}

	return out, nil
}