package main

import (
	"github.com/emersion/go-imap/v2"
	"github.com/emersion/go-imap/v2/imapserver"
	"io"
)

type (
	user    = User
	mailbox = MailboxView
)

// UserSession represents a session tied to a specific user.
//
// UserSession implements imapserver.Session. Typically, a UserSession pointer
// is embedded into a larger struct which overrides Login.
type UserSession struct {
	*user    // immutable
	*mailbox // may be nil
}

var _ imapserver.SessionIMAP4rev2 = (*UserSession)(nil)

// NewUserSession creates a new user session.
func NewUserSession(user *User) *UserSession {
	return &UserSession{user: user}
}

type ByteLiteral struct {
	io.Reader
	size int64
}

func (l *ByteLiteral) Size() int64 {
	return l.size
}

func (sess *UserSession) Append(mboxName string, r imap.LiteralReader, options *imap.AppendOptions) (*imap.AppendData, error) {
	mbox, err := sess.user.mailbox(mboxName)
	if err != nil {
		return nil, err
	}
	view := mbox.NewView()
	defer func() {
		err := view.Close()
		if err != nil {
			log("Failed to close view: "+err.Error()+", resource leaks may occur", 1)
		}
	}()
	println("INITIAL APPEND ENTRYPOINT SUCCESS")
	return view.appendLiteral(&ByteLiteral{Reader: r, size: r.Size()}, options)
}

func (sess *UserSession) Close() error {
	if sess != nil && sess.mailbox != nil {
		return sess.mailbox.Close()
	}
	return nil
}

func (sess *UserSession) Select(name string, _ *imap.SelectOptions) (*imap.SelectData, error) {
	mbox, err := sess.user.mailbox(name)
	if err != nil {
		return nil, err
	}
	sess.mailbox = mbox.NewView()
	return mbox.selectData()
}

func (sess *UserSession) Unselect() error {
	err := sess.mailbox.Close()
	if err != nil {
		return err
	}
	sess.mailbox = nil
	return nil
}

func (sess *UserSession) Copy(numSet imap.NumSet, destName string) (data *imap.CopyData, fErr error) {
	dest, err := sess.user.mailbox(destName)
	if err != nil {
		return nil, &imap.Error{
			Type: imap.StatusResponseTypeNo,
			Code: imap.ResponseCodeTryCreate,
			Text: "No such mailbox",
		}
	} else if sess.mailbox != nil && dest == sess.mailbox.Mailbox {
		return nil, &imap.Error{
			Type: imap.StatusResponseTypeNo,
			Text: "Source and destination mailboxes are identical",
		}
	}

	destView := dest.NewView()
	defer func() {
		err := destView.Close()
		if err != nil {
			log("Failed to close view: "+err.Error()+", resource leaks may occur", 1)
		}
	}()

	var sourceUIDs, destUIDs imap.UIDSet
	err = sess.mailbox.forEach(numSet, func(seqNum uint32, msg *message) {
		appendData, err := destView.copyMsg(msg)
		if err != nil {
			fErr = err
			return
		}
		sourceUIDs.AddNum(msg.uid)
		destUIDs.AddNum(appendData.UID)
	})
	if err != nil {
		return nil, err
	}
	if fErr != nil {
		return nil, fErr
	}

	return &imap.CopyData{
		UIDValidity: dest.UIDValidity,
		SourceUIDs:  sourceUIDs,
		DestUIDs:    destUIDs,
	}, nil
}

func (sess *UserSession) Move(w *imapserver.MoveWriter, numSet imap.NumSet, destName string) (fErr error) {
	dest, err := sess.user.mailbox(destName)
	if err != nil {
		return &imap.Error{
			Type: imap.StatusResponseTypeNo,
			Code: imap.ResponseCodeTryCreate,
			Text: "No such mailbox",
		}
	} else if sess.mailbox != nil && dest == sess.mailbox.Mailbox {
		return &imap.Error{
			Type: imap.StatusResponseTypeNo,
			Text: "Source and destination mailboxes are identical",
		}
	}

	destView := dest.NewView()
	defer func() {
		err := destView.Close()
		if err != nil {
			log("Failed to close view: "+err.Error()+", resource leaks may occur", 1)
		}
	}()

	var sourceUIDs, destUIDs imap.UIDSet
	err = sess.mailbox.forEach(numSet, func(seqNum uint32, msg *message) {
		var appendData *imap.AppendData
		appendData, fErr = destView.copyMsg(msg)
		if fErr != nil {
			return
		}
		sourceUIDs.AddNum(msg.uid)
		destUIDs.AddNum(appendData.UID)
	})
	if err != nil {
		return err
	}
	if fErr != nil {
		return fErr
	}

	err = w.WriteCopyData(&imap.CopyData{
		UIDValidity: dest.UIDValidity,
		SourceUIDs:  sourceUIDs,
		DestUIDs:    destUIDs,
	})
	if err != nil {
		return err
	}

	println(sourceUIDs.String())
	err = sess.mailbox.Expunge(nil, &sourceUIDs)
	if err != nil {
		return err
	}

	return nil
}

func (sess *UserSession) Poll(w *imapserver.UpdateWriter, allowExpunge bool) error {
	if sess.mailbox == nil {
		return nil
	}
	return sess.mailbox.Poll(w, allowExpunge)
}

func (sess *UserSession) Idle(w *imapserver.UpdateWriter, stop <-chan struct{}) error {
	if sess.mailbox == nil {
		return nil // TODO
	}
	return sess.mailbox.Idle(w, stop)
}