//go:build notmuch
// +build notmuch

package notmuch

import (
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"

	"github.com/emersion/go-maildir"

	"git.sr.ht/~rjarry/aerc/lib/log"
	"git.sr.ht/~rjarry/aerc/lib/rfc822"
	"git.sr.ht/~rjarry/aerc/models"
	"git.sr.ht/~rjarry/aerc/worker/lib"
	notmuch "git.sr.ht/~rjarry/aerc/worker/notmuch/lib"
	"git.sr.ht/~rjarry/aerc/worker/types"
)

type Message struct {
	uid models.UID
	key string
	db  *notmuch.DB
}

// NewReader returns a reader for a message
func (m *Message) NewReader() (io.ReadCloser, error) {
	name, err := m.Filename()
	if err != nil {
		return nil, err
	}
	return os.Open(name)
}

// MessageInfo populates a models.MessageInfo struct for the message.
func (m *Message) MessageInfo() (*models.MessageInfo, error) {
	info, err := rfc822.MessageInfo(m)
	if err != nil {
		return nil, err
	}
	if filenames, err := m.db.MsgFilenames(m.key); err != nil {
		log.Errorf("failed to obtain filenames: %v", err)
	} else {
		info.Filenames = filenames
		// if size retrieval fails, just return info and log error
		if len(filenames) > 0 {
			if info.Size, err = lib.FileSize(filenames[0]); err != nil {
				log.Errorf("failed to obtain file size: %v", err)
			}
		}
	}
	return info, nil
}

// NewBodyPartReader creates a new io.Reader for the requested body part(s) of
// the message.
func (m *Message) NewBodyPartReader(requestedParts []int) (io.Reader, error) {
	name, err := m.Filename()
	if err != nil {
		return nil, err
	}
	f, err := os.Open(name)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	msg, err := rfc822.ReadMessage(f)
	if err != nil {
		return nil, fmt.Errorf("could not read message: %w", err)
	}
	return rfc822.FetchEntityPartReader(msg, requestedParts)
}

// SetFlag adds or removes a flag from the message.
// Notmuch doesn't support all the flags, and for those this errors.
func (m *Message) SetFlag(flag models.Flags, enable bool) error {
	// Translate the flag into a notmuch tag, ignoring no-op flags.
	tag, ok := flagToTag[flag]
	if !ok {
		return fmt.Errorf("Notmuch doesn't support flag %v", flag)
	}

	// Get the current state of the flag.
	// Note that notmuch handles some flags in an inverted sense
	oldState := false
	tags, err := m.Tags()
	if err != nil {
		return err
	}
	for _, t := range tags {
		if t == tag {
			oldState = true
			break
		}
	}

	if flagToInvert[flag] {
		enable = !enable
	}

	switch {
	case oldState == enable:
		return nil
	case enable:
		return m.AddTag(tag)
	default:
		return m.RemoveTag(tag)
	}
}

// MarkAnswered either adds or removes the "replied" tag from the message.
func (m *Message) MarkAnswered(answered bool) error {
	return m.SetFlag(models.AnsweredFlag, answered)
}

// MarkForwarded either adds or removes the "forwarded" tag from the message.
func (m *Message) MarkForwarded(forwarded bool) error {
	return m.SetFlag(models.ForwardedFlag, forwarded)
}

// MarkRead either adds or removes the maildir.FlagSeen flag from the message.
func (m *Message) MarkRead(seen bool) error {
	return m.SetFlag(models.SeenFlag, seen)
}

// tags returns the notmuch tags of a message
func (m *Message) Tags() ([]string, error) {
	return m.db.MsgTags(m.key)
}

func (m *Message) Labels() ([]string, error) {
	return m.Tags()
}

func (m *Message) ModelFlags() (models.Flags, error) {
	var flags models.Flags = models.SeenFlag
	tags, err := m.Tags()
	if err != nil {
		return 0, err
	}
	for _, tag := range tags {
		flag := tagToFlag[tag]
		if flagToInvert[flag] {
			flags &^= flag
		} else {
			flags |= flag
		}
	}
	return flags, nil
}

func (m *Message) UID() models.UID {
	return m.uid
}

func (m *Message) Filename() (string, error) {
	return m.db.MsgFilename(m.key)
}

// AddTag adds a single tag.
// Consider using *Message.ModifyTags for multiple additions / removals
// instead of looping over a tag array
func (m *Message) AddTag(tag string) error {
	return m.ModifyTags([]string{tag}, nil)
}

// RemoveTag removes a single tag.
// Consider using *Message.ModifyTags for multiple additions / removals
// instead of looping over a tag array
func (m *Message) RemoveTag(tag string) error {
	return m.ModifyTags(nil, []string{tag})
}

func (m *Message) ModifyTags(add, remove []string) error {
	return m.db.MsgModifyTags(m.key, add, remove)
}

func (m *Message) Remove(curDir maildir.Dir, mfs types.MultiFileStrategy) error {
	rm, del, err := m.filenamesForStrategy(mfs, curDir)
	if err != nil {
		return err
	}

	rm = append(rm, del...)
	return m.deleteFiles(rm)
}

func (m *Message) Copy(curDir, destDir maildir.Dir, mfs types.MultiFileStrategy) error {
	cp, del, err := m.filenamesForStrategy(mfs, curDir)
	if err != nil {
		return err
	}

	for _, filename := range cp {
		source, key := parseFilename(filename)
		if key == "" {
			return fmt.Errorf("failed to parse message filename: %s", filename)
		}

		newKey, err := source.Copy(destDir, key)
		if err != nil {
			return err
		}
		newFilename, err := destDir.Filename(newKey)
		if err != nil {
			return err
		}
		_, err = m.db.IndexFile(newFilename)
		if err != nil {
			return err
		}
	}

	return m.deleteFiles(del)
}

func (m *Message) Move(curDir, destDir maildir.Dir, mfs types.MultiFileStrategy) error {
	move, del, err := m.filenamesForStrategy(mfs, curDir)
	if err != nil {
		return err
	}

	for _, filename := range move {
		// Remove encoded UID information from the key to prevent sync issues
		name := lib.StripUIDFromMessageFilename(filepath.Base(filename))
		dest := filepath.Join(string(destDir), "cur", name)

		if err := os.Rename(filename, dest); err != nil {
			return err
		}

		if _, err = m.db.IndexFile(dest); err != nil {
			return err
		}

		if err := m.db.DeleteMessage(filename); err != nil {
			return err
		}
	}

	return m.deleteFiles(del)
}

func (m *Message) deleteFiles(filenames []string) error {
	for _, filename := range filenames {
		if err := os.Remove(filename); err != nil {
			return err
		}

		if err := m.db.DeleteMessage(filename); err != nil {
			return err
		}
	}

	return nil
}

func (m *Message) filenamesForStrategy(strategy types.MultiFileStrategy,
	curDir maildir.Dir,
) (act, del []string, err error) {
	filenames, err := m.db.MsgFilenames(m.key)
	if err != nil {
		return nil, nil, err
	}
	return filterForStrategy(filenames, strategy, curDir)
}

func filterForStrategy(filenames []string, strategy types.MultiFileStrategy,
	curDir maildir.Dir,
) (act, del []string, err error) {
	if curDir == "" &&
		(strategy == types.ActDir || strategy == types.ActDirDelRest) {
		strategy = types.Refuse
	}

	if len(filenames) < 2 {
		return filenames, []string{}, nil
	}

	act = []string{}
	rest := []string{}
	switch strategy {
	case types.Refuse:
		return nil, nil, fmt.Errorf("refusing to act on multiple files")
	case types.ActAll:
		act = filenames
	case types.ActOne:
		fallthrough
	case types.ActOneDelRest:
		act = filenames[:1]
		rest = filenames[1:]
	case types.ActDir:
		fallthrough
	case types.ActDirDelRest:
		for _, filename := range filenames {
			if filepath.Dir(filepath.Dir(filename)) == string(curDir) {
				act = append(act, filename)
			} else {
				rest = append(rest, filename)
			}
		}
	default:
		return nil, nil, fmt.Errorf("invalid multi-file strategy %v", strategy)
	}

	switch strategy {
	case types.ActOneDelRest:
		fallthrough
	case types.ActDirDelRest:
		del = rest
	default:
		del = []string{}
	}

	return act, del, nil
}

func parseFilename(filename string) (maildir.Dir, string) {
	base := filepath.Base(filename)
	dir := filepath.Dir(filename)
	dir, curdir := filepath.Split(dir)
	if curdir != "cur" {
		return "", ""
	}
	split := strings.Split(base, ":")
	if len(split) < 2 {
		return maildir.Dir(dir), ""
	}
	key := split[0]
	return maildir.Dir(dir), key
}