package appstate

import (
	"errors"
	"fmt"
	"slices"
	"strings"
	"time"

	"git.julianfamily.org/keepassgo/internal/apiapproval"
	"git.julianfamily.org/keepassgo/internal/apiaudit"
	"git.julianfamily.org/keepassgo/internal/apitokens"
	"git.julianfamily.org/keepassgo/internal/vault"
	"git.julianfamily.org/keepassgo/internal/vaultview"
	"git.julianfamily.org/keepassgo/internal/webdav"
)

type Section string

var (
	ErrAttachmentAlreadyExists = errors.New("attachment already exists")
	ErrAttachmentNotFound      = errors.New("attachment not found")
)

const (
	SectionEntries    Section = ""
	SectionTemplates  Section = "templates"
	SectionRecycleBin Section = "recycle-bin"
	SectionAPITokens  Section = "api-tokens"
	SectionAPIAudit   Section = "api-audit"
	SectionAbout      Section = "about"
)

const entriesRootLabel = "Root"
const templatesRootLabel = "Templates"

type CurrentSession interface {
	Current() (vault.Model, error)
}

type MutableSession interface {
	CurrentSession
	Replace(vault.Model)
}

type LockableSession interface {
	CurrentSession
	Lock() error
	Unlock(vault.MasterKey) error
}

type MasterKeyChangeableSession interface {
	CurrentSession
	ChangeMasterKey(vault.MasterKey) error
}

type SaveableSession interface {
	CurrentSession
	Save() error
}

type AutoSaveableSession interface {
	SaveableSession
	HasSaveTarget() bool
}

type RemoteAwareSession interface {
	IsRemote() bool
}

type SynchronizableSession interface {
	CurrentSession
	Synchronize() error
}

type AdvancedSynchronizableSession interface {
	CurrentSession
	SynchronizeFromLocal(string) error
	SynchronizeFromLocalBytes(string, []byte) error
	SynchronizeToLocal(string) error
	SynchronizeFromRemote(webdav.Client, string) error
	SynchronizeToRemote(webdav.Client, string) error
}

type CreateableSession interface {
	CurrentSession
	Create(vault.Model, vault.MasterKey) error
}

type OpenableSession interface {
	CurrentSession
	Open(string, vault.MasterKey) error
}

type SaveAsSession interface {
	CurrentSession
	SaveAs(string) error
}

type RemoteOpenableSession interface {
	CurrentSession
	OpenRemote(webdav.Client, string, vault.MasterKey) error
}

type WarningSession interface {
	ConsumeWarning() string
}

type SecurityConfigurableSession interface {
	ConfigureSecurity(vault.SecuritySettings) error
	SecuritySettings() vault.SecuritySettings
}

type ApprovalManager interface {
	Pending() []apiapproval.Request
	Resolve(string, apiapproval.Outcome) (apiapproval.Request, *apitokens.PolicyRule, error)
}

type State struct {
	Session         CurrentSession
	Approvals       ApprovalManager
	AuditLog        *apiaudit.Log
	AutoSaveRemote  bool
	Section         Section
	CurrentPath     []string
	SearchQuery     string
	SelectedEntryID string
	Dirty           bool
	StatusMessage   string
	ErrorMessage    string
}

func (s *State) PendingApprovals() []apiapproval.Request {
	if s.Approvals == nil {
		return nil
	}
	return s.Approvals.Pending()
}

func (s *State) ResolveApproval(id string, outcome apiapproval.Outcome) error {
	if s.Approvals == nil {
		return fmt.Errorf("approval manager is not configured")
	}
	_, _, err := s.Approvals.Resolve(id, outcome)
	return err
}

func (s *State) APITokens() ([]apitokens.Token, error) {
	model, err := s.currentModel()
	if err != nil {
		return nil, err
	}
	return apitokens.Entries(model)
}

func (s *State) RemoteProfiles() ([]vault.RemoteProfile, error) {
	model, err := s.currentModel()
	if err != nil {
		return nil, err
	}
	profiles := slices.Clone(model.RemoteProfiles)
	slices.SortFunc(profiles, func(a, b vault.RemoteProfile) int {
		switch {
		case a.Name < b.Name:
			return -1
		case a.Name > b.Name:
			return 1
		case a.ID < b.ID:
			return -1
		case a.ID > b.ID:
			return 1
		default:
			return 0
		}
	})
	return profiles, nil
}

func (s *State) RemoteCredentialEntries() ([]vault.Entry, error) {
	model, err := s.currentModel()
	if err != nil {
		return nil, err
	}
	entries := slices.Clone(model.Entries)
	slices.SortFunc(entries, func(a, b vault.Entry) int {
		switch {
		case a.Title < b.Title:
			return -1
		case a.Title > b.Title:
			return 1
		case a.ID < b.ID:
			return -1
		case a.ID > b.ID:
			return 1
		default:
			return 0
		}
	})
	return entries, nil
}

func (s *State) IssueAPIToken(name, clientName string, expiresAt *time.Time, now time.Time) (apitokens.Token, string, error) {
	result, err := s.mutateAPITokens(apiaudit.EventTokenIssued, "issued API token", func(model *vault.Model) (tokenMutationResult, error) {
		token, secret, err := apitokens.Issue(name, clientName, expiresAt, now)
		if err != nil {
			return tokenMutationResult{}, err
		}
		apitokens.Upsert(model, token)
		return tokenMutationResult{token: token, secret: secret}, nil
	})
	if err != nil {
		return apitokens.Token{}, "", err
	}
	return result.token, result.secret, nil
}

func (s *State) RotateAPIToken(id string, now time.Time) (apitokens.Token, string, error) {
	result, err := s.mutateAPITokens(apiaudit.EventTokenRotated, "rotated API token", func(model *vault.Model) (tokenMutationResult, error) {
		token, err := apitokens.Find(*model, id)
		if err != nil {
			return tokenMutationResult{}, err
		}
		token, secret, err := apitokens.Rotate(token, now)
		if err != nil {
			return tokenMutationResult{}, err
		}
		apitokens.Upsert(model, token)
		return tokenMutationResult{token: token, secret: secret}, nil
	})
	if err != nil {
		return apitokens.Token{}, "", err
	}
	return result.token, result.secret, nil
}

func (s *State) UpsertAPIToken(token apitokens.Token) error {
	_, err := s.mutateAPITokens(apiaudit.EventTokenUpdated, "updated API token", func(model *vault.Model) (tokenMutationResult, error) {
		apitokens.Upsert(model, token)
		return tokenMutationResult{token: token}, nil
	})
	return err
}

func (s *State) DisableAPIToken(id string) error {
	_, err := s.mutateAPITokens(apiaudit.EventTokenDisabled, "disabled API token", func(model *vault.Model) (tokenMutationResult, error) {
		token, err := apitokens.Find(*model, id)
		if err != nil {
			return tokenMutationResult{}, err
		}
		token = apitokens.Disable(token)
		apitokens.Upsert(model, token)
		return tokenMutationResult{token: token}, nil
	})
	return err
}

func (s *State) RevokeAPIToken(id string, when time.Time) error {
	_, err := s.mutateAPITokens(apiaudit.EventTokenRevoked, "revoked API token", func(model *vault.Model) (tokenMutationResult, error) {
		token, err := apitokens.Find(*model, id)
		if err != nil {
			return tokenMutationResult{}, err
		}
		token = apitokens.Revoke(token, when)
		apitokens.Upsert(model, token)
		return tokenMutationResult{token: token}, nil
	})
	return err
}

func (s *State) DeleteAPIToken(id string) error {
	_, err := s.mutateAPITokens(apiaudit.EventTokenDeleted, "deleted API token", func(model *vault.Model) (tokenMutationResult, error) {
		token, err := apitokens.Find(*model, id)
		if err != nil {
			return tokenMutationResult{}, err
		}
		if err := apitokens.Delete(model, id); err != nil {
			return tokenMutationResult{}, err
		}
		return tokenMutationResult{token: token}, nil
	})
	return err
}

type tokenMutationResult struct {
	token  apitokens.Token
	secret string
}

func (s *State) mutateAPITokens(eventType apiaudit.EventType, message string, mutate func(*vault.Model) (tokenMutationResult, error)) (tokenMutationResult, error) {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return tokenMutationResult{}, fmt.Errorf("session is not mutable")
	}
	model, err := session.Current()
	if err != nil {
		return tokenMutationResult{}, err
	}
	result, err := mutate(&model)
	if err != nil {
		return tokenMutationResult{}, err
	}
	session.Replace(model)
	if err := s.markDirtyAndAutoSave(); err != nil {
		return tokenMutationResult{}, err
	}
	s.recordTokenAudit(eventType, result.token, message)
	return result, nil
}

func (s *State) recordTokenAudit(eventType apiaudit.EventType, token apitokens.Token, message string) {
	if s.AuditLog == nil {
		return
	}
	s.AuditLog.Record(apiaudit.Event{
		Type:       eventType,
		TokenID:    token.ID,
		TokenName:  token.Name,
		ClientName: token.ClientName,
		Resource: apitokens.Resource{
			Kind:    apitokens.ResourceEntry,
			Path:    apitokens.EntryPath,
			EntryID: token.ID,
		},
		Message: message,
	})
}

func (s *State) SecuritySettings() (vault.SecuritySettings, error) {
	security, ok := s.Session.(SecurityConfigurableSession)
	if !ok {
		return vault.SecuritySettings{}, fmt.Errorf("session does not expose security settings")
	}
	return security.SecuritySettings(), nil
}

func (s *State) ConfigureSecurity(settings vault.SecuritySettings) error {
	security, ok := s.Session.(SecurityConfigurableSession)
	if !ok {
		return fmt.Errorf("session does not expose security settings")
	}
	if err := security.ConfigureSecurity(settings); err != nil {
		return err
	}
	return s.markDirtyAndAutoSave()
}

func (s *State) ShowSection(section Section) {
	s.Section = section
	s.CurrentPath = nil
	s.SelectedEntryID = ""
}

func (s *State) SetSearchQuery(query string) {
	s.SearchQuery = query
}

func (s *State) BeginNewEntry() {
	s.SelectedEntryID = ""
	s.StatusMessage = ""
	s.ErrorMessage = ""
}

func (s *State) SetActionResult(label string, err error) {
	if err != nil {
		s.ErrorMessage = err.Error()
		s.StatusMessage = ""
		return
	}

	s.ErrorMessage = ""
	s.StatusMessage = label + " complete"
}

func (s *State) VisibleEntries() ([]vault.Entry, error) {
	model, err := s.currentModel()
	if err != nil {
		return nil, err
	}

	entries := s.entriesForSection(model)
	if strings.TrimSpace(s.SearchQuery) != "" {
		return filterEntries(entries, s.SearchQuery), nil
	}

	if s.Section == SectionEntries {
		return entriesInPath(entries, logicalEntriesPathForModel(model, s.CurrentPath)), nil
	}
	if s.Section == SectionRecycleBin || len(s.CurrentPath) == 0 {
		return entries, nil
	}

	return entriesInPath(entries, s.CurrentPath), nil
}

func (s *State) ChildGroups() ([]string, error) {
	if strings.TrimSpace(s.SearchQuery) != "" {
		return nil, nil
	}

	model, err := s.currentModel()
	if err != nil {
		return nil, err
	}

	if s.Section != SectionEntries {
		if s.Section == SectionTemplates {
			return vaultview.VaultTemplates(model).ChildGroups(templatesViewPath(s.CurrentPath)), nil
		}
		return childGroups(s.entriesForSection(model), s.CurrentPath), nil
	}

	return vaultview.VaultRoot(model).ChildGroups(entriesViewPathForModel(model, s.CurrentPath)), nil
}

func (s *State) SelectVisibleIndex(index int) error {
	entries, err := s.VisibleEntries()
	if err != nil {
		return err
	}
	if index < 0 || index >= len(entries) {
		return fmt.Errorf("visible index %d out of range", index)
	}

	s.SelectedEntryID = entries[index].ID
	return nil
}

func (s *State) ToggleVisibleIndex(index int) error {
	entries, err := s.VisibleEntries()
	if err != nil {
		return err
	}
	if index < 0 || index >= len(entries) {
		return fmt.Errorf("visible index %d out of range", index)
	}

	if s.SelectedEntryID == entries[index].ID {
		s.SelectedEntryID = ""
		return nil
	}

	s.SelectedEntryID = entries[index].ID
	return nil
}

func (s *State) currentModel() (vault.Model, error) {
	if s.Session == nil {
		return vault.Model{}, nil
	}
	return s.Session.Current()
}

func (s *State) entriesForSection(model vault.Model) []vault.Entry {
	switch s.Section {
	case SectionTemplates:
		return logicalTemplateEntries(vaultview.VaultTemplates(model).EntriesUnderPath(nil))
	case SectionRecycleBin:
		return logicalEntries(vaultview.VaultRecycleBin(model).EntriesUnderPath(nil))
	case SectionAPITokens, SectionAPIAudit, SectionAbout:
		return nil
	default:
		return logicalEntries(vaultview.VaultRoot(model).EntriesUnderPath(nil))
	}
}

func (s State) SearchPathContext(entry vault.Entry) string {
	path := slices.Clone(entry.Path)
	switch s.Section {
	case SectionTemplates:
		path = logicalTemplatePath(path)
	case SectionRecycleBin:
		path = append([]string{"Recycle Bin"}, logicalEntriesPath(path)...)
	case SectionEntries:
		path = logicalEntriesPath(path)
	}
	return strings.Join(path, " / ")
}

func entriesInPath(entries []vault.Entry, path []string) []vault.Entry {
	var out []vault.Entry
	for _, entry := range entries {
		if slices.Equal(entry.Path, path) {
			out = append(out, entry)
		}
	}
	slices.SortFunc(out, func(a, b vault.Entry) int {
		switch {
		case a.Title < b.Title:
			return -1
		case a.Title > b.Title:
			return 1
		default:
			return 0
		}
	})
	return out
}

func filterEntries(entries []vault.Entry, query string) []vault.Entry {
	query = strings.TrimSpace(strings.ToLower(query))
	if query == "" {
		return nil
	}

	var out []vault.Entry
	for _, entry := range entries {
		haystack := strings.ToLower(
			entry.Title + " " +
				entry.Username + " " +
				entry.URL + " " +
				strings.Join(entry.Path, " "),
		)
		if !strings.Contains(haystack, query) {
			continue
		}
		out = append(out, entry)
	}
	slices.SortFunc(out, func(a, b vault.Entry) int {
		switch {
		case a.Title < b.Title:
			return -1
		case a.Title > b.Title:
			return 1
		default:
			return 0
		}
	})
	return out
}

func logicalEntriesPathForModel(model vault.Model, path []string) []string {
	if len(path) == 0 {
		return []string{entriesRootLabel}
	}
	if path[0] == entriesRootLabel {
		return append([]string(nil), path...)
	}
	if usesPhysicalEntriesRoot(model) && path[0] == vaultview.KeepassRoot {
		path = path[1:]
	}
	return append([]string{entriesRootLabel}, append([]string(nil), path...)...)
}

func logicalEntriesPath(path []string) []string {
	if len(path) == 0 {
		return []string{entriesRootLabel}
	}
	if path[0] == entriesRootLabel {
		return append([]string(nil), path...)
	}
	if path[0] == vaultview.KeepassRoot {
		path = path[1:]
	}
	return append([]string{entriesRootLabel}, append([]string(nil), path...)...)
}

func logicalTemplatePath(path []string) []string {
	if len(path) == 0 {
		return []string{templatesRootLabel}
	}
	if path[0] == templatesRootLabel {
		return append([]string(nil), path...)
	}
	return append([]string{templatesRootLabel}, append([]string(nil), path...)...)
}

func templatesViewPath(path []string) []string {
	if len(path) == 0 {
		return nil
	}
	if path[0] == templatesRootLabel {
		return append([]string(nil), path[1:]...)
	}
	return append([]string(nil), path...)
}

func entriesViewPathForModel(model vault.Model, path []string) []string {
	if len(path) == 0 {
		return nil
	}
	switch {
	case usesPhysicalEntriesRoot(model) && path[0] == entriesRootLabel:
		return append([]string(nil), path[1:]...)
	case usesLogicalEntriesRoot(model):
		return append([]string(nil), path...)
	case path[0] == entriesRootLabel:
		return append([]string(nil), path[1:]...)
	default:
		return append([]string(nil), path...)
	}
}

func logicalEntry(entry vault.Entry) vault.Entry {
	entry.Path = logicalEntriesPath(entry.Path)
	for i := range entry.History {
		entry.History[i] = logicalEntry(entry.History[i])
	}
	return entry
}

func logicalEntries(entries []vault.Entry) []vault.Entry {
	if len(entries) == 0 {
		return nil
	}
	out := make([]vault.Entry, len(entries))
	for i := range entries {
		out[i] = logicalEntry(entries[i])
	}
	return out
}

func logicalTemplateEntry(entry vault.Entry) vault.Entry {
	entry.Path = logicalTemplatePath(entry.Path)
	for i := range entry.History {
		entry.History[i] = logicalTemplateEntry(entry.History[i])
	}
	return entry
}

func logicalTemplateEntries(entries []vault.Entry) []vault.Entry {
	if len(entries) == 0 {
		return nil
	}
	out := make([]vault.Entry, len(entries))
	for i := range entries {
		out[i] = logicalTemplateEntry(entries[i])
	}
	return out
}

func entryForModel(model vault.Model, entry vault.Entry) vault.Entry {
	entry.Path = entriesViewPathForModel(model, entry.Path)
	for i := range entry.History {
		entry.History[i] = entryForModel(model, entry.History[i])
	}
	return entry
}

func templateEntryForModel(entry vault.Entry) vault.Entry {
	entry.Path = templatesViewPath(entry.Path)
	for i := range entry.History {
		entry.History[i] = templateEntryForModel(entry.History[i])
	}
	return entry
}

func usesPhysicalEntriesRoot(model vault.Model) bool {
	if len(model.Entries) == 0 && len(model.Groups) == 0 && len(model.RecycleBin) == 0 {
		return true
	}
	for _, group := range model.Groups {
		if len(group) > 0 && group[0] == vaultview.KeepassRoot {
			return true
		}
	}
	for _, entry := range model.Entries {
		if len(entry.Path) > 0 && entry.Path[0] == vaultview.KeepassRoot {
			return true
		}
	}
	for _, entry := range model.RecycleBin {
		if len(entry.Path) > 0 && entry.Path[0] == vaultview.KeepassRoot {
			return true
		}
	}
	return false
}

func usesLogicalEntriesRoot(model vault.Model) bool {
	for _, group := range model.Groups {
		if len(group) > 0 && group[0] == entriesRootLabel {
			return true
		}
	}
	for _, entry := range model.Entries {
		if len(entry.Path) > 0 && entry.Path[0] == entriesRootLabel {
			return true
		}
	}
	for _, entry := range model.RecycleBin {
		if len(entry.Path) > 0 && entry.Path[0] == entriesRootLabel {
			return true
		}
	}
	return false
}

func childGroups(entries []vault.Entry, path []string) []string {
	seen := map[string]bool{}
	var groups []string
	for _, entry := range entries {
		if len(path) > len(entry.Path) {
			continue
		}
		if !slices.Equal(entry.Path[:len(path)], path) {
			continue
		}
		if len(entry.Path) == len(path) {
			continue
		}
		group := entry.Path[len(path)]
		if seen[group] {
			continue
		}
		seen[group] = true
		groups = append(groups, group)
	}
	slices.Sort(groups)
	return groups
}

func sectionGroupView(model vault.Model, section Section) vaultview.View {
	switch section {
	case SectionTemplates:
		return vaultview.VaultTemplates(model)
	default:
		return vaultview.VaultRoot(model)
	}
}

func sectionGroupViewPath(model vault.Model, section Section, path []string) []string {
	switch section {
	case SectionTemplates:
		return templatesViewPath(path)
	default:
		return entriesViewPathForModel(model, path)
	}
}

func sectionGroupLogicalPath(model vault.Model, section Section, path []string) []string {
	switch section {
	case SectionTemplates:
		return logicalTemplatePath(path)
	default:
		return logicalEntriesPathForModel(model, path)
	}
}

func (s *State) DeleteSelectedEntry() error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	if err := model.DeleteEntry(s.SelectedEntryID); err != nil {
		return err
	}

	session.Replace(model)
	s.SelectedEntryID = ""
	return s.markDirtyAndAutoSave()
}

func (s *State) RestoreEntry(id string) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	if err := model.RestoreEntry(id); err != nil {
		return err
	}

	session.Replace(model)
	return s.markDirtyAndAutoSave()
}

func (s *State) UpsertEntry(entry vault.Entry) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	model.UpsertEntry(vaultview.VaultRoot(model).ToPhysicalEntry(entryForModel(model, entry)))
	session.Replace(model)
	s.SelectedEntryID = entry.ID
	return s.markDirtyAndAutoSave()
}

func (s *State) UpsertTemplate(entry vault.Entry) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	model.UpsertTemplate(vaultview.VaultTemplates(model).ToPhysicalEntry(templateEntryForModel(entry)))
	session.Replace(model)
	s.SelectedEntryID = entry.ID
	return s.markDirtyAndAutoSave()
}

func (s *State) InstantiateTemplate(templateID string, overrides vault.Entry) (vault.Entry, error) {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return vault.Entry{}, fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return vault.Entry{}, err
	}

	entry, err := model.InstantiateTemplate(templateID, vaultview.VaultRoot(model).ToPhysicalEntry(entryForModel(model, overrides)))
	if err != nil {
		return vault.Entry{}, err
	}

	session.Replace(model)
	s.SelectedEntryID = entry.ID
	if err := s.markDirtyAndAutoSave(); err != nil {
		return vault.Entry{}, err
	}
	return logicalEntry(entry), nil
}

func (s *State) DeleteTemplate(id string) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	if err := model.DeleteTemplate(id); err != nil {
		return err
	}

	session.Replace(model)
	if s.SelectedEntryID == id {
		s.SelectedEntryID = ""
	}
	return s.markDirtyAndAutoSave()
}

func (s *State) DuplicateSelectedEntry(duplicateID string) (vault.Entry, error) {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return vault.Entry{}, fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return vault.Entry{}, err
	}

	duplicate, err := model.DuplicateEntry(s.SelectedEntryID, duplicateID)
	if err != nil {
		return vault.Entry{}, err
	}

	session.Replace(model)
	s.SelectedEntryID = duplicate.ID
	if err := s.markDirtyAndAutoSave(); err != nil {
		return vault.Entry{}, err
	}
	return duplicate, nil
}

func (s *State) RestoreSelectedEntryVersion(historyIndex int) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	if err := model.RestoreEntryVersion(s.SelectedEntryID, historyIndex); err != nil {
		return err
	}

	session.Replace(model)
	return s.markDirtyAndAutoSave()
}

func (s *State) Lock() error {
	session, ok := s.Session.(LockableSession)
	if !ok {
		return fmt.Errorf("session is not lockable")
	}

	if err := session.Lock(); err != nil {
		return err
	}

	s.SelectedEntryID = ""
	return nil
}

func (s *State) Unlock(key vault.MasterKey) error {
	session, ok := s.Session.(LockableSession)
	if !ok {
		return fmt.Errorf("session is not lockable")
	}

	if err := session.Unlock(key); err != nil {
		return err
	}
	if warningSession, ok := s.Session.(WarningSession); ok {
		s.StatusMessage = warningSession.ConsumeWarning()
	}
	return nil
}

func (s *State) ChangeMasterKey(key vault.MasterKey) error {
	session, ok := s.Session.(MasterKeyChangeableSession)
	if !ok {
		return fmt.Errorf("session does not support master key changes")
	}

	if err := session.ChangeMasterKey(key); err != nil {
		return err
	}

	return s.markDirtyAndAutoSave()
}

func (s *State) EnterGroup(name string) {
	s.CurrentPath = append(append([]string(nil), s.CurrentPath...), name)
	s.SelectedEntryID = ""
}

func (s *State) NavigateToPath(path []string) {
	s.CurrentPath = append([]string(nil), path...)
	s.SelectedEntryID = ""
}

func (s *State) Save() error {
	session, ok := s.Session.(SaveableSession)
	if !ok {
		return fmt.Errorf("session is not saveable")
	}

	if err := session.Save(); err != nil {
		return err
	}

	s.Dirty = false
	return nil
}

func (s *State) markDirtyAndAutoSave() error {
	s.Dirty = true
	session, ok := s.Session.(SaveableSession)
	if !ok {
		return nil
	}
	if autosave, ok := s.Session.(AutoSaveableSession); ok && !autosave.HasSaveTarget() {
		return nil
	}
	if remote, ok := s.Session.(RemoteAwareSession); ok && remote.IsRemote() && !s.AutoSaveRemote {
		return nil
	}
	if err := session.Save(); err != nil {
		return err
	}
	s.Dirty = false
	return nil
}

func (s *State) Synchronize() error {
	session, ok := s.Session.(SynchronizableSession)
	if !ok {
		return fmt.Errorf("session is not synchronizable")
	}

	if err := session.Synchronize(); err != nil {
		return err
	}

	s.Dirty = false
	return nil
}

func (s *State) SynchronizeFromLocal(path string) error {
	session, ok := s.Session.(AdvancedSynchronizableSession)
	if !ok {
		return fmt.Errorf("session is not advanced-synchronizable")
	}
	if err := session.SynchronizeFromLocal(path); err != nil {
		return err
	}
	s.Dirty = false
	return nil
}

func (s *State) SynchronizeFromLocalBytes(name string, content []byte) error {
	session, ok := s.Session.(AdvancedSynchronizableSession)
	if !ok {
		return fmt.Errorf("session is not advanced-synchronizable")
	}
	if err := session.SynchronizeFromLocalBytes(name, content); err != nil {
		return err
	}
	s.Dirty = false
	return nil
}

func (s *State) SynchronizeToLocal(path string) error {
	session, ok := s.Session.(AdvancedSynchronizableSession)
	if !ok {
		return fmt.Errorf("session is not advanced-synchronizable")
	}
	if err := session.SynchronizeToLocal(path); err != nil {
		return err
	}
	s.Dirty = true
	return nil
}

func (s *State) SynchronizeFromRemote(client webdav.Client, path string) error {
	session, ok := s.Session.(AdvancedSynchronizableSession)
	if !ok {
		return fmt.Errorf("session is not advanced-synchronizable")
	}
	if err := session.SynchronizeFromRemote(client, path); err != nil {
		return err
	}
	s.Dirty = false
	return nil
}

func (s *State) SynchronizeToRemote(client webdav.Client, path string) error {
	session, ok := s.Session.(AdvancedSynchronizableSession)
	if !ok {
		return fmt.Errorf("session is not advanced-synchronizable")
	}
	if err := session.SynchronizeToRemote(client, path); err != nil {
		return err
	}
	s.Dirty = true
	return nil
}

func (s *State) CreateVault(key vault.MasterKey) error {
	session, ok := s.Session.(CreateableSession)
	if !ok {
		return fmt.Errorf("session is not createable")
	}

	if err := session.Create(vault.Model{}, key); err != nil {
		return err
	}

	s.CurrentPath = nil
	s.SelectedEntryID = ""
	s.Dirty = false
	return nil
}

func (s *State) OpenVault(path string, key vault.MasterKey) error {
	session, ok := s.Session.(OpenableSession)
	if !ok {
		return fmt.Errorf("session is not openable")
	}

	if err := session.Open(path, key); err != nil {
		return err
	}

	s.CurrentPath = nil
	s.SelectedEntryID = ""
	s.Dirty = false
	if warningSession, ok := s.Session.(WarningSession); ok {
		s.StatusMessage = warningSession.ConsumeWarning()
	}
	return nil
}

func (s *State) SaveAs(path string) error {
	session, ok := s.Session.(SaveAsSession)
	if !ok {
		return fmt.Errorf("session is not save-as capable")
	}

	if err := session.SaveAs(path); err != nil {
		return err
	}

	s.Dirty = false
	return nil
}

func (s *State) OpenRemoteVault(client webdav.Client, path string, key vault.MasterKey) error {
	session, ok := s.Session.(RemoteOpenableSession)
	if !ok {
		return fmt.Errorf("session is not remote-openable")
	}

	if err := session.OpenRemote(client, path, key); err != nil {
		return err
	}

	s.CurrentPath = nil
	s.SelectedEntryID = ""
	s.Dirty = false
	if warningSession, ok := s.Session.(WarningSession); ok {
		s.StatusMessage = warningSession.ConsumeWarning()
	}
	return nil
}

func (s *State) OpenBoundRemoteVault(binding RemoteBinding, key vault.MasterKey) error {
	model, err := s.currentModel()
	if err != nil {
		return err
	}

	resolved, err := binding.Resolve(model)
	if err != nil {
		return err
	}

	client := webdav.Client{
		BaseURL:  resolved.Profile.BaseURL,
		Username: resolved.Credentials.Username,
		Password: resolved.Credentials.Password,
	}
	return s.OpenRemoteVault(client, resolved.Profile.Path, key)
}

func (s *State) ConfigureRemoteBinding(input RemoteBindingInput) (RemoteBinding, error) {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return RemoteBinding{}, fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return RemoteBinding{}, err
	}

	binding, err := ConfigureRemoteBinding(&model, input)
	if err != nil {
		return RemoteBinding{}, err
	}

	session.Replace(model)
	if err := s.markDirtyAndAutoSave(); err != nil {
		return RemoteBinding{}, err
	}
	return binding, nil
}

func (s *State) RemoveRemoteBinding(binding RemoteBinding) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	if err := RemoveRemoteBinding(&model, binding); err != nil {
		return err
	}

	session.Replace(model)
	return s.markDirtyAndAutoSave()
}

func (s *State) CreateGroup(name string) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	view := sectionGroupView(model, s.Section)
	model.CreateGroup(view.ToPhysicalPath(sectionGroupViewPath(model, s.Section, s.CurrentPath)), name)
	session.Replace(model)
	return s.markDirtyAndAutoSave()
}

func (s *State) MoveCurrentGroup(parent []string) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}
	model, err := session.Current()
	if err != nil {
		return err
	}
	view := sectionGroupView(model, s.Section)
	current := sectionGroupLogicalPath(model, s.Section, s.CurrentPath)
	currentViewPath := sectionGroupViewPath(model, s.Section, current)
	parentViewPath := sectionGroupViewPath(model, s.Section, parent)
	if err := model.MoveGroup(view.ToPhysicalPath(currentViewPath), view.ToPhysicalPath(parentViewPath)); err != nil {
		return err
	}
	session.Replace(model)
	if len(currentViewPath) > 0 {
		s.CurrentPath = sectionGroupLogicalPath(model, s.Section, append(append([]string(nil), parentViewPath...), currentViewPath[len(currentViewPath)-1]))
	}
	return s.markDirtyAndAutoSave()
}

func (s *State) RenameCurrentGroup(newName string) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	view := sectionGroupView(model, s.Section)
	if err := model.RenameGroup(view.ToPhysicalPath(sectionGroupViewPath(model, s.Section, s.CurrentPath)), newName); err != nil {
		return err
	}

	session.Replace(model)
	if len(s.CurrentPath) > 0 {
		s.CurrentPath = append(append([]string(nil), s.CurrentPath[:len(s.CurrentPath)-1]...), newName)
	}
	return s.markDirtyAndAutoSave()
}

func (s *State) MoveSelectedEntry(path []string) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	if err := model.MoveEntry(s.SelectedEntryID, vaultview.VaultRoot(model).ToPhysicalPath(entriesViewPathForModel(model, path))); err != nil {
		return err
	}

	session.Replace(model)
	return s.markDirtyAndAutoSave()
}

func (s *State) DeleteCurrentGroup() error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	view := sectionGroupView(model, s.Section)
	if err := model.DeleteGroup(view.ToPhysicalPath(sectionGroupViewPath(model, s.Section, s.CurrentPath))); err != nil {
		return err
	}

	session.Replace(model)
	if len(s.CurrentPath) > 0 {
		s.CurrentPath = append([]string(nil), s.CurrentPath[:len(s.CurrentPath)-1]...)
	}
	s.SelectedEntryID = ""
	return s.markDirtyAndAutoSave()
}

func (s *State) AddAttachmentToSelectedEntry(name string, content []byte) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	for i := range model.Entries {
		if model.Entries[i].ID != s.SelectedEntryID {
			continue
		}
		if model.Entries[i].Attachments == nil {
			model.Entries[i].Attachments = map[string][]byte{}
		}
		if _, exists := model.Entries[i].Attachments[name]; exists {
			return ErrAttachmentAlreadyExists
		}
		model.Entries[i].Attachments[name] = append([]byte(nil), content...)
		session.Replace(model)
		return s.markDirtyAndAutoSave()
	}

	return vault.ErrEntryNotFound
}

func (s *State) ReplaceAttachmentOnSelectedEntry(name string, content []byte) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	for i := range model.Entries {
		if model.Entries[i].ID != s.SelectedEntryID {
			continue
		}
		if _, exists := model.Entries[i].Attachments[name]; !exists {
			return ErrAttachmentNotFound
		}
		model.Entries[i].Attachments[name] = append([]byte(nil), content...)
		session.Replace(model)
		return s.markDirtyAndAutoSave()
	}

	return vault.ErrEntryNotFound
}

func (s *State) DeleteAttachmentFromSelectedEntry(name string) error {
	session, ok := s.Session.(MutableSession)
	if !ok {
		return fmt.Errorf("session is not mutable")
	}

	model, err := session.Current()
	if err != nil {
		return err
	}

	for i := range model.Entries {
		if model.Entries[i].ID != s.SelectedEntryID {
			continue
		}
		if _, exists := model.Entries[i].Attachments[name]; !exists {
			return ErrAttachmentNotFound
		}
		delete(model.Entries[i].Attachments, name)
		if len(model.Entries[i].Attachments) == 0 {
			model.Entries[i].Attachments = nil
		}
		session.Replace(model)
		return s.markDirtyAndAutoSave()
	}

	return vault.ErrEntryNotFound
}