package main

import (
	"fmt"
	"os"
	"slices"
	"strconv"
	"strings"

	"gioui.org/widget"
	"git.julianfamily.org/keepassgo/clipboard"
	"git.julianfamily.org/keepassgo/passwords"
	"git.julianfamily.org/keepassgo/vault"
)

func (u *ui) attachmentInput() (string, []byte, error) {
	name := strings.TrimSpace(u.attachmentName.Text())
	if name == "" {
		return "", nil, fmt.Errorf("attachment name is required")
	}

	path := strings.TrimSpace(u.attachmentPath.Text())
	if path == "" {
		return "", nil, fmt.Errorf("attachment path is required")
	}

	info, err := os.Stat(path)
	if err != nil {
		return "", nil, fmt.Errorf("stat attachment: %w", err)
	}
	if info.Size() > maxAttachmentBytes {
		return "", nil, fmt.Errorf("attachment too large: %d bytes exceeds %d byte limit", info.Size(), maxAttachmentBytes)
	}

	content, err := os.ReadFile(path)
	if err != nil {
		return "", nil, fmt.Errorf("read attachment: %w", err)
	}
	return name, content, nil
}

func (u *ui) loadSelectedEntryIntoEditor() {
	u.resetPasswordPeek()
	u.clearGeneratedPasswordDraft()
	u.selectedHistoryIndex = -1
	u.historyIndex.SetText("")

	item, ok := u.selectedEntry()
	if !ok {
		u.entryID.SetText("")
		u.entryTitle.SetText("")
		u.entryUsername.SetText("")
		u.entryPassword.SetText("")
		u.entryURL.SetText("")
		u.entryNotes.SetText("")
		u.entryTags.SetText("")
		u.entryPath.SetText(strings.Join(u.displayPath(), " / "))
		u.entryFields.SetText("")
		u.setCustomFieldRows(nil)
		u.attachmentName.SetText("")
		u.attachmentPath.SetText("")
		u.exportAttachmentPath.SetText("")
		return
	}

	u.entryID.SetText(item.ID)
	u.entryTitle.SetText(item.Title)
	u.entryUsername.SetText(item.Username)
	u.entryPassword.SetText(item.Password)
	u.entryURL.SetText(item.URL)
	u.entryNotes.SetText(item.Notes)
	u.entryTags.SetText(strings.Join(item.Tags, ", "))
	u.entryPath.SetText(strings.Join(u.displayEntryPath(item.Path), " / "))
	u.entryFields.SetText(marshalFields(item.Fields))
	u.setCustomFieldRows(item.Fields)
	u.attachmentName.SetText("")
	u.attachmentPath.SetText("")
	u.exportAttachmentPath.SetText("")
}

func (u *ui) setCustomFieldRows(fields map[string]string) {
	u.customFieldKeys = nil
	u.customFieldValues = nil
	u.removeCustomFields = nil
	if len(fields) == 0 {
		u.appendCustomFieldRow("", "")
		return
	}
	keys := make([]string, 0, len(fields))
	for key := range fields {
		keys = append(keys, key)
	}
	slices.Sort(keys)
	for _, key := range keys {
		u.appendCustomFieldRow(key, fields[key])
	}
}

func (u *ui) appendCustomFieldRow(key, value string) {
	keyEditor := widget.Editor{SingleLine: true, Submit: false}
	keyEditor.SetText(key)
	valueEditor := widget.Editor{SingleLine: true, Submit: false}
	valueEditor.SetText(value)
	u.customFieldKeys = append(u.customFieldKeys, keyEditor)
	u.customFieldValues = append(u.customFieldValues, valueEditor)
	u.removeCustomFields = append(u.removeCustomFields, widget.Clickable{})
}

func (u *ui) removeCustomFieldRow(index int) {
	if index < 0 || index >= len(u.customFieldKeys) {
		return
	}
	u.customFieldKeys = append(u.customFieldKeys[:index], u.customFieldKeys[index+1:]...)
	u.customFieldValues = append(u.customFieldValues[:index], u.customFieldValues[index+1:]...)
	u.removeCustomFields = append(u.removeCustomFields[:index], u.removeCustomFields[index+1:]...)
	if len(u.customFieldKeys) == 0 {
		u.appendCustomFieldRow("", "")
	}
}

func (u *ui) currentCustomFields() (map[string]string, error) {
	fields := map[string]string{}
	for i := range u.customFieldKeys {
		key := strings.TrimSpace(u.customFieldKeys[i].Text())
		value := strings.TrimSpace(u.customFieldValues[i].Text())
		if key == "" && value == "" {
			continue
		}
		if key == "" {
			return nil, fmt.Errorf("custom field name is required")
		}
		fields[key] = value
	}
	if len(fields) == 0 && strings.TrimSpace(u.entryFields.Text()) != "" {
		return parseFields(u.entryFields.Text())
	}
	if len(fields) == 0 {
		return nil, nil
	}
	return fields, nil
}

func (u *ui) visibleHistory() []vault.Entry {
	item, ok := u.selectedEntry()
	if !ok || len(item.History) == 0 {
		return nil
	}
	return append([]vault.Entry(nil), item.History...)
}

func (u *ui) selectedHistoryEntry() (vault.Entry, bool) {
	history := u.visibleHistory()
	if u.selectedHistoryIndex < 0 || u.selectedHistoryIndex >= len(history) {
		return vault.Entry{}, false
	}
	return history[u.selectedHistoryIndex], true
}

func (u *ui) selectHistoryVersion(index int) error {
	history := u.visibleHistory()
	if index < 0 || index >= len(history) {
		return fmt.Errorf("history index %d out of range", index)
	}

	u.selectedHistoryIndex = index
	u.historyIndex.SetText(strconv.Itoa(index))
	return nil
}

func (u *ui) saveEntryAction() error {
	entry, err := u.editorEntry()
	if err != nil {
		return err
	}
	if err := u.state.UpsertEntry(entry); err != nil {
		return err
	}
	u.editingEntry = false
	u.clearGeneratedPasswordDraft()
	u.filter()
	return nil
}

func (u *ui) duplicateSelectedEntryAction() error {
	baseID := strings.TrimSpace(u.state.SelectedEntryID)
	if baseID == "" {
		return fmt.Errorf("no entry selected")
	}

	duplicateID := baseID + "-copy"
	if _, err := u.state.DuplicateSelectedEntry(duplicateID); err != nil {
		return err
	}

	u.loadSelectedEntryIntoEditor()
	u.filter()
	return nil
}

func (u *ui) deleteSelectedEntryAction() error {
	if err := u.state.DeleteSelectedEntry(); err != nil {
		return err
	}

	u.loadSelectedEntryIntoEditor()
	u.filter()
	return nil
}

func (u *ui) restoreSelectedRecycleEntryAction() error {
	id := strings.TrimSpace(u.state.SelectedEntryID)
	if id == "" {
		return fmt.Errorf("no recycle-bin entry selected")
	}
	if err := u.state.RestoreEntry(id); err != nil {
		return err
	}
	u.filter()
	return nil
}

func (u *ui) saveTemplateAction() error {
	entry, err := u.editorEntry()
	if err != nil {
		return err
	}
	if len(entry.Path) == 0 {
		entry.Path = []string{"Templates"}
	}
	if err := u.state.UpsertTemplate(entry); err != nil {
		return err
	}
	u.editingEntry = false
	u.clearGeneratedPasswordDraft()
	u.filter()
	return nil
}

func (u *ui) deleteSelectedTemplateAction() error {
	id := strings.TrimSpace(u.state.SelectedEntryID)
	if id == "" {
		return fmt.Errorf("no template selected")
	}
	if err := u.state.DeleteTemplate(id); err != nil {
		return err
	}
	u.loadSelectedEntryIntoEditor()
	u.filter()
	return nil
}

func (u *ui) createGroupAction() error {
	u.clearDeleteGroupConfirmation()
	return u.state.CreateGroup(strings.TrimSpace(u.groupName.Text()))
}

func (u *ui) moveCurrentGroupAction() error {
	u.clearDeleteGroupConfirmation()
	if len(u.displayPath()) == 0 {
		return fmt.Errorf("no current group selected")
	}
	return u.state.MoveCurrentGroup(parsePath(u.groupParentPath.Text()))
}

func (u *ui) renameGroupAction() error {
	u.clearDeleteGroupConfirmation()
	return u.state.RenameCurrentGroup(strings.TrimSpace(u.groupName.Text()))
}

func (u *ui) deleteCurrentGroupAction() error {
	if !u.deleteGroupPendingConfirmation() {
		return fmt.Errorf("confirm deleting the empty group first")
	}
	if err := u.state.DeleteCurrentGroup(); err != nil {
		return err
	}
	u.clearDeleteGroupConfirmation()
	u.currentPath = append([]string(nil), u.state.CurrentPath...)
	u.syncedPath = append([]string(nil), u.state.CurrentPath...)
	u.filter()
	return nil
}

func (u *ui) instantiateSelectedTemplateAction() error {
	templateID := strings.TrimSpace(u.state.SelectedEntryID)
	if templateID == "" {
		return fmt.Errorf("no template selected")
	}

	entry, err := u.editorEntry()
	if err != nil {
		return err
	}
	if _, err := u.state.InstantiateTemplate(templateID, entry); err != nil {
		return err
	}
	u.filter()
	return nil
}

func (u *ui) addAttachmentAction() error {
	name, content, err := u.attachmentInput()
	if err != nil {
		return err
	}
	if err := u.state.AddAttachmentToSelectedEntry(name, content); err != nil {
		return err
	}
	u.loadSelectedEntryIntoEditor()
	u.attachmentName.SetText(name)
	u.filter()
	return nil
}

func (u *ui) replaceAttachmentAction() error {
	name, content, err := u.attachmentInput()
	if err != nil {
		return err
	}
	if err := u.state.ReplaceAttachmentOnSelectedEntry(name, content); err != nil {
		return err
	}
	u.loadSelectedEntryIntoEditor()
	u.attachmentName.SetText(name)
	u.filter()
	return nil
}

func (u *ui) exportAttachmentAction() error {
	item, ok := u.selectedEntry()
	if !ok {
		return fmt.Errorf("no entry selected")
	}

	name := strings.TrimSpace(u.attachmentName.Text())
	content, ok := item.Attachments[name]
	if !ok {
		return fmt.Errorf("attachment not found")
	}

	exportPath := strings.TrimSpace(u.exportAttachmentPath.Text())
	if exportPath == "" {
		return fmt.Errorf("export attachment path is required")
	}
	if err := os.WriteFile(exportPath, content, 0o600); err != nil {
		return fmt.Errorf("write attachment export: %w", err)
	}
	return nil
}

func (u *ui) removeAttachmentAction() error {
	name := strings.TrimSpace(u.attachmentName.Text())
	if name == "" {
		return fmt.Errorf("attachment name is required")
	}

	if err := u.state.DeleteAttachmentFromSelectedEntry(name); err != nil {
		return err
	}
	u.loadSelectedEntryIntoEditor()
	u.filter()
	return nil
}

func (u *ui) restoreSelectedHistoryAction() error {
	index, err := u.selectedHistoryVersionIndex()
	if err != nil {
		return err
	}
	if err := u.state.RestoreSelectedEntryVersion(index); err != nil {
		return err
	}
	u.loadSelectedEntryIntoEditor()
	u.filter()
	return nil
}

func (u *ui) selectedHistoryVersionIndex() (int, error) {
	text := strings.TrimSpace(u.historyIndex.Text())
	if text != "" {
		index, err := strconv.Atoi(text)
		if err != nil {
			return 0, fmt.Errorf("invalid history index: %w", err)
		}
		return index, nil
	}
	if u.selectedHistoryIndex >= 0 {
		return u.selectedHistoryIndex, nil
	}
	return 0, fmt.Errorf("no history version selected")
}

func (u *ui) copySelectedFieldAction(target clipboard.Target) error {
	model, err := u.state.Session.Current()
	if err != nil {
		return err
	}

	service := clipboard.Service{Writer: u.clipboardWriter}
	return service.Copy(model, u.state.SelectedEntryID, target)
}

func (u *ui) generatePasswordAction() error {
	profile, err := passwords.LookupDefaultProfile(u.passwordProfile.Text())
	if err != nil {
		return err
	}

	password, err := passwords.Generate(profile)
	if err != nil {
		return err
	}
	u.entryPassword.SetText(password)
	u.generatedPasswordDraft = true
	return nil
}

func (u *ui) editorEntry() (vault.Entry, error) {
	path := parsePath(u.entryPath.Text())
	if root := u.hiddenVaultRoot(); root != "" && (len(path) == 0 || path[0] != root) {
		path = append([]string{root}, path...)
	}
	fields, err := u.currentCustomFields()
	if err != nil {
		return vault.Entry{}, err
	}

	return vault.Entry{
		ID:       strings.TrimSpace(u.entryID.Text()),
		Title:    strings.TrimSpace(u.entryTitle.Text()),
		Username: strings.TrimSpace(u.entryUsername.Text()),
		Password: u.entryPassword.Text(),
		URL:      strings.TrimSpace(u.entryURL.Text()),
		Notes:    strings.TrimSpace(u.entryNotes.Text()),
		Tags:     parseTags(u.entryTags.Text()),
		Path:     path,
		Fields:   fields,
	}, nil
}

func parsePath(text string) []string {
	var out []string
	for _, part := range strings.Split(text, "/") {
		part = strings.TrimSpace(part)
		if part == "" {
			continue
		}
		out = append(out, part)
	}
	return out
}

func parseTags(text string) []string {
	var out []string
	for _, part := range strings.Split(text, ",") {
		part = strings.TrimSpace(part)
		if part == "" {
			continue
		}
		out = append(out, part)
	}
	return out
}

func parseFields(text string) (map[string]string, error) {
	if strings.TrimSpace(text) == "" {
		return nil, nil
	}

	fields := map[string]string{}
	for _, line := range strings.Split(text, "\n") {
		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}
		key, value, ok := strings.Cut(line, "=")
		if !ok {
			return nil, fmt.Errorf("invalid field line %q", line)
		}
		fields[strings.TrimSpace(key)] = strings.TrimSpace(value)
	}
	return fields, nil
}

func marshalFields(fields map[string]string) string {
	if len(fields) == 0 {
		return ""
	}

	lines := make([]string, 0, len(fields))
	for key, value := range fields {
		lines = append(lines, key+"="+value)
	}
	return strings.Join(lines, "\n")
}

func (u *ui) clearGeneratedPasswordDraft() {
	u.generatedPasswordDraft = false
}

func (u *ui) attachmentActionSummary() string {
	items := u.selectedAttachmentItems()
	if len(items) == 0 {
		return "No attachments yet. Add one below to store a file with this entry."
	}

	name := strings.TrimSpace(u.attachmentName.Text())
	if name == "" {
		return "Select an attachment above, then replace it, export it, or remove it below."
	}

	for _, item := range items {
		if item.Name == name {
			return fmt.Sprintf("Selected attachment %q. Replace it, export it, or remove it below.", name)
		}
	}

	return fmt.Sprintf("Attachment %q is not on this entry yet. Add it as new, or select an existing attachment above.", name)
}