package appui

import (
	"fmt"
	"strconv"
	"strings"

	"gioui.org/io/key"
	"git.julianfamily.org/keepassgo/internal/appstate"
)

type focusID string

type detailField string

const (
	focusSearch focusID = "search"

	detailFieldID              detailField = "id"
	detailFieldTitle           detailField = "title"
	detailFieldUsername        detailField = "username"
	detailFieldPassword        detailField = "password"
	detailFieldURL             detailField = "url"
	detailFieldPath            detailField = "path"
	detailFieldTags            detailField = "tags"
	detailFieldPasswordProfile detailField = "password-profile"
	detailFieldNotes           detailField = "notes"
	detailFieldFields          detailField = "fields"
	detailFieldHistoryIndex    detailField = "history-index"
)

func breadcrumbFocusID(index int) focusID {
	return focusID(fmt.Sprintf("breadcrumb:%d", index))
}

func listFocusID(index int) focusID {
	return focusID(fmt.Sprintf("list:%d", index))
}

func detailFocusID(field detailField) focusID {
	return focusID("detail:" + string(field))
}

func (u *ui) handleKeyPress(name key.Name, modifiers key.Modifiers) bool {
	if u.handleShortcutKey(name, modifiers) {
		return true
	}
	if u.isVaultLocked() && name == key.NameReturn {
		u.startUnlockAction()
		return true
	}
	if u.shouldShowLifecycleSetup() && name == key.NameReturn {
		if u.lifecycleMode == "remote" {
			u.startOpenRemoteAction()
		} else {
			u.startOpenVaultAction()
		}
		return true
	}

	switch name {
	case key.NameTab:
		delta := 1
		if modifiers.Contain(key.ModShift) {
			delta = -1
		}
		u.moveKeyboardFocus(delta)
		return true
	case key.NameLeftArrow, key.NameRightArrow, key.NameUpArrow, key.NameDownArrow, key.NameReturn:
		return u.handleFocusedKey(name)
	default:
		return false
	}
}

func (u *ui) moveKeyboardFocus(delta int) {
	order := u.focusOrder()
	if len(order) == 0 {
		return
	}

	current := canonicalFocusID(u.keyboardFocus)
	index := 0
	for i, item := range order {
		if canonicalFocusID(item) == current {
			index = i
			break
		}
	}

	index += delta
	if index < 0 {
		index = len(order) - 1
	}
	if index >= len(order) {
		index = 0
	}
	u.setKeyboardFocus(order[index])
}

func (u *ui) focusOrder() []focusID {
	if u.isVaultLocked() {
		return []focusID{detailFocusID(detailFieldPassword)}
	}
	order := []focusID{focusSearch}
	if u.state.Section != appstate.SectionRecycleBin {
		order = append(order, breadcrumbFocusID(0))
	}
	if len(u.visible) > 0 {
		order = append(order, listFocusID(u.focusedListIndexOrZero()))
	}
	order = append(order, detailFocusID(u.focusedDetailFieldOrDefault()))
	return order
}

func (u *ui) setKeyboardFocus(id focusID) {
	u.keyboardFocus = id
	if strings.HasPrefix(string(id), "list:") {
		u.focusListIndex(focusIndex(id))
	}
}

func (u *ui) handleFocusedKey(name key.Name) bool {
	switch {
	case u.keyboardFocus == focusSearch:
		if name == key.NameDownArrow && len(u.visible) > 0 {
			u.setKeyboardFocus(listFocusID(u.focusedListIndexOrZero()))
			return true
		}
	case strings.HasPrefix(string(u.keyboardFocus), "breadcrumb:"):
		return u.handleBreadcrumbKey(name)
	case strings.HasPrefix(string(u.keyboardFocus), "list:"):
		return u.handleListKey(name)
	case strings.HasPrefix(string(u.keyboardFocus), "detail:"):
		return u.handleDetailKey(name)
	}
	return false
}

func (u *ui) handleBreadcrumbKey(name key.Name) bool {
	crumbs := u.breadcrumbLabels()
	if len(crumbs) == 0 {
		return false
	}

	index := focusIndex(u.keyboardFocus)
	switch name {
	case key.NameLeftArrow:
		if index > 0 {
			u.keyboardFocus = breadcrumbFocusID(index - 1)
		}
		return true
	case key.NameRightArrow:
		if index < len(crumbs)-1 {
			u.keyboardFocus = breadcrumbFocusID(index + 1)
		}
		return true
	case key.NameDownArrow:
		if len(u.visible) > 0 {
			u.setKeyboardFocus(listFocusID(u.focusedListIndexOrZero()))
		}
		return true
	case key.NameReturn:
		u.activateBreadcrumb(index)
		return true
	default:
		return false
	}
}

func (u *ui) handleListKey(name key.Name) bool {
	if len(u.visible) == 0 {
		return false
	}

	index := focusIndex(u.keyboardFocus)
	switch name {
	case key.NameUpArrow:
		if index > 0 {
			u.setKeyboardFocus(listFocusID(index - 1))
		}
		return true
	case key.NameDownArrow:
		if index < len(u.visible)-1 {
			u.setKeyboardFocus(listFocusID(index + 1))
		}
		return true
	case key.NameLeftArrow:
		u.keyboardFocus = breadcrumbFocusID(len(u.breadcrumbLabels()) - 1)
		return true
	case key.NameRightArrow, key.NameReturn:
		u.keyboardFocus = detailFocusID(u.focusedDetailFieldOrDefault())
		return true
	default:
		return false
	}
}

func (u *ui) handleDetailKey(name key.Name) bool {
	fields := detailFocusOrder()
	index := u.focusedDetailIndex()

	switch name {
	case key.NameUpArrow:
		if index > 0 {
			u.keyboardFocus = detailFocusID(fields[index-1])
		}
		return true
	case key.NameDownArrow:
		if index < len(fields)-1 {
			u.keyboardFocus = detailFocusID(fields[index+1])
		}
		return true
	case key.NameLeftArrow:
		if len(u.visible) > 0 {
			u.setKeyboardFocus(listFocusID(u.focusedListIndexOrZero()))
		}
		return true
	default:
		return false
	}
}

func (u *ui) handleShortcutKey(name key.Name, modifiers key.Modifiers) bool {
	if !modifiers.Contain(key.ModShortcut) {
		return false
	}

	switch name {
	case "F":
		_ = u.performShortcut(shortcutSearch)
	case "S":
		_ = u.performShortcut(shortcutSave)
	case "L":
		_ = u.performShortcut(shortcutLock)
	case "N":
		_ = u.performShortcut(shortcutNewEntry)
	case "U":
		_ = u.performShortcut(shortcutCopyUser)
	case "P":
		_ = u.performShortcut(shortcutCopyPassword)
	case "O":
		_ = u.performShortcut(shortcutCopyURL)
	default:
		return false
	}

	return true
}

func (u *ui) activateBreadcrumb(index int) {
	var path []string
	if index <= 0 {
		path = nil
	} else {
		crumbs := u.breadcrumbLabels()
		path = append([]string{}, crumbs[1:index+1]...)
	}
	u.state.NavigateToPath(path)
	u.filter()
	if index >= len(u.breadcrumbLabels()) {
		index = len(u.breadcrumbLabels()) - 1
	}
	if index < 0 {
		index = 0
	}
	u.keyboardFocus = breadcrumbFocusID(index)
}

func (u *ui) breadcrumbLabels() []string {
	if u.state.Section == appstate.SectionRecycleBin {
		return nil
	}

	labels := append([]string{"Vault"}, u.state.CurrentPath...)
	if u.state.Section == appstate.SectionTemplates {
		labels = append([]string{"Templates"}, u.state.CurrentPath...)
	}
	return labels
}

func (u *ui) focusListIndex(index int) {
	if len(u.visible) == 0 {
		return
	}
	if index < 0 {
		index = 0
	}
	if index >= len(u.visible) {
		index = len(u.visible) - 1
	}

	u.keyboardFocus = listFocusID(index)
	u.state.SelectedEntryID = u.visible[index].ID
	u.loadSelectedEntryIntoEditor()
}

func (u *ui) focusedListIndexOrZero() int {
	if strings.HasPrefix(string(u.keyboardFocus), "list:") {
		index := focusIndex(u.keyboardFocus)
		if index >= 0 && index < len(u.visible) {
			return index
		}
	}

	for i, item := range u.visible {
		if item.ID == u.state.SelectedEntryID {
			return i
		}
	}

	return 0
}

func (u *ui) focusedDetailFieldOrDefault() detailField {
	if strings.HasPrefix(string(u.keyboardFocus), "detail:") {
		name := strings.TrimPrefix(string(u.keyboardFocus), "detail:")
		for _, field := range detailFocusOrder() {
			if string(field) == name {
				return field
			}
		}
	}

	return detailFieldTitle
}

func (u *ui) focusedDetailIndex() int {
	current := u.focusedDetailFieldOrDefault()
	for i, field := range detailFocusOrder() {
		if field == current {
			return i
		}
	}
	return 0
}

func detailFocusOrder() []detailField {
	return []detailField{
		detailFieldID,
		detailFieldTitle,
		detailFieldUsername,
		detailFieldPassword,
		detailFieldURL,
		detailFieldPath,
		detailFieldTags,
		detailFieldPasswordProfile,
		detailFieldNotes,
		detailFieldFields,
		detailFieldHistoryIndex,
	}
}

func canonicalFocusID(id focusID) focusID {
	switch {
	case strings.HasPrefix(string(id), "breadcrumb:"):
		return breadcrumbFocusID(0)
	case strings.HasPrefix(string(id), "list:"):
		return listFocusID(0)
	case strings.HasPrefix(string(id), "detail:"):
		return detailFocusID(detailFieldTitle)
	default:
		return id
	}
}

func focusIndex(id focusID) int {
	_, value, ok := strings.Cut(string(id), ":")
	if !ok {
		return 0
	}

	index, err := strconv.Atoi(value)
	if err != nil {
		return 0
	}
	return index
}