// Copyright (c) 2026 Storm Dragon
// SPDX-License-Identifier: GPL-3.0-or-later

package preferences

import (
	"fmt"
	"path/filepath"
	"slices"

	"git.stormux.org/storm/fenrir/internal/config"
	"git.stormux.org/storm/fenrir/internal/input"
	"git.stormux.org/storm/fenrir/internal/interaction"
)

type modifierOption struct{ name, Label string }

var modifierOptions = []modifierOption{
	{name: "KEY_KP0", Label: "Keypad Insert"},
	{name: "KEY_INSERT", Label: "Insert"},
	{name: "KEY_CAPSLOCK", Label: "Caps Lock"},
	{name: "KEY_META", Label: "Super"},
}

func reader_names(settings config.Settings) []string {
	if settings.Keyboard.FenrirKeys != nil {
		return settings.Keyboard.FenrirKeys
	}
	// Running applications supply the resolved layout's keys at startup.
	// Standalone forms use the built-in layout defaults.
	var names []string
	switch filepath.Base(settings.Keyboard.Layout) {
	case "laptop", "laptop.toml":
		names = []string{"KEY_KP0", "KEY_INSERT", "KEY_CAPSLOCK"}
	default:
		names = []string{"KEY_KP0", "KEY_INSERT", "KEY_META"}
	}
	available, err := input.Available_fenrir_keys(names, settings.General.ScriptKeys)
	if err != nil {
		return []string{}
	}
	return available
}

func modifier_checked(names []string, name string) bool {
	keys, _ := input.Modifier_codes(names)
	option, _ := input.Modifier_codes([]string{name})
	for key := range option {
		if keys[key] {
			return true
		}
	}
	return false
}

func modifier_controls(settings config.Settings) []interaction.Control {
	var controls []interaction.Control
	for _, role := range []struct {
		id, Label string
		names     []string
	}{
		{id: "fenrir_key.", Label: "Fenrir keys", names: reader_names(settings)},
		{id: "script_key.", Label: "Script keys", names: settings.General.ScriptKeys},
	} {
		options := slices.Clone(modifierOptions)
		if role.id == "script_key." {
			options = append(options, modifierOption{name: "KEY_COMPOSE", Label: "Compose"})
		}
		for _, option := range options {
			controls = append(controls, interaction.Control{ID: role.id + option.name, Label: option.Label, Group: role.Label, Kind: interaction.CheckBox, Checked: modifier_checked(role.names, option.name)})
		}
	}
	return controls
}

func selected_modifiers(values map[string]interaction.Control, prefix string, names []string, options []modifierOption) ([]string, bool, error) {
	selected := slices.Clone(names)
	changed := false
	for _, option := range options {
		control, ok := values["keyboard."+prefix+option.name]
		if !ok {
			return nil, false, fmt.Errorf("missing modifier checkbox %s", option.name)
		}
		if control.Checked == modifier_checked(names, option.name) {
			continue
		}
		changed = true
		if control.Checked {
			selected = append(selected, option.name)
			continue
		}
		selected = slices.DeleteFunc(selected, func(name string) bool { return modifier_checked([]string{name}, option.name) })
	}
	return selected, changed, nil
}

func modifier_settings(values map[string]interaction.Control, base *config.Settings) error {
	reader, changed, err := selected_modifiers(values, "fenrir_key.", reader_names(*base), modifierOptions)
	if err != nil {
		return err
	}
	scripts, _, err := selected_modifiers(values, "script_key.", base.General.ScriptKeys, append(slices.Clone(modifierOptions), modifierOption{name: "KEY_COMPOSE", Label: "Compose"}))
	if err != nil {
		return err
	}
	if err := input.Validate_modifier_keys(reader, scripts); err != nil {
		return err
	}
	if changed {
		base.Keyboard.FenrirKeys = reader
	}
	base.General.ScriptKeys = scripts
	return nil
}