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

package app

import (
	"context"
	"errors"
	"reflect"
	"time"

	"git.stormux.org/storm/cthulhu/internal/config"
	"git.stormux.org/storm/cthulhu/internal/input"
	"git.stormux.org/storm/cthulhu/internal/preferences"
)

func (worker *preferencesWorker) response(message string, accepted bool) preferences.Response {
	settings := worker.settings
	if worker.editingActive {
		settings = worker.editing
	}
	store, err := config.NewStore(settings.Path)
	if err == nil {
		_, err = store.Load()
	}
	return preferences.Response{Values: preferences.FromSettings(settings), CanSave: err == nil,
		Message: message, Accepted: accepted}
}

func (worker *preferencesWorker) apply(ctx context.Context, request preferences.Request) preferences.Response {
	base := worker.settings
	if worker.editingActive {
		base = worker.editing
	}
	next, err := request.Values.Merge(base)
	if err != nil {
		return worker.response("Settings were not applied: "+err.Error(), false)
	}
	return worker.applyNext(ctx, next, request.Save, request.Close)
}

func (worker *preferencesWorker) applyNext(ctx context.Context, next config.Settings, save, close bool) preferences.Response {
	scopeApp := worker.activeApp
	if worker.editingActive {
		scopeApp = worker.editApp
	}
	if err := config.Validate(next); err != nil {
		return worker.response("Settings were not applied: "+err.Error(), false)
	}
	if save && !worker.response("", false).CanSave {
		return worker.response("This settings file cannot be saved by the Go preview. Use Apply for this session.", false)
	}
	if err := worker.applyRuntime(ctx, next); err != nil {
		return worker.response(err.Error(), false)
	}
	if worker.editingActive {
		worker.editing = next
	}
	if scopeApp != "" {
		worker.appSettings[scopeApp] = next
	} else {
		oldGlobal := worker.globalSettings
		for application, settings := range worker.appSettings {
			worker.appSettings[application] = config.RebaseApplicationSettings(oldGlobal, next, settings)
		}
		worker.globalSettings = next
	}
	message := "Settings applied for this session."
	if save {
		store, err := config.NewStore(next.Path)
		if err == nil {
			if scopeApp != "" {
				err = store.SaveForApplication(scopeApp, next)
			} else {
				err = store.Save(next)
			}
		}
		if err != nil {
			message = "Applied for this session, but could not save: " + err.Error()
		} else {
			message = "Settings applied and saved."
		}
	}
	response := worker.response(message, true)
	response.Close = close && save && message == "Settings applied and saved."
	if worker.editingActive && worker.editApp != worker.activeApp {
		previousApp := worker.activeApp
		worker.activeApp = ""
		if previousApp != "" {
			worker.switchApplication(ctx, previousApp)
		}
	}
	return response
}

func (worker *preferencesWorker) applyRuntime(ctx context.Context, next config.Settings) error {
	keyboardChanged := next.KeyboardLayout != worker.settings.KeyboardLayout || !reflect.DeepEqual(next.CthulhuModifierKeys, worker.settings.CthulhuModifierKeys)
	bindingsChanged := keyboardChanged || !reflect.DeepEqual(next.KeyBindings, worker.settings.KeyBindings)
	bindingsCommitted := false
	if bindingsChanged {
		if worker.bindings == nil {
			return errors.New("Key bindings cannot be changed by this input backend.")
		}
		if err := worker.apply_keyboard(ctx, next, keyboardChanged); err != nil {
			return errors.New("Key bindings were not applied: " + err.Error())
		}
		defer func() {
			if !bindingsCommitted {
				rollbackCtx, cancel := context.WithTimeout(context.Background(), time.Second)
				defer cancel()
				if err := worker.apply_keyboard(rollbackCtx, worker.settings, keyboardChanged); err != nil {
					worker.logger.Error("restore key bindings after failed preferences apply", "error", err)
				}
			}
		}()
	}
	speechChanged := next.SpeechServerFactory != worker.settings.SpeechServerFactory ||
		!reflect.DeepEqual(next.UppercaseVoice, worker.settings.UppercaseVoice) ||
		!reflect.DeepEqual(next.HyperlinkVoice, worker.settings.HyperlinkVoice) ||
		!reflect.DeepEqual(next.SystemVoice, worker.settings.SystemVoice) ||
		next.HardwareSpeechDevice != worker.settings.HardwareSpeechDevice ||
		next.HardwareSpeechBaudRate != worker.settings.HardwareSpeechBaudRate || !reflect.DeepEqual(speechSettingsFromConfig(next), speechSettingsFromConfig(worker.settings)) ||
		next.UseCustomEchoVoice != worker.settings.UseCustomEchoVoice ||
		(next.UseCustomEchoVoice && !reflect.DeepEqual(echoSpeechSettings(next), echoSpeechSettings(worker.settings)))
	if next.EnableSpeech && (speechChanged || !worker.settings.EnableSpeech) {
		if message := worker.apply_speech_settings(ctx, next); message != "" {
			return errors.New(message)
		}
	}
	if next.EnableBraille != worker.settings.EnableBraille {
		if worker.braille == nil {
			return errors.New("Braille is unavailable in this build.")
		}
		if err := worker.braille.Configure(ctx, next.EnableBraille); err != nil {
			return errors.New("Braille settings were not applied: " + err.Error())
		}
	}
	if next.EnableContractedBraille != worker.settings.EnableContractedBraille ||
		next.BrailleContractionTable != worker.settings.BrailleContractionTable {
		if updater, ok := worker.braille.(interface{ SetContraction(bool, string) }); ok {
			updater.SetContraction(next.EnableContractedBraille, next.BrailleContractionTable)
		}
	}
	bindingsCommitted = true
	worker.commit_settings(next)
	return nil
}

func (worker *preferencesWorker) apply_keyboard(ctx context.Context, settings config.Settings, keyboardChanged bool) error {
	if updater, ok := worker.bindings.(interface {
		SetKeyboardConfiguration(context.Context, input.KeyboardLayout, []string, []input.BindingOverride) error
	}); ok {
		return updater.SetKeyboardConfiguration(ctx, input.KeyboardLayout(settings.KeyboardLayout), settings.CthulhuModifierKeys, settings.KeyBindings)
	}
	if keyboardChanged {
		return errors.New("this input backend cannot change Cthulhu keys or keyboard layout")
	}
	return worker.bindings.SetKeyBindings(ctx, settings.KeyBindings)
}

func (worker *preferencesWorker) apply_speech_settings(ctx context.Context, next config.Settings) string {
	var err error

	if worker.updater == nil {
		return "Speech is disabled or this backend cannot change settings."
	}
	if updater, ok := worker.updater.(interface {
		UpdateConfiguration(context.Context, config.Settings) error
	}); ok {
		err = updater.UpdateConfiguration(ctx, next)
	} else if updater, ok := worker.updater.(speechSettingsUpdater); ok {
		if next.UseCustomEchoVoice {
			return "This speech backend cannot use a custom echo voice."
		}
		err = updater.UpdateSettings(ctx, speechSettingsFromConfig(next))
	} else {
		return "This backend cannot change speech settings."
	}
	if err != nil {
		return "Settings were not applied: " + err.Error()
	}
	return ""
}

// Commit follows the existing backend updates and keyboard rollback boundary.
// It publishes settings to runtime consumers without changing their ownership.
func (worker *preferencesWorker) commit_settings(next config.Settings) {
	soundChanged := soundConfiguration(next) != soundConfiguration(worker.settings)
	worker.settings = next
	if updater, ok := worker.braille.(interface{ SetWordWrap(bool) }); ok {
		updater.SetWordWrap(next.Braille.WordWrap)
	}
	if worker.speechWorker != nil && !next.EnableSpeech {
		worker.speechWorker.SetEnabled(false)
	}
	if worker.history != nil {
		worker.history.setLimit(next.SpeechHistoryLimit)
		if worker.refreshHistory != nil {
			worker.refreshHistory()
		}
	}
	if worker.documentReview != nil {
		worker.documentReview.SetDocumentBrailleEnabled(next.EnableBraille)
	}
	// Configure cancels playback. An application switch or unrelated setting
	// must leave the startup cue running when its sound policy is unchanged.
	if worker.sound != nil && soundChanged {
		worker.sound.Configure(soundConfiguration(next))
	}
	if worker.geometry != nil {
		worker.geometry.SetCaptureSoundGeometry(captureSoundGeometry(next))
	}
	if worker.textAttributes != nil {
		worker.textAttributes.SetCaptureTextAttributes(captureTextAttributes(next))
	}
	if worker.live != nil {
		worker.live.Store(next)
	}
	if worker.speechWorker != nil && next.EnableSpeech {
		worker.speechWorker.SetEnabled(true)
	}
}