// Fenrir console screen reader.
// Copyright (c) 2026 Storm Dragon
// SPDX-License-Identifier: GPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
// more details.
//
// You should have received a copy of the GNU General Public License along with
// this program. If not, see <https://www.gnu.org/licenses/gpl-3.0.html>.

package app

import (
	"fmt"
	"slices"
	"strings"

	"git.stormux.org/storm/fenrir/internal/config"
	"git.stormux.org/storm/fenrir/internal/i18n"
	"git.stormux.org/storm/fenrir/internal/speech"
)

type modifierSettings struct{ fenrirKeys, scriptKeys []string }

// applicationSettings separates the effective configuration from the save draft.
// The draft retains next-launch menu choices; session mute, automatic reading,
// and attribute overrides are not implicitly copied into it.
type applicationSettings struct {
	pendingModifiers *modifierSettings
	live             config.Settings
	saveDraft        config.Settings
	resetBase        config.Settings // Last loaded or successfully saved settings.
	remoteFields     map[string]uint64
	remoteRevision   uint64
	speechAvailable  bool // The startup connection cannot be enabled by a remote setting.
}

// configure_reader applies startup settings, including next-launch-only fields.
func (a *application) configure_reader() {
	a.configure_screen()
	a.engine.Configure(a.settings.live.Reading.Automatic, a.settings.live.Reading.CursorEcho)
	a.engine.Configure_indentation(a.settings.live.Reading.Indentation)
	a.engine.Configure_attributes(a.settings.live.Reading.Attributes, a.settings.live.Reading.AttributeFormat)
	a.engine.Configure_progress(a.settings.live.Presentation.Progress.Enabled)
	a.engine.Configure_tracking(a.settings.live.Reading.Mode)
	a.engine.Configure_review(a.settings.live.Review.LineBreak, a.settings.live.Review.EndOfScreen, a.settings.live.Review.LeaveReviewOnCursorChange, a.settings.live.Review.LeaveReviewOnScreenChange)
	a.engine.Configure_echo(a.settings.live.Keyboard.CharacterEcho, a.settings.live.Keyboard.WordEcho, a.settings.live.Keyboard.EchoOnCapsLock)
}

func (a *application) configure_screen() {
	if !a.options.TerminalMode {
		if source, ok := a.source.(interface{ Configure_ignored_vts([]int) }); ok {
			source.Configure_ignored_vts(a.settings.live.Screen.IgnoredVTs)
		}
	}
}

// preview_spelling invalidates queued feedback when menu previews change.
// The modal host restores the previous values on cancellation.
func (a *application) preview_spelling(reading config.Reading) {
	if a.settings.live.Reading.Spellcheck != reading.Spellcheck || a.settings.live.Reading.SpellcheckSound != reading.SpellcheckSound ||
		a.settings.live.Reading.SpellcheckReadWord != reading.SpellcheckReadWord || a.settings.live.Reading.SpellcheckSayMisspelled != reading.SpellcheckSayMisspelled {
		a.spellFeedback++
	}
	a.settings.live.Reading.Spellcheck = reading.Spellcheck
	a.settings.live.Reading.SpellcheckReadWord = reading.SpellcheckReadWord
	a.settings.live.Reading.SpellcheckSayMisspelled = reading.SpellcheckSayMisspelled
	a.settings.live.Reading.SpellcheckSound = reading.SpellcheckSound
}

// apply_saved_settings keeps the complete saved draft but applies only fields
// supported live. Device, layout and backend changes wait until the next launch.
func (a *application) apply_saved_settings(saved config.Settings, speechApplied bool) {
	if speechApplied {
		copy_speech_selection(&a.settings.live.Presentation.Speech, saved.Presentation.Speech)
	}
	if !slices.Equal(saved.Keyboard.FenrirKeys, a.settings.live.Keyboard.FenrirKeys) || !slices.Equal(saved.General.ScriptKeys, a.settings.live.General.ScriptKeys) {
		a.settings.pendingModifiers = &modifierSettings{fenrirKeys: slices.Clone(saved.Keyboard.FenrirKeys), scriptKeys: slices.Clone(saved.General.ScriptKeys)}
	} else {
		a.settings.pendingModifiers = nil
	}
	a.settings.saveDraft = saved
	a.settings.resetBase = saved
	a.settings.live.InternalUI = saved.InternalUI
	a.settings.live.Screen = saved.Screen
	a.configure_screen()
	a.preview_spelling(saved.Reading)
	a.settings.live.Presentation.DateTime = saved.Presentation.DateTime
	a.settings.live.Reading.PunctuationLevel = saved.Reading.PunctuationLevel
	a.settings.live.Reading.Emoticons = saved.Reading.Emoticons
	a.settings.live.Reading.RepeatedSymbols = saved.Reading.RepeatedSymbols
	a.settings.live.Reading.RepeatedSymbolsMin = saved.Reading.RepeatedSymbolsMin
	a.settings.live.Reading.Attributes = saved.Reading.Attributes
	a.settings.live.Reading.AttributeFormat = saved.Reading.AttributeFormat
	a.engine.Configure_attributes(saved.Reading.Attributes, saved.Reading.AttributeFormat)
	a.settings.live.Reading.Indentation = saved.Reading.Indentation
	a.engine.Configure_indentation(saved.Reading.Indentation)
	a.settings.live.Reading.RaisePitchForCapitals = saved.Reading.RaisePitchForCapitals
	a.settings.live.Reading.BeepForCapitals = saved.Reading.BeepForCapitals
	a.settings.live.Reading.SayCapForCapitals = saved.Reading.SayCapForCapitals
	a.voice.punctuationLevel = saved.Reading.PunctuationLevel
	a.settings.live.Presentation.Speech.Rate = saved.Presentation.Speech.Rate
	a.settings.live.Presentation.Speech.Pitch = saved.Presentation.Speech.Pitch
	a.settings.live.Presentation.Speech.Volume = saved.Presentation.Speech.Volume
	a.voice.Configure(speech_parameters(a.settings.live))
	a.settings.live.Keyboard.CharacterEcho = saved.Keyboard.CharacterEcho
	a.settings.live.Keyboard.WordEcho = saved.Keyboard.WordEcho
	a.settings.live.Keyboard.EchoOnCapsLock = saved.Keyboard.EchoOnCapsLock
	a.engine.Configure_echo(a.settings.live.Keyboard.CharacterEcho, a.settings.live.Keyboard.WordEcho, a.settings.live.Keyboard.EchoOnCapsLock)
	a.quick.changed = false
	a.quick.selectionChanged = false
	a.settings.live.Presentation.Sound.Volume = saved.Presentation.Sound.Volume
	if a.cues != nil {
		a.cues.Set_volume(saved.Presentation.Sound.Volume)
	}
	a.settings.live.Presentation.Progress = saved.Presentation.Progress
	a.engine.Configure_progress(saved.Presentation.Progress.Enabled)
	if a.cues != nil {
		a.cues.Clear_progress()
	}
	a.settings.live.Clipboard = saved.Clipboard
	a.clipboards.configure(saved.Clipboard)
}

// apply_pending_modifiers runs on the event loop after menu closure. Native
// adapters defer while keys are held; failure leaves the prior runtime intact.
func (a *application) apply_pending_modifiers() {
	pending := a.settings.pendingModifiers
	if pending == nil || a.ui.active {
		return
	}
	applied, err := a.keyboards.Update_modifiers(pending.fenrirKeys, pending.scriptKeys)
	if err != nil {
		a.settings.pendingModifiers = nil
		a.voice.Say(i18n.Format("Settings saved, but key changes could not be applied: {0}. Previous keys remain active.", err.Error()))
		return
	}
	if !applied {
		return
	}
	a.settings.live.Keyboard.FenrirKeys = pending.fenrirKeys
	a.settings.live.General.ScriptKeys = pending.scriptKeys
	a.settings.pendingModifiers = nil
}

// Quick commands have already changed live values and configured speech when
// needed. Refresh the reader without copying session overrides into the draft.
func (a *application) apply_quick_settings() {
	a.voice.punctuationLevel = a.settings.live.Reading.PunctuationLevel
	a.engine.Configure_echo(a.settings.live.Keyboard.CharacterEcho, a.settings.live.Keyboard.WordEcho, a.settings.live.Keyboard.EchoOnCapsLock)
	a.engine.Configure_indentation(a.settings.live.Reading.Indentation)
	a.engine.Configure_attributes(a.settings.live.Reading.Attributes, a.settings.live.Reading.AttributeFormat)
}

func (a *application) open_settings() {
	if a.saver.busy || a.speechPending {
		a.ui.failed("Could not open Fenrir Menu: {0}", fmt.Errorf("settings save in progress"))
		return
	}
	a.settings.live.Reading.Mode = a.engine.Tracking_mode()
	a.ui.speechOverride = nil
	if a.quick.selectionChanged {
		selected := a.settings.live.Presentation.Speech
		a.ui.speechOverride = &selected
	}
	if selected := a.overrideCurrent; selected != nil {
		a.ui.open_application_settings(a.settings_to_save(), selected.path, selected.base, i18n.T(selected.adapter.Name()))
		return
	}
	if a.quick.changed {
		a.ui.open_settings(a.settings.live, a.options.ConfigPath, a.settings.live)
	} else {
		a.ui.open_settings(a.settings.live, a.options.ConfigPath)
	}
}

func (a *application) save_settings() {
	if a.saves_unavailable() {
		a.voice.Say(i18n.T("Save unavailable."))
		return
	}
	if a.speechPending {
		a.voice.Say(i18n.T("Failed to save settings."))
		return
	}
	if a.start_settings_save(a.settings_path(), a.settings_to_save()) {
		a.saver.revision = a.settings.remoteRevision
	}
}

// Menu writes share admission and completion with quick/remote saves. Only
// presentation belongs to the modal generation; a committed write belongs to
// the application even after Escape or a session handoff closes its form.
func (a *application) save_menu_settings(doc *config.Document, draft config.Settings, done func(error)) bool {
	if a.saves_unavailable() {
		a.voice.Say(i18n.T("Save unavailable."))
		return false
	}
	if a.speechPending {
		a.ui.failed("Could not save settings: {0}", fmt.Errorf("speech selection in progress"))
		return false
	}
	previousDraft := a.settings.saveDraft
	speechApplied := a.settings.speechAvailable && draft.Presentation.Speech.Driver == a.settings.live.Presentation.Speech.Driver && !same_speech_selection(draft.Presentation.Speech, a.settings.saveDraft.Presentation.Speech)
	if !a.saver.start(a.ctx, draft, func() error {
		var prepared speech.Transport
		if speechApplied {
			var err error
			prepared, err = a.prepareSpeech(draft.Presentation.Speech)
			if err != nil {
				return err
			}
		}
		if err := doc.Save(draft); err != nil {
			if prepared != nil {
				prepared.Close()
			}
			return err
		}
		if prepared != nil {
			if err := a.replace_speech(prepared); err != nil {
				return &savedSpeechError{err: err}
			}
			return nil
		}
		return nil
	}) {
		a.ui.failed("Could not save settings: {0}", fmt.Errorf("settings save in progress"))
		return false
	}
	a.saver.revision = a.settings.remoteRevision
	quickRevision := a.quick.revision
	a.saver.menuDone = func(err error) {
		if settings_committed(err) {
			merged := draft
			// settings_save_result already removed overrides included in the
			// commit. Remaining remote fields were assigned after admission.
			copy_remote_settings(&merged, a.settings.saveDraft, a.settings.remoteFields)
			newerQuick := false
			for _, definition := range config.Definitions() {
				if a.quick.fields[definition.Path] > quickRevision {
					if err := definition.Set(&merged, definition.Value(a.settings.live)); err != nil {
						panic(err)
					}
					newerQuick = true
				}
			}
			// Progress is shortcut/file-only and has no editable definition.
			if a.quick.fields["presentation.progress.enabled"] > quickRevision {
				merged.Presentation.Progress = a.settings.live.Presentation.Progress
			}
			if a.overrideCurrent != nil {
				live := config.Apply_application_settings(a.effective_settings(), merged)
				if merged.Presentation.Speech.Enabled == previousDraft.Presentation.Speech.Enabled {
					live.Presentation.Speech.Enabled = !a.muted
				}
				if merged.Reading.Automatic == previousDraft.Reading.Automatic {
					live.Reading.Automatic = a.engine.Automatic_reading()
				}
				if !speechApplied || err != nil {
					copy_speech_selection(&live.Presentation.Speech, a.settings.live.Presentation.Speech)
				}
				a.apply_remote_state(live, false)
				a.configure_reader()
				a.settings.saveDraft = merged
				a.quick.selectionChanged = false
			} else {
				a.apply_saved_settings(merged, speechApplied && err == nil)
			}
			a.settings.resetBase = draft // RESET reflects disk, not later overrides.
			a.quick.changed = newerQuick
		}
		done(err)
	}
	return true
}

func (a *application) settings_to_save() config.Settings {
	saved := a.settings.saveDraft
	copy_quick_settings(&saved, a.settings.live)
	if a.quick.selectionChanged {
		copy_speech_selection(&saved.Presentation.Speech, a.settings.live.Presentation.Speech)
	}
	return saved
}

func (a *application) effective_settings() config.Settings {
	base := a.settings.live
	base.Presentation.Speech.Enabled = !a.muted
	base.Reading.Automatic = a.engine.Automatic_reading()
	base.Reading.Mode = a.engine.Tracking_mode()
	return base
}

// Remote assignments are validated against effective session state, then
// separately overlaid on the save draft so unrelated next-launch choices survive.
func (a *application) apply_remote_settings(text string) string {
	if err := a.check_application_remote(text); err != nil {
		return err.Error()
	}
	updated, err := remote_settings(a.effective_settings(), text)
	if err != nil {
		return err.Error()
	}
	if updated.Presentation.Speech.Enabled && !a.settings.speechAvailable {
		return "Speech was disabled at startup; enable it in settings and relaunch"
	}
	// Apply only the requested assignments to the persistence
	// draft, retaining unrelated next-launch menu settings.
	draftBase := a.settings.saveDraft
	_, parameters, _ := strings.Cut(text, " ")
	for _, assignment := range remote_assignments(parameters) {
		path, _, _ := strings.Cut(assignment, "=")
		switch strings.ToLower(strings.TrimSpace(path)) {
		case "reading#mode", "focus#cursor", "focus#highlight":
			// Resolve paired flags against the running mode, even if the
			// next-launch draft started with a different mode.
			draftBase.Reading.Mode = a.engine.Tracking_mode()
		}
	}
	persisted, err := remote_settings(draftBase, text)
	if err != nil {
		return err.Error()
	}
	a.settings.saveDraft = persisted
	if !same_speech_selection(updated.Presentation.Speech, a.settings.live.Presentation.Speech) {
		a.quick.selectionChanged = false
	}
	a.settings.remoteRevision++
	restoreSpeech := false
	for _, assignment := range remote_assignments(parameters) {
		path, _, _ := strings.Cut(assignment, "=")
		path = strings.ToLower(strings.TrimSpace(path))
		a.settings.remoteFields[path] = a.settings.remoteRevision
		if path == "speech#enabled" {
			restoreSpeech = updated.Presentation.Speech.Enabled
		}
	}
	a.apply_remote_state(updated, restoreSpeech)
	return ""
}

func (a *application) apply_remote_state(updated config.Settings, restoreSpeech bool) {
	base := a.effective_settings()
	speechChanged := updated.Presentation.Speech.Enabled != !a.muted
	restored := restoreSpeech && updated.Presentation.Speech.Enabled && a.temporarySilence
	if restored {
		a.temporarySilence = false
	}
	if speechChanged {
		a.muted = a.voice.Toggle_mute()
	}
	a.settings.live = updated
	a.configure_screen()
	if speech_parameters(base) != speech_parameters(updated) {
		a.voice.Configure(speech_parameters(updated))
	}
	a.voice.punctuationLevel = updated.Reading.PunctuationLevel
	if base.Presentation.Sound.Volume != updated.Presentation.Sound.Volume && a.cues != nil {
		a.cues.Set_volume(updated.Presentation.Sound.Volume)
	}
	a.engine.Configure(a.settings.live.Reading.Automatic, a.settings.live.Reading.CursorEcho)
	a.engine.Configure_progress(a.settings.live.Presentation.Progress.Enabled)
	if !a.settings.live.Presentation.Sound.Enabled && a.cues != nil {
		a.cues.Clear_progress()
		a.engine.Reset_progress()
	}
	a.engine.Configure_echo(a.settings.live.Keyboard.CharacterEcho, a.settings.live.Keyboard.WordEcho, a.settings.live.Keyboard.EchoOnCapsLock)
	a.engine.Configure_tracking(a.settings.live.Reading.Mode)
	if base.Reading.Indentation != updated.Reading.Indentation {
		a.engine.Configure_indentation(updated.Reading.Indentation)
	}
	if base.Reading.Attributes != updated.Reading.Attributes || base.Reading.AttributeFormat != updated.Reading.AttributeFormat {
		a.engine.Configure_attributes(updated.Reading.Attributes, updated.Reading.AttributeFormat)
	}
	if speechChanged || restored {
		a.present_speech_state()
	}
}