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

package preferences

import (
	"slices"
	"strings"

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

type Discovery struct {
	Driver  string
	Catalog speech.Catalog
	Err     error
}

// Discover_choices runs only in a worker, never on the input loop.
func Discover_choices(settings config.Settings) Discovery {
	driver, err := speech.Find_driver(settings.Presentation.Speech.Driver)
	if err == nil {
		err = driver.Availability()
	}
	if err != nil {
		return Discovery{Driver: settings.Presentation.Speech.Driver, Err: err}
	}
	if driver.Catalog == nil {
		return Discovery{Driver: driver.ID}
	}
	catalog, err := driver.Catalog(speech.Options{})
	return Discovery{Driver: driver.ID, Catalog: catalog, Err: err}
}

func (d Discovery) Choices(settings config.Settings) Choices {
	selected := settings.Presentation.Speech
	// Driver changes apply on relaunch. A catalog captured for the old driver
	// must never supply Speech Dispatcher voices to a hardware selection.
	if d.Driver != "" && d.Driver != selected.Driver {
		d = Discovery{}
	}
	result := Choices{}
	modules := []config.Choice{{ID: "", Label: "default"}}
	for _, module := range d.Catalog.Modules {
		modules = append(modules, config.Choice{ID: module, Label: module})
	}
	result["presentation.speech.module"] = preserve_choice(modules, selected.Module, d.Err)
	voices := d.Catalog.Voices[selected.Module]
	err := d.Err
	if moduleErr := d.Catalog.Errors[selected.Module]; moduleErr != nil {
		err = moduleErr
	}
	languages := []config.Choice{{ID: "", Label: "default"}}
	seen := map[string]bool{}
	for _, voice := range voices {
		if !seen[voice.Language] {
			languages = append(languages, config.Choice{ID: voice.Language, Label: voice.Language})
			seen[voice.Language] = true
		}
	}
	result["presentation.speech.language"] = preserve_choice(languages, selected.Language, err)
	filtered := voices
	if selected.Language != "" {
		filtered = speech.Language_voices(voices, selected.Language)
	} else {
		espeak := strings.Contains(strings.ToLower(selected.Module), "espeak")
		if selected.Module == "" {
			for module, candidates := range d.Catalog.Voices {
				if strings.Contains(strings.ToLower(module), "espeak") && slices.Equal(voices, candidates) {
					espeak = true
					break
				}
			}
		}
		if espeak {
			filtered = speech.Language_voices(voices, "")
		}
	}
	voiceChoices := []config.Choice{{ID: "", Label: "default"}}
	for _, voice := range filtered {
		voiceChoices = append(voiceChoices, config.Choice{ID: voice.Name, Label: voice.Name})
	}
	// Locale filtering must not turn a valid saved voice into an offline choice.
	for _, voice := range voices {
		if selected.Language == "" && voice.Name == selected.Voice && !slices.ContainsFunc(voiceChoices, func(c config.Choice) bool { return c.ID == voice.Name }) {
			voiceChoices = append(voiceChoices, config.Choice{ID: voice.Name, Label: voice.Name})
		}
	}
	result["presentation.speech.voice"] = preserve_choice(voiceChoices, selected.Voice, err)
	return result
}

func preserve_choice(choices []config.Choice, saved string, err error) []config.Choice {
	if err != nil {
		choices[0].Unavailable = err.Error()
	}
	if slices.ContainsFunc(choices, func(c config.Choice) bool { return c.ID == saved }) {
		return choices
	}
	reason := "not reported by the selected speech driver"
	if err != nil {
		reason = err.Error()
	}
	return append(choices, config.Choice{ID: saved, Label: saved, Unavailable: reason})
}

// Refresh_speech updates driver visibility and dependent choices. Driver changes
// keep hidden edits; module/language changes clear their dependent selections.
// The result tells the host when a different driver's catalog may be needed.
func (d Discovery) Refresh_speech(session *interaction.Session, previous *config.Settings) bool {
	next := *previous
	values := session.Values()
	for path, target := range map[string]*string{
		"presentation.speech.driver":   &next.Presentation.Speech.Driver,
		"presentation.speech.module":   &next.Presentation.Speech.Module,
		"presentation.speech.language": &next.Presentation.Speech.Language,
		"presentation.speech.voice":    &next.Presentation.Speech.Voice,
	} {
		control, ok := values[path]
		if !ok && path == "presentation.speech.driver" {
			continue
		}
		if !ok || control.Selected < 0 || control.Selected >= len(control.Choices) {
			return false
		}
		*target = control.Choices[control.Selected].ID
	}
	moduleChanged := next.Presentation.Speech.Module != previous.Presentation.Speech.Module
	languageChanged := next.Presentation.Speech.Language != previous.Presentation.Speech.Language
	driverChanged := next.Presentation.Speech.Driver != previous.Presentation.Speech.Driver
	*previous = next
	if driverChanged {
		driver, _ := speech.Find_driver(next.Presentation.Speech.Driver)
		session.Set_hidden("presentation", "speech.test", !driver.Hardware)
		for _, definition := range config.Definitions() {
			if definition.SpeechCapability != "" {
				session.Set_hidden("presentation", strings.TrimPrefix(definition.Path, "presentation."), !definition.Available(next))
			}
		}
		// Keep each backend's hidden selections intact while another driver is
		// selected. The host supplies that driver's cached/discovered catalog.
		return true
	}
	if !driverChanged && !moduleChanged && !languageChanged {
		return false
	}
	if moduleChanged {
		next.Presentation.Speech.Language = ""
	}
	next.Presentation.Speech.Voice = ""
	choices := d.Choices(next)
	if moduleChanged {
		session.Replace_choices("presentation", "speech.language", interaction_choices(choices["presentation.speech.language"]), "")
	}
	session.Replace_choices("presentation", "speech.voice", interaction_choices(choices["presentation.speech.voice"]), "")
	*previous = next
	return false
}

// Refresh_catalog applies a worker result to the current selector draft. It
// never moves focus or resets a selection made while discovery was pending.
func (d Discovery) Refresh_catalog(session *interaction.Session, selected config.Settings) {
	choices := d.Choices(selected)
	for path, value := range map[string]string{
		"presentation.speech.module":   selected.Presentation.Speech.Module,
		"presentation.speech.language": selected.Presentation.Speech.Language,
		"presentation.speech.voice":    selected.Presentation.Speech.Voice,
	} {
		session.Replace_choices("presentation", strings.TrimPrefix(path, "presentation."), interaction_choices(choices[path]), value)
	}
}

func interaction_choices(choices []config.Choice) []interaction.Choice {
	result := make([]interaction.Choice, 0, len(choices))
	for _, choice := range choices {
		result = append(result, interaction.Choice{ID: choice.ID, Label: choice.Label, Unavailable: choice.Unavailable})
	}
	return result
}