// 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 config

import (
	"bytes"
	"fmt"

	"github.com/pelletier/go-toml/v2"
)

// decode_v1 is the explicit migration boundary for the prototype's flat
// speech/sound tables. Unknown keys and mixed old/new schemas are rejected.
func decode_v1(data []byte) (Settings, error) {
	defaults := Defaults()
	type oldSpeech struct {
		Enabled bool   `toml:"enabled"`
		Rate    int    `toml:"rate"`
		Module  string `toml:"module"`
		Socket  string `toml:"socket"`
	}
	old := struct {
		Version   int       `toml:"version"`
		Review    Review    `toml:"review"`
		Speech    oldSpeech `toml:"speech"`
		Sound     Sound     `toml:"sound"`
		Keyboard  Keyboard  `toml:"keyboard"`
		Reading   Reading   `toml:"reading"`
		Clipboard Clipboard `toml:"clipboard"`
		General   General   `toml:"general"`
		Scripts   Scripts   `toml:"scripts"`
		Remote    Remote    `toml:"remote"`
	}{Review: defaults.Review, Version: 1, Speech: oldSpeech{Enabled: true, Rate: defaults.Presentation.Speech.Rate}, Sound: defaults.Presentation.Sound, Keyboard: defaults.Keyboard, Reading: defaults.Reading, Clipboard: defaults.Clipboard, General: defaults.General, Scripts: defaults.Scripts, Remote: defaults.Remote}
	if err := toml.NewDecoder(bytes.NewReader(data)).DisallowUnknownFields().Decode(&old); err != nil {
		return Settings{}, fmt.Errorf("parse version 1 settings: %w", err)
	}
	defaults.Presentation.Speech.Enabled = old.Speech.Enabled
	defaults.Presentation.Speech.Rate = old.Speech.Rate
	defaults.Presentation.Speech.Module = old.Speech.Module
	defaults.Presentation.Sound = old.Sound
	defaults.Keyboard, defaults.Reading, defaults.Clipboard = old.Keyboard, old.Reading, old.Clipboard
	defaults.General, defaults.Scripts, defaults.Remote = old.General, old.Scripts, old.Remote
	defaults.Review = old.Review
	return defaults, defaults.Validate()
}

// Version 2 briefly exposed Socket under Presentation. Migrate it away without
// carrying an endpoint override into either runtime settings or future saves.
func decode_v2(data []byte) (Settings, error) {
	defaults := Defaults()
	var old struct {
		Version      int    `toml:"version"`
		Review       Review `toml:"review"`
		Presentation struct {
			Speech struct {
				Speech
				Socket string `toml:"socket"`
			} `toml:"speech"`
			Sound Sound `toml:"sound"`
		} `toml:"presentation"`
		Keyboard  Keyboard  `toml:"keyboard"`
		Reading   Reading   `toml:"reading"`
		Clipboard Clipboard `toml:"clipboard"`
		General   General   `toml:"general"`
		Scripts   Scripts   `toml:"scripts"`
		Remote    Remote    `toml:"remote"`
	}
	old.Version = 2
	old.Review = defaults.Review
	old.Presentation.Speech.Speech = defaults.Presentation.Speech
	old.Presentation.Sound = defaults.Presentation.Sound
	old.Keyboard, old.Reading, old.Clipboard = defaults.Keyboard, defaults.Reading, defaults.Clipboard
	old.General, old.Scripts, old.Remote = defaults.General, defaults.Scripts, defaults.Remote
	if err := toml.NewDecoder(bytes.NewReader(data)).DisallowUnknownFields().Decode(&old); err != nil {
		return Settings{}, fmt.Errorf("parse version 2 settings: %w", err)
	}
	defaults.Presentation.Speech = old.Presentation.Speech.Speech
	defaults.Presentation.Sound = old.Presentation.Sound
	defaults.Keyboard, defaults.Reading, defaults.Clipboard = old.Keyboard, old.Reading, old.Clipboard
	defaults.General, defaults.Scripts, defaults.Remote = old.General, old.Scripts, old.Remote
	defaults.Review = old.Review
	return defaults, defaults.Validate()
}