// 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 sound

import (
	"bytes"
	_ "embed"
	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"slices"
	"strings"
	"time"

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

	"git.stormux.org/storm/fenrir/internal/presentation"
)

//go:embed soundicons.toml
var defaultIcons []byte

const sampleRate = 48000
const maxDuration = 10 * time.Second

type clip struct {
	samples      []float32
	finished     chan struct{} // shutdown sample submission
	notification *notificationPlayback
}
type iconMap struct {
	Icons map[presentation.Cue]string `toml:"icons"`
}

// Validate_theme accepts a single pack name or an absolute pack directory.
func Validate_theme(theme string) error {
	if strings.TrimSpace(theme) == "" || strings.ContainsAny(theme, "\x00\r\n") || theme == "." || theme == ".." || (!filepath.IsAbs(theme) && filepath.Base(theme) != theme) {
		return fmt.Errorf("sound theme must be a name or an absolute directory")
	}
	return nil
}

func Theme_paths(home, theme string) []string {
	if filepath.IsAbs(theme) {
		return []string{theme}
	}
	paths := []string{filepath.Join(home, ".local/stormux/fenrir/sounds", theme)}
	if executable, err := os.Executable(); err == nil {
		paths = append(paths, filepath.Join(filepath.Dir(executable), "config", "sound", theme))
	}
	return append(paths,
		filepath.Join("/usr/share/sounds/fenrir", theme),
		filepath.Join("/usr/share/sounds/fenrirscreenreader", theme),
	)
}

// Theme_names is used by the settings worker, never by the input/audio loop.
// Limit directory enumeration; retain saved choices separately in the form.
func Theme_names(home string) []string {
	names := map[string]bool{"default": true}
	for _, path := range Theme_paths(home, "default") {
		directory, err := os.Open(filepath.Dir(path))
		if err != nil {
			continue
		}
		entries, _ := directory.ReadDir(256)
		directory.Close()
		for _, entry := range entries {
			if entry.IsDir() && Validate_theme(entry.Name()) == nil {
				names[entry.Name()] = true
			}
		}
	}
	result := []string{"default"}
	for name := range names {
		if name != "default" {
			result = append(result, name)
		}
	}
	slices.Sort(result[1:])
	return result
}

// Load and resample once, before input grabs. No disk or decoding work belongs
// on the input loop or the audio callback. Python soundicons.conf is not read.
func load_theme(roots []string) (map[presentation.Cue]*clip, error) {
	var root string
	for _, candidate := range roots {
		info, err := os.Stat(candidate)
		if err == nil && info.IsDir() {
			root = candidate
			break
		}
		if err != nil && !errors.Is(err, os.ErrNotExist) {
			return nil, err
		}
	}
	if root == "" {
		return nil, fmt.Errorf("selected Fenrir sound pack not found")
	}
	file, err := os.Open(filepath.Join(root, "soundicons.toml"))
	var data []byte
	if errors.Is(err, os.ErrNotExist) {
		data, err = defaultIcons, nil
	} else if err == nil {
		data, err = io.ReadAll(io.LimitReader(file, (64<<10)+1))
		err = errors.Join(err, file.Close())
	}
	if err != nil {
		return nil, err
	}
	if len(data) > 64<<10 {
		return nil, fmt.Errorf("soundicons.toml exceeds 64 KiB")
	}
	var icons iconMap
	if err := toml.NewDecoder(bytes.NewReader(data)).DisallowUnknownFields().Decode(&icons); err != nil {
		return nil, fmt.Errorf("soundicons.toml: %w", err)
	}
	var known iconMap
	if err := toml.Unmarshal(defaultIcons, &known); err != nil {
		return nil, err
	}
	clips := make(map[presentation.Cue]*clip)
	var problems []error
	for cue, name := range icons.Icons {
		if _, ok := known.Icons[cue]; !ok {
			return nil, fmt.Errorf("unknown sound cue %q", cue)
		}
		if name == "" || filepath.Base(name) != name || name == "." || name == ".." {
			return nil, fmt.Errorf("sound cue %q requires a filename in the theme directory", cue)
		}
		item, err := decode_file(filepath.Join(root, name))
		if err != nil {
			problems = append(problems, fmt.Errorf("%s: %w", cue, err))
			continue
		}
		clips[cue] = item
	}
	return clips, errors.Join(problems...)
}

func decode_file(path string) (*clip, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer file.Close()
	info, err := file.Stat()
	if err != nil {
		return nil, err
	}
	if !info.Mode().IsRegular() || info.Size() > 4<<20 {
		return nil, fmt.Errorf("sound must be a regular WAV file at most 4 MiB")
	}
	return decode_wav(io.LimitReader(file, (4<<20)+1))
}