using System.IO;
using System.Text.Json;
using RgbLedStripController.Core;
using MediaColor = System.Windows.Media.Color;

namespace RgbLedStripController.Services;

public sealed class SettingsStore
{
    private readonly string _settingsPath;
    private readonly SemaphoreSlim _writeLock = new(1, 1);
    private readonly JsonSerializerOptions _jsonOptions = new()
    {
        WriteIndented = true,
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase
    };

    public SettingsStore()
    {
        var settingsDirectory = Path.Combine(
            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
            "RgbLedStripController");

        _settingsPath = Path.Combine(settingsDirectory, "settings.json");
    }

    public async Task<SettingsSnapshot> LoadAsync(CancellationToken cancellationToken = default)
    {
        if (!File.Exists(_settingsPath))
        {
            return CreateDefaultSnapshot();
        }

        try
        {
            await using var stream = File.OpenRead(_settingsPath);
            var stored = await JsonSerializer.DeserializeAsync<StoredSettings>(stream, _jsonOptions, cancellationToken);

            return new SettingsSnapshot(
                stored?.KnownDevices ?? [],
                new Dictionary<string, string>(stored?.DeviceAliases ?? new Dictionary<string, string>(), StringComparer.OrdinalIgnoreCase),
                ParseColor(stored?.SelectedColorHex),
                stored?.Brightness ?? 100,
                stored?.EffectSpeed ?? 50,
                stored?.CurrentMode ?? LightingMode.Rgb,
                stored?.GrayscaleLevel ?? 100,
                stored?.TemperatureLevel ?? 50,
                stored?.SelectedEffectId ?? 0,
                stored?.IsPoweredOn ?? false);
        }
        catch
        {
            return CreateDefaultSnapshot();
        }
    }

    public async Task SaveAsync(SettingsSnapshot snapshot, CancellationToken cancellationToken = default)
    {
        await _writeLock.WaitAsync(cancellationToken);

        try
        {
            var directory = Path.GetDirectoryName(_settingsPath);
            if (!string.IsNullOrWhiteSpace(directory))
            {
                Directory.CreateDirectory(directory);
            }

            await using var stream = File.Create(_settingsPath);
            var stored = new StoredSettings
            {
                KnownDevices = snapshot.KnownDevices.ToList(),
                DeviceAliases = new Dictionary<string, string>(snapshot.DeviceAliases, StringComparer.OrdinalIgnoreCase),
                SelectedColorHex = $"#{snapshot.SelectedColor.R:X2}{snapshot.SelectedColor.G:X2}{snapshot.SelectedColor.B:X2}",
                Brightness = snapshot.Brightness,
                EffectSpeed = snapshot.EffectSpeed,
                CurrentMode = snapshot.CurrentMode,
                GrayscaleLevel = snapshot.GrayscaleLevel,
                TemperatureLevel = snapshot.TemperatureLevel,
                SelectedEffectId = snapshot.SelectedEffectId,
                IsPoweredOn = snapshot.IsPoweredOn
            };

            await JsonSerializer.SerializeAsync(stream, stored, _jsonOptions, cancellationToken);
        }
        finally
        {
            _writeLock.Release();
        }
    }

    private static SettingsSnapshot CreateDefaultSnapshot()
        => new(
            [],
            new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase),
            MediaColor.FromRgb(255, 106, 78),
            100,
            50,
            LightingMode.Rgb,
            100,
            50,
            0,
            false);

    private static MediaColor ParseColor(string? value)
    {
        if (string.IsNullOrWhiteSpace(value) || value.Length != 7 || value[0] != '#')
        {
            return MediaColor.FromRgb(255, 106, 78);
        }

        return MediaColor.FromRgb(
            Convert.ToByte(value.Substring(1, 2), 16),
            Convert.ToByte(value.Substring(3, 2), 16),
            Convert.ToByte(value.Substring(5, 2), 16));
    }

    private sealed class StoredSettings
    {
        public List<DeviceProfile> KnownDevices { get; set; } = [];

        public Dictionary<string, string> DeviceAliases { get; set; } = new(StringComparer.OrdinalIgnoreCase);

        public string? SelectedColorHex { get; set; }

        public byte Brightness { get; set; }

        public byte EffectSpeed { get; set; }

        public LightingMode CurrentMode { get; set; }

        public byte GrayscaleLevel { get; set; }

        public byte TemperatureLevel { get; set; }

        public byte SelectedEffectId { get; set; }

        public bool IsPoweredOn { get; set; }
    }
}