using System.IO;
using System.Text.Json;
using Microsoft.Extensions.Options;
using SSPCTester.Devices.Config;

namespace SSPCTester.UI.Services;

/// <summary>将机器本地配置保存到 LocalAppData，不修改发布目录。</summary>
public sealed class UserSettingsStore : IDisposable
{
    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        WriteIndented = true,
        Encoder = System.Text.Encodings.Web.JavaScriptEncoder.UnsafeRelaxedJsonEscaping
    };

    private readonly DeviceOptions _devices;
    private readonly StorageOptions _storage;
    private readonly ReportOptions _report;
    private readonly ConsoleOptions _console;
    private readonly SemaphoreSlim _writeLock = new(1, 1);

    public UserSettingsStore(
        IOptions<DeviceOptions> devices,
        IOptions<StorageOptions> storage,
        IOptions<ReportOptions> report,
        IOptions<ConsoleOptions> console)
    {
        _devices = devices.Value;
        _storage = storage.Value;
        _report = report.Value;
        _console = console.Value;
    }

    public static string SettingsPath => Path.Combine(
        Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
        "SSPCTester", "settings.json");

    /// <summary>
    /// Loads console presets directly from the user settings JSON so preset arrays
    /// replace the defaults as a whole. IConfiguration merges arrays by index and
    /// cannot represent a deleted item or an explicitly empty preset list.
    /// </summary>
    public static ConsoleOptions? LoadConsoleOptions()
    {
        try
        {
            string path = SettingsPath;
            if (!File.Exists(path)) return null;

            using var document = JsonDocument.Parse(File.ReadAllText(path));
            if (!document.RootElement.TryGetProperty(ConsoleOptions.SectionName, out var consoleElement))
                return null;

            var console = consoleElement.Deserialize<ConsoleOptions>(JsonOptions);
            if (console is null) return null;

            EnsureConsoleDefaults(console);
            return console;
        }
        catch
        {
            return null;
        }
    }

    public async Task SaveAsync()
    {
        await SaveAsync(_devices, _storage, _report, _console).ConfigureAwait(false);
    }

    public async Task SaveAsync(DeviceOptions devices, StorageOptions storage, ReportOptions report)
    {
        await SaveAsync(devices, storage, report, _console).ConfigureAwait(false);
    }

    public async Task SaveAsync(DeviceOptions devices, StorageOptions storage, ReportOptions report, ConsoleOptions console)
    {
        await _writeLock.WaitAsync().ConfigureAwait(false);
        try
        {
            string path = SettingsPath;
            Directory.CreateDirectory(Path.GetDirectoryName(path)!);
            string temp = path + ".tmp";
            var snapshot = CreateSnapshot(devices, storage, report, console);
            var model = new
            {
                Devices = snapshot.Devices,
                Storage = snapshot.Storage,
                Report = snapshot.Report,
                Console = snapshot.Console
            };
            await File.WriteAllTextAsync(temp, JsonSerializer.Serialize(model, JsonOptions)).ConfigureAwait(false);
            File.Move(temp, path, true);
            WriteDaqSaveTrace(path, snapshot.Devices);
        }
        finally { _writeLock.Release(); }
    }

    public SettingsSnapshot? LoadSnapshot()
    {
        try
        {
            string path = SettingsPath;
            if (!File.Exists(path)) return null;
            var json = File.ReadAllText(path);
            var payload = JsonSerializer.Deserialize<SettingsPayload>(json, JsonOptions);
            if (payload is null) return null;
            return CreateSnapshot(payload.Devices, payload.Storage, payload.Report, payload.Console);
        }
        catch
        {
            return null;
        }
    }

    private static SettingsSnapshot CreateSnapshot(DeviceOptions devices, StorageOptions storage, ReportOptions report, ConsoleOptions console)
    {
        var copiedDevices = JsonSerializer.Deserialize<DeviceOptions>(JsonSerializer.Serialize(devices, JsonOptions)) ?? new DeviceOptions();
        var copiedStorage = JsonSerializer.Deserialize<StorageOptions>(JsonSerializer.Serialize(storage, JsonOptions)) ?? new StorageOptions();
        var copiedReport = JsonSerializer.Deserialize<ReportOptions>(JsonSerializer.Serialize(report, JsonOptions)) ?? new ReportOptions();
        var copiedConsole = JsonSerializer.Deserialize<ConsoleOptions>(JsonSerializer.Serialize(console, JsonOptions)) ?? new ConsoleOptions();
        copiedDevices.Daq.Channels = DaqChannelOptionsNormalizer.Normalize(copiedDevices.Daq.Channels);
        EnsureConsoleDefaults(copiedConsole);
        return new SettingsSnapshot(copiedDevices, copiedStorage, copiedReport, copiedConsole);
    }

    private static void EnsureConsoleDefaults(ConsoleOptions console)
    {
        if (console.PowerPresets == null)
            console.PowerPresets = ConsoleOptions.DefaultPowerPresets();
        if (console.LoadPresets == null)
            console.LoadPresets = ConsoleOptions.DefaultLoadPresets();
    }

    private void WriteDaqSaveTrace(string settingsPath, DeviceOptions devices)
    {
        try
        {
            string logDir = Path.Combine(
                Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
                "SSPCTester", "Logs");
            Directory.CreateDirectory(logDir);
            string channels = string.Join(", ", devices.Daq.Channels
                .OrderBy(x => x.PhysicalChannel)
                .Select(x => $"CH{x.PhysicalChannel}:{x.Role}/{x.IsCalibrated}"));
            File.AppendAllText(
                Path.Combine(logDir, "settings-save.log"),
                $"{DateTime.Now:yyyy-MM-dd HH:mm:ss.fff} {settingsPath} Pre={devices.Daq.PreTriggerMs:R} Post={devices.Daq.PostTriggerMs:R} Channels=[{channels}]{Environment.NewLine}");
        }
        catch { }
    }

    public void Dispose() => _writeLock.Dispose();
}

public sealed record SettingsSnapshot(DeviceOptions Devices, StorageOptions Storage, ReportOptions Report, ConsoleOptions Console);

internal sealed class SettingsPayload
{
    public DeviceOptions Devices { get; set; } = new();
    public StorageOptions Storage { get; set; } = new();
    public ReportOptions Report { get; set; } = new();
    public ConsoleOptions Console { get; set; } = new();
}