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

namespace SSPCTester.UI.Services;

/// <summary>将机器本地硬件配置保存到 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 SemaphoreSlim _writeLock = new(1, 1);
    private readonly object _timerLock = new();
    private Timer? _timer;

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

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

    public void ScheduleSave()
    {
        lock (_timerLock)
        {
            _timer?.Dispose();
            _timer = new Timer(async _ =>
            {
                try { await SaveAsync().ConfigureAwait(false); }
                catch { /* 后续显式保存或退出时会再次尝试 */ }
            }, null, 600, Timeout.Infinite);
        }
    }

    public async Task SaveAsync()
    {
        await _writeLock.WaitAsync().ConfigureAwait(false);
        try
        {
            string path = SettingsPath;
            Directory.CreateDirectory(Path.GetDirectoryName(path)!);
            string temp = path + ".tmp";
            _devices.Daq.Channels = DaqChannelOptionsNormalizer.Normalize(_devices.Daq.Channels);
            var model = new
            {
                Devices = _devices,
                Storage = _storage,
                Report = _report
            };
            await File.WriteAllTextAsync(temp, JsonSerializer.Serialize(model, JsonOptions)).ConfigureAwait(false);
            File.Move(temp, path, true);
            WriteDaqSaveTrace(path);
        }
        finally { _writeLock.Release(); }
    }

    private void WriteDaqSaveTrace(string settingsPath)
    {
        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()
    {
        lock (_timerLock) { _timer?.Dispose(); }
        _writeLock.Dispose();
    }
}