namespace Evergreen.Health.Application.Health.Sleep;

public enum ReservedSleepPhase { Disabled, WaitingForBed, Settling, Guiding, Music, Stopped }
public enum SleepWorkflowActionKind { PrepareEnvironment, StartGentleRightMassage, RequestGuidance, RestartMusicAtFifty, StartLightFade }
public sealed record SleepWorkflowAction(SleepWorkflowActionKind Kind, GuidanceClip? Clip = null, int? VolumePercent = null);

/// <summary>
/// 只规划未来动作：没有 HostedService、设备命令或 API 路由，本版默认 Disabled。
/// 实际接入时由场景协调层消费动作，不能从传感器适配器直接控制家具。
/// </summary>
public sealed class ReservedSleepWorkflow
{
    private readonly SleepWorkflowOptions _options;
    private readonly GuidanceCatalog _guidance;
    private DateTimeOffset? _occupiedSince;
    private DateTimeOffset? _fadeAt;
    private GuidanceClip? _pendingClip;
    private bool _fadeIssued;
    private bool _initialGuide;
    public ReservedSleepPhase Phase { get; private set; } = ReservedSleepPhase.Disabled;

    public ReservedSleepWorkflow(SleepWorkflowOptions options, GuidanceCatalog guidance)
        => (_options, _guidance) = (options, guidance);

    public IReadOnlyList<SleepWorkflowAction> Start()
    {
        _occupiedSince = null; _fadeAt = null; _pendingClip = null; _fadeIssued = false; _initialGuide = false;
        Phase = _options.Enabled ? ReservedSleepPhase.WaitingForBed : ReservedSleepPhase.Disabled;
        return _options.Enabled ? [new(SleepWorkflowActionKind.PrepareEnvironment)] : [];
    }

    public IReadOnlyList<SleepWorkflowAction> Observe(SleepObservation observation, DateTimeOffset now)
    {
        if (Phase is not (ReservedSleepPhase.WaitingForBed or ReservedSleepPhase.Settling)) return [];
        var fresh = observation.Availability == SleepDataAvailability.Available && observation.ObservedAt is not null &&
            now - observation.ObservedAt <= _options.MaximumObservationAge && observation.ObservedAt <= now.AddMinutes(1);
        if (!fresh || observation.Presence != BedPresence.Occupied)
        {
            _occupiedSince = null; Phase = ReservedSleepPhase.WaitingForBed; return [];
        }
        _occupiedSince ??= now;
        Phase = ReservedSleepPhase.Settling;
        if (now - _occupiedSince < _options.StableBedDuration) return [];
        _pendingClip = _guidance.InitialRelaxation;
        _initialGuide = true;
        Phase = ReservedSleepPhase.Guiding;
        return [new(SleepWorkflowActionKind.StartGentleRightMassage),
            new(SleepWorkflowActionKind.RequestGuidance, _pendingClip, _options.GuidanceVolumePercent)];
    }

    public IReadOnlyList<SleepWorkflowAction> GuidanceCompleted(string clipKey, bool completed, DateTimeOffset now)
    {
        if (Phase != ReservedSleepPhase.Guiding || !completed || _pendingClip?.Key != clipKey || !_pendingClip.Playable) return [];
        Phase = ReservedSleepPhase.Music;
        if (_initialGuide) _fadeAt = now + _options.PostGuidanceFadeDelay;
        return [new(SleepWorkflowActionKind.RestartMusicAtFifty, VolumePercent: 50)];
    }

    public IReadOnlyList<SleepWorkflowAction> RequestReminder(GuidanceClip clip)
    {
        if (!_options.Enabled || Phase != ReservedSleepPhase.Music) return [];
        _initialGuide = false; _pendingClip = clip; Phase = ReservedSleepPhase.Guiding;
        return [new(SleepWorkflowActionKind.RequestGuidance, clip, _options.GuidanceVolumePercent)];
    }

    public IReadOnlyList<SleepWorkflowAction> Tick(DateTimeOffset now)
    {
        if (Phase != ReservedSleepPhase.Music || _fadeIssued || _fadeAt is null || now < _fadeAt) return [];
        _fadeIssued = true; return [new(SleepWorkflowActionKind.StartLightFade)];
    }

    public void Stop()
    {
        Phase = ReservedSleepPhase.Stopped; _occupiedSince = null; _fadeAt = null; _pendingClip = null;
    }
}