namespace IronTelemetry.Client;

/// <summary>
/// Ambient journey context that automatically flows through async calls.
/// Level 1 integration - no manual ID passing required.
/// </summary>
public static class JourneyContext
{
    private static readonly AsyncLocal<JourneyScope?> _currentJourney = new();
    private static readonly AsyncLocal<StepScope?> _currentStep = new();

    /// <summary>
    /// Gets the current journey, if any.
    /// </summary>
    public static JourneyScope? Current => _currentJourney.Value;

    /// <summary>
    /// Gets the current step, if any.
    /// </summary>
    public static StepScope? CurrentStep => _currentStep.Value;

    /// <summary>
    /// Gets the current journey ID, if any.
    /// </summary>
    public static string? CurrentJourneyId => _currentJourney.Value?.JourneyId;

    /// <summary>
    /// Gets the current step ID, if any.
    /// </summary>
    public static string? CurrentStepId => _currentStep.Value?.StepId;

    /// <summary>
    /// Start a new journey. All telemetry within this scope will be correlated.
    /// </summary>
    /// <param name="name">The journey name (e.g., "Checkout Flow", "User Onboarding")</param>
    /// <returns>A disposable scope - dispose to end the journey</returns>
    public static JourneyScope StartJourney(string name)
    {
        var journey = new JourneyScope(name);
        _currentJourney.Value = journey;
        return journey;
    }

    /// <summary>
    /// Start a step within the current journey.
    /// If no journey exists, one is created automatically.
    /// </summary>
    /// <param name="name">The step name (e.g., "Validate Cart", "Process Payment")</param>
    /// <param name="category">Optional category (e.g., "business", "technical", "navigation")</param>
    /// <returns>A disposable scope - dispose to end the step</returns>
    public static StepScope StartStep(string name, string? category = null)
    {
        // Auto-create journey if none exists
        if (_currentJourney.Value == null)
        {
            StartJourney("Auto Journey");
        }

        var step = new StepScope(_currentJourney.Value!, name, category);
        _currentStep.Value = step;
        return step;
    }

    /// <summary>
    /// Set the user for the current journey.
    /// </summary>
    public static void SetUser(string userId, string? email = null, string? username = null)
    {
        if (_currentJourney.Value != null)
        {
            _currentJourney.Value.SetUser(userId, email, username);
        }

        // Also set on the global client
        IronTelemetry.SetUser(userId, email, username);
    }

    /// <summary>
    /// Add metadata to the current journey.
    /// </summary>
    public static void SetMetadata(string key, object value)
    {
        _currentJourney.Value?.SetMetadata(key, value);
    }

    /// <summary>
    /// Mark the current step as failed.
    /// </summary>
    public static void FailCurrentStep(string? reason = null)
    {
        _currentStep.Value?.Fail(reason);
    }

    internal static void ClearJourney()
    {
        _currentJourney.Value = null;
        _currentStep.Value = null;
    }

    internal static void ClearStep()
    {
        _currentStep.Value = null;
    }
}

/// <summary>
/// Represents an active journey scope.
/// </summary>
public class JourneyScope : IDisposable
{
    private readonly DateTime _startTime;
    private bool _disposed;

    public string JourneyId { get; }
    public string Name { get; }
    public string? UserId { get; private set; }
    public string? UserEmail { get; private set; }
    public string? Username { get; private set; }
    public JourneyStatus Status { get; private set; } = JourneyStatus.InProgress;
    public Dictionary<string, object> Metadata { get; } = new();

    internal JourneyScope(string name)
    {
        JourneyId = Guid.NewGuid().ToString();
        Name = name;
        _startTime = DateTime.UtcNow;

        // Send journey start event
        TelemetryClient.CurrentClient?.EnqueueJourneyStart(this);
    }

    public void SetUser(string userId, string? email = null, string? username = null)
    {
        UserId = userId;
        UserEmail = email;
        Username = username;
    }

    public void SetMetadata(string key, object value)
    {
        Metadata[key] = value;
    }

    public void Complete()
    {
        Status = JourneyStatus.Completed;
    }

    public void Fail(string? reason = null)
    {
        Status = JourneyStatus.Failed;
        if (reason != null)
        {
            Metadata["failureReason"] = reason;
        }
    }

    public void Abandon()
    {
        Status = JourneyStatus.Abandoned;
    }

    public void Dispose()
    {
        if (_disposed) return;
        _disposed = true;

        var duration = DateTime.UtcNow - _startTime;
        Metadata["durationMs"] = duration.TotalMilliseconds;

        // If still in progress, mark as completed
        if (Status == JourneyStatus.InProgress)
        {
            Status = JourneyStatus.Completed;
        }

        // Send journey end event
        TelemetryClient.CurrentClient?.EnqueueJourneyEnd(this);

        JourneyContext.ClearJourney();
    }
}

/// <summary>
/// Represents an active step within a journey.
/// </summary>
public class StepScope : IDisposable
{
    private readonly JourneyScope _journey;
    private readonly DateTime _startTime;
    private readonly StepScope? _parentStep;
    private bool _disposed;

    public string StepId { get; }
    public string Name { get; }
    public string? Category { get; }
    public StepStatus Status { get; private set; } = StepStatus.InProgress;
    public string? FailureReason { get; private set; }
    public Dictionary<string, object> Data { get; } = new();

    internal StepScope(JourneyScope journey, string name, string? category)
    {
        _journey = journey;
        _parentStep = JourneyContext.CurrentStep;
        StepId = Guid.NewGuid().ToString();
        Name = name;
        Category = category;
        _startTime = DateTime.UtcNow;

        // Send step start event
        TelemetryClient.CurrentClient?.EnqueueStepStart(this, journey.JourneyId);
    }

    public string? ParentStepId => _parentStep?.StepId;

    public void SetData(string key, object value)
    {
        Data[key] = value;
    }

    public void Complete()
    {
        Status = StepStatus.Completed;
    }

    public void Fail(string? reason = null)
    {
        Status = StepStatus.Failed;
        FailureReason = reason;
    }

    public void Skip(string? reason = null)
    {
        Status = StepStatus.Skipped;
        if (reason != null)
        {
            Data["skipReason"] = reason;
        }
    }

    public void Dispose()
    {
        if (_disposed) return;
        _disposed = true;

        var duration = DateTime.UtcNow - _startTime;
        Data["durationMs"] = duration.TotalMilliseconds;

        // If still in progress, mark as completed
        if (Status == StepStatus.InProgress)
        {
            Status = StepStatus.Completed;
        }

        // Send step end event
        TelemetryClient.CurrentClient?.EnqueueStepEnd(this, _journey.JourneyId);

        // Restore parent step as current
        JourneyContext.ClearStep();
    }
}

/// <summary>
/// Journey status for SDK tracking.
/// </summary>
public enum JourneyStatus
{
    InProgress,
    Completed,
    Failed,
    Abandoned
}

/// <summary>
/// Step status for SDK tracking.
/// </summary>
public enum StepStatus
{
    InProgress,
    Completed,
    Failed,
    Skipped
}