// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.

using Microsoft.Extensions.Diagnostics.HealthChecks;
using StellaOps.Eventing.Storage;

namespace StellaOps.Timeline.WebService.Endpoints;

/// <summary>
/// Health check endpoints.
/// </summary>
public static class HealthEndpoints
{
    /// <summary>
    /// Maps health check endpoints.
    /// </summary>
    public static void MapHealthEndpoints(this IEndpointRouteBuilder app)
    {
        app.MapHealthChecks("/health");
        app.MapHealthChecks("/health/ready", new Microsoft.AspNetCore.Diagnostics.HealthChecks.HealthCheckOptions
        {
            Predicate = check => check.Tags.Contains("ready")
        });
        app.MapHealthChecks("/health/live", new Microsoft.AspNetCore.Diagnostics.HealthChecks.HealthCheckOptions
        {
            Predicate = check => check.Tags.Contains("live")
        });
    }
}

/// <summary>
/// Health check for timeline service.
/// </summary>
public sealed class TimelineHealthCheck : IHealthCheck
{
    private readonly ITimelineEventStore _eventStore;

    /// <summary>
    /// Initializes a new instance of the <see cref="TimelineHealthCheck"/> class.
    /// </summary>
    public TimelineHealthCheck(ITimelineEventStore eventStore)
    {
        _eventStore = eventStore;
    }

    /// <inheritdoc/>
    public async Task<HealthCheckResult> CheckHealthAsync(
        HealthCheckContext context,
        CancellationToken cancellationToken = default)
    {
        try
        {
            // Simple check - try to count events for a nonexistent correlation
            // This validates database connectivity
            await _eventStore.CountByCorrelationIdAsync("__health_check__", cancellationToken);
            return HealthCheckResult.Healthy("Timeline service is healthy");
        }
        catch (Exception ex)
        {
            return HealthCheckResult.Unhealthy("Timeline service is unhealthy", ex);
        }
    }
}