using Microsoft.Extensions.Diagnostics.HealthChecks;
using Microsoft.Extensions.Options;
using StellaOps.AirGap.Time.Models;
using StellaOps.AirGap.Time.Services;

namespace StellaOps.AirGap.Time.Health;

public sealed class TimeAnchorHealthCheck : IHealthCheck
{
    private readonly TimeStatusService _statusService;
    private readonly IOptions<AirGapOptions> _options;
    private readonly TimeProvider _timeProvider;

    public TimeAnchorHealthCheck(TimeStatusService statusService, IOptions<AirGapOptions> options, TimeProvider timeProvider)
    {
        _statusService = statusService;
        _options = options;
        _timeProvider = timeProvider;
    }

    public async Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
    {
        var opts = _options.Value;
        var status = await _statusService.GetStatusAsync(opts.TenantId, _timeProvider.GetUtcNow(), cancellationToken).ConfigureAwait(false);

        if (status.Anchor == TimeAnchor.Unknown)
        {
            return HealthCheckResult.Unhealthy("time-anchor-missing");
        }

        if (status.Staleness.IsBreach)
        {
            return HealthCheckResult.Unhealthy("time-anchor-stale");
        }

        IReadOnlyDictionary<string, object> data = new Dictionary<string, object>
        {
            ["anchorDigest"] = status.Anchor.TokenDigest,
            ["ageSeconds"] = status.Staleness.AgeSeconds,
            ["warningSeconds"] = status.Staleness.WarningSeconds,
            ["breachSeconds"] = status.Staleness.BreachSeconds
        };

        if (status.Staleness.IsWarning)
        {
            return HealthCheckResult.Degraded("time-anchor-warning", data: data);
        }

        return HealthCheckResult.Healthy("time-anchor-healthy", data);
    }
}