using Microsoft.Extensions.Diagnostics.HealthChecks;
using Microsoft.Extensions.Options;
using ZB.MOM.WW.ScadaBridge.Transport;
using ZB.MOM.WW.ScadaBridge.Transport.Signing;

namespace ZB.MOM.WW.ScadaBridge.Host.Health;

/// <summary>
/// /health/ready entry (ScadaBridge#110): Degraded while a cluster marked
/// <c>Transport:Signing:ProductionBoundary</c> still accepts unsigned bundles. Degraded maps
/// to HTTP 200 in the shared health tier, so it is visible on the Overview dashboard without
/// taking the node out of rotation. Exposes only booleans — never key material.
/// </summary>
public sealed class BundleSigningPolicyHealthCheck : IHealthCheck
{
    private readonly IOptionsMonitor<TransportOptions> _options;

    /// <summary>Initializes the check.</summary>
    /// <param name="options">Transport options.</param>
    public BundleSigningPolicyHealthCheck(IOptionsMonitor<TransportOptions> options)
    {
        _options = options ?? throw new ArgumentNullException(nameof(options));
    }

    /// <inheritdoc />
    public Task<HealthCheckResult> CheckHealthAsync(
        HealthCheckContext context, CancellationToken cancellationToken = default)
    {
        var signing = _options.CurrentValue.Signing;
        var data = new Dictionary<string, object>(StringComparer.Ordinal)
        {
            ["productionBoundary"] = signing.ProductionBoundary,
            ["requireSignedBundles"] = signing.RequireSignedBundles,
            ["signingEnabled"] = signing.Enabled,
            ["trustedKeys"] = signing.TrustedKeys.Count,
        };

        var advisory = BundleSigningPolicyAdvisory.Evaluate(signing);
        return Task.FromResult(advisory is null
            ? HealthCheckResult.Healthy("Bundle signing policy OK.", data)
            : HealthCheckResult.Degraded(advisory, data: data));
    }
}