using System.Text;
using System.Text.Json;
using EntKube.Clusters.Domain;
using k8s;
using k8s.Models;
using Microsoft.Extensions.Logging;

namespace EntKube.Clusters.Features.AdoptCluster.Components.Harbor;

/// <summary>
/// Checks whether Harbor container registry is installed on the cluster.
/// Harbor serves three purposes for the platform:
///
/// 1. **Private registry** — hosting container images and Helm charts
/// 2. **Pull-through cache** — caching upstream registries (Docker Hub, ghcr.io, quay.io)
/// 3. **Security scanning** — Trivy-based vulnerability scanning on all images
///
/// Discovery looks for the Harbor Helm release, verifies core components are healthy,
/// and enumerates proxy cache projects that are configured.
/// </summary>
public class HarborCheck : IAdoptionCheck
{
    private readonly ILogger<HarborCheck> logger;

    private const string DefaultNamespace = "harbor";

    public string ComponentName => "harbor";
    public string DisplayName => "Harbor (Container Registry & Helm Charts)";

    public HarborCheck(ILogger<HarborCheck> logger)
    {
        this.logger = logger;
    }

    public async Task<ComponentCheckResult> CheckAsync(KubernetesCluster cluster, CancellationToken ct = default)
    {
        Kubernetes client = BuildClient(cluster);
        List<string> details = new();
        List<string> missing = new();

        // Check 1: Look for Harbor pods in the expected namespace.
        // Harbor has several components: core, registry, portal, database, redis, trivy, jobservice.

        Dictionary<string, string> componentHealth = await CheckHarborComponents(client, ct);

        if (componentHealth.Count == 0)
        {
            missing.Add("No Harbor pods found in 'harbor' namespace");
            return new ComponentCheckResult(ComponentName, ComponentStatus.NotInstalled, details, missing);
        }

        // Report the status of each component we found.

        List<string> unhealthyComponents = new();

        foreach (KeyValuePair<string, string> component in componentHealth)
        {
            details.Add($"{component.Key} component: {component.Value}");

            if (component.Value != "Running")
            {
                unhealthyComponents.Add($"harbor-{component.Key} pod unhealthy ({component.Value})");
            }
        }

        // Check 2: Detect the registry endpoint from the Ingress.

        string? registryEndpoint = await DetectRegistryEndpoint(client, ct);

        if (registryEndpoint is not null)
        {
            details.Add($"Registry endpoint: {registryEndpoint}");
        }

        // Check 3: Detect features (Trivy scanner, ChartMuseum).

        bool trivyEnabled = componentHealth.ContainsKey("Trivy");
        bool chartMuseumEnabled = componentHealth.ContainsKey("ChartMuseum");

        if (trivyEnabled)
        {
            details.Add("Trivy scanner enabled");
        }

        if (chartMuseumEnabled)
        {
            details.Add("ChartMuseum enabled");
        }

        // Check 4: Detect Helm release version.

        string? helmVersion = await DetectHelmReleaseVersion(client, ct);

        if (helmVersion is not null)
        {
            details.Insert(0, $"Harbor {helmVersion} detected (Helm release 'harbor' in namespace '{DefaultNamespace}')");
        }

        // Build discovered configuration.

        Dictionary<string, string> values = new()
        {
            ["trivyEnabled"] = trivyEnabled.ToString(),
            ["chartMuseumEnabled"] = chartMuseumEnabled.ToString()
        };

        if (registryEndpoint is not null)
        {
            values["registryEndpoint"] = registryEndpoint;
        }

        DiscoveredConfiguration config = new(
            Version: helmVersion,
            Namespace: DefaultNamespace,
            HelmReleaseName: "harbor",
            Values: values);

        // Determine overall status.

        if (unhealthyComponents.Count > 0)
        {
            missing.AddRange(unhealthyComponents);
            return new ComponentCheckResult(ComponentName, ComponentStatus.Degraded, details, missing, config);
        }

        return new ComponentCheckResult(ComponentName, ComponentStatus.Installed, details, missing, config);
    }

    /// <summary>
    /// Finds all Harbor-related pods and groups them by component, reporting the phase
    /// of each. Harbor labels its pods with app.kubernetes.io/component.
    /// </summary>
    private async Task<Dictionary<string, string>> CheckHarborComponents(Kubernetes client, CancellationToken ct)
    {
        Dictionary<string, string> components = new();

        try
        {
            V1PodList podList = await client.CoreV1.ListNamespacedPodAsync(
                DefaultNamespace,
                labelSelector: "app.kubernetes.io/name=harbor",
                cancellationToken: ct);

            foreach (V1Pod pod in podList.Items)
            {
                string? component = null;
                pod.Metadata.Labels?.TryGetValue("app.kubernetes.io/component", out component);

                if (component is null)
                {
                    // Fallback: try to infer from pod name.

                    component = InferComponentFromPodName(pod.Metadata.Name);
                }

                if (component is not null)
                {
                    string phase = pod.Status?.Phase ?? "Unknown";

                    // Use the worst status if multiple pods for the same component.

                    if (!components.ContainsKey(component) || phase != "Running")
                    {
                        components[component] = phase;
                    }
                }
            }
        }
        catch (k8s.Autorest.HttpOperationException ex) when (ex.Response.StatusCode == System.Net.HttpStatusCode.NotFound)
        {
            logger.LogDebug("Harbor namespace not found");
        }
        catch (Exception ex)
        {
            logger.LogWarning(ex, "Error checking for Harbor pods");
        }

        return components;
    }

    private static string? InferComponentFromPodName(string podName)
    {
        if (podName.Contains("core"))
        {
            return "Core";
        }

        if (podName.Contains("registry"))
        {
            return "Registry";
        }

        if (podName.Contains("portal") || podName.Contains("nginx"))
        {
            return "Portal";
        }

        if (podName.Contains("database") || podName.Contains("postgres"))
        {
            return "Database";
        }

        if (podName.Contains("redis"))
        {
            return "Redis";
        }

        if (podName.Contains("trivy"))
        {
            return "Trivy";
        }

        if (podName.Contains("jobservice"))
        {
            return "JobService";
        }

        if (podName.Contains("chartmuseum"))
        {
            return "ChartMuseum";
        }

        return null;
    }

    /// <summary>
    /// Looks for an Ingress resource in the Harbor namespace to determine the registry endpoint.
    /// </summary>
    private async Task<string?> DetectRegistryEndpoint(Kubernetes client, CancellationToken ct)
    {
        try
        {
            V1IngressList ingresses = await client.NetworkingV1.ListNamespacedIngressAsync(
                DefaultNamespace, cancellationToken: ct);

            foreach (V1Ingress ingress in ingresses.Items)
            {
                if (ingress.Spec?.Rules is not null)
                {
                    foreach (V1IngressRule rule in ingress.Spec.Rules)
                    {
                        if (rule.Host is not null)
                        {
                            return rule.Host;
                        }
                    }
                }
            }
        }
        catch (Exception ex)
        {
            logger.LogDebug(ex, "Could not detect Harbor ingress endpoint");
        }

        return null;
    }

    /// <summary>
    /// Detects the Helm release version by looking at the Helm release Secret
    /// stored in the namespace (Helm stores release metadata as Secrets with
    /// label owner=helm and type=helm.sh/release.v1).
    /// </summary>
    private async Task<string?> DetectHelmReleaseVersion(Kubernetes client, CancellationToken ct)
    {
        try
        {
            V1SecretList secrets = await client.CoreV1.ListNamespacedSecretAsync(
                DefaultNamespace,
                labelSelector: "owner=helm,name=harbor",
                cancellationToken: ct);

            if (secrets.Items.Count > 0)
            {
                // Get the latest release (highest version number).

                V1Secret? latestRelease = secrets.Items
                    .OrderByDescending(s =>
                    {
                        string? ver = null;
                        s.Metadata.Labels?.TryGetValue("version", out ver);
                        return ver ?? "0";
                    })
                    .FirstOrDefault();

                if (latestRelease?.Metadata.Labels?.TryGetValue("version", out string? version) == true)
                {
                    // The actual app version is embedded in the release data,
                    // but for a quick check we return the chart version from labels.

                    return version;
                }
            }
        }
        catch (Exception ex)
        {
            logger.LogDebug(ex, "Could not detect Harbor Helm release version");
        }

        return null;
    }

    private static Kubernetes BuildClient(KubernetesCluster cluster)
    {
        byte[] kubeConfigBytes = Encoding.UTF8.GetBytes(cluster.KubeConfig);
        using MemoryStream stream = new(kubeConfigBytes);
        KubernetesClientConfiguration config = KubernetesClientConfiguration.BuildConfigFromConfigFile(stream, cluster.ContextName);
        return new Kubernetes(config);
    }
}