package gcp

import (
	"encoding/base64"
	"fmt"

	"github.com/pulumi/pulumi-gcp/sdk/v8/go/gcp"
	"github.com/pulumi/pulumi-gcp/sdk/v8/go/gcp/container"
	"github.com/pulumi/pulumi-gcp/sdk/v8/go/gcp/storage"
	"github.com/pulumi/pulumi-kubernetes/sdk/v4/go/kubernetes"
	corev1 "github.com/pulumi/pulumi-kubernetes/sdk/v4/go/kubernetes/core/v1"
	metav1 "github.com/pulumi/pulumi-kubernetes/sdk/v4/go/kubernetes/meta/v1"
	"github.com/pulumi/pulumi/sdk/v3/go/pulumi"
	"github.com/pulumi/pulumi/sdk/v3/go/pulumi/config"

	"github.com/modelcontextprotocol/registry/deploy/infra/pkg/providers"
)

// Provider implements the ClusterProvider interface for Google Kubernetes Engine
type Provider struct{}

// createGCPProvider creates a GCP provider with explicit credentials if configured
func createGCPProvider(ctx *pulumi.Context, name string) (*gcp.Provider, error) {
	gcpConf := config.New(ctx, "gcp")

	// Get project ID from config
	projectID := gcpConf.Get("project")
	if projectID == "" {
		return nil, fmt.Errorf("GCP project ID not configured. Set gcp:project")
	}

	// Get region from config or use default
	region := gcpConf.Get("region")
	if region == "" {
		region = "us-central1"
	}

	// Get credentials from config (base64 encoded service account JSON)
	credentials := gcpConf.Get("credentials")
	if credentials != "" {
		// Decode the base64 credentials
		decodedCreds, err := base64.StdEncoding.DecodeString(credentials)
		if err != nil {
			return nil, fmt.Errorf("failed to decode GCP credentials: %w", err)
		}
		credentials = string(decodedCreds)
	}

	// Create a GCP provider with explicit credentials if provided
	if credentials != "" {
		return gcp.NewProvider(ctx, name, &gcp.ProviderArgs{
			Project:     pulumi.String(projectID),
			Region:      pulumi.String(region),
			Credentials: pulumi.String(credentials),
		})
	}

	return nil, nil
}

// CreateCluster creates a Google Kubernetes Engine cluster
func (p *Provider) CreateCluster(ctx *pulumi.Context, environment string) (*providers.ProviderInfo, error) {
	// Get configuration
	gcpConf := config.New(ctx, "gcp")

	// Get project ID from config
	projectID := gcpConf.Get("project")
	if projectID == "" {
		return nil, fmt.Errorf("GCP project ID not configured. Set gcp:project")
	}

	// Get region from config or use default
	region := gcpConf.Get("region")
	if region == "" {
		region = "us-central1"
	}

	// Create GCP provider with explicit credentials if configured
	gcpProvider, err := createGCPProvider(ctx, "gcp-explicit")
	if err != nil {
		return nil, err
	}

	// Create GKE cluster
	clusterName := fmt.Sprintf("mcp-registry-%s", environment)

	// Use a specific zone instead of region for zonal cluster
	zone := fmt.Sprintf("%s-b", region)

	// Configure the GKE cluster
	clusterArgs := &container.ClusterArgs{
		Name:        pulumi.String(clusterName),
		Location:    pulumi.String(zone),
		Project:     pulumi.String(projectID),
		Description: pulumi.String(fmt.Sprintf("MCP Registry %s GKE Cluster", environment)),

		// Initial node count (will be managed by node pool)
		InitialNodeCount: pulumi.Int(1),

		// Remove default node pool after cluster creation
		RemoveDefaultNodePool: pulumi.Bool(true),

		AddonsConfig: &container.ClusterAddonsConfigArgs{
			// Disable as we use ingress-nginx
			HttpLoadBalancing: &container.ClusterAddonsConfigHttpLoadBalancingArgs{
				Disabled: pulumi.Bool(true),
			},
		},
	}

	// Add provider if we have explicit credentials
	clusterOpts := []pulumi.ResourceOption{}
	if gcpProvider != nil {
		clusterOpts = append(clusterOpts, pulumi.Provider(gcpProvider))
	}

	cluster, err := container.NewCluster(ctx, clusterName, clusterArgs, clusterOpts...)
	if err != nil {
		return nil, fmt.Errorf("failed to create GKE cluster: %w", err)
	}

	// Create a managed node pool for the cluster
	nodePoolName := fmt.Sprintf("%s-nodepool", clusterName)
	nodePoolArgs := &container.NodePoolArgs{
		Cluster:  cluster.Name,
		Location: pulumi.String(zone),
		Project:  pulumi.String(projectID),

		// Node pool configuration
		NodeCount: pulumi.Int(2),
		NodeConfig: &container.NodePoolNodeConfigArgs{
			MachineType: pulumi.String("e2-standard-2"),
			DiskSizeGb:  pulumi.Int(20),
			DiskType:    pulumi.String("pd-standard"),
		},

		// Node management configuration
		Management: &container.NodePoolManagementArgs{
			AutoRepair:  pulumi.Bool(true),
			AutoUpgrade: pulumi.Bool(true),
		},
	}

	// Add provider if we have explicit credentials
	nodePoolOpts := []pulumi.ResourceOption{}
	if gcpProvider != nil {
		nodePoolOpts = append(nodePoolOpts, pulumi.Provider(gcpProvider))
	}

	nodePool, err := container.NewNodePool(ctx, nodePoolName, nodePoolArgs, nodePoolOpts...)
	if err != nil {
		return nil, fmt.Errorf("failed to create node pool: %w", err)
	}

	// Create Kubernetes provider using the cluster directly
	k8sProvider, err := kubernetes.NewProvider(ctx, "k8s-provider", &kubernetes.ProviderArgs{
		Kubeconfig: pulumi.All(cluster.Endpoint, cluster.MasterAuth).ApplyT(func(args []any) (string, error) {
			endpoint := args[0].(string)
			masterAuth := args[1].(container.ClusterMasterAuth)
			context := fmt.Sprintf("%s_%s_%s", projectID, zone, clusterName)

			// Extract CA certificate
			caCert := ""
			if masterAuth.ClusterCaCertificate != nil {
				caCert = *masterAuth.ClusterCaCertificate
			}

			// Create kubeconfig using gke-gcloud-auth-plugin
			kubeconfigYAML := fmt.Sprintf(`apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: %s
    server: https://%s
  name: %s
contexts:
- context:
    cluster: %s
    user: %s
  name: %s
current-context: %s
kind: Config
preferences: {}
users:
- name: %s
  user:
    exec:
      apiVersion: client.authentication.k8s.io/v1beta1
      command: gke-gcloud-auth-plugin
      installHint: Install gke-gcloud-auth-plugin for use with kubectl by following
        https://cloud.google.com/blog/products/containers-kubernetes/kubectl-auth-changes-in-gke
      provideClusterInfo: true
`, caCert, endpoint, context, context, context, context, context, context)

			return kubeconfigYAML, nil
		}).(pulumi.StringOutput),
	}, pulumi.DependsOn([]pulumi.Resource{cluster, nodePool}))
	if err != nil {
		return nil, fmt.Errorf("failed to create Kubernetes provider: %w", err)
	}

	return &providers.ProviderInfo{
		Name:     nodePool.Cluster,
		Provider: k8sProvider,
	}, nil
}

// CreateBackupStorage creates GCS bucket with HMAC credentials for S3-compatible access
func (p *Provider) CreateBackupStorage(ctx *pulumi.Context, cluster *providers.ProviderInfo, environment string) (*providers.BackupStorageInfo, error) {
	gcpConf := config.New(ctx, "gcp")
	projectID := gcpConf.Get("project")
	if projectID == "" {
		return nil, fmt.Errorf("GCP project ID not configured. Set gcp:project")
	}

	// Create GCP provider with explicit credentials if configured
	gcpProvider, err := createGCPProvider(ctx, "gcp-explicit-backup")
	if err != nil {
		return nil, err
	}

	// Set resource options with provider if we have explicit credentials
	resourceOpts := []pulumi.ResourceOption{}
	if gcpProvider != nil {
		resourceOpts = append(resourceOpts, pulumi.Provider(gcpProvider))
	}

	// Create GCS bucket for backups
	bucketName := fmt.Sprintf("mcp-registry-%s-backups", environment)
	bucket, err := storage.NewBucket(ctx, "backup-bucket", &storage.BucketArgs{
		Name:         pulumi.String(bucketName),
		Location:     pulumi.String("US"),
		StorageClass: pulumi.String("STANDARD"),
		LifecycleRules: storage.BucketLifecycleRuleArray{
			&storage.BucketLifecycleRuleArgs{
				Action: &storage.BucketLifecycleRuleActionArgs{
					Type: pulumi.String("Delete"),
				},
				Condition: &storage.BucketLifecycleRuleConditionArgs{
					Age: pulumi.Int(60), // Keep backups for 60 days (K8up manages pruning at 28 days, GCS deletion is a safety net)
				},
			},
		},
		UniformBucketLevelAccess: pulumi.Bool(true),
		Versioning: &storage.BucketVersioningArgs{
			Enabled: pulumi.Bool(true),
		},
		Labels: pulumi.StringMap{
			"environment": pulumi.String(environment),
			"purpose":     pulumi.String("k8up-backups"),
		},
	}, resourceOpts...)
	if err != nil {
		return nil, fmt.Errorf("failed to create backup bucket: %w", err)
	}

	// Use the existing Pulumi service account instead of creating a new one
	// The service account email is pulumi-svc@<project>.iam.gserviceaccount.com
	serviceAccountEmail := fmt.Sprintf("pulumi-svc@%s.iam.gserviceaccount.com", projectID)

	// Grant the service account access to the bucket
	_, err = storage.NewBucketIAMMember(ctx, "backup-bucket-iam", &storage.BucketIAMMemberArgs{
		Bucket: bucket.Name,
		Role:   pulumi.String("roles/storage.objectAdmin"),
		Member: pulumi.Sprintf("serviceAccount:%s", pulumi.String(serviceAccountEmail)),
	}, resourceOpts...)
	if err != nil {
		return nil, fmt.Errorf("failed to grant bucket access: %w", err)
	}

	// Create HMAC key for S3-compatible access
	hmacKey, err := storage.NewHmacKey(ctx, "backup-hmac-key", &storage.HmacKeyArgs{
		ServiceAccountEmail: pulumi.String(serviceAccountEmail),
		Project:             pulumi.String(projectID),
	}, resourceOpts...)
	if err != nil {
		return nil, fmt.Errorf("failed to create HMAC key: %w", err)
	}

	// Create Kubernetes secret with S3-compatible credentials
	backupSecret, err := corev1.NewSecret(ctx, "k8up-backup-credentials", &corev1.SecretArgs{
		Metadata: &metav1.ObjectMetaArgs{
			Name:      pulumi.String("k8up-backup-credentials"),
			Namespace: pulumi.String("default"),
			Labels: pulumi.StringMap{
				"k8up.io/backup": pulumi.String("true"),
				"environment":    pulumi.String(environment),
			},
		},
		Type: pulumi.String("Opaque"),
		StringData: pulumi.StringMap{
			"AWS_ACCESS_KEY_ID":     hmacKey.AccessId,
			"AWS_SECRET_ACCESS_KEY": hmacKey.Secret,
		},
	}, pulumi.Provider(cluster.Provider))
	if err != nil {
		return nil, fmt.Errorf("failed to create backup credentials secret: %w", err)
	}

	return &providers.BackupStorageInfo{
		Endpoint:    "https://storage.googleapis.com",
		BucketName:  bucketName,
		Credentials: backupSecret,
	}, nil
}