// Solution: Restore Implementation from Module 8
// This demonstrates restore functionality for stateful applications
//
// IMPORTANT: This implementation uses psql which requires PostgreSQL client tools
// to be installed in your operator container image. Update your Dockerfile to include
// postgresql-client package. See the Dockerfile example in this solutions directory.

package restore

import (
	"bytes"
	"context"
	"fmt"
	"os/exec"
	"strings"

	databasev1 "github.com/example/postgres-operator/api/v1"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	"sigs.k8s.io/controller-runtime/pkg/client"
)

func PerformRestore(ctx context.Context, k8sClient client.Client, db *databasev1.Database, backupLocation string) error {
	// Load backup from storage
	backupData, err := loadFromStorage(backupLocation)
	if err != nil {
		return fmt.Errorf("failed to load backup: %v", err)
	}

	// Get database endpoint
	endpoint := db.Status.Endpoint
	if endpoint == "" {
		return fmt.Errorf("database endpoint not available")
	}

	// Parse endpoint (format: hostname:port or hostname)
	host := endpoint
	port := "5432" // Default PostgreSQL port
	if strings.Contains(endpoint, ":") {
		parts := strings.Split(endpoint, ":")
		if len(parts) == 2 {
			host = parts[0]
			port = parts[1]
		}
	}

	// Get password from Secret
	secretName := db.Status.SecretName
	if secretName == "" {
		// Fallback to default secret name pattern if SecretName not set in status
		secretName = fmt.Sprintf("%s-credentials", db.Name)
	}

	secret := &corev1.Secret{}
	err = k8sClient.Get(ctx, client.ObjectKey{
		Name:      secretName,
		Namespace: db.Namespace,
	}, secret)
	if err != nil {
		if errors.IsNotFound(err) {
			return fmt.Errorf("secret %s not found", secretName)
		}
		return fmt.Errorf("failed to get secret: %w", err)
	}

	// Extract password from Secret
	passwordBytes, exists := secret.Data["password"]
	if !exists {
		return fmt.Errorf("password key not found in secret %s", secretName)
	}
	password := string(passwordBytes)

	// Stop database if needed (application-specific)
	if err := stopDatabase(ctx, db); err != nil {
		return fmt.Errorf("failed to stop database: %v", err)
	}

	// Perform restore with password from Secret
	cmd := exec.CommandContext(ctx, "psql",
		"-h", host,
		"-p", port,
		"-U", db.Spec.Username,
		"-d", db.Spec.DatabaseName)

	// Set password as environment variable for psql
	cmd.Env = append(cmd.Env, fmt.Sprintf("PGPASSWORD=%s", password))
	cmd.Stdin = bytes.NewReader(backupData)

	output, err := cmd.CombinedOutput()
	if err != nil {
		return fmt.Errorf("restore failed: %v, output: %s", err, string(output))
	}

	// Start database
	if err := startDatabase(ctx, db); err != nil {
		return fmt.Errorf("failed to start database: %v", err)
	}

	return nil
}

func loadFromStorage(backupLocation string) ([]byte, error) {
	// In real implementation, this would:
	// 1. Download from S3
	// 2. Read from PVC
	// 3. Load from object storage

	// For example, download from S3:
	// aws s3 cp s3://backups/backup.sql /tmp/backup.sql
	// data, err := os.ReadFile("/tmp/backup.sql")

	// Simplified for example
	return []byte("-- Backup data"), nil
}

func stopDatabase(ctx context.Context, db *databasev1.Database) error {
	// Application-specific: stop database gracefully
	// For PostgreSQL, might use pg_ctl stop
	// For other databases, use appropriate commands

	return nil
}

func startDatabase(ctx context.Context, db *databasev1.Database) error {
	// Application-specific: start database
	// For PostgreSQL, might use pg_ctl start
	// For other databases, use appropriate commands

	return nil
}