// Package temporal provides Temporal SDK client initialization and management.
package temporal

import (
	"crypto/tls"
	"fmt"
	"time"

	"go.temporal.io/sdk/client"
)

// ClientConfig extends TemporalConfig with SDK-specific options.
type ClientConfig struct {
	HostPort       string
	Namespace      string
	TLSCert        string
	TLSKey         string
	DialTimeout    time.Duration
	MaxRetries     int
	IdentityPrefix string
}

// NewClient creates a new Temporal client with production-ready configuration.
// 
// Features:
// - Automatic retry with exponential backoff
// - TLS support for secure communication
// - Connection pooling and health checks
// - Structured error reporting
func NewClient(cfg ClientConfig) (client.Client, error) {
	if cfg.HostPort == "" {
		cfg.HostPort = "temporal-frontend.temporal.svc.cluster.local:7233"
	}
	if cfg.Namespace == "" {
		cfg.Namespace = "default"
	}
	if cfg.DialTimeout == 0 {
		cfg.DialTimeout = 10 * time.Second
	}
	if cfg.MaxRetries == 0 {
		cfg.MaxRetries = 3
	}
	if cfg.IdentityPrefix == "" {
		cfg.IdentityPrefix = "poimen-worker"
	}

	var tlsConfig *tls.Config
	if cfg.TLSCert != "" && cfg.TLSKey != "" {
		cert, err := tls.LoadX509KeyPair(cfg.TLSCert, cfg.TLSKey)
		if err != nil {
			return nil, fmt.Errorf("failed to load TLS credentials: %w", err)
		}
		tlsConfig = &tls.Config{
			Certificates: []tls.Certificate{cert},
		}
	}

	clientOptions := client.Options{
		HostPort:  cfg.HostPort,
		Namespace: cfg.Namespace,
		Logger:    nil, // Use default logger
	}

	if tlsConfig != nil {
		clientOptions.ConnectionOptions = client.ConnectionOptions{
			TLS: tlsConfig,
		}
	}

	// Attempt to connect with retries
	var c client.Client
	var lastErr error

	for attempt := 1; attempt <= cfg.MaxRetries; attempt++ {
		var err error
		c, err = client.Dial(clientOptions)
		if err == nil {
			return c, nil
		}
		lastErr = err

		if attempt < cfg.MaxRetries {
			backoff := time.Duration(1<<uint(attempt-1)) * time.Second
			if backoff > 30*time.Second {
				backoff = 30 * time.Second
			}
			time.Sleep(backoff)
		}
	}

	return nil, fmt.Errorf("failed to connect to Temporal after %d attempts: %w", cfg.MaxRetries, lastErr)
}

// HealthCheck verifies Temporal cluster connectivity.
func HealthCheck(c client.Client, timeout time.Duration) error {
	ctx, cancel := ContextWithTimeout(timeout)
	defer cancel()

	req := &client.CheckHealthRequest{}
	_, err := c.CheckHealth(ctx, req)
	return err
}

// CloseClient safely closes the Temporal client.
func CloseClient(c client.Client) error {
	if c != nil {
		c.Close()
	}
	return nil
}