package slurm

import (
	"fmt"
	"net/http"
	"time"
)

// ClientOption configures a Client via functional options.
type ClientOption func(*clientConfig) error

type clientConfig struct {
	jwtKeyPath string
	username   string
	ttl        time.Duration
	leeway     time.Duration
	httpClient *http.Client
}

func defaultClientConfig() *clientConfig {
	return &clientConfig{
		ttl:    30 * time.Minute,
		leeway: 30 * time.Second,
	}
}

// WithJWTKey specifies the path to the JWT key file.
func WithJWTKey(path string) ClientOption {
	return func(c *clientConfig) error {
		c.jwtKeyPath = path
		return nil
	}
}

// WithUsername specifies the Slurm username for JWT authentication.
func WithUsername(username string) ClientOption {
	return func(c *clientConfig) error {
		c.username = username
		return nil
	}
}

// WithTokenTTL sets the JWT token time-to-live (default: 30 minutes).
func WithTokenTTL(ttl time.Duration) ClientOption {
	return func(c *clientConfig) error {
		c.ttl = ttl
		return nil
	}
}

// WithTokenLeeway sets the JWT token refresh leeway (default: 30 seconds).
func WithTokenLeeway(leeway time.Duration) ClientOption {
	return func(c *clientConfig) error {
		c.leeway = leeway
		return nil
	}
}

// WithHTTPClient specifies a custom HTTP client.
func WithHTTPClient(client *http.Client) ClientOption {
	return func(c *clientConfig) error {
		c.httpClient = client
		return nil
	}
}

// NewClientWithOpts creates a new Slurm API client using functional options.
// If WithJWTKey and WithUsername are provided, JWT authentication is configured
// automatically. If no JWT options are provided, http.DefaultClient is used.
func NewClientWithOpts(baseURL string, opts ...ClientOption) (*Client, error) {
	cfg := defaultClientConfig()
	for _, opt := range opts {
		if err := opt(cfg); err != nil {
			return nil, err
		}
	}

	var httpClient *http.Client

	if cfg.jwtKeyPath != "" && cfg.username != "" {
		key, err := ReadJWTKey(cfg.jwtKeyPath)
		if err != nil {
			return nil, fmt.Errorf("read JWT key: %w", err)
		}

		transportOpts := []JWTTransportOption{
			WithTTL(cfg.ttl),
			WithLeeway(cfg.leeway),
		}

		tr := NewJWTAuthTransport(cfg.username, key, transportOpts...)
		httpClient = tr.Client()
	} else if cfg.httpClient != nil {
		httpClient = cfg.httpClient
	} else {
		httpClient = http.DefaultClient
	}

	return NewClient(baseURL, httpClient)
}