// Package kube provides shared Kubernetes client bootstrapping for the tools in
// benvin-utils: a single loader that works both in-cluster and from a local
// kubeconfig, plus a helper that returns the core and metrics clients together.
package kube

import (
	"fmt"
	"os"
	"path/filepath"

	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
	metricsv "k8s.io/metrics/pkg/client/clientset/versioned"
)

// LoadConfig resolves a *rest.Config, preferring in-cluster credentials, then
// the explicit path, then $KUBECONFIG, then ~/.kube/config.
func LoadConfig(explicit string) (*rest.Config, error) {
	if cfg, err := rest.InClusterConfig(); err == nil {
		return cfg, nil
	}
	path := explicit
	if path == "" {
		path = os.Getenv("KUBECONFIG")
	}
	if path == "" {
		if home, err := os.UserHomeDir(); err == nil {
			path = filepath.Join(home, ".kube", "config")
		}
	}
	cfg, err := clientcmd.BuildConfigFromFlags("", path)
	if err != nil {
		return nil, fmt.Errorf("load kubeconfig %q: %w", path, err)
	}
	return cfg, nil
}

// Clients returns the core and metrics clientsets for the resolved config.
func Clients(explicit string) (kubernetes.Interface, metricsv.Interface, error) {
	cfg, err := LoadConfig(explicit)
	if err != nil {
		return nil, nil, err
	}
	core, err := kubernetes.NewForConfig(cfg)
	if err != nil {
		return nil, nil, fmt.Errorf("core client: %w", err)
	}
	mc, err := metricsv.NewForConfig(cfg)
	if err != nil {
		return nil, nil, fmt.Errorf("metrics client: %w", err)
	}
	return core, mc, nil
}