package controller

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

	"k8s.io/client-go/rest"
	ctrl "sigs.k8s.io/controller-runtime"
	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
	"sigs.k8s.io/controller-runtime/pkg/webhook"
)

var (
	defaultMetricsBindAddress = ":8080"
	defaultLeaderElection     = false
)

// private options struct, this struct is mutated via the public `Option`
// functions
type options struct {
	config         *rest.Config
	ctrlOptions    ctrl.Options
	webHookOptions webhook.Options
}

// Option is used to configure a controller
type Option func(*options)

// WithCfg sets an explicit K8s client rest configuration, if one isn't provided,
// the `ctrl.GetConfigOrDie()` is used.
func WithCfg(c *rest.Config) Option {
	return func(o *options) {
		o.config = c
	}
}

// WithLeaderElection enables leader election for the controller, defaults to
// false
func WithLeaderElection() Option {
	return func(o *options) {
		o.ctrlOptions.LeaderElection = true
	}
}

// WithMetricsAddress sets the specific bind address for the controller, defaults
// to ":8080"
func WithMetricsAddress(a string) Option {
	return func(o *options) {
		o.ctrlOptions.Metrics.BindAddress = a
	}
}

// WithCertDir is the directory that contains the server key and certificate.
func WithCertDir(certDir string) Option {
	return func(o *options) {
		o.webHookOptions.CertDir = certDir
	}
}

// WithPort is the port that the webhook server serves at.
func WithPort(port int) Option {
	return func(o *options) {
		o.webHookOptions.Port = port
	}
}

func WithPProf(route string, h http.Handler) Option {
	return func(o *options) {
		o.ctrlOptions.Metrics.ExtraHandlers[route] = h
	}
}

func WithGracefulTimeout(timeout time.Duration) Option {
	return func(o *options) {
		o.ctrlOptions.GracefulShutdownTimeout = &timeout
	}
}

// ProcessOptions applies the provided options to the default controller
// configuration and produces a K8s client configuration and base set of options
// for creating a controller with the controller-runtime package.
func ProcessOptions(opts ...Option) (*rest.Config, ctrl.Options) {
	o := &options{
		ctrlOptions: ctrl.Options{
			Metrics:        metricsserver.Options{BindAddress: defaultMetricsBindAddress},
			LeaderElection: defaultLeaderElection},
	}
	for _, opt := range opts {
		opt(o)
	}

	if o.config == nil {
		// we don't use ctrl.GetConfigOrDie() here so that we can loudly panic,
		// since consumers won't be able to do anythin with the error.
		// if you call ctrl.GetConfigOrDie() and the logger has not been set up,
		// you won't get any logs.
		var err error
		o.config, err = ctrl.GetConfig()
		if err != nil {
			panic(fmt.Sprintf("failed to get Kube client config: %s", err.Error()))
		}
	}

	o.ctrlOptions.WebhookServer = webhook.NewServer(o.webHookOptions)

	return o.config, o.ctrlOptions
}