package cmd

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	_ "net/http/pprof"
	"os"
	"strings"

	"github.com/stakater/Reloader/internal/pkg/constants"
	"github.com/stakater/Reloader/internal/pkg/leadership"

	"github.com/sirupsen/logrus"
	"github.com/spf13/cobra"
	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"

	"github.com/stakater/Reloader/internal/pkg/controller"
	"github.com/stakater/Reloader/internal/pkg/metrics"
	"github.com/stakater/Reloader/internal/pkg/options"
	"github.com/stakater/Reloader/internal/pkg/util"
	"github.com/stakater/Reloader/pkg/common"
	"github.com/stakater/Reloader/pkg/kube"
)

// NewReloaderCommand starts the reloader controller
func NewReloaderCommand() *cobra.Command {
	cmd := &cobra.Command{
		Use:     "reloader",
		Short:   "A watcher for your Kubernetes cluster",
		PreRunE: validateFlags,
		Run:     startReloader,
	}

	// options
	util.ConfigureReloaderFlags(cmd)

	return cmd
}

func validateFlags(*cobra.Command, []string) error {
	// Ensure the reload strategy is one of the following...
	var validReloadStrategy bool
	valid := []string{constants.EnvVarsReloadStrategy, constants.AnnotationsReloadStrategy}
	for _, s := range valid {
		if s == options.ReloadStrategy {
			validReloadStrategy = true
		}
	}

	if !validReloadStrategy {
		err := fmt.Sprintf("%s must be one of: %s", constants.ReloadStrategyFlag, strings.Join(valid, ", "))
		return errors.New(err)
	}

	// Validate that HA options are correct
	if options.EnableHA {
		if err := validateHAEnvs(); err != nil {
			return err
		}
	}

	return nil
}

func configureLogging(logFormat, logLevel string) error {
	switch logFormat {
	case "json":
		logrus.SetFormatter(&logrus.JSONFormatter{})
	default:
		// just let the library use default on empty string.
		if logFormat != "" {
			return fmt.Errorf("unsupported logging formatter: %q", logFormat)
		}
	}
	// set log level
	level, err := logrus.ParseLevel(logLevel)
	if err != nil {
		return err
	}
	logrus.SetLevel(level)
	return nil
}

func validateHAEnvs() error {
	podName, podNamespace := getHAEnvs()

	if podName == "" {
		return fmt.Errorf("%s not set, cannot run in HA mode without %s set", constants.PodNameEnv, constants.PodNameEnv)
	}
	if podNamespace == "" {
		return fmt.Errorf("%s not set, cannot run in HA mode without %s set", constants.PodNamespaceEnv, constants.PodNamespaceEnv)
	}
	return nil
}

func getHAEnvs() (string, string) {
	podName := os.Getenv(constants.PodNameEnv)
	podNamespace := os.Getenv(constants.PodNamespaceEnv)

	return podName, podNamespace
}

// resolveWatchNamespaces determines the set of namespaces to watch and whether
// Reloader runs in global (all-namespaces) mode. Precedence:
//  1. an explicit --namespaces list (scoped mode) — watch exactly those namespaces;
//  2. the KUBERNETES_NAMESPACE env var (single-namespace mode);
//  3. otherwise watch all namespaces (global mode).
func resolveWatchNamespaces(namespaces []string, kubernetesNamespace string) ([]string, bool) {
	if len(namespaces) > 0 {
		return namespaces, false
	}
	if len(kubernetesNamespace) > 0 {
		return []string{kubernetesNamespace}, false
	}
	return []string{v1.NamespaceAll}, true
}

// namespaceWatchScopeMessage returns the startup log message describing the
// namespace scope Reloader will watch when KUBERNETES_NAMESPACE is unset
// (global mode). It reflects --namespaces-to-ignore so the log is not
// misleading when namespace filtering is configured.
func namespaceWatchScopeMessage(ignoredNamespaces []string) string {
	if len(ignoredNamespaces) > 0 {
		return fmt.Sprintf(
			"KUBERNETES_NAMESPACE is unset, will detect changes in all namespaces except: %s.",
			strings.Join(ignoredNamespaces, ", "),
		)
	}
	return "KUBERNETES_NAMESPACE is unset, will detect changes in all namespaces."
}

func startReloader(cmd *cobra.Command, args []string) {
	common.GetCommandLineOptions()
	err := configureLogging(options.LogFormat, options.LogLevel)
	if err != nil {
		logrus.Warn(err)
	}

	logrus.Info("Starting Reloader")
	watchNamespaces, isGlobal := resolveWatchNamespaces(options.Namespaces, os.Getenv("KUBERNETES_NAMESPACE"))
	if !isGlobal && len(options.Namespaces) > 0 {
		logrus.Infof("Watching scoped namespaces: %s", strings.Join(watchNamespaces, ", "))
	}

	// create the clientset
	clientset, err := kube.GetKubernetesClient()
	if err != nil {
		logrus.Fatal(err)
	}

	ignoredResourcesList, err := util.GetIgnoredResourcesList()
	if err != nil {
		logrus.Fatal(err)
	}

	// namespaces-to-ignore and namespace-selector only make sense when watching all
	// namespaces. In single-namespace and scoped modes the watched set is already
	// explicit, so both are intentionally left empty.
	ignoredNamespacesList := []string{}
	namespaceLabelSelector := ""

	if isGlobal {
		ignoredNamespacesList = options.NamespacesToIgnore
		logrus.Warn(namespaceWatchScopeMessage(ignoredNamespacesList))
		namespaceLabelSelector, err = common.GetNamespaceLabelSelector(options.NamespaceSelectors)
		if err != nil {
			logrus.Fatal(err)
		}
	} else if len(options.NamespacesToIgnore) > 0 {
		logrus.Warnf("namespaces-to-ignore is set but is only honored in global mode (watchGlobally=true); ignoring it.")
	}

	resourceLabelSelector, err := common.GetResourceLabelSelector(options.ResourceSelectors)
	if err != nil {
		logrus.Fatal(err)
	}

	if len(namespaceLabelSelector) > 0 {
		logrus.Warnf("namespace-selector is set, will only detect changes in namespaces with these labels: %s.", namespaceLabelSelector)
	}

	if len(resourceLabelSelector) > 0 {
		logrus.Warnf("resource-label-selector is set, will only detect changes on resources with these labels: %s.", resourceLabelSelector)
	}

	if options.WebhookUrl != "" {
		logrus.Warnf("webhook-url is set, will only send webhook, no resources will be reloaded")
	}

	collectors := metrics.SetupPrometheusEndpoint()

	var controllers []*controller.Controller
	for _, currentNamespace := range watchNamespaces {
		for k := range kube.ResourceMap {
			if k == constants.SecretProviderClassController && !shouldRunCSIController() {
				continue
			}

			if ignoredResourcesList.Contains(k) || (len(namespaceLabelSelector) == 0 && k == "namespaces") {
				continue
			}

			c, err := controller.NewController(clientset, k, currentNamespace, ignoredNamespacesList, namespaceLabelSelector, resourceLabelSelector, collectors)
			if err != nil {
				logrus.Fatalf("%s", err)
			}

			controllers = append(controllers, c)

			// If HA is enabled we only run the controller when
			if options.EnableHA {
				continue
			}
			// Now let's start the controller
			stop := make(chan struct{})
			defer close(stop)
			logrus.Infof("Starting Controller to watch resource type: %s in namespace: %s", k, currentNamespace)
			go c.Run(1, stop)
		}
	}

	// Run leadership election
	if options.EnableHA {
		podName, podNamespace := getHAEnvs()
		lock := leadership.GetNewLock(clientset.CoordinationV1(), constants.LockName, podName, podNamespace)
		ctx, cancel := context.WithCancel(context.Background())
		defer cancel()
		leadership.RunLeaderElection(lock, ctx, cancel, podName, controllers)
	}

	common.PublishMetaInfoConfigmap(clientset)

	if options.EnablePProf {
		go startPProfServer()
	}

	leadership.SetupLivenessEndpoint()
	logrus.Fatal(http.ListenAndServe(constants.DefaultHttpListenAddr, nil))
}

func startPProfServer() {
	logrus.Infof("Starting pprof server on %s", options.PProfAddr)
	if err := http.ListenAndServe(options.PProfAddr, nil); err != nil {
		logrus.Errorf("Failed to start pprof server: %v", err)
	}
}

func shouldRunCSIController() bool {
	if !options.EnableCSIIntegration {
		logrus.Info("Skipping secretproviderclasspodstatuses controller: EnableCSIIntegration is disabled")
		return false
	}
	if !kube.IsCSIInstalled {
		logrus.Info("Skipping secretproviderclasspodstatuses controller: CSI CRDs not installed")
		return false
	}
	return true
}