package controller

import (
	"context"
	"crypto/sha256"
	"maps"
	"reflect"

	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/fields"
	"k8s.io/apimachinery/pkg/types"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	"sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"

	"code.icb4dc0.de/prskr/supabase-operator/api"
)

func ptrOf[T any](val T) *T {
	return &val
}

func boolValueOf(ptr *bool) bool {
	if ptr == nil {
		return false
	}

	return *ptr
}

func MergeLabels(source map[string]string, toAppend ...map[string]string) map[string]string {
	result := make(map[string]string, len(source)+len(toAppend))
	maps.Copy(result, source)

	for _, additionalLabels := range toAppend {
		for k, v := range additionalLabels {
			if _, exists := result[k]; exists {
				continue
			}

			result[k] = v
		}
	}

	return result
}

func MergeEnv(source []corev1.EnvVar, toAppend ...corev1.EnvVar) []corev1.EnvVar {
	existingKeys := make(map[string]bool, len(source)+len(toAppend))

	merged := append(make([]corev1.EnvVar, 0, len(source)+len(toAppend)), source...)

	for _, v := range source {
		existingKeys[v.Name] = true
	}

	for _, v := range toAppend {
		if _, alreadyPresent := existingKeys[v.Name]; alreadyPresent {
			continue
		}
		merged = append(merged, v)
		existingKeys[v.Name] = true
	}

	return merged
}

func ValueOrFallback[T any](value, fallback T) T {
	rval := reflect.ValueOf(value)
	if rval.IsZero() {
		return fallback
	}

	return value
}

func HashStrings(vals ...string) []byte {
	h := sha256.New()

	for _, v := range vals {
		h.Write([]byte(v))
	}

	return h.Sum(nil)
}

func HashBytes(vals ...[]byte) []byte {
	h := sha256.New()

	for _, v := range vals {
		h.Write(v)
	}

	return h.Sum(nil)
}

func FieldSelectorEventHandler[TItem metav1.Object, TList api.ObjectList[TItem]](
	cli client.Client,
	fieldSelector string,
) handler.TypedEventHandler[client.Object, reconcile.Request] {
	return handler.EnqueueRequestsFromMapFunc(func(ctx context.Context, obj client.Object) []reconcile.Request {
		var (
			list             TList
			selectorInstance = client.MatchingFieldsSelector{
				Selector: fields.OneTermEqualSelector(fieldSelector, obj.GetName()),
			}
			logger = log.FromContext(ctx, "object", obj.GetName(), "namespace", obj.GetNamespace())
		)

		list = reflect.New(reflect.TypeOf(list).Elem()).Interface().(TList)

		if err := cli.List(ctx, list, selectorInstance, client.InNamespace(obj.GetNamespace())); err != nil {
			logger.Error(err, "could not list items for field selector event handler")
			return nil
		}

		requests := make([]reconcile.Request, 0)

		for item := range list.Iter() {
			requests = append(requests, reconcile.Request{
				NamespacedName: types.NamespacedName{
					Name:      item.GetName(),
					Namespace: obj.GetNamespace(),
				},
			})
		}

		return requests
	})
}