/*
Copyright 2021 The Karmada Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package resourceinterpreter

import (
	"context"

	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	corev1 "k8s.io/client-go/listers/core/v1"
	"k8s.io/klog/v2"

	configv1alpha1 "github.com/karmada-io/karmada/pkg/apis/config/v1alpha1"
	workv1alpha2 "github.com/karmada-io/karmada/pkg/apis/work/v1alpha2"
	"github.com/karmada-io/karmada/pkg/resourceinterpreter/customized/declarative"
	"github.com/karmada-io/karmada/pkg/resourceinterpreter/customized/webhook"
	"github.com/karmada-io/karmada/pkg/resourceinterpreter/customized/webhook/request"
	"github.com/karmada-io/karmada/pkg/resourceinterpreter/default/native"
	"github.com/karmada-io/karmada/pkg/resourceinterpreter/default/thirdparty"
	"github.com/karmada-io/karmada/pkg/util/fedinformer/genericmanager"
)

// ResourceInterpreter manages both default and customized webhooks to interpret custom resource structure.
type ResourceInterpreter interface {
	// Start starts running the component and will never stop running until the context is closed or an error occurs.
	Start(ctx context.Context) (err error)

	// HookEnabled tells if any hook exist for specific resource type and operation.
	HookEnabled(objGVK schema.GroupVersionKind, operationType configv1alpha1.InterpreterOperation) bool

	// GetReplicas returns the desired replicas of the object as well as the requirements of each replica.
	GetReplicas(object *unstructured.Unstructured) (replica int32, replicaRequires *workv1alpha2.ReplicaRequirements, err error)

	// ReviseReplica revises the replica of the given object.
	ReviseReplica(object *unstructured.Unstructured, replica int64) (*unstructured.Unstructured, error)

	// Retain returns the objects that based on the "desired" object but with values retained from the "observed" object.
	Retain(desired *unstructured.Unstructured, observed *unstructured.Unstructured) (retained *unstructured.Unstructured, err error)

	// AggregateStatus returns the objects that based on the 'object' but with status aggregated.
	AggregateStatus(object *unstructured.Unstructured, aggregatedStatusItems []workv1alpha2.AggregatedStatusItem) (*unstructured.Unstructured, error)

	// GetDependencies returns the dependent resources of the given object.
	GetDependencies(object *unstructured.Unstructured) (dependencies []configv1alpha1.DependentObjectReference, err error)

	// ReflectStatus returns the status of the object.
	ReflectStatus(object *unstructured.Unstructured) (status *runtime.RawExtension, err error)

	// InterpretHealth returns the health state of the object.
	InterpretHealth(object *unstructured.Unstructured) (healthy bool, err error)

	// other common method
}

// NewResourceInterpreter builds a new ResourceInterpreter object.
func NewResourceInterpreter(informer genericmanager.SingleClusterInformerManager, serviceLister corev1.ServiceLister) ResourceInterpreter {
	return &customResourceInterpreterImpl{
		informer:      informer,
		serviceLister: serviceLister,
	}
}

type customResourceInterpreterImpl struct {
	informer      genericmanager.SingleClusterInformerManager
	serviceLister corev1.ServiceLister

	configurableInterpreter *declarative.ConfigurableInterpreter
	customizedInterpreter   *webhook.CustomizedInterpreter
	thirdpartyInterpreter   *thirdparty.ConfigurableInterpreter
	defaultInterpreter      *native.DefaultInterpreter
}

// Start starts running the component and will never stop running until the context is closed or an error occurs.
func (i *customResourceInterpreterImpl) Start(ctx context.Context) (err error) {
	klog.Infof("Starting custom resource interpreter.")

	i.customizedInterpreter, err = webhook.NewCustomizedInterpreter(i.informer, i.serviceLister)
	if err != nil {
		return
	}
	i.configurableInterpreter = declarative.NewConfigurableInterpreter(i.informer)

	i.thirdpartyInterpreter = thirdparty.NewConfigurableInterpreter()
	i.defaultInterpreter = native.NewDefaultInterpreter()

	i.informer.Start()
	<-ctx.Done()
	klog.Infof("Stopped as stopCh closed.")
	return nil
}

// HookEnabled tells if any hook exist for specific resource type and operation.
func (i *customResourceInterpreterImpl) HookEnabled(objGVK schema.GroupVersionKind, operation configv1alpha1.InterpreterOperation) bool {
	return i.defaultInterpreter.HookEnabled(objGVK, operation) ||
		i.thirdpartyInterpreter.HookEnabled(objGVK, operation) ||
		i.configurableInterpreter.HookEnabled(objGVK, operation) ||
		i.customizedInterpreter.HookEnabled(objGVK, operation)
}

// GetReplicas returns the desired replicas of the object as well as the requirements of each replica.
func (i *customResourceInterpreterImpl) GetReplicas(object *unstructured.Unstructured) (replica int32, requires *workv1alpha2.ReplicaRequirements, err error) {
	var hookEnabled bool

	replica, requires, hookEnabled, err = i.configurableInterpreter.GetReplicas(object)
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}

	replica, requires, hookEnabled, err = i.customizedInterpreter.GetReplicas(context.TODO(), &request.Attributes{
		Operation: configv1alpha1.InterpreterOperationInterpretReplica,
		Object:    object,
	})
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}
	replica, requires, hookEnabled, err = i.thirdpartyInterpreter.GetReplicas(object)
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}

	replica, requires, err = i.defaultInterpreter.GetReplicas(object)
	return
}

// ReviseReplica revises the replica of the given object.
func (i *customResourceInterpreterImpl) ReviseReplica(object *unstructured.Unstructured, replica int64) (*unstructured.Unstructured, error) {
	obj, hookEnabled, err := i.configurableInterpreter.ReviseReplica(object, replica)
	if err != nil {
		return nil, err
	}
	if hookEnabled {
		return obj, nil
	}

	klog.V(4).Infof("Revise replicas for object: %v %s/%s with webhook interpreter.", object.GroupVersionKind(), object.GetNamespace(), object.GetName())
	obj, hookEnabled, err = i.customizedInterpreter.Patch(context.TODO(), &request.Attributes{
		Operation:   configv1alpha1.InterpreterOperationReviseReplica,
		Object:      object,
		ReplicasSet: int32(replica),
	})
	if err != nil {
		return nil, err
	}
	if hookEnabled {
		return obj, nil
	}
	obj, hookEnabled, err = i.thirdpartyInterpreter.ReviseReplica(object, replica)
	if err != nil {
		return nil, err
	}
	if hookEnabled {
		return obj, nil
	}

	return i.defaultInterpreter.ReviseReplica(object, replica)
}

// Retain returns the objects that based on the "desired" object but with values retained from the "observed" object.
func (i *customResourceInterpreterImpl) Retain(desired *unstructured.Unstructured, observed *unstructured.Unstructured) (*unstructured.Unstructured, error) {
	obj, hookEnabled, err := i.configurableInterpreter.Retain(desired, observed)
	if err != nil {
		return nil, err
	}
	if hookEnabled {
		return obj, nil
	}

	klog.V(4).Infof("Retain object: %v %s/%s with webhook interpreter.", desired.GroupVersionKind(), desired.GetNamespace(), desired.GetName())
	obj, hookEnabled, err = i.customizedInterpreter.Patch(context.TODO(), &request.Attributes{
		Operation:   configv1alpha1.InterpreterOperationRetain,
		Object:      desired,
		ObservedObj: observed,
	})
	if err != nil {
		return nil, err
	}
	if hookEnabled {
		return obj, nil
	}
	obj, hookEnabled, err = i.thirdpartyInterpreter.Retain(desired, observed)
	if err != nil {
		return nil, err
	}
	if hookEnabled {
		return obj, nil
	}

	return i.defaultInterpreter.Retain(desired, observed)
}

// AggregateStatus returns the objects that based on the 'object' but with status aggregated.
func (i *customResourceInterpreterImpl) AggregateStatus(object *unstructured.Unstructured, aggregatedStatusItems []workv1alpha2.AggregatedStatusItem) (*unstructured.Unstructured, error) {
	obj, hookEnabled, err := i.configurableInterpreter.AggregateStatus(object, aggregatedStatusItems)
	if err != nil {
		return nil, err
	}
	if hookEnabled {
		return obj, nil
	}

	klog.V(4).Infof("Aggregate status of object: %v %s/%s with webhook interpreter.", object.GroupVersionKind(), object.GetNamespace(), object.GetName())
	obj, hookEnabled, err = i.customizedInterpreter.Patch(context.TODO(), &request.Attributes{
		Operation:        configv1alpha1.InterpreterOperationAggregateStatus,
		Object:           object.DeepCopy(),
		AggregatedStatus: aggregatedStatusItems,
	})
	if err != nil {
		return nil, err
	}
	if hookEnabled {
		return obj, nil
	}
	obj, hookEnabled, err = i.thirdpartyInterpreter.AggregateStatus(object, aggregatedStatusItems)
	if err != nil {
		return nil, err
	}
	if hookEnabled {
		return obj, nil
	}

	return i.defaultInterpreter.AggregateStatus(object, aggregatedStatusItems)
}

// GetDependencies returns the dependent resources of the given object.
func (i *customResourceInterpreterImpl) GetDependencies(object *unstructured.Unstructured) (dependencies []configv1alpha1.DependentObjectReference, err error) {
	dependencies, hookEnabled, err := i.configurableInterpreter.GetDependencies(object)
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}

	dependencies, hookEnabled, err = i.customizedInterpreter.GetDependencies(context.TODO(), &request.Attributes{
		Operation: configv1alpha1.InterpreterOperationInterpretDependency,
		Object:    object,
	})
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}
	dependencies, hookEnabled, err = i.thirdpartyInterpreter.GetDependencies(object)
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}

	dependencies, err = i.defaultInterpreter.GetDependencies(object)
	return
}

// ReflectStatus returns the status of the object.
func (i *customResourceInterpreterImpl) ReflectStatus(object *unstructured.Unstructured) (status *runtime.RawExtension, err error) {
	status, hookEnabled, err := i.configurableInterpreter.ReflectStatus(object)
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}
	status, hookEnabled, err = i.customizedInterpreter.ReflectStatus(context.TODO(), &request.Attributes{
		Operation: configv1alpha1.InterpreterOperationInterpretStatus,
		Object:    object,
	})
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}
	status, hookEnabled, err = i.thirdpartyInterpreter.ReflectStatus(object)
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}
	status, err = i.defaultInterpreter.ReflectStatus(object)
	return
}

// InterpretHealth returns the health state of the object.
func (i *customResourceInterpreterImpl) InterpretHealth(object *unstructured.Unstructured) (healthy bool, err error) {
	healthy, hookEnabled, err := i.configurableInterpreter.InterpretHealth(object)
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}

	healthy, hookEnabled, err = i.customizedInterpreter.InterpretHealth(context.TODO(), &request.Attributes{
		Operation: configv1alpha1.InterpreterOperationInterpretHealth,
		Object:    object,
	})
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}
	healthy, hookEnabled, err = i.thirdpartyInterpreter.InterpretHealth(object)
	if err != nil {
		return
	}
	if hookEnabled {
		return
	}

	healthy, err = i.defaultInterpreter.InterpretHealth(object)
	return
}