package apiserver

import (
	"context"
	"fmt"
	"k8s.io/apiserver/pkg/endpoints/handlers"
	"net/http"

	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/meta"
	metainternalversion "k8s.io/apimachinery/pkg/apis/meta/internalversion"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	metav1beta1 "k8s.io/apimachinery/pkg/apis/meta/v1beta1"
	"k8s.io/apimachinery/pkg/apis/meta/v1beta1/validation"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apiserver/pkg/endpoints/handlers/negotiation"
	"k8s.io/apiserver/pkg/endpoints/handlers/responsewriters"
	utiltrace "k8s.io/utils/trace"
)

// transformObject takes the object as returned by storage and ensures it is in
// the client's desired form, as well as ensuring any API level fields like self-link
// are properly set.
func transformObject(ctx context.Context, obj runtime.Object, opts interface{}, mediaType negotiation.MediaTypeOptions, scope *handlers.RequestScope, req *http.Request) (runtime.Object, error) {
	if _, ok := obj.(*metav1.Status); ok {
		return obj, nil
	}
	if err := setObjectSelfLink(ctx, obj, req, scope.Namer); err != nil {
		return nil, err
	}

	switch target := mediaType.Convert; {
	case target == nil:
		return obj, nil

	case target.Kind == "PartialObjectMetadata":
		return asPartialObjectMetadata(obj, target.GroupVersion())

	case target.Kind == "PartialObjectMetadataList":
		return asPartialObjectMetadataList(obj, target.GroupVersion())

	case target.Kind == "Table":
		options, ok := opts.(*metav1beta1.TableOptions)
		if !ok {
			return nil, fmt.Errorf("unexpected TableOptions, got %T", opts)
		}
		return asTable(ctx, obj, options, scope, target.GroupVersion())

	default:
		accepted, _ := negotiation.MediaTypesForSerializer(metainternalversion.Codecs)
		err := negotiation.NewNotAcceptableError(accepted)
		return nil, err
	}
}

// optionsForTransform will load and validate any additional query parameter options for
// a conversion or return an error.
func optionsForTransform(mediaType negotiation.MediaTypeOptions, req *http.Request) (interface{}, error) {
	switch target := mediaType.Convert; {
	case target == nil:
	case target.Kind == "Table" && (target.GroupVersion() == metav1beta1.SchemeGroupVersion || target.GroupVersion() == metav1.SchemeGroupVersion):
		opts := &metav1beta1.TableOptions{}
		if err := metav1beta1.ParameterCodec.DecodeParameters(req.URL.Query(), metav1beta1.SchemeGroupVersion, opts); err != nil {
			return nil, err
		}
		switch errs := validation.ValidateTableOptions(opts); len(errs) {
		case 0:
			return opts, nil
		case 1:
			return nil, errors.NewBadRequest(fmt.Sprintf("Unable to convert to Table as requested: %v", errs[0].Error()))
		default:
			return nil, errors.NewBadRequest(fmt.Sprintf("Unable to convert to Table as requested: %v", errs))
		}
	}
	return nil, nil
}

// targetEncodingForTransform returns the appropriate serializer for the input media type
func targetEncodingForTransform(scope *handlers.RequestScope, mediaType negotiation.MediaTypeOptions, req *http.Request) (schema.GroupVersionKind, runtime.NegotiatedSerializer, bool) {
	switch target := mediaType.Convert; {
	case target == nil:
	case (target.Kind == "PartialObjectMetadata" || target.Kind == "PartialObjectMetadataList" || target.Kind == "Table") &&
		(target.GroupVersion() == metav1beta1.SchemeGroupVersion || target.GroupVersion() == metav1.SchemeGroupVersion):
		return *target, metainternalversion.Codecs, true
	}
	return scope.Kind, scope.Serializer, false
}

// transformResponseObject takes an object loaded from storage and performs any necessary transformations.
// Will write the complete response object.
func transformResponseObject(ctx context.Context, scope *handlers.RequestScope, trace *utiltrace.Trace, req *http.Request, w http.ResponseWriter, statusCode int, mediaType negotiation.MediaTypeOptions, result runtime.Object) {
	options, err := optionsForTransform(mediaType, req)
	if err != nil {
		errResponse(scope, err, w, req)
		return
	}
	obj, err := transformObject(ctx, result, options, mediaType, scope, req)
	if err != nil {
		errResponse(scope, err, w, req)
		return
	}
	kind, serializer, _ := targetEncodingForTransform(scope, mediaType, req)
	responsewriters.WriteObjectNegotiated(serializer, scope, kind.GroupVersion(), w, req, statusCode, obj)
}

// errNotAcceptable indicates Accept negotiation has failed
type errNotAcceptable struct {
	message string
}

func newNotAcceptableError(message string) error {
	return errNotAcceptable{message}
}

func (e errNotAcceptable) Error() string {
	return e.message
}

func (e errNotAcceptable) Status() metav1.Status {
	return metav1.Status{
		Status:  metav1.StatusFailure,
		Code:    http.StatusNotAcceptable,
		Reason:  metav1.StatusReason("NotAcceptable"),
		Message: e.Error(),
	}
}

func asTable(ctx context.Context, result runtime.Object, opts *metav1beta1.TableOptions, scope *handlers.RequestScope, groupVersion schema.GroupVersion) (runtime.Object, error) {
	switch groupVersion {
	case metav1beta1.SchemeGroupVersion, metav1.SchemeGroupVersion:
	default:
		return nil, newNotAcceptableError(fmt.Sprintf("no Table exists in group version %s", groupVersion))
	}

	obj, err := scope.TableConvertor.ConvertToTable(ctx, result, opts)
	if err != nil {
		return nil, err
	}

	table := (*metav1.Table)(obj)

	for i := range table.Rows {
		item := &table.Rows[i]
		switch opts.IncludeObject {
		case metav1.IncludeObject:
			item.Object.Object, err = scope.Convertor.ConvertToVersion(item.Object.Object, scope.Kind.GroupVersion())
			if err != nil {
				return nil, err
			}
		// TODO: rely on defaulting for the value here?
		case metav1.IncludeMetadata, "":
			m, err := meta.Accessor(item.Object.Object)
			if err != nil {
				return nil, err
			}
			// TODO: turn this into an internal type and do conversion in order to get object kind automatically set?
			partial := meta.AsPartialObjectMetadata(m)
			partial.GetObjectKind().SetGroupVersionKind(groupVersion.WithKind("PartialObjectMetadata"))
			item.Object.Object = partial
		case metav1.IncludeNone:
			item.Object.Object = nil
		default:
			err = errors.NewBadRequest(fmt.Sprintf("unrecognized includeObject value: %q", opts.IncludeObject))
			return nil, err
		}
	}

	return table, nil
}

func asPartialObjectMetadata(result runtime.Object, groupVersion schema.GroupVersion) (runtime.Object, error) {
	if meta.IsListType(result) {
		err := newNotAcceptableError(fmt.Sprintf("you requested PartialObjectMetadata, but the requested object is a list (%T)", result))
		return nil, err
	}
	switch groupVersion {
	case metav1beta1.SchemeGroupVersion, metav1.SchemeGroupVersion:
	default:
		return nil, newNotAcceptableError(fmt.Sprintf("no PartialObjectMetadataList exists in group version %s", groupVersion))
	}
	m, err := meta.Accessor(result)
	if err != nil {
		return nil, err
	}
	partial := meta.AsPartialObjectMetadata(m)
	partial.GetObjectKind().SetGroupVersionKind(groupVersion.WithKind("PartialObjectMetadata"))
	return partial, nil
}

func asPartialObjectMetadataList(result runtime.Object, groupVersion schema.GroupVersion) (runtime.Object, error) {
	li, ok := result.(metav1.ListInterface)
	if !ok {
		return nil, newNotAcceptableError(fmt.Sprintf("you requested PartialObjectMetadataList, but the requested object is not a list (%T)", result))
	}

	gvk := groupVersion.WithKind("PartialObjectMetadata")
	switch {
	case groupVersion == metav1beta1.SchemeGroupVersion:
		list := &metav1beta1.PartialObjectMetadataList{}
		err := meta.EachListItem(result, func(obj runtime.Object) error {
			m, err := meta.Accessor(obj)
			if err != nil {
				return err
			}
			partial := meta.AsPartialObjectMetadata(m)
			partial.GetObjectKind().SetGroupVersionKind(gvk)
			list.Items = append(list.Items, *partial)
			return nil
		})
		if err != nil {
			return nil, err
		}
		list.SelfLink = li.GetSelfLink()
		list.ResourceVersion = li.GetResourceVersion()
		list.Continue = li.GetContinue()
		return list, nil

	case groupVersion == metav1.SchemeGroupVersion:
		list := &metav1.PartialObjectMetadataList{}
		err := meta.EachListItem(result, func(obj runtime.Object) error {
			m, err := meta.Accessor(obj)
			if err != nil {
				return err
			}
			partial := meta.AsPartialObjectMetadata(m)
			partial.GetObjectKind().SetGroupVersionKind(gvk)
			list.Items = append(list.Items, *partial)
			return nil
		})
		if err != nil {
			return nil, err
		}
		list.SelfLink = li.GetSelfLink()
		list.ResourceVersion = li.GetResourceVersion()
		list.Continue = li.GetContinue()
		return list, nil

	default:
		return nil, newNotAcceptableError(fmt.Sprintf("no PartialObjectMetadataList exists in group version %s", groupVersion))
	}
}