/*
Copyright 2018 The Kubernetes 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 apiserver

import (
	"fmt"

	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions"
)

// getSchemaForVersion returns the validation schema for given version in given CRD.
func getSchemaForVersion(crd *apiextensions.CustomResourceDefinition, version string) (*apiextensions.CustomResourceValidation, error) {
	if !hasPerVersionSchema(crd.Spec.Versions) {
		return crd.Spec.Validation, nil
	}
	if crd.Spec.Validation != nil {
		return nil, fmt.Errorf("malformed CustomResourceDefinition %s version %s: top-level and per-version schemas must be mutual exclusive", crd.Name, version)
	}
	for _, v := range crd.Spec.Versions {
		if version == v.Name {
			return v.Schema, nil
		}
	}
	return nil, fmt.Errorf("version %s not found in CustomResourceDefinition: %v", version, crd.Name)
}

// getSubresourcesForVersion returns the subresources for given version in given CRD.
func getSubresourcesForVersion(crd *apiextensions.CustomResourceDefinition, version string) (*apiextensions.CustomResourceSubresources, error) {
	if !hasPerVersionSubresources(crd.Spec.Versions) {
		return crd.Spec.Subresources, nil
	}
	if crd.Spec.Subresources != nil {
		return nil, fmt.Errorf("malformed CustomResourceDefinition %s version %s: top-level and per-version subresources must be mutual exclusive", crd.Name, version)
	}
	for _, v := range crd.Spec.Versions {
		if version == v.Name {
			return v.Subresources, nil
		}
	}
	return nil, fmt.Errorf("version %s not found in CustomResourceDefinition: %v", version, crd.Name)
}

// getColumnsForVersion returns the columns for given version in given CRD.
// NOTE: the newly logically-defaulted columns is not pointing to the original CRD object.
// One cannot mutate the original CRD columns using the logically-defaulted columns. Please iterate through
// the original CRD object instead.
func getColumnsForVersion(crd *apiextensions.CustomResourceDefinition, version string) ([]apiextensions.CustomResourceColumnDefinition, error) {
	if !hasPerVersionColumns(crd.Spec.Versions) {
		return serveDefaultColumnsIfEmpty(crd.Spec.AdditionalPrinterColumns), nil
	}
	if len(crd.Spec.AdditionalPrinterColumns) > 0 {
		return nil, fmt.Errorf("malformed CustomResourceDefinition %s version %s: top-level and per-version additionalPrinterColumns must be mutual exclusive", crd.Name, version)
	}
	for _, v := range crd.Spec.Versions {
		if version == v.Name {
			return serveDefaultColumnsIfEmpty(v.AdditionalPrinterColumns), nil
		}
	}
	return nil, fmt.Errorf("version %s not found in CustomResourceDefinition: %v", version, crd.Name)
}

// serveDefaultColumnsIfEmpty applies logically defaulting to columns, if the input columns is empty.
// NOTE: in this way, the newly logically-defaulted columns is not pointing to the original CRD object.
// One cannot mutate the original CRD columns using the logically-defaulted columns. Please iterate through
// the original CRD object instead.
func serveDefaultColumnsIfEmpty(columns []apiextensions.CustomResourceColumnDefinition) []apiextensions.CustomResourceColumnDefinition {
	if len(columns) > 0 {
		return columns
	}
	return []apiextensions.CustomResourceColumnDefinition{
		{Name: "Age", Type: "date", Description: "", JSONPath: ".metadata.creationTimestamp"},
	}
}

// hasPerVersionSchema returns true if a CRD uses per-version schema.
func hasPerVersionSchema(versions []apiextensions.CustomResourceDefinitionVersion) bool {
	for _, v := range versions {
		if v.Schema != nil {
			return true
		}
	}
	return false
}

// hasPerVersionSubresources returns true if a CRD uses per-version subresources.
func hasPerVersionSubresources(versions []apiextensions.CustomResourceDefinitionVersion) bool {
	for _, v := range versions {
		if v.Subresources != nil {
			return true
		}
	}
	return false
}

// hasPerVersionColumns returns true if a CRD uses per-version columns.
func hasPerVersionColumns(versions []apiextensions.CustomResourceDefinitionVersion) bool {
	for _, v := range versions {
		if len(v.AdditionalPrinterColumns) > 0 {
			return true
		}
	}
	return false
}
