// Copyright (c) 2018 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under the Apache Software License, v. 2 except as noted otherwise in the LICENSE file
//
// 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 validation

import (
	"fmt"
	"regexp"
	"time"

	"github.com/gardener/gardener/pkg/apis/core"
	"github.com/gardener/gardener/pkg/apis/core/helper"
	"github.com/gardener/gardener/pkg/utils"

	"github.com/Masterminds/semver"
	apivalidation "k8s.io/apimachinery/pkg/api/validation"
	metav1validation "k8s.io/apimachinery/pkg/apis/meta/v1/validation"
	"k8s.io/apimachinery/pkg/util/sets"
	"k8s.io/apimachinery/pkg/util/validation/field"
)

// ValidateCloudProfile validates a CloudProfile object when it is initially created.
func ValidateCloudProfileCreation(cloudProfile *core.CloudProfile) field.ErrorList {
	allErrs := field.ErrorList{}
	fldPath := field.NewPath("spec")

	// check that during creation no version can have an expiration date in the past
	fldPathKubernetes := fldPath.Child("kubernetes", "versions")
	for index, version := range cloudProfile.Spec.Kubernetes.Versions {
		allErrs = append(allErrs, validateVersionExpiration(version, fldPathKubernetes.Index(index))...)
	}

	fldPathMachineImage := fldPath.Child("machineImages")
	for index, image := range cloudProfile.Spec.MachineImages {
		fldPathImage := fldPathMachineImage.Index(index)
		for index, version := range image.Versions {
			fldPathImageVersion := fldPathImage.Child("versions")
			allErrs = append(allErrs, validateVersionExpiration(version, fldPathImageVersion.Index(index))...)
		}
	}

	allErrs = append(allErrs, ValidateCloudProfile(cloudProfile)...)

	return allErrs
}

// validateVersionExpiration validates that the version has no expiration date in the past
func validateVersionExpiration(version core.ExpirableVersion, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	if version.ExpirationDate != nil && version.ExpirationDate.Time.UTC().Before(time.Now().UTC()) {
		allErrs = append(allErrs, field.Forbidden(fldPath, fmt.Sprintf("unable to create version %q. Creating a version with expiration date in the past is not allowed", version.Version)))
	}
	return allErrs
}

// ValidateCloudProfile validates a CloudProfile object.
func ValidateCloudProfile(cloudProfile *core.CloudProfile) field.ErrorList {
	allErrs := field.ErrorList{}

	allErrs = append(allErrs, apivalidation.ValidateObjectMeta(&cloudProfile.ObjectMeta, false, ValidateName, field.NewPath("metadata"))...)
	allErrs = append(allErrs, ValidateCloudProfileSpec(&cloudProfile.Spec, field.NewPath("spec"))...)

	return allErrs
}

// ValidateCloudProfileUpdate validates a CloudProfile object before an update.
func ValidateCloudProfileUpdate(newProfile, oldProfile *core.CloudProfile) field.ErrorList {
	allErrs := field.ErrorList{}

	allErrs = append(allErrs, apivalidation.ValidateObjectMetaUpdate(&newProfile.ObjectMeta, &oldProfile.ObjectMeta, field.NewPath("metadata"))...)
	allErrs = append(allErrs, ValidateCloudProfileSpecUpdate(&newProfile.Spec, &oldProfile.Spec, field.NewPath("spec"))...)
	allErrs = append(allErrs, ValidateCloudProfile(newProfile)...)

	return allErrs
}

// ValidateCloudProfileSpecUpdate validates the spec update of a CloudProfile
func ValidateCloudProfileSpecUpdate(new, old *core.CloudProfileSpec, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	allErrs = append(allErrs, validateCloudProfileVersionsUpdate(new.Kubernetes.Versions, old.Kubernetes.Versions, fldPath.Child("kubernetes", "versions"))...)

	for _, oldImage := range old.MachineImages {
		for index, newImage := range new.MachineImages {
			if oldImage.Name == newImage.Name {
				allErrs = append(allErrs, validateCloudProfileVersionsUpdate(newImage.Versions, oldImage.Versions, fldPath.Child("machineImages").Index(index).Child("versions"))...)
			}
		}
	}

	return allErrs
}

// ValidateCloudProfileAddedVersions validates versions added to the CloudProfile
func ValidateCloudProfileAddedVersions(versions []core.ExpirableVersion, addedVersions map[string]int, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	for _, index := range addedVersions {
		version := versions[index]
		allErrs = append(allErrs, validateVersionExpiration(version, fldPath.Index(index))...)
	}
	return allErrs
}

// validateCloudProfileVersionsUpdate validates versions added to the CloudProfile
func validateCloudProfileVersionsUpdate(new, old []core.ExpirableVersion, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	versions := helper.GetAddedVersions(old, new)
	allErrs = append(allErrs, ValidateCloudProfileAddedVersions(new, versions, fldPath)...)
	return allErrs
}

// ValidateCloudProfileSpec validates the specification of a CloudProfile object.
func ValidateCloudProfileSpec(spec *core.CloudProfileSpec, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}

	if len(spec.Type) == 0 {
		allErrs = append(allErrs, field.Required(fldPath.Child("type"), "must provide a provider type"))
	}

	allErrs = append(allErrs, validateKubernetesSettings(spec.Kubernetes, fldPath.Child("kubernetes"))...)
	allErrs = append(allErrs, validateMachineImages(spec.MachineImages, fldPath.Child("machineImages"))...)
	allErrs = append(allErrs, validateMachineTypes(spec.MachineTypes, fldPath.Child("machineTypes"))...)
	allErrs = append(allErrs, validateVolumeTypes(spec.VolumeTypes, fldPath.Child("volumeTypes"))...)
	allErrs = append(allErrs, validateRegions(spec.Regions, fldPath.Child("regions"))...)
	if spec.SeedSelector != nil {
		allErrs = append(allErrs, metav1validation.ValidateLabelSelector(spec.SeedSelector, fldPath.Child("seedSelector"))...)
	}

	if spec.CABundle != nil {
		_, err := utils.DecodeCertificate([]byte(*(spec.CABundle)))
		if err != nil {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("caBundle"), *(spec.CABundle), "caBundle is not a valid PEM-encoded certificate"))
		}
	}

	return allErrs
}

func validateKubernetesSettings(kubernetes core.KubernetesSettings, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	if len(kubernetes.Versions) == 0 {
		allErrs = append(allErrs, field.Required(fldPath.Child("versions"), "must provide at least one Kubernetes version"))
	}
	latestKubernetesVersion, err := helper.DetermineLatestExpirableVersion(kubernetes.Versions)
	if err != nil {
		allErrs = append(allErrs, field.Invalid(fldPath, latestKubernetesVersion, "failed to determine latest kubernetes version from cloud profile"))
	}
	if latestKubernetesVersion.ExpirationDate != nil {
		allErrs = append(allErrs, field.Invalid(fldPath.Child("versions[]").Child("expirationDate"), latestKubernetesVersion.ExpirationDate, fmt.Sprintf("expiration date of latest kubernetes version ('%s') must not be set", latestKubernetesVersion.Version)))
	}

	versionsFound := sets.NewString()
	r, _ := regexp.Compile(`^([0-9]+\.){2}[0-9]+$`)
	for i, version := range kubernetes.Versions {
		idxPath := fldPath.Child("versions").Index(i)
		if !r.MatchString(version.Version) {
			allErrs = append(allErrs, field.Invalid(idxPath, version, fmt.Sprintf("all Kubernetes versions must match the regex %s", r)))
		} else if versionsFound.Has(version.Version) {
			allErrs = append(allErrs, field.Duplicate(idxPath.Child("version"), version.Version))
		} else {
			versionsFound.Insert(version.Version)
		}
		allErrs = append(allErrs, validateExpirableVersion(version, kubernetes.Versions, idxPath)...)
	}

	return allErrs
}

var supportedVersionClassifications = sets.NewString(string(core.ClassificationPreview), string(core.ClassificationSupported), string(core.ClassificationDeprecated))

func validateExpirableVersion(version core.ExpirableVersion, allVersions []core.ExpirableVersion, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}
	if version.Classification != nil && !supportedVersionClassifications.Has(string(*version.Classification)) {
		allErrs = append(allErrs, field.NotSupported(fldPath.Child("classification"), *version.Classification, supportedVersionClassifications.List()))
	}

	if version.Classification != nil && *version.Classification == core.ClassificationSupported {
		currentSemVer, err := semver.NewVersion(version.Version)
		if err != nil {
			// check is already performed by caller, avoid duplicate error
			return allErrs
		}

		filteredVersions, err := helper.FindVersionsWithSameMajorMinor(helper.FilterVersionsWithClassification(allVersions, core.ClassificationSupported), *currentSemVer)
		if err != nil {
			// check is already performed by caller, avoid duplicate error
			return allErrs
		}

		// do not allow adding multiple supported versions per minor version
		if len(filteredVersions) > 0 {
			allErrs = append(allErrs, field.Forbidden(fldPath, fmt.Sprintf("unable to add version %q with classification %q. Only one %q version is allowed per minor version", version.Version, core.ClassificationSupported, core.ClassificationSupported)))
		}
	}

	return allErrs
}

func validateMachineTypes(machineTypes []core.MachineType, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}

	if len(machineTypes) == 0 {
		allErrs = append(allErrs, field.Required(fldPath, "must provide at least one machine type"))
	}

	names := make(map[string]struct{}, len(machineTypes))

	for i, machineType := range machineTypes {
		idxPath := fldPath.Index(i)
		namePath := idxPath.Child("name")
		cpuPath := idxPath.Child("cpu")
		gpuPath := idxPath.Child("gpu")
		memoryPath := idxPath.Child("memory")

		if len(machineType.Name) == 0 {
			allErrs = append(allErrs, field.Required(namePath, "must provide a name"))
		}

		if _, ok := names[machineType.Name]; ok {
			allErrs = append(allErrs, field.Duplicate(namePath, machineType.Name))
			break
		}
		names[machineType.Name] = struct{}{}

		allErrs = append(allErrs, validateResourceQuantityValue("cpu", machineType.CPU, cpuPath)...)
		allErrs = append(allErrs, validateResourceQuantityValue("gpu", machineType.GPU, gpuPath)...)
		allErrs = append(allErrs, validateResourceQuantityValue("memory", machineType.Memory, memoryPath)...)
	}

	return allErrs
}

func validateMachineImages(machineImages []core.MachineImage, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}

	if len(machineImages) == 0 {
		allErrs = append(allErrs, field.Required(fldPath, "must provide at least one machine image"))
	}

	latestMachineImages, err := helper.DetermineLatestMachineImageVersions(machineImages)
	if err != nil {
		allErrs = append(allErrs, field.Invalid(fldPath, latestMachineImages, "failed to determine latest machine images from cloud profile"))
	}

	for imageName, latestImage := range latestMachineImages {
		if latestImage.ExpirationDate != nil {
			allErrs = append(allErrs, field.Invalid(fldPath.Child("expirationDate"), latestImage.ExpirationDate, fmt.Sprintf("expiration date of latest image ('%s','%s') must not be set", imageName, latestImage.Version)))
		}
	}

	duplicateNameVersion := sets.String{}
	duplicateName := sets.String{}
	for i, image := range machineImages {
		idxPath := fldPath.Index(i)
		if duplicateName.Has(image.Name) {
			allErrs = append(allErrs, field.Duplicate(idxPath, image.Name))
		}
		duplicateName.Insert(image.Name)

		if len(image.Name) == 0 {
			allErrs = append(allErrs, field.Required(idxPath.Child("name"), "machine image name must not be empty"))
		}

		if len(image.Versions) == 0 {
			allErrs = append(allErrs, field.Required(idxPath.Child("versions"), fmt.Sprintf("must provide at least one version for the machine image '%s'", image.Name)))
		}

		for index, machineVersion := range image.Versions {
			versionsPath := idxPath.Child("versions").Index(index)
			key := fmt.Sprintf("%s-%s", image.Name, machineVersion.Version)
			if duplicateNameVersion.Has(key) {
				allErrs = append(allErrs, field.Duplicate(versionsPath, key))
			}
			duplicateNameVersion.Insert(key)
			if len(machineVersion.Version) == 0 {
				allErrs = append(allErrs, field.Required(versionsPath.Child("version"), machineVersion.Version))
			}

			_, err := semver.NewVersion(machineVersion.Version)
			if err != nil {
				allErrs = append(allErrs, field.Invalid(versionsPath.Child("version"), machineVersion.Version, "could not parse version. Use a semantic version. In case there is no semantic version for this image use the extensibility provider (define mapping in the CloudProfile) to map to the actual non semantic version"))
			}
			allErrs = append(allErrs, validateExpirableVersion(machineVersion, image.Versions, versionsPath)...)
		}
	}

	return allErrs
}

func validateVolumeTypes(volumeTypes []core.VolumeType, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}

	names := make(map[string]struct{}, len(volumeTypes))

	for i, volumeType := range volumeTypes {
		idxPath := fldPath.Index(i)
		namePath := idxPath.Child("name")
		classPath := idxPath.Child("class")

		if len(volumeType.Name) == 0 {
			allErrs = append(allErrs, field.Required(namePath, "must provide a name"))
		}

		if _, ok := names[volumeType.Name]; ok {
			allErrs = append(allErrs, field.Duplicate(namePath, volumeType.Name))
			break
		}
		names[volumeType.Name] = struct{}{}

		if len(volumeType.Class) == 0 {
			allErrs = append(allErrs, field.Required(classPath, "must provide a class"))
		}
	}

	return allErrs
}

func validateRegions(regions []core.Region, fldPath *field.Path) field.ErrorList {
	allErrs := field.ErrorList{}

	if len(regions) == 0 {
		allErrs = append(allErrs, field.Required(fldPath, "must provide at least one region"))
	}

	regionsFound := sets.NewString()
	for i, region := range regions {
		idxPath := fldPath.Index(i)
		namePath := idxPath.Child("name")
		zonesPath := idxPath.Child("zones")

		if len(region.Name) == 0 {
			allErrs = append(allErrs, field.Required(namePath, "must provide a region name"))
		} else if regionsFound.Has(region.Name) {
			allErrs = append(allErrs, field.Duplicate(namePath, region.Name))
		} else {
			regionsFound.Insert(region.Name)
		}

		zonesFound := sets.NewString()
		for j, zone := range region.Zones {
			namePath := zonesPath.Index(j).Child("name")
			if len(zone.Name) == 0 {
				allErrs = append(allErrs, field.Required(namePath, "zone name cannot be empty"))
			} else if zonesFound.Has(zone.Name) {
				allErrs = append(allErrs, field.Duplicate(namePath, zone.Name))
			} else {
				zonesFound.Insert(zone.Name)
			}
		}
	}
	return allErrs
}