// Copyright Istio 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 crd

import (
	"context"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"sync"

	"github.com/hashicorp/go-multierror"
	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions"
	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
	apiextensionsv1beta1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1"
	apiextval "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation"
	structuralschema "k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
	"k8s.io/apiextensions-apiserver/pkg/apiserver/schema/cel"
	structuraldefaulting "k8s.io/apiextensions-apiserver/pkg/apiserver/schema/defaulting"
	structurallisttype "k8s.io/apiextensions-apiserver/pkg/apiserver/schema/listtype"
	structuralpruning "k8s.io/apiextensions-apiserver/pkg/apiserver/schema/pruning"
	"k8s.io/apiextensions-apiserver/pkg/apiserver/validation"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	kubeyaml "k8s.io/apimachinery/pkg/util/yaml"
	celconfig "k8s.io/apiserver/pkg/apis/cel"
	"sigs.k8s.io/yaml"

	"istio.io/istio/pkg/slices"
	"istio.io/istio/pkg/test"
	"istio.io/istio/pkg/test/env"
	"istio.io/istio/pkg/test/util/yml"
	"istio.io/istio/pkg/util/sets"
)

// Validator returns a new validator for custom resources
// Warning: this is meant for usage in tests only
type Validator struct {
	byGvk      map[schema.GroupVersionKind]validation.SchemaCreateValidator
	structural map[schema.GroupVersionKind]*structuralschema.Structural
	cel        map[schema.GroupVersionKind]*cel.Validator
	// If enabled, resources without a validator will be ignored. Otherwise, they will fail.
	SkipMissing bool
}

type ValidationIgnorer struct {
	mu                  sync.RWMutex
	patternsByNamespace map[string]sets.String
}

// NewValidationIgnorer initializes the ignorer for the validatior, pairs are in namespace/namePattern format.
func NewValidationIgnorer(pairs ...string) *ValidationIgnorer {
	vi := &ValidationIgnorer{
		patternsByNamespace: make(map[string]sets.String),
	}
	for _, pair := range pairs {
		parts := strings.SplitN(pair, "/", 2)
		if len(parts) != 2 {
			continue
		}
		vi.Add(parts[0], parts[1])
	}
	return vi
}

func (iv *ValidationIgnorer) Add(namespace, pattern string) {
	iv.mu.Lock()
	defer iv.mu.Unlock()
	if iv.patternsByNamespace[namespace] == nil {
		iv.patternsByNamespace[namespace] = sets.String{}
	}
	iv.patternsByNamespace[namespace].Insert(pattern)
}

// ShouldIgnore checks if a given namespaced name should be ignored based on the patterns.
func (iv *ValidationIgnorer) ShouldIgnore(namespace, name string) bool {
	iv.mu.RLock()
	defer iv.mu.RUnlock()

	patterns, exists := iv.patternsByNamespace[namespace]
	if !exists {
		return false
	}

	for _, pattern := range patterns.UnsortedList() {
		match, err := regexp.MatchString(pattern, name)
		if err != nil {
			continue
		}
		if match {
			return true
		}
	}
	return false
}

func (v *Validator) ValidateCustomResourceYAML(data string, ignorer *ValidationIgnorer) error {
	var errs *multierror.Error
	for _, item := range yml.SplitString(data) {
		obj := &unstructured.Unstructured{}
		if err := yaml.Unmarshal([]byte(item), obj); err != nil {
			return err
		}
		if ignorer != nil && ignorer.ShouldIgnore(obj.GetNamespace(), obj.GetName()) {
			continue
		}
		errs = multierror.Append(errs, v.ValidateCustomResource(obj))
	}
	return errs.ErrorOrNil()
}

func (v *Validator) ValidateCustomResource(o runtime.Object) error {
	content, err := runtime.DefaultUnstructuredConverter.ToUnstructured(o)
	if err != nil {
		return err
	}

	un := &unstructured.Unstructured{Object: content}
	vd, f := v.byGvk[un.GroupVersionKind()]
	if !f {
		if v.SkipMissing {
			return nil
		}
		return fmt.Errorf("failed to validate type %v: no validator found", un.GroupVersionKind())
	}
	// Fill in defaults
	structural := v.structural[un.GroupVersionKind()]
	structuraldefaulting.Default(un.Object, structural)
	if err := validation.ValidateCustomResource(nil, un.Object, vd).ToAggregate(); err != nil {
		return fmt.Errorf("%v/%v/%v: %v", un.GroupVersionKind().Kind, un.GetName(), un.GetNamespace(), err)
	}
	if err := structurallisttype.ValidateListSetsAndMaps(nil, structural, un.Object).ToAggregate(); err != nil {
		return fmt.Errorf("%v/%v/%v: %v", un.GroupVersionKind().Kind, un.GetName(), un.GetNamespace(), err)
	}
	pruneOpts := structuralschema.UnknownFieldPathOptions{TrackUnknownFieldPaths: true}
	unknownFieldPaths := structuralpruning.PruneWithOptions(un.DeepCopy().Object, structural, false, pruneOpts)
	unknownFieldPaths = slices.FilterInPlace(unknownFieldPaths, func(s string) bool {
		// Some CRDs don't spell out all the fields in metadata, and k8s doesn't care
		return !strings.HasPrefix(s, "metadata.")
	})
	if len(unknownFieldPaths) > 0 {
		return fmt.Errorf("%v/%v/%v: unknown fields %v", un.GroupVersionKind().Kind, un.GetName(), un.GetNamespace(), unknownFieldPaths)
	}

	errs, _ := v.cel[un.GroupVersionKind()].Validate(context.Background(), nil, structural, un.Object, nil, celconfig.RuntimeCELCostBudget)
	if errs.ToAggregate() != nil {
		return fmt.Errorf("%v/%v/%v: %v", un.GroupVersionKind().Kind, un.GetName(), un.GetNamespace(), errs.ToAggregate().Error())
	}
	return nil
}

func NewValidatorFromFiles(files ...string) (*Validator, error) {
	crds := []apiextensions.CustomResourceDefinition{}
	closers := make([]io.Closer, 0, len(files))
	defer func() {
		for _, closer := range closers {
			closer.Close()
		}
	}()
	for _, file := range files {
		data, err := os.Open(file)
		if err != nil {
			return nil, fmt.Errorf("failed to read input yaml file: %v", err)
		}
		closers = append(closers, data)

		yamlDecoder := kubeyaml.NewYAMLOrJSONDecoder(data, 512*1024)
		for {
			un := &unstructured.Unstructured{}
			err = yamlDecoder.Decode(&un)
			if err == io.EOF {
				break
			}
			if err != nil {
				return nil, err
			}
			crd := apiextensions.CustomResourceDefinition{}
			switch un.GroupVersionKind() {
			case schema.GroupVersionKind{
				Group:   "apiextensions.k8s.io",
				Version: "v1",
				Kind:    "CustomResourceDefinition",
			}:
				crdv1 := apiextensionsv1.CustomResourceDefinition{}
				if err := runtime.DefaultUnstructuredConverter.
					FromUnstructured(un.UnstructuredContent(), &crdv1); err != nil {
					return nil, err
				}
				if err := apiextensionsv1.Convert_v1_CustomResourceDefinition_To_apiextensions_CustomResourceDefinition(&crdv1, &crd, nil); err != nil {
					return nil, err
				}
			case schema.GroupVersionKind{
				Group:   "apiextensions.k8s.io",
				Version: "v1beta1",
				Kind:    "CustomResourceDefinition",
			}:
				crdv1beta1 := apiextensionsv1beta1.CustomResourceDefinition{}
				if err := runtime.DefaultUnstructuredConverter.
					FromUnstructured(un.UnstructuredContent(), &crdv1beta1); err != nil {
					return nil, err
				}
				if err := apiextensionsv1beta1.Convert_v1beta1_CustomResourceDefinition_To_apiextensions_CustomResourceDefinition(&crdv1beta1, &crd, nil); err != nil {
					return nil, err
				}
			default:
				return nil, fmt.Errorf("unknown CRD type: %v", un.GroupVersionKind())
			}
			crds = append(crds, crd)
		}
	}
	return NewValidatorFromCRDs(crds...)
}

func NewValidatorFromCRDs(crds ...apiextensions.CustomResourceDefinition) (*Validator, error) {
	v := &Validator{
		byGvk:      map[schema.GroupVersionKind]validation.SchemaCreateValidator{},
		structural: map[schema.GroupVersionKind]*structuralschema.Structural{},
		cel:        map[schema.GroupVersionKind]*cel.Validator{},
	}
	for _, crd := range crds {
		versions := crd.Spec.Versions
		if len(versions) == 0 {
			versions = []apiextensions.CustomResourceDefinitionVersion{{Name: crd.Spec.Version}} // nolint: staticcheck
		}
		crd.Status.StoredVersions = slices.Map(versions, func(e apiextensions.CustomResourceDefinitionVersion) string {
			return e.Name
		})
		errs := apiextval.ValidateCustomResourceDefinition(context.Background(), &crd)
		if len(errs) > 0 {
			return nil, fmt.Errorf("CRD %v is not valid: %v", crd.Name, errs.ToAggregate())
		}
		for _, ver := range versions {
			gvk := schema.GroupVersionKind{
				Group:   crd.Spec.Group,
				Version: ver.Name,
				Kind:    crd.Spec.Names.Kind,
			}
			crdSchema := ver.Schema
			if crdSchema == nil {
				crdSchema = crd.Spec.Validation
			}
			if crdSchema == nil {
				return nil, fmt.Errorf("crd did not have validation defined")
			}

			schemaValidator, _, err := validation.NewSchemaValidator(crdSchema.OpenAPIV3Schema)
			if err != nil {
				return nil, err
			}
			structural, err := structuralschema.NewStructural(crdSchema.OpenAPIV3Schema)
			if err != nil {
				return nil, err
			}

			v.byGvk[gvk] = schemaValidator
			v.structural[gvk] = structural
			// CEL programs are compiled and cached here
			if celv := cel.NewValidator(structural, true, celconfig.PerCallLimit); celv != nil {
				v.cel[gvk] = celv
			}

		}
	}

	return v, nil
}

func NewIstioValidator(t test.Failer) *Validator {
	v, err := NewValidatorFromFiles(
		filepath.Join(env.IstioSrc, "tests/integration/pilot/testdata/gateway-api-inference-extension-crd.yaml"),
		filepath.Join(env.IstioSrc, "tests/integration/pilot/testdata/gateway-api-crd.yaml"),
		filepath.Join(env.IstioSrc, "manifests/charts/base/files/crd-all.gen.yaml"),
	)
	if err != nil {
		t.Fatal(err)
	}
	return v
}
