/*
Copyright The Helm 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 rules

import (
	"fmt"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"strings"

	"github.com/pkg/errors"
	"sigs.k8s.io/yaml"

	"helm.sh/helm/v3/pkg/chart/loader"
	"helm.sh/helm/v3/pkg/chartutil"
	"helm.sh/helm/v3/pkg/engine"
	"helm.sh/helm/v3/pkg/lint/support"
)

var (
	crdHookSearch     = regexp.MustCompile(`"?helm\.sh/hook"?:\s+crd-install`)
	releaseTimeSearch = regexp.MustCompile(`\.Release\.Time`)
)

// validName is a regular expression for names.
//
// This is different than action.ValidName. It conforms to the regular expression
// `kubectl` says it uses, plus it disallows empty names.
//
// For details, see https://kubernetes.io/docs/concepts/overview/working-with-objects/names/#names
var validName = regexp.MustCompile(`^[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*$`)

// Templates lints the templates in the Linter.
func Templates(linter *support.Linter, values map[string]interface{}, namespace string, strict bool) {
	fpath := "templates/"
	templatesPath := filepath.Join(linter.ChartDir, fpath)

	templatesDirExist := linter.RunLinterRule(support.WarningSev, fpath, validateTemplatesDir(templatesPath))

	// Templates directory is optional for now
	if !templatesDirExist {
		return
	}

	// Load chart and parse templates
	chart, err := loader.Load(linter.ChartDir)

	chartLoaded := linter.RunLinterRule(support.ErrorSev, fpath, err)

	if !chartLoaded {
		return
	}

	options := chartutil.ReleaseOptions{
		Name:      "test-release",
		Namespace: namespace,
	}

	cvals, err := chartutil.CoalesceValues(chart, values)
	if err != nil {
		return
	}
	valuesToRender, err := chartutil.ToRenderValues(chart, cvals, options, nil)
	if err != nil {
		linter.RunLinterRule(support.ErrorSev, fpath, err)
		return
	}
	var e engine.Engine
	e.LintMode = true
	renderedContentMap, err := e.Render(chart, valuesToRender)

	renderOk := linter.RunLinterRule(support.ErrorSev, fpath, err)

	if !renderOk {
		return
	}

	/* Iterate over all the templates to check:
	- It is a .yaml file
	- All the values in the template file is defined
	- {{}} include | quote
	- Generated content is a valid Yaml file
	- Metadata.Namespace is not set
	*/
	for _, template := range chart.Templates {
		fileName, data := template.Name, template.Data
		fpath = fileName

		linter.RunLinterRule(support.ErrorSev, fpath, validateAllowedExtension(fileName))
		// These are v3 specific checks to make sure and warn people if their
		// chart is not compatible with v3
		linter.RunLinterRule(support.WarningSev, fpath, validateNoCRDHooks(data))
		linter.RunLinterRule(support.ErrorSev, fpath, validateNoReleaseTime(data))

		// We only apply the following lint rules to yaml files
		if filepath.Ext(fileName) != ".yaml" || filepath.Ext(fileName) == ".yml" {
			continue
		}

		// NOTE: disabled for now, Refs https://github.com/helm/helm/issues/1463
		// Check that all the templates have a matching value
		//linter.RunLinterRule(support.WarningSev, fpath, validateNoMissingValues(templatesPath, valuesToRender, preExecutedTemplate))

		// NOTE: disabled for now, Refs https://github.com/helm/helm/issues/1037
		// linter.RunLinterRule(support.WarningSev, fpath, validateQuotes(string(preExecutedTemplate)))

		renderedContent := renderedContentMap[path.Join(chart.Name(), fileName)]
		if strings.TrimSpace(renderedContent) != "" {
			var yamlStruct K8sYamlStruct
			// Even though K8sYamlStruct only defines a few fields, an error in any other
			// key will be raised as well
			err := yaml.Unmarshal([]byte(renderedContent), &yamlStruct)

			// If YAML linting fails, we sill progress. So we don't capture the returned state
			// on this linter run.
			linter.RunLinterRule(support.ErrorSev, fpath, validateYamlContent(err))
			linter.RunLinterRule(support.ErrorSev, fpath, validateMetadataName(&yamlStruct))
			linter.RunLinterRule(support.ErrorSev, fpath, validateNoDeprecations(&yamlStruct))
			linter.RunLinterRule(support.ErrorSev, fpath, validateMatchSelector(&yamlStruct, renderedContent))
		}
	}
}

// Validation functions
func validateTemplatesDir(templatesPath string) error {
	if fi, err := os.Stat(templatesPath); err != nil {
		return errors.New("directory not found")
	} else if !fi.IsDir() {
		return errors.New("not a directory")
	}
	return nil
}

func validateAllowedExtension(fileName string) error {
	ext := filepath.Ext(fileName)
	validExtensions := []string{".yaml", ".yml", ".tpl", ".txt"}

	for _, b := range validExtensions {
		if b == ext {
			return nil
		}
	}

	return errors.Errorf("file extension '%s' not valid. Valid extensions are .yaml, .yml, .tpl, or .txt", ext)
}

func validateYamlContent(err error) error {
	return errors.Wrap(err, "unable to parse YAML")
}

func validateMetadataName(obj *K8sYamlStruct) error {
	// This will return an error if the characters do not abide by the standard OR if the
	// name is left empty.
	if validName.MatchString(obj.Metadata.Name) {
		return nil
	}
	return fmt.Errorf("object name does not conform to Kubernetes naming requirements: %q", obj.Metadata.Name)
}

func validateNoCRDHooks(manifest []byte) error {
	if crdHookSearch.Match(manifest) {
		return errors.New("manifest is a crd-install hook. This hook is no longer supported in v3 and all CRDs should also exist the crds/ directory at the top level of the chart")
	}
	return nil
}

func validateNoReleaseTime(manifest []byte) error {
	if releaseTimeSearch.Match(manifest) {
		return errors.New(".Release.Time has been removed in v3, please replace with the `now` function in your templates")
	}
	return nil
}

// validateMatchSelector ensures that template specs have a selector declared.
// See https://github.com/helm/helm/issues/1990
func validateMatchSelector(yamlStruct *K8sYamlStruct, manifest string) error {
	switch yamlStruct.Kind {
	case "Deployment", "ReplicaSet", "DaemonSet", "StatefulSet":
		// verify that matchLabels or matchExpressions is present
		if !(strings.Contains(manifest, "matchLabels") || strings.Contains(manifest, "matchExpressions")) {
			return fmt.Errorf("a %s must contain matchLabels or matchExpressions, and %q does not", yamlStruct.Kind, yamlStruct.Metadata.Name)
		}
	}
	return nil
}

// K8sYamlStruct stubs a Kubernetes YAML file.
//
// DEPRECATED: In Helm 4, this will be made a private type, as it is for use only within
// the rules package.
type K8sYamlStruct struct {
	APIVersion string `json:"apiVersion"`
	Kind       string
	Metadata   k8sYamlMetadata
}

type k8sYamlMetadata struct {
	Namespace string
	Name      string
}