/*
Copyright 2015 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 cmd

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"reflect"
	gruntime "runtime"
	"strings"

	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/meta"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/apimachinery/pkg/util/mergepatch"
	"k8s.io/apimachinery/pkg/util/strategicpatch"
	"k8s.io/apimachinery/pkg/util/validation/field"
	"k8s.io/apimachinery/pkg/util/yaml"
	"k8s.io/kubernetes/pkg/api"
	"k8s.io/kubernetes/pkg/kubectl"
	"k8s.io/kubernetes/pkg/kubectl/cmd/templates"
	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
	"k8s.io/kubernetes/pkg/kubectl/cmd/util/editor"
	"k8s.io/kubernetes/pkg/kubectl/resource"
	"k8s.io/kubernetes/pkg/printers"
	"k8s.io/kubernetes/pkg/util/crlf"
	"k8s.io/kubernetes/pkg/util/i18n"

	jsonpatch "github.com/evanphx/json-patch"
	"github.com/golang/glog"
	"github.com/spf13/cobra"
)

var (
	editLong = templates.LongDesc(`
		Edit a resource from the default editor.

		The edit command allows you to directly edit any API resource you can retrieve via the
		command line tools. It will open the editor defined by your KUBE_EDITOR, or EDITOR
		environment variables, or fall back to 'vi' for Linux or 'notepad' for Windows.
		You can edit multiple objects, although changes are applied one at a time. The command
		accepts filenames as well as command line arguments, although the files you point to must
		be previously saved versions of resources.

		Editing is done with the API version used to fetch the resource.
		To edit using a specific API version, fully-qualify the resource, version, and group.

		The default format is YAML. To edit in JSON, specify "-o json".

		The flag --windows-line-endings can be used to force Windows line endings,
		otherwise the default for your operating system will be used.

		In the event an error occurs while updating, a temporary file will be created on disk
		that contains your unapplied changes. The most common error when updating a resource
		is another editor changing the resource on the server. When this occurs, you will have
		to apply your changes to the newer version of the resource, or update your temporary
		saved copy to include the latest resource version.`)

	editExample = templates.Examples(`
		# Edit the service named 'docker-registry':
		kubectl edit svc/docker-registry

		# Use an alternative editor
		KUBE_EDITOR="nano" kubectl edit svc/docker-registry

		# Edit the job 'myjob' in JSON using the v1 API format:
		kubectl edit job.v1.batch/myjob -o json

		# Edit the deployment 'mydeployment' in YAML and save the modified config in its annotation:
		kubectl edit deployment/mydeployment -o yaml --save-config`)
)

func NewCmdEdit(f cmdutil.Factory, out, errOut io.Writer) *cobra.Command {
	options := &resource.FilenameOptions{}

	// retrieve a list of handled resources from printer as valid args
	validArgs, argAliases := []string{}, []string{}
	p, err := f.Printer(nil, printers.PrintOptions{
		ColumnLabels: []string{},
	})
	cmdutil.CheckErr(err)
	if p != nil {
		validArgs = p.HandledResources()
		argAliases = kubectl.ResourceAliases(validArgs)
	}

	cmd := &cobra.Command{
		Use:     "edit (RESOURCE/NAME | -f FILENAME)",
		Short:   i18n.T("Edit a resource on the server"),
		Long:    editLong,
		Example: fmt.Sprintf(editExample),
		Run: func(cmd *cobra.Command, args []string) {
			err := RunEdit(f, out, errOut, cmd, args, options)
			cmdutil.CheckErr(err)
		},
		ValidArgs:  validArgs,
		ArgAliases: argAliases,
	}
	usage := "to use to edit the resource"
	cmdutil.AddFilenameOptionFlags(cmd, options, usage)
	cmdutil.AddValidateFlags(cmd)
	cmd.Flags().StringP("output", "o", "yaml", "Output format. One of: yaml|json.")

	cmd.Flags().Bool("windows-line-endings", gruntime.GOOS == "windows", "Use Windows line-endings (default Unix line-endings)")
	cmdutil.AddApplyAnnotationFlags(cmd)
	cmdutil.AddRecordFlag(cmd)
	cmdutil.AddInclude3rdPartyFlags(cmd)
	return cmd
}

func RunEdit(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args []string, options *resource.FilenameOptions) error {
	return runEdit(f, out, errOut, cmd, args, options, NormalEditMode)
}

// runEdit performs an interactive edit on the resources specified by filename or resource builder args.
// in NormalEditMode, all resources are edited as a single list.
// in CreateEditMode, resources are edited one-by-one.
// TODO: refactor runEdit and editFn into smaller simpler chunks
func runEdit(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args []string, options *resource.FilenameOptions, editMode EditMode) error {
	o, err := getPrinter(cmd)
	if err != nil {
		return err
	}

	mapper, originalResult, updatedResultsGetter, cmdNamespace, err := getMapperAndResult(f, args, options, editMode)
	if err != nil {
		return err
	}

	encoder := f.JSONEncoder()

	var (
		windowsLineEndings = cmdutil.GetFlagBool(cmd, "windows-line-endings")
		edit               = editor.NewDefaultEditor(f.EditorEnvs())
	)

	// editFn is invoked for each edit session (once with a list for normal edit, once for each individual resource in a edit-on-create invocation)
	editFn := func(infos []*resource.Info) error {
		var (
			results  = editResults{}
			original = []byte{}
			edited   = []byte{}
			file     string
		)

		containsError := false

		// loop until we succeed or cancel editing
		for {
			// get the object we're going to serialize as input to the editor
			var originalObj runtime.Object
			switch len(infos) {
			case 1:
				originalObj = infos[0].Object
			default:
				l := &unstructured.UnstructuredList{
					Object: map[string]interface{}{
						"kind":       "List",
						"apiVersion": "v1",
						"metadata":   map[string]interface{}{},
					},
				}
				for _, info := range infos {
					l.Items = append(l.Items, info.Object.(*unstructured.Unstructured))
				}
				originalObj = l
			}

			// generate the file to edit
			buf := &bytes.Buffer{}
			var w io.Writer = buf
			if windowsLineEndings {
				w = crlf.NewCRLFWriter(w)
			}

			if o.addHeader {
				results.header.writeTo(w)
			}

			if !containsError {
				if err := o.printer.PrintObj(originalObj, w); err != nil {
					return preservedFile(err, results.file, errOut)
				}
				original = buf.Bytes()
			} else {
				// In case of an error, preserve the edited file.
				// Remove the comments (header) from it since we already
				// have included the latest header in the buffer above.
				buf.Write(manualStrip(edited))
			}

			// launch the editor
			editedDiff := edited
			edited, file, err = edit.LaunchTempFile(fmt.Sprintf("%s-edit-", filepath.Base(os.Args[0])), o.ext, buf)
			if err != nil {
				return preservedFile(err, results.file, errOut)
			}
			// If we're retrying the loop because of an error, and no change was made in the file, short-circuit
			if containsError && bytes.Equal(stripComments(editedDiff), stripComments(edited)) {
				return preservedFile(fmt.Errorf("%s", "Edit cancelled, no valid changes were saved."), file, errOut)
			}
			// cleanup any file from the previous pass
			if len(results.file) > 0 {
				os.Remove(results.file)
			}
			glog.V(4).Infof("User edited:\n%s", string(edited))

			// Apply validation
			schema, err := f.Validator(cmdutil.GetFlagBool(cmd, "validate"), cmdutil.GetFlagString(cmd, "schema-cache-dir"))
			if err != nil {
				return preservedFile(err, file, errOut)
			}
			err = schema.ValidateBytes(stripComments(edited))
			if err != nil {
				results = editResults{
					file: file,
				}
				containsError = true
				fmt.Fprintln(errOut, results.addError(errors.NewInvalid(api.Kind(""), "", field.ErrorList{field.Invalid(nil, "The edited file failed validation", fmt.Sprintf("%v", err))}), infos[0]))
				continue
			}

			// Compare content without comments
			if bytes.Equal(stripComments(original), stripComments(edited)) {
				os.Remove(file)
				fmt.Fprintln(errOut, "Edit cancelled, no changes made.")
				return nil
			}

			lines, err := hasLines(bytes.NewBuffer(edited))
			if err != nil {
				return preservedFile(err, file, errOut)
			}
			if !lines {
				os.Remove(file)
				fmt.Fprintln(errOut, "Edit cancelled, saved file was empty.")
				return nil
			}

			results = editResults{
				file: file,
			}

			// parse the edited file
			updatedInfos, err := updatedResultsGetter(edited).Infos()
			if err != nil {
				// syntax error
				containsError = true
				results.header.reasons = append(results.header.reasons, editReason{head: fmt.Sprintf("The edited file had a syntax error: %v", err)})
				continue
			}
			// not a syntax error as it turns out...
			containsError = false
			updatedVisitor := resource.InfoListVisitor(updatedInfos)

			// need to make sure the original namespace wasn't changed while editing
			if err := updatedVisitor.Visit(resource.RequireNamespace(cmdNamespace)); err != nil {
				return preservedFile(err, file, errOut)
			}

			// iterate through all items to apply annotations
			if err := visitAnnotation(cmd, f, updatedVisitor, encoder); err != nil {
				return preservedFile(err, file, errOut)
			}

			switch editMode {
			case NormalEditMode:
				err = visitToPatch(infos, updatedVisitor, mapper, encoder, out, errOut, &results, file)
			case EditBeforeCreateMode:
				err = visitToCreate(updatedVisitor, mapper, out, errOut, &results, file)
			default:
				err = fmt.Errorf("Unsupported edit mode %q", editMode)
			}
			if err != nil {
				return preservedFile(err, results.file, errOut)
			}

			// Handle all possible errors
			//
			// 1. retryable: propose kubectl replace -f
			// 2. notfound: indicate the location of the saved configuration of the deleted resource
			// 3. invalid: retry those on the spot by looping ie. reloading the editor
			if results.retryable > 0 {
				fmt.Fprintf(errOut, "You can run `%s replace -f %s` to try this update again.\n", filepath.Base(os.Args[0]), file)
				return cmdutil.ErrExit
			}
			if results.notfound > 0 {
				fmt.Fprintf(errOut, "The edits you made on deleted resources have been saved to %q\n", file)
				return cmdutil.ErrExit
			}

			if len(results.edit) == 0 {
				if results.notfound == 0 {
					os.Remove(file)
				} else {
					fmt.Fprintf(out, "The edits you made on deleted resources have been saved to %q\n", file)
				}
				return nil
			}

			if len(results.header.reasons) > 0 {
				containsError = true
			}
		}
	}

	switch editMode {
	// If doing normal edit we cannot use Visit because we need to edit a list for convenience. Ref: #20519
	case NormalEditMode:
		infos, err := originalResult.Infos()
		if err != nil {
			return err
		}
		return editFn(infos)
	// If doing an edit before created, we don't want a list and instead want the normal behavior as kubectl create.
	case EditBeforeCreateMode:
		return originalResult.Visit(func(info *resource.Info, err error) error {
			return editFn([]*resource.Info{info})
		})
	default:
		return fmt.Errorf("Unsupported edit mode %q", editMode)
	}
}

func getPrinter(cmd *cobra.Command) (*editPrinterOptions, error) {
	switch format := cmdutil.GetFlagString(cmd, "output"); format {
	case "json":
		return &editPrinterOptions{
			printer:   &printers.JSONPrinter{},
			ext:       ".json",
			addHeader: false,
		}, nil
	// If flag -o is not specified, use yaml as default
	case "yaml", "":
		return &editPrinterOptions{
			printer:   &printers.YAMLPrinter{},
			ext:       ".yaml",
			addHeader: true,
		}, nil
	default:
		return nil, cmdutil.UsageError(cmd, "The flag 'output' must be one of yaml|json")
	}
}

type resultGetter func([]byte) *resource.Result

// getMapperAndResult obtains the initial set of resources to edit, and returns:
// * mapper: restmapper used for printing objects
// * result: initial set of resources to edit. contains latest versions from the server when in normal editing mode
// * resultGetter: function that returns a set of resources parsed from user input. used to get resources from edited file.
// * cmdNamespace: namespace the edit was invoked with. used to verify namespaces don't change during editing.
// * error: any error that occurs fetching initial resources or building results.
func getMapperAndResult(f cmdutil.Factory, args []string, options *resource.FilenameOptions, editMode EditMode) (meta.RESTMapper, *resource.Result, resultGetter, string, error) {
	if editMode != NormalEditMode && editMode != EditBeforeCreateMode {
		return nil, nil, nil, "", fmt.Errorf("Unsupported edit mode %q", editMode)
	}

	cmdNamespace, enforceNamespace, err := f.DefaultNamespace()
	if err != nil {
		return nil, nil, nil, "", err
	}
	mapper, typer, err := f.UnstructuredObject()
	if err != nil {
		return nil, nil, nil, "", err
	}

	b := resource.NewBuilder(mapper, typer, resource.ClientMapperFunc(f.UnstructuredClientForMapping), unstructured.UnstructuredJSONScheme)
	if editMode == NormalEditMode {
		// if in normal mode, also read from args, and fetch latest from the server
		b = b.ResourceTypeOrNameArgs(true, args...).Latest()
	}

	originalResult := b.NamespaceParam(cmdNamespace).DefaultNamespace().
		FilenameParam(enforceNamespace, options).
		ContinueOnError().
		Flatten().
		Do()
	err = originalResult.Err()
	if err != nil {
		return nil, nil, nil, "", err
	}

	updatedResultGetter := func(data []byte) *resource.Result {
		// resource builder to read objects from edited data
		return resource.NewBuilder(mapper, typer, resource.ClientMapperFunc(f.UnstructuredClientForMapping), unstructured.UnstructuredJSONScheme).
			Stream(bytes.NewReader(data), "edited-file").
			ContinueOnError().
			Flatten().
			Do()
	}

	return mapper, originalResult, updatedResultGetter, cmdNamespace, err
}

func visitToPatch(
	originalInfos []*resource.Info,
	patchVisitor resource.Visitor,
	mapper meta.RESTMapper,
	encoder runtime.Encoder,
	out, errOut io.Writer,
	results *editResults,
	file string,
) error {
	err := patchVisitor.Visit(func(info *resource.Info, incomingErr error) error {
		editObjUID, err := meta.NewAccessor().UID(info.Object)
		if err != nil {
			return err
		}

		var originalInfo *resource.Info
		for _, i := range originalInfos {
			originalObjUID, err := meta.NewAccessor().UID(i.Object)
			if err != nil {
				return err
			}
			if editObjUID == originalObjUID {
				originalInfo = i
				break
			}
		}
		if originalInfo == nil {
			return fmt.Errorf("no original object found for %#v", info.Object)
		}

		originalSerialization, err := runtime.Encode(encoder, originalInfo.Object)
		if err != nil {
			return err
		}
		editedSerialization, err := runtime.Encode(encoder, info.Object)
		if err != nil {
			return err
		}

		// compute the patch on a per-item basis
		// use strategic merge to create a patch
		originalJS, err := yaml.ToJSON(originalSerialization)
		if err != nil {
			return err
		}
		editedJS, err := yaml.ToJSON(editedSerialization)
		if err != nil {
			return err
		}

		if reflect.DeepEqual(originalJS, editedJS) {
			// no edit, so just skip it.
			cmdutil.PrintSuccess(mapper, false, out, info.Mapping.Resource, info.Name, false, "skipped")
			return nil
		}

		preconditions := []mergepatch.PreconditionFunc{
			mergepatch.RequireKeyUnchanged("apiVersion"),
			mergepatch.RequireKeyUnchanged("kind"),
			mergepatch.RequireMetadataKeyUnchanged("name"),
		}

		// Create the versioned struct from the type defined in the mapping
		// (which is the API version we'll be submitting the patch to)
		versionedObject, err := api.Scheme.New(info.Mapping.GroupVersionKind)
		var patchType types.PatchType
		var patch []byte
		switch {
		case runtime.IsNotRegisteredError(err):
			// fall back to generic JSON merge patch
			patchType = types.MergePatchType
			patch, err = jsonpatch.CreateMergePatch(originalJS, editedJS)
			if err != nil {
				glog.V(4).Infof("Unable to calculate diff, no merge is possible: %v", err)
				return err
			}
			for _, precondition := range preconditions {
				if !precondition(patch) {
					glog.V(4).Infof("Unable to calculate diff, no merge is possible: %v", err)
					return fmt.Errorf("%s", "At least one of apiVersion, kind and name was changed")
				}
			}
		case err != nil:
			return err
		default:
			patchType = types.StrategicMergePatchType
			patch, err = strategicpatch.CreateTwoWayMergePatch(originalJS, editedJS, versionedObject, preconditions...)
			if err != nil {
				glog.V(4).Infof("Unable to calculate diff, no merge is possible: %v", err)
				if mergepatch.IsPreconditionFailed(err) {
					return fmt.Errorf("%s", "At least one of apiVersion, kind and name was changed")
				}
				return err
			}
		}

		patched, err := resource.NewHelper(info.Client, info.Mapping).Patch(info.Namespace, info.Name, patchType, patch)
		if err != nil {
			fmt.Fprintln(errOut, results.addError(err, info))
			return nil
		}
		info.Refresh(patched, true)
		cmdutil.PrintSuccess(mapper, false, out, info.Mapping.Resource, info.Name, false, "edited")
		return nil
	})
	return err
}

func visitToCreate(createVisitor resource.Visitor, mapper meta.RESTMapper, out, errOut io.Writer, results *editResults, file string) error {
	err := createVisitor.Visit(func(info *resource.Info, incomingErr error) error {
		if err := createAndRefresh(info); err != nil {
			return err
		}
		cmdutil.PrintSuccess(mapper, false, out, info.Mapping.Resource, info.Name, false, "created")
		return nil
	})
	return err
}

func visitAnnotation(cmd *cobra.Command, f cmdutil.Factory, annotationVisitor resource.Visitor, encoder runtime.Encoder) error {
	// iterate through all items to apply annotations
	err := annotationVisitor.Visit(func(info *resource.Info, incomingErr error) error {
		// If the flag is true, create or update the annotation. Otherwise, NOP
		if cmdutil.GetFlagBool(cmd, cmdutil.ApplyAnnotationsFlag) {
			if err := kubectl.CreateOrUpdateAnnotation(true, info, encoder); err != nil {
				return err
			}
		}
		if cmdutil.ShouldRecord(cmd, info) {
			if err := cmdutil.RecordChangeCause(info.Object, f.Command(cmd, false)); err != nil {
				return err
			}
		}
		return nil
	})
	return err
}

type EditMode string

const (
	NormalEditMode       EditMode = "normal_mode"
	EditBeforeCreateMode EditMode = "edit_before_create_mode"
)

// editReason preserves a message about the reason this file must be edited again
type editReason struct {
	head  string
	other []string
}

// editHeader includes a list of reasons the edit must be retried
type editHeader struct {
	reasons []editReason
}

// writeTo outputs the current header information into a stream
func (h *editHeader) writeTo(w io.Writer) error {
	fmt.Fprint(w, `# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
`)
	for _, r := range h.reasons {
		if len(r.other) > 0 {
			fmt.Fprintf(w, "# %s:\n", r.head)
		} else {
			fmt.Fprintf(w, "# %s\n", r.head)
		}
		for _, o := range r.other {
			fmt.Fprintf(w, "# * %s\n", o)
		}
		fmt.Fprintln(w, "#")
	}
	return nil
}

func (h *editHeader) flush() {
	h.reasons = []editReason{}
}

type editPrinterOptions struct {
	printer   printers.ResourcePrinter
	ext       string
	addHeader bool
}

// editResults capture the result of an update
type editResults struct {
	header    editHeader
	retryable int
	notfound  int
	edit      []*resource.Info
	file      string

	version schema.GroupVersion
}

func (r *editResults) addError(err error, info *resource.Info) string {
	switch {
	case errors.IsInvalid(err):
		r.edit = append(r.edit, info)
		reason := editReason{
			head: fmt.Sprintf("%s %q was not valid", info.Mapping.Resource, info.Name),
		}
		if err, ok := err.(errors.APIStatus); ok {
			if details := err.Status().Details; details != nil {
				for _, cause := range details.Causes {
					reason.other = append(reason.other, fmt.Sprintf("%s: %s", cause.Field, cause.Message))
				}
			}
		}
		r.header.reasons = append(r.header.reasons, reason)
		return fmt.Sprintf("error: %s %q is invalid", info.Mapping.Resource, info.Name)
	case errors.IsNotFound(err):
		r.notfound++
		return fmt.Sprintf("error: %s %q could not be found on the server", info.Mapping.Resource, info.Name)
	default:
		r.retryable++
		return fmt.Sprintf("error: %s %q could not be patched: %v", info.Mapping.Resource, info.Name, err)
	}
}

// preservedFile writes out a message about the provided file if it exists to the
// provided output stream when an error happens. Used to notify the user where
// their updates were preserved.
func preservedFile(err error, path string, out io.Writer) error {
	if len(path) > 0 {
		if _, err := os.Stat(path); !os.IsNotExist(err) {
			fmt.Fprintf(out, "A copy of your changes has been stored to %q\n", path)
		}
	}
	return err
}

// hasLines returns true if any line in the provided stream is non empty - has non-whitespace
// characters, or the first non-whitespace character is a '#' indicating a comment. Returns
// any errors encountered reading the stream.
func hasLines(r io.Reader) (bool, error) {
	// TODO: if any files we read have > 64KB lines, we'll need to switch to bytes.ReadLine
	// TODO: probably going to be secrets
	s := bufio.NewScanner(r)
	for s.Scan() {
		if line := strings.TrimSpace(s.Text()); len(line) > 0 && line[0] != '#' {
			return true, nil
		}
	}
	if err := s.Err(); err != nil && err != io.EOF {
		return false, err
	}
	return false, nil
}

// stripComments will transform a YAML file into JSON, thus dropping any comments
// in it. Note that if the given file has a syntax error, the transformation will
// fail and we will manually drop all comments from the file.
func stripComments(file []byte) []byte {
	stripped := file
	stripped, err := yaml.ToJSON(stripped)
	if err != nil {
		stripped = manualStrip(file)
	}
	return stripped
}

// manualStrip is used for dropping comments from a YAML file
func manualStrip(file []byte) []byte {
	stripped := []byte{}
	lines := bytes.Split(file, []byte("\n"))
	for i, line := range lines {
		if bytes.HasPrefix(bytes.TrimSpace(line), []byte("#")) {
			continue
		}
		stripped = append(stripped, line...)
		if i < len(lines)-1 {
			stripped = append(stripped, '\n')
		}
	}
	return stripped
}