// Copyright 2019 The Kubernetes Authors.
// SPDX-License-Identifier: Apache-2.0

package set

import (
	"errors"
	"regexp"
	"sort"
	"strings"

	"github.com/spf13/cobra"
	"sigs.k8s.io/kustomize/v3/pkg/commands/kustfile"
	"sigs.k8s.io/kustomize/v3/pkg/fs"
	"sigs.k8s.io/kustomize/v3/pkg/image"
)

type setImageOptions struct {
	imageMap map[string]image.Image
}

var pattern = regexp.MustCompile("^(.*):([a-zA-Z0-9._-]*)$")

// errors

var (
	errImageNoArgs      = errors.New("no image specified")
	errImageInvalidArgs = errors.New(`invalid format of image, use one of the following options:
- <image>=<newimage>:<newtag>
- <image>=<newimage>@<newtag>
- <image>=<newimage>
- <image>:<newtag>
- <image>@<digest>`)
)

const separator = "="

// newCmdSetImage sets the new names, tags or digests for images in the kustomization.
func newCmdSetImage(fsys fs.FileSystem) *cobra.Command {
	var o setImageOptions

	cmd := &cobra.Command{
		Use:   "image",
		Short: `Sets images and their new names, new tags or digests in the kustomization file`,
		Example: `
The command
  set image postgres=eu.gcr.io/my-project/postgres:latest my-app=my-registry/my-app@sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3
will add

images:
- name: postgres
  newName: eu.gcr.io/my-project/postgres
  newTag: latest
- digest: sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3
  name: my-app
  newName: my-registry/my-app

to the kustomization file if it doesn't exist,
and overwrite the previous ones if the image name exists.

The command
  set image node:8.15.0 mysql=mariadb alpine@sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3
will add

images:
- name: node
  newTag: 8.15.0
- name: mysql
  newName: mariadb
- digest: sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3
  name: alpine

to the kustomization file if it doesn't exist,
and overwrite the previous ones if the image name exists.
`,
		RunE: func(cmd *cobra.Command, args []string) error {
			err := o.Validate(args)
			if err != nil {
				return err
			}
			return o.RunSetImage(fsys)
		},
	}
	return cmd
}

type overwrite struct {
	name   string
	digest string
	tag    string
}

// Validate validates setImage command.
func (o *setImageOptions) Validate(args []string) error {
	if len(args) == 0 {
		return errImageNoArgs
	}

	o.imageMap = make(map[string]image.Image)

	for _, arg := range args {

		img, err := parse(arg)
		if err != nil {
			return err
		}
		o.imageMap[img.Name] = img
	}
	return nil
}

// RunSetImage runs setImage command.
func (o *setImageOptions) RunSetImage(fSys fs.FileSystem) error {
	mf, err := kustfile.NewKustomizationFile(fSys)
	if err != nil {
		return err
	}
	m, err := mf.Read()
	if err != nil {
		return err
	}

	// append only new images from kustomize file
	for _, im := range m.Images {
		if _, ok := o.imageMap[im.Name]; ok {
			continue
		}

		o.imageMap[im.Name] = im
	}

	var images []image.Image
	for _, v := range o.imageMap {
		images = append(images, v)
	}

	sort.Slice(images, func(i, j int) bool {
		return images[i].Name < images[j].Name
	})

	m.Images = images
	return mf.Write(m)
}

func parse(arg string) (image.Image, error) {

	// matches if there is an image name to overwrite
	// <image>=<new-image><:|@><new-tag>
	if s := strings.Split(arg, separator); len(s) == 2 {
		p, err := parseOverwrite(s[1], true)
		return image.Image{
			Name:    s[0],
			NewName: p.name,
			NewTag:  p.tag,
			Digest:  p.digest,
		}, err
	}

	// matches only for <tag|digest> overwrites
	// <image><:|@><new-tag>
	p, err := parseOverwrite(arg, false)
	return image.Image{
		Name:   p.name,
		NewTag: p.tag,
		Digest: p.digest,
	}, err
}

// parseOverwrite parses the overwrite parameters
// from the given arg into a struct
func parseOverwrite(arg string, overwriteImage bool) (overwrite, error) {
	// match <image>@<digest>
	if d := strings.Split(arg, "@"); len(d) > 1 {
		return overwrite{
			name:   d[0],
			digest: d[1],
		}, nil
	}

	// match <image>:<tag>
	if t := pattern.FindStringSubmatch(arg); len(t) == 3 {
		return overwrite{
			name: t[1],
			tag:  t[2],
		}, nil
	}

	// match <image>
	if len(arg) > 0 && overwriteImage {
		return overwrite{
			name: arg,
		}, nil
	}
	return overwrite{}, errImageInvalidArgs
}