package cmd

import (
	"errors"
	"context"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"github.com/containers/image/v5/transports/alltransports"
	"github.com/containers/image/v5/signature"
	"github.com/containers/image/v5/copy"
	"github.com/spf13/cobra"
)

var pctx *signature.PolicyContext
const distributionPrefix = "v2"


//---
//--- Image converter
type OCIPlatform struct {
}

type OCIImageManifest struct {
	MediaType string `json:"mediaType"`
	Digest string `json:"digest"`
	Size int `json:"size"`
	Platform *OCIPlatform `json:"platform,omitempty"`
}

type OCIImageIndex struct {
	SchemaVersion int `json:"schemaVersion"`
	MediaType string `json:"mediaType"`
	Manifests []OCIImageManifest `json:"manifests"`
}

type OCILayout {
	ImageLayoutVersion string `json:"imageLayoutVersion"`
}
func NewOCILayout() OCILayout {
	return OCILayout{"1.0.0"}
}
func (o OCILayout) WriteTo(root string) error {
	txt, err := json.Marshal(o)
	if err != nil {
		return err
	}
	
	txtPath := filepath.Join(root, "oci-layout")
	err = ioutil.WriteFile(txtPath, txt, 0644)
	return err
}

type OCISystemImage struct {
	path string
	os string
	arch string
}
func (o OCISystemImage) String() string {
	return fmt.Sprintf("[oci system image; os:%s, arch:%s, path:%s]", o.os, o.arch, o.path)
}

type OCIMultiArch struct {
	name string
	tag string
	path string
	images []OCISystemImage
}

func NewOCIMultiArch(nametag string) (*OCIMultiArch, error) {
 	ntspl := strings.Split(nametag, ":")
	if len(ntspl) != 2 {
		return nil, errors.New("nametag must be of the form 'name:tag'")
	}

	tmp, err := os.MkdirTemp("", "alba-oci")
	if err != nil {
		return nil, err
	}

	return &OCIMultiArch {
		name: ntspl[0],
		tag: ntspl[1],
		path: tmp,
		images: []OCISystemImage{},
	}, nil
}

func (o *OCIMultiArch) Close() error {
	return os.RemoveAll(o.path)
}

func (o *OCIMultiArch) LoadFromDockerArchives(path string) error {
	fmt.Printf("-- load docker archives --\n")
	imgDirList, err := os.ReadDir(path)
	if err != nil {
		return err
	}

	for idx, imgFile := range imgDirList {
		imgFilename := imgFile.Name()

		// Check extension
		archivePath := filepath.Join(path, imgFilename)
		if !(strings.HasSuffix(imgFilename, ".tar.gz") || strings.HasSuffix(imgFilename, ".tgz")) {
			fmt.Printf("skipping %s: not a tar.gz archive\n", archivePath)
			continue
		}

		// Check we can extract info from the filename
		infos := strings.Split(imgFilename, ".")
		if len(infos) != 3 && len(infos) != 4 {
			fmt.Printf("skipping %s: format is <goos>.<goarch>.tar.gz\n", archivePath)
			continue
		}
		goos := infos[0]
		goarch := infos[1]

		srcRef, err := alltransports.ParseImageName(fmt.Sprintf("docker-archive:%s", archivePath))
		if err != nil {
			return err
		}

		ociPath := filepath.Join(o.path, strconv.FormatInt(int64(idx), 10))
		dstRef, err := alltransports.ParseImageName(fmt.Sprintf("oci:%s", ociPath))
		if err != nil {
			return err
		}


		_, err = copy.Image(context.Background(), pctx, dstRef, srcRef, &copy.Options{})
		if err != nil {
			return err
		}
		img := OCISystemImage {
			path: ociPath,
			os: goos,
			arch: goarch,
		}
		fmt.Printf("%s -> %s\n", archivePath, img)
		o.images = append(o.images, img)
	}

	return nil
}

func (o *OCIMultiArch) MergeSystemImages() error {
	fmt.Printf("-- merge system images --\n")
	multiArchRoot := filepath.Join(o.path, "multi")

	// Create root
	err := os.Mkdir(multiArchRoot, 0750)
	if err != nil {
		return err
	}

	// Create blob path
	multiBlobPath := filepath.Join(multiArchRoot, 'blobs', 'sha256')
	err := os.MkdirAll(multiBlobPath)
	if err != nil {
		return err
	}


	// Create oci-layout file
	err := NewOCILayout().WriteTo(multiArchRoot)
	if err != nil {
		return err
	}
	fmt.Printf("-> oci-layout\n")

	// Create index.json
	err, index := NewOCIIndex()
	fmt.Printf("-> index.json\n")


	// Copy blobs
	for _, img := range o.images {
		blobCounter := 0
		blobPath := filepath.Join(img.path, 'blobs', 'sha256')
		blobList, err := os.ReadDir(blobPath)
		if err != nil {
			return err
		}
		for _, blobFile := range blobList {
			src, err := io.Open(filepath.Join(blobPath, blobFile.Name()))
			if err != nil {
				return err
			}
			defer src.Close()

			dst, err := io.Create(filepath.Join(multiBlobPath, blobFile.Name()))
			if err != nil {
				return err
			}
			defer dst.Close()

			_, err := io.Copy(dst, src)
			if err != nil {
				return err
			}
			blobCounter += 1

		}
		fmt.Printf("%s -> %s (%d items)\n", blobPath, multiBlobPath, blobCounter)
	}
	return nil
}

func (o *OCIMultiArch) UploadImage(url string) error {
	return nil
}


//---
//--- Command logic

var containerCmd = &cobra.Command{
  Use: "container",
  Short: "Manage container images",
  Long: "Publish software on an S3 target following the OCI specification",
}

var containerTag string
var containerPublishCmd = &cobra.Command{
  Use: "push [folder] [remote]", // https://gocloud.dev/howto/blob/#s3-compatible
  Short: "Publish a container image",
  Long: "Copy .tar.gz files in the specified folder on the S3 target so that they match the OCI distribution specification",
  Args: cobra.ExactArgs(2),
  Run: func(cmd *cobra.Command, args []string) {
	localPath := args[0]
	remotePath := args[1]
        
	oi, err := NewOCIMultiArch(containerTag)
	if err != nil {
                fmt.Println(err)
                os.Exit(1)
	}
	//defer oi.Close()

	if err = oi.LoadFromDockerArchives(localPath); err != nil {
                fmt.Println(err)
                os.Exit(1)
	}

	if err = oi.MergeSystemImages(); err != nil {
                fmt.Println(err)
                os.Exit(1)
	}

	if err = oi.UploadImage(remotePath); err != nil {
                fmt.Println(err)
                os.Exit(1)
	}

	fmt.Printf("✅ push succeeded\n")
  },
}

func init() {
	var err error

	// @FIXME: this policy feature is probably here for something, so we should not bypass it
	// but as there is no documentation around the error on how to easily and quickly doing it the right way,
	// I am just disabling it. Thanks again security people for yet another convoluted incomprehensible undocumented stuff.
	policy := &signature.Policy{Default: []signature.PolicyRequirement{signature.NewPRInsecureAcceptAnything()}}
	pctx, err = signature.NewPolicyContext(policy)
	if err != nil {
                fmt.Println(err)
                os.Exit(1)
	}

	containerPublishCmd.Flags().StringVarP(&containerTag, "tag", "t", "", "Tag of the project, eg. albatros:0.9")
	containerPublishCmd.MarkFlagRequired("tag")

	containerCmd.AddCommand(containerPublishCmd)
	RootCmd.AddCommand(containerCmd)
}