package main

// make sure we don't need to import CLI-related packages here..
import (
        "context"
        "flag"
        "fmt"
        "os"

        "github.com/docker/distribution/reference"
        "github.com/docker/docker/api/types"
        "github.com/docker/docker/client"
        "github.com/docker/docker/client/clientutil"
        "github.com/docker/docker/pkg/jsonmessage"
        "github.com/docker/docker/registry"
)

// pullImageDumb is simple but dumb
func pullImageDumb(s string) error {
        cli, err := client.NewEnvClient()
        if err != nil {
                return err
        }
        responseBody, err := cli.ImagePull(context.TODO(), s, types.ImagePullOptions{})
        if err != nil {
                return err
        }
        defer responseBody.Close()
        return jsonmessage.DisplayJSONMessagesStream(responseBody, os.Stdout, os.Stdout.Fd(), true, nil)
}

// pullImageEx supports credential helpers.
// still too complicated... :-(
func pullImageEx(s string) error {
        distributionRef, err := reference.ParseNormalizedNamed(s)
        if err != nil {
                return err
        }
        repoInfo, err := registry.ParseRepositoryInfo(distributionRef)
        if err != nil {
                return err
        }
        cli, err := client.NewEnvClient()
        if err != nil {
                return err
        }
        cfg, err := clientutil.LoadDefaultConfigFile()
        if err != nil {
                return err
        }
        authConfig, err := clientutil.ResolveAuthConfig(context.TODO(), cli, cfg, repoInfo.Index)
        if err != nil {
                return err
        }
        encodedAuth, err := clientutil.EncodeAuthToBase64(authConfig)
        if err != nil {
                return err
        }
        responseBody, err := cli.ImagePull(context.TODO(), reference.FamiliarString(distributionRef), types.ImagePullOptions{
                RegistryAuth: encodedAuth,
        })
        if err != nil {
                return err
        }
        defer responseBody.Close()
        return jsonmessage.DisplayJSONMessagesStream(responseBody, os.Stdout, os.Stdout.Fd(), true, nil)
}

func main() {
        ex := flag.Bool("ex", false, "enables credential helpers")
        flag.Parse()
        img := flag.Args()[0]

        var err error
        if *ex {
                err = pullImageEx(img)
        } else {
                err = pullImageDumb(img)
        }

        if err != nil {
                fmt.Fprintf(os.Stderr, "%v\n", err)
                os.Exit(1)
        }
}