package repocli

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"

	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
)

const (
	MediaTypeOIIv1  = "application/vnd.oci.image.index.v1+json"
	MediatypeDDMLv2 = "application/vnd.docker.distribution.manifest.list.v2+json"

	MediatypeDDMv2 = "application/vnd.docker.distribution.manifest.v2+json"
	MediaTypeOIMv1 = "application/vnd.oci.image.manifest.v1+json"
)

type Downloader struct {
	cli *Client
}

func NewDownloader(client *Client) *Downloader {
	return &Downloader{
		cli: client,
	}
}

func (down *Downloader) Pull(ctx context.Context, rawref, dir, os, arch string) error {
	var err error
	ref, err := NewReference(rawref)
	if err != nil {
		return err
	}
	rawrepo := ref.Repo()
	tag := ref.Tag()

	exist, mime, man, err := down.cli.GetManifest(ctx, rawrepo, tag)
	if err != nil {
		return err
	}
	if !exist {
		err = errors.New("Manifest not found")
		return err
	}

	if mime == MediaTypeOIIv1 || mime == MediatypeDDMLv2 {
		var index ocispec.Index
		err = json.Unmarshal(man, &index)
		if err != nil {
			return err
		}
		for _, descr := range index.Manifests {
			if descr.Platform != nil {
				cond := descr.Platform.Architecture == arch
				cond = cond && descr.Platform.OS == os
				if cond {
					tag = descr.Digest.String()
				}
			}
		}
	}
	fmt.Printf("Tag: %s\n", tag)
	exist, mime, man, err = down.cli.GetManifest(ctx, rawrepo, tag)
	if err != nil {
		return err
	}
	fmt.Printf("Mime: %s\n", mime)
	if !exist {
		err = errors.New("Manifest not found")
		return err
	}
	if mime != MediaTypeOIMv1 && mime != MediatypeDDMv2 {
		err = errors.New("Unknown manifest media type")
		return err
	}
	var manifest ocispec.Manifest
	err = json.Unmarshal(man, &manifest)
	if err != nil {
		return err
	}
	"oci-layout"
	"index.json"

	layers := make([]ocispec.Descriptor, 0)
	layers = append(layers, manifest.Config)
	layers = append(layers, manifest.Layers...)
	for _, layer := range layers {
		digest := layer.Digest.String()
		exist, err := down.cli.GetBlob(ctx, rawrepo, io.Discard, digest)
		if err != nil {
			return err
		}
		if !exist {
			err = errors.New("Layer not found")
			return err
		}
		fmt.Printf("Layer type: %s\n", layer.MediaType)

	}
	return err
}