/*
   Copyright 2023 Docker Compose CLI 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 ocipush

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"path/filepath"
	"time"

	pusherrors "github.com/containerd/containerd/remotes/errors"
	"github.com/distribution/reference"
	"github.com/docker/buildx/util/imagetools"
	"github.com/docker/compose/v2/pkg/api"
	"github.com/opencontainers/go-digest"
	"github.com/opencontainers/image-spec/specs-go"
	v1 "github.com/opencontainers/image-spec/specs-go/v1"
)

// clientAuthStatusCodes are client (4xx) errors that are authentication
// related.
var clientAuthStatusCodes = []int{
	http.StatusUnauthorized,
	http.StatusForbidden,
	http.StatusProxyAuthRequired,
}

type Pushable struct {
	Descriptor v1.Descriptor
	Data       []byte
}

func DescriptorForComposeFile(path string, content []byte) v1.Descriptor {
	return v1.Descriptor{
		MediaType: "application/vnd.docker.compose.file+yaml",
		Digest:    digest.FromString(string(content)),
		Size:      int64(len(content)),
		Annotations: map[string]string{
			"com.docker.compose.version": api.ComposeVersion,
			"com.docker.compose.file":    filepath.Base(path),
		},
	}
}

func PushManifest(
	ctx context.Context,
	resolver *imagetools.Resolver,
	named reference.Named,
	layers []Pushable,
	ociVersion api.OCIVersion,
) error {
	// prepare to push the manifest by pushing the layers
	layerDescriptors := make([]v1.Descriptor, len(layers))
	for i := range layers {
		layerDescriptors[i] = layers[i].Descriptor
		if err := resolver.Push(ctx, named, layers[i].Descriptor, layers[i].Data); err != nil {
			return err
		}
	}

	if ociVersion != "" {
		// if a version was explicitly specified, use it
		return createAndPushManifest(ctx, resolver, named, layerDescriptors, ociVersion)
	}

	// try to push in the OCI 1.1 format but fallback to OCI 1.0 on 4xx errors
	// (other than auth) since it's most likely the result of the registry not
	// having support
	err := createAndPushManifest(ctx, resolver, named, layerDescriptors, api.OCIVersion1_1)
	var pushErr pusherrors.ErrUnexpectedStatus
	if errors.As(err, &pushErr) && isNonAuthClientError(pushErr.StatusCode) {
		// TODO(milas): show a warning here (won't work with logrus)
		return createAndPushManifest(ctx, resolver, named, layerDescriptors, api.OCIVersion1_0)
	}
	return err
}

func createAndPushManifest(
	ctx context.Context,
	resolver *imagetools.Resolver,
	named reference.Named,
	layers []v1.Descriptor,
	ociVersion api.OCIVersion,
) error {
	toPush, err := generateManifest(layers, ociVersion)
	if err != nil {
		return err
	}
	for _, p := range toPush {
		err = resolver.Push(ctx, named, p.Descriptor, p.Data)
		if err != nil {
			return err
		}
	}
	return nil
}

func isNonAuthClientError(statusCode int) bool {
	if statusCode < 400 || statusCode >= 500 {
		// not a client error
		return false
	}
	for _, v := range clientAuthStatusCodes {
		if statusCode == v {
			// client auth error
			return false
		}
	}
	// any other 4xx client error
	return true
}

func generateManifest(layers []v1.Descriptor, ociCompat api.OCIVersion) ([]Pushable, error) {
	var toPush []Pushable
	var config v1.Descriptor
	var artifactType string
	switch ociCompat {
	case api.OCIVersion1_0:
		configData, err := json.Marshal(v1.ImageConfig{})
		if err != nil {
			return nil, err
		}
		config = v1.Descriptor{
			MediaType: v1.MediaTypeImageConfig,
			Digest:    digest.FromBytes(configData),
			Size:      int64(len(configData)),
		}
		// N.B. OCI 1.0 does NOT support specifying the artifact type, so it's
		//		left as an empty string to omit it from the marshaled JSON
		artifactType = ""
		toPush = append(toPush, Pushable{Descriptor: config, Data: configData})
	case api.OCIVersion1_1:
		config = v1.DescriptorEmptyJSON
		artifactType = "application/vnd.docker.compose.project"
		// N.B. the descriptor has the data embedded in it
		toPush = append(toPush, Pushable{Descriptor: config, Data: nil})
	default:
		return nil, fmt.Errorf("unsupported OCI version: %s", ociCompat)
	}

	manifest, err := json.Marshal(v1.Manifest{
		Versioned:    specs.Versioned{SchemaVersion: 2},
		MediaType:    v1.MediaTypeImageManifest,
		ArtifactType: artifactType,
		Config:       config,
		Layers:       layers,
		Annotations: map[string]string{
			"org.opencontainers.image.created": time.Now().Format(time.RFC3339),
		},
	})
	if err != nil {
		return nil, err
	}

	manifestDescriptor := v1.Descriptor{
		MediaType: v1.MediaTypeImageManifest,
		Digest:    digest.FromString(string(manifest)),
		Size:      int64(len(manifest)),
		Annotations: map[string]string{
			"com.docker.compose.version": api.ComposeVersion,
		},
		ArtifactType: artifactType,
	}
	toPush = append(toPush, Pushable{Descriptor: manifestDescriptor, Data: manifest})
	return toPush, nil
}