/*
Copyright 2018 Google LLC

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 cache

import (
	"fmt"
	"io/ioutil"
	"path"

	"github.com/GoogleContainerTools/kaniko/pkg/config"
	"github.com/google/go-containerregistry/pkg/name"
	"github.com/google/go-containerregistry/pkg/v1/remote"
	"github.com/google/go-containerregistry/pkg/v1/tarball"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
)

// WarmCache populates the cache
func WarmCache(opts *config.WarmerOptions) error {
	cacheDir := opts.CacheDir
	images := opts.Images
	logrus.Debugf("%s\n", cacheDir)
	logrus.Debugf("%s\n", images)

	for _, image := range images {
		cacheRef, err := name.NewTag(image, name.WeakValidation)
		if err != nil {
			return errors.Wrap(err, fmt.Sprintf("Failed to verify image name: %s", image))
		}
		img, err := remote.Image(cacheRef)
		if err != nil || img == nil {
			return errors.Wrap(err, fmt.Sprintf("Failed to retrieve image: %s", image))
		}

		digest, err := img.Digest()
		if err != nil {
			return errors.Wrap(err, fmt.Sprintf("Failed to retrieve digest: %s", image))
		}
		cachePath := path.Join(cacheDir, digest.String())

		if !opts.Force {
			_, err := LocalSource(&opts.CacheOptions, digest.String())
			if err == nil {
				continue
			}
		}

		err = tarball.WriteToFile(cachePath, cacheRef, img)
		if err != nil {
			return errors.Wrap(err, fmt.Sprintf("Failed to write %s to cache", image))
		}

		mfst, err := img.RawManifest()
		if err != nil {
			return errors.Wrap(err, fmt.Sprintf("Failed to retrieve manifest for %s", image))
		}
		mfstPath := cachePath + ".json"
		if err := ioutil.WriteFile(mfstPath, mfst, 0666); err != nil {
			return errors.Wrap(err, fmt.Sprintf("Failed to save manifest for %s", image))
		}
		logrus.Debugf("Wrote %s to cache", image)
	}
	return nil
}