// Copyright (c) 2021 Tigera, Inc. All rights reserved.

// 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 builder

import (
	"fmt"
	"os"
	"strings"

	"github.com/coreos/go-semver/semver"
	"github.com/sirupsen/logrus"
	"gopkg.in/yaml.v2"
)

// Global configuration for releases.
var (
	// Registries to which all release images are pushed.
	registries = []string{
		"docker.io/calico",
		"quay.io/calico",
		"gcr.io/projectcalico-org",
		"eu.gcr.io/projectcalico-org",
		"asia.gcr.io/projectcalico-org",
		"us.gcr.io/projectcalico-org",
	}

	// Git configuration for publishing to GitHub.
	organization = "projectcalico"
	repo         = "calico"
	origin       = "origin"
)

func NewReleaseBuilder(runner CommandRunner) *ReleaseBuilder {
	return &ReleaseBuilder{
		runner: runner,
	}
}

type ReleaseBuilder struct {
	// Allow specification of command runner so it can be overridden in tests.
	runner CommandRunner
}

// releaseImages returns the set of images that should be expected for a release.
// This function needs to be kept up-to-date with the actual release artifacts produced for a
// release if images are added or removed.
func releaseImages(version, operatorVersion string) []string {
	return []string{
		fmt.Sprintf("quay.io/tigera/operator:%s", operatorVersion),
		fmt.Sprintf("calico/typha:%s", version),
		fmt.Sprintf("calico/ctl:%s", version),
		fmt.Sprintf("calico/node:%s", version),
		fmt.Sprintf("calico/cni:%s", version),
		fmt.Sprintf("calico/apiserver:%s", version),
		fmt.Sprintf("calico/kube-controllers:%s", version),
		fmt.Sprintf("calico/dikastes:%s", version),
		fmt.Sprintf("calico/pod2daemon-flexvol:%s", version),
		fmt.Sprintf("calico/csi:%s", version),
		fmt.Sprintf("calico/key-cert-provisioner:%s", version),
		fmt.Sprintf("calico/node-driver-registrar:%s", version),
		fmt.Sprintf("calico/cni-windows:%s", version),
		fmt.Sprintf("calico/node-windows:%s", version),
	}
}

func (r *ReleaseBuilder) BuildMetadata(dir string) error {
	type metadata struct {
		Version          string   `json:"version"`
		OperatorVersion  string   `json:"operator_version" yaml:"operatorVersion"`
		Images           []string `json:"images"`
		HelmChartVersion string   `json:"helm_chart_version" yaml:"helmChartVersion"`
	}

	// Determine the versions to use based on the manifests, which should
	// have already been updated with the correct tags.
	calicoVersion, operatorVersion := r.getVersionsFromManifests()

	m := metadata{
		Version:          calicoVersion,
		OperatorVersion:  operatorVersion,
		Images:           releaseImages(calicoVersion, operatorVersion),
		HelmChartVersion: calicoVersion,
	}

	// Render it as yaml and write it to a file.
	bs, err := yaml.Marshal(m)
	if err != nil {
		return err
	}

	err = os.WriteFile(fmt.Sprintf("%s/metadata.yaml", dir), []byte(bs), 0o644)
	if err != nil {
		return err
	}

	return nil
}

// BuildRelease creates a Calico release.
func (r *ReleaseBuilder) BuildRelease() error {
	// Check that we're not already on a git tag.
	out, err := r.git("describe", "--exact-match", "--tags", "HEAD")
	if err == nil {
		// On a current tag.
		return fmt.Errorf("Already on a tag (%s), refusing to create release", out)
	}

	// Check that the repository is not a shallow clone. We need correct history.
	out, err = r.git("rev-parse", "--is-shallow-repository")
	if err != nil {
		return fmt.Errorf("rev-parse failed: %s", err)
	}
	if strings.TrimSpace(out) == "true" {
		return fmt.Errorf("Attempt to release from a shallow clone is not possible")
	}

	// Check that the environment has the necessary prereqs.
	if err := r.releasePrereqs(); err != nil {
		return err
	}

	// Determine the last tag on this branch.
	out, err = r.git("describe", "--tags", "--dirty", "--always", "--abbrev=12")
	if err != nil {
		logrus.WithError(err).Fatal("Failed to git describe")
	}
	logrus.WithField("out", out).Info("Current git describe")

	// Determine the release version to use based on the last tag.
	ver, err := r.determineReleaseVersion(out)
	if err != nil {
		return err
	}

	err = r.assertReleaseNotesPresent(ver)
	if err != nil {
		return err
	}

	// Assert that manifests are using the correct version.
	err = r.assertManifestVersions(ver)
	if err != nil {
		return err
	}

	branch := r.determineBranch()
	logrus.WithFields(logrus.Fields{"branch": branch, "version": ver}).Infof("Creating Calico release from branch")
	_, err = r.git("tag", ver)
	if err != nil {
		return fmt.Errorf("Failed to tag release: %s", err)
	}

	// Successfully tagged. If we fail to release after this stage, we need to delete the tag.
	defer func() {
		if err != nil {
			logrus.WithError(err).Warn("Failed to release, cleaning up tag")
			r.git("tag", "-d", ver)
		}
	}()

	// Build container images for the release.
	if err = r.buildContainerImages(ver); err != nil {
		return err
	}

	// Build the helm charts
	r.runner.Run("make", []string{"chart"}, []string{})

	// Build OpenShift bundle.
	r.runner.Run("make", []string{"bin/ocp.tgz"}, []string{})

	// TODO: Assert the produced images are OK. e.g., have correct
	// commit and version information compiled in.

	// Build artifacts to upload to github.
	if err = r.collectGithubArtifacts(ver); err != nil {
		return err
	}

	return nil
}

func (r *ReleaseBuilder) PublishRelease() error {
	// Determine the currently checked-out tag.
	ver, err := r.git("describe", "--exact-match", "--tags", "HEAD")
	if err != nil {
		return fmt.Errorf("failed to get tag for checked-out commit, is there one? %s", err)
	}

	// Check that the environment has the necessary prereqs.
	if err = r.publishPrereqs(ver); err != nil {
		return err
	}

	// Publish container images.
	if err = r.publishContainerImages(ver); err != nil {
		return fmt.Errorf("failed to publish container images: %s", err)
	}

	// If all else is successful, push the git tag.
	if _, err = r.git("push", origin, ver); err != nil {
		return fmt.Errorf("failed to push git tag: %s", err)
	}

	// Publish the release to github.
	if err = r.publishGithubRelease(ver); err != nil {
		return fmt.Errorf("failed to publish github release: %s", err)
	}

	return nil
}

func (r *ReleaseBuilder) NewBranch() error {
	// Check that we're on the master branch. We always cut branches from master.
	branch := r.determineBranch()
	if branch != "master" {
		return fmt.Errorf("Release branches can only be cut from master")
	}

	// Determine the version for the branch. We can get this from the previous dev tag.
	out, err := r.git("describe", "--tags", "--dirty", "--always", "--abbrev=12")
	if err != nil {
		logrus.WithError(err).Fatal("Failed to git describe")
	}
	logrus.WithField("out", out).Info("Current git describe")
	if !strings.Contains(out, "-0.dev") {
		return fmt.Errorf("Unable to determine release branch name from tag: %s", out)
	}

	// Determine the name of the new branch.
	nextBranchVersion := strings.Split(out, "-0.dev")[0]
	sv, err := semver.NewVersion(strings.TrimPrefix(nextBranchVersion, "v"))
	if err != nil {
		return fmt.Errorf("error creating new semver version: %w", err)
	}
	branchName := fmt.Sprintf("release-v%d.%d", sv.Major, sv.Minor)
	logrus.WithField("branch", branchName).Info("Next release branch")

	// Determine the next -0.dev tag.
	nextVersion := fmt.Sprintf("v%d.%d.0", sv.Major, sv.Minor+1)
	newDevTag := fmt.Sprintf("%s-0.dev", nextVersion)
	logrus.WithField("tag", newDevTag).Info("Next dev tag")

	// Create a new branch from the current master.
	r.gitOrFail("checkout", "-b", branchName)
	r.gitOrFail("push", origin, branchName)

	// Create the new dev tag on master and push it.
	r.gitOrFail("checkout", "master")
	r.gitOrFail("commit", "--allow-empty", "-m", fmt.Sprintf("Begin development on %s", nextVersion))
	r.gitOrFail("tag", newDevTag)
	r.gitOrFail("push", origin, "master")
	r.gitOrFail("push", origin, newDevTag)

	return nil
}

// Check general prerequisites for cutting and publishing a release.
func (r *ReleaseBuilder) releasePrereqs() error {
	// Check that we're not on the master branch. We never cut releases from master.
	branch := r.determineBranch()
	if branch == "master" {
		return fmt.Errorf("Cannot cut release from branch: %s", branch)
	}

	// Make sure we have a github token - needed for publishing to GH.
	// Strictly only needed for publishing, but we check during release anyway so
	// that we don't get all the way through the build to find out we're missing it!
	if token := os.Getenv("GITHUB_TOKEN"); token == "" {
		return fmt.Errorf("No GITHUB_TOKEN present in environment")
	}

	// TODO: Make sure the environment isn't dirty.
	return nil
}

// Prerequisites specific to publishing a release.
func (r *ReleaseBuilder) publishPrereqs(ver string) error {
	// TODO: Verify all required artifacts are present.
	return r.releasePrereqs()
}

// We include the following GitHub artifacts on each release. This function assumes
// that they have already been built, and simply wraps them up.
//
// - release-vX.Y.Z.tgz: contains images, manifests, and binaries.
// - tigera-operator-vX.Y.Z.tgz: contains the helm v3 chart.
// - calico-windows-vX.Y.Z.zip: Calico for Windows zip archive for non-HPC installation.
// - calicoctl/bin: All calicoctl binaries.
//
// This function also generates checksums for each artifact that is uploaded to the release.
func (r *ReleaseBuilder) collectGithubArtifacts(ver string) error {
	// Final artifacts will be moved here.
	uploadDir := r.uploadDir(ver)
	// TODO: Delete if already exists.
	err := os.MkdirAll(uploadDir, os.ModePerm)
	if err != nil {
		return fmt.Errorf("failed to create dir: %s", err)
	}

	// Add in a release metadata file.
	err = r.BuildMetadata(uploadDir)
	if err != nil {
		return fmt.Errorf("failed to build release metadata file: %s", err)
	}

	// We attach calicoctl binaries directly to the release as well.
	files, err := os.ReadDir("calicoctl/bin/")
	if err != nil {
		return err
	}
	for _, b := range files {
		if _, err := r.runner.Run("cp", []string{fmt.Sprintf("calicoctl/bin/%s", b.Name()), uploadDir}, nil); err != nil {
			return err
		}
	}

	// Build and add in the complete release tarball.
	if err = r.buildReleaseTar(ver, uploadDir); err != nil {
		return err
	}

	// Add in the already-built windows zip archive, the Windows install script, ocp bundle, and the helm chart.
	if _, err := r.runner.Run("cp", []string{fmt.Sprintf("node/dist/calico-windows-%s.zip", ver), uploadDir}, nil); err != nil {
		return err
	}
	if _, err := r.runner.Run("cp", []string{"node/dist/install-calico-windows.ps1", uploadDir}, nil); err != nil {
		return err
	}
	if _, err := r.runner.Run("cp", []string{fmt.Sprintf("bin/tigera-operator-%s.tgz", ver), uploadDir}, nil); err != nil {
		return err
	}
	if _, err := r.runner.Run("cp", []string{"bin/ocp.tgz", uploadDir}, nil); err != nil {
		return err
	}

	// Generate a SHA256SUMS file containing the checksums for each artifact
	// that we attach to the release. These can be confirmed by end users via the following command:
	// sha256sum -c --ignore-missing SHA256SUMS
	files, err = os.ReadDir(uploadDir)
	if err != nil {
		return err
	}
	sha256args := []string{}
	for _, f := range files {
		sha256args = append(sha256args, f.Name())
	}
	output, err := r.runner.RunInDir(uploadDir, "sha256sum", sha256args, nil)
	if err != nil {
		return err
	}
	err = os.WriteFile(fmt.Sprintf("%s/SHA256SUMS", uploadDir), []byte(output), 0o644)
	if err != nil {
		return err
	}

	return nil
}

func (r *ReleaseBuilder) uploadDir(ver string) string {
	return fmt.Sprintf("_output/upload/%s", ver)
}

// Builds the complete release tar for upload to github.
// - release-vX.Y.Z.tgz: contains images, manifests, and binaries.
// TODO: We should produce a tar per architecture that we ship.
// TODO: We should produce windows tars
func (r *ReleaseBuilder) buildReleaseTar(ver string, targetDir string) error {
	// Create tar files for container image that are shipped.
	releaseBase := fmt.Sprintf("_output/release-%s", ver)
	err := os.MkdirAll(releaseBase+"/images", os.ModePerm)
	if err != nil {
		return fmt.Errorf("Failed to create images dir: %s", err)
	}
	outFmt := "_output/release-%s/images/%s"
	registry := registries[0]
	images := map[string]string{
		fmt.Sprintf("%s/node:%s", registry, ver):                         fmt.Sprintf(outFmt, ver, "calico-node.tar"),
		fmt.Sprintf("%s/typha:%s", registry, ver):                        fmt.Sprintf(outFmt, ver, "calico-typha.tar"),
		fmt.Sprintf("%s/cni:%s", registry, ver):                          fmt.Sprintf(outFmt, ver, "calico-cni.tar"),
		fmt.Sprintf("%s/kube-controllers:%s", registry, ver):             fmt.Sprintf(outFmt, ver, "calico-kube-controllers.tar"),
		fmt.Sprintf("%s/pod2daemon-flexvol:%s", registry, ver):           fmt.Sprintf(outFmt, ver, "calico-pod2daemon.tar"),
		fmt.Sprintf("%s/key-cert-provisioner:%s", registry, ver):         fmt.Sprintf(outFmt, ver, "calico-key-cert-provisioner.tar"),
		fmt.Sprintf("%s/dikastes:%s", registry, ver):                     fmt.Sprintf(outFmt, ver, "calico-dikastes.tar"),
		fmt.Sprintf("%s/flannel-migration-controller:%s", registry, ver): fmt.Sprintf(outFmt, ver, "calico-flannel-migration-controller.tar"),
	}
	for img, out := range images {
		err = r.archiveContainerImage(out, img)
		if err != nil {
			return err
		}

	}

	// Add in release binaries that we ship.
	binDir := fmt.Sprintf("%s/bin", releaseBase)
	err = os.MkdirAll(binDir, os.ModePerm)
	if err != nil {
		return fmt.Errorf("Failed to create images dir: %s", err)
	}

	binaries := map[string]string{
		// CNI plugin binaries are all placed in github dir.
		"cni-plugin/bin/": binDir + "/cni",

		// Calicoctl binaries.
		"calicoctl/bin/": binDir + "/calicoctl",

		// Felix binaries.
		"felix/bin/calico-bpf": binDir,
	}
	for src, dst := range binaries {
		if _, err := r.runner.Run("cp", []string{"-r", src, dst}, nil); err != nil {
			return err
		}
	}

	// Add in manifests directory generated from the docs.
	if _, err := r.runner.Run("cp", []string{"-r", "manifests", releaseBase}, nil); err != nil {
		return err
	}

	// tar up the whole thing, and copy it to the target directory
	if _, err := r.runner.Run("tar", []string{
		"-czvf",
		fmt.Sprintf("_output/release-%s.tgz", ver),
		"-C",
		"_output",
		fmt.Sprintf("release-%s/manifests", ver),
		fmt.Sprintf("release-%s/bin", ver),
		fmt.Sprintf("release-%s/images", ver),
	}, nil); err != nil {
		return err
	}
	if _, err := r.runner.Run("cp", []string{fmt.Sprintf("_output/release-%s.tgz", ver), targetDir}, nil); err != nil {
		return err
	}
	return nil
}

func (r *ReleaseBuilder) buildContainerImages(ver string) error {
	releaseDirs := []string{
		"node",
		"pod2daemon",
		"key-cert-provisioner",
		"cni-plugin",
		"apiserver",
		"kube-controllers",
		"calicoctl",
		"app-policy",
		"typha",
		"felix",
	}

	windowsReleaseDirs := []string{
		"node",
		"cni-plugin",
	}

	// Build env.
	env := append(os.Environ(),
		fmt.Sprintf("VERSION=%s", ver),
		fmt.Sprintf("DEV_REGISTRIES=%s", strings.Join(registries, " ")),
	)

	for _, dir := range releaseDirs {
		out, err := r.makeInDirectoryWithOutput(dir, "release-build", env...)
		if err != nil {
			logrus.Error(out)
			return fmt.Errorf("Failed to build %s: %s", dir, err)
		}
		logrus.Info(out)
	}

	for _, dir := range windowsReleaseDirs {
		out, err := r.makeInDirectoryWithOutput(dir, "image-windows", env...)
		if err != nil {
			logrus.Error(out)
			return fmt.Errorf("Failed to build %s: %s", dir, err)
		}
		logrus.Info(out)
	}
	return nil
}

func (r *ReleaseBuilder) publishGithubRelease(ver string) error {
	releaseNoteTemplate := `
Release notes can be found [on GitHub](https://github.com/projectcalico/calico/blob/{version}/release-notes/{version}-release-notes.md)

Attached to this release are the following artifacts:

- {release_tar}: container images, binaries, and kubernetes manifests.
- {calico_windows_zip}: Calico for Windows.
- {helm_chart}: Calico Helm v3 chart.
- ocp.tgz: Manifest bundle for OpenShift.

Additional links:

- [VPP data plane release information](https://github.com/projectcalico/vpp-dataplane/blob/master/RELEASE_NOTES.md)

`
	sv, err := semver.NewVersion(strings.TrimPrefix(ver, "v"))
	if err != nil {
		return err
	}
	formatters := []string{
		// Alternating placeholder / filler. We can't use backticks in the multiline string above,
		// so we replace anything that needs to be backticked into it here.
		"{version}", ver,
		"{branch}", fmt.Sprintf("release-v%d.%d", sv.Major, sv.Minor),
		"{release_stream}", fmt.Sprintf("v%d.%d", sv.Major, sv.Minor),
		"{release_tar}", fmt.Sprintf("`release-%s.tgz`", ver),
		"{calico_windows_zip}", fmt.Sprintf("`calico-windows-%s.zip`", ver),
		"{helm_chart}", fmt.Sprintf("`tigera-operator-%s.tgz`", ver),
	}
	replacer := strings.NewReplacer(formatters...)
	releaseNote := replacer.Replace(releaseNoteTemplate)

	args := []string{
		"-username", organization,
		"-repository", repo,
		"-name", ver,
		"-body", releaseNote,
		"-draft",
		ver,
		r.uploadDir(ver),
	}
	_, err = r.runner.Run("./hack/release/ghr", args, nil)
	return err
}

func (r *ReleaseBuilder) publishContainerImages(ver string) error {
	releaseDirs := []string{
		"pod2daemon",
		"key-cert-provisioner",
		"cni-plugin",
		"apiserver",
		"kube-controllers",
		"calicoctl",
		"app-policy",
		"typha",
		"node",
	}

	windowsReleaseDirs := []string{
		"node",
		"cni-plugin",
	}

	env := append(os.Environ(),
		fmt.Sprintf("IMAGETAG=%s", ver),
		fmt.Sprintf("VERSION=%s", ver),
		"RELEASE=true",
		"CONFIRM=true",
		fmt.Sprintf("DEV_REGISTRIES=%s", strings.Join(registries, " ")),
	)

	// We allow for a certain number of retries when publishing each directory, since
	// network flakes can occasionally result in images failing to push.
	maxRetries := 1
	for _, dir := range releaseDirs {
		attempt := 0
		for {
			out, err := r.makeInDirectoryWithOutput(dir, "release-publish", env...)
			if err != nil {
				if attempt < maxRetries {
					logrus.WithField("attempt", attempt).WithError(err).Warn("Publish failed, retrying")
					attempt++
					continue
				}
				logrus.Error(out)
				return fmt.Errorf("Failed to publish %s: %s", dir, err)
			}

			// Success - move on to the next directory.
			logrus.Info(out)
			break
		}
	}
	for _, dir := range windowsReleaseDirs {
		attempt := 0
		for {
			out, err := r.makeInDirectoryWithOutput(dir, "release-windows", env...)
			if err != nil {
				if attempt < maxRetries {
					logrus.WithField("attempt", attempt).WithError(err).Warn("Publish failed, retrying")
					attempt++
					continue
				}
				logrus.Error(out)
				return fmt.Errorf("Failed to publish %s: %s", dir, err)
			}

			// Success - move on to the next directory.
			logrus.Info(out)
			break
		}
	}
	return nil
}

func (r *ReleaseBuilder) assertReleaseNotesPresent(ver string) error {
	// Validate that the release notes for this version are present,
	// fail if not.

	releaseNotesPath := fmt.Sprintf("release-notes/%s-release-notes.md", ver)
	releaseNotesStat, err := os.Stat(releaseNotesPath)
	// If we got an error, handle that?
	if err != nil {
		return fmt.Errorf("release notes file is invalid: %s", err.Error())
	}
	if releaseNotesStat.Size() == 0 {
		return fmt.Errorf("release notes file is invalid: file is 0 bytes")
	} else if releaseNotesStat.IsDir() {
		return fmt.Errorf("release notes file is invalid: %s is a directory", releaseNotesPath)
	}
	return nil
}

func (r *ReleaseBuilder) assertManifestVersions(ver string) error {
	// Go through a subset of yaml files in manifests/ and extract the images
	// that they use. Verify that the images are using the given version.
	// We also do the manifests/ocp/ yaml to check the calico/ctl image is correct.
	manifests := []string{"calico.yaml", "ocp/02-tigera-operator.yaml"}

	for _, m := range manifests {
		args := []string{"-Po", `image:\K(.*)`, m}
		out, err := r.runner.RunInDir("manifests", "grep", args, nil)
		if err != nil {
			return err
		}
		imgs := strings.Split(out, "\n")
		for _, i := range imgs {
			if strings.Contains(i, "operator") {
				// We don't handle the operator image here yet, since
				// the version is different.
				continue
			}
			if !strings.HasSuffix(i, ver) {
				return fmt.Errorf("Incorrect image version (expected %s) in manifest %s: %s", ver, m, i)
			}
		}
	}

	return nil
}

// getVersionsFromManifests returns the Calico and Operator versions in-use by this
// release based on the generated manifests to be used for this release.
func (r *ReleaseBuilder) getVersionsFromManifests() (string, string) {
	manifests := []string{"calico.yaml", "tigera-operator.yaml"}

	var operatorVersion, version string
	for _, m := range manifests {
		args := []string{"-Po", `image:\K(.*)`, m}
		out, err := r.runner.RunInDir("manifests", "grep", args, nil)
		if err != nil {
			panic(err)
		}

		imgs := strings.Split(out, "\n")

		for _, i := range imgs {
			if strings.Contains(i, "operator") && operatorVersion == "" {
				splits := strings.SplitAfter(i, ":")
				operatorVersion = splits[len(splits)-1]
				logrus.Infof("Using version %s from image %s", version, i)
			} else if strings.Contains(i, "calico/") && version == "" {
				splits := strings.SplitAfter(i, ":")
				version = splits[len(splits)-1]
				logrus.Infof("Using version %s from image %s", version, i)
			}
			if operatorVersion != "" && version != "" {
				break
			}
		}
		if operatorVersion != "" && version != "" {
			break
		}
	}

	if version == "" || operatorVersion == "" {
		panic("Missing version!")
	}

	return version, operatorVersion
}

// determineReleaseVersion uses historical clues to figure out the next semver
// release number to use for this release.
func (r *ReleaseBuilder) determineReleaseVersion(previousTag string) (string, error) {
	// There are two types of tag that this might be - either it was a previous patch release,
	// or it was a "vX.Y.Z-0.dev" tag produced when cutting the release branch.
	if strings.Contains(previousTag, "-0.dev") {
		// This is the first release from this branch - we can simply extract the version from
		// the dev tag.
		return strings.Split(previousTag, "-0.dev")[0], nil
	} else {
		// This is a patch release - we need to parse the previous, and
		// bump the patch version.
		previousVersion := strings.Split(previousTag, "-")[0]
		logrus.WithField("previousVersion", previousVersion).Info("Previous version")
		v, err := semver.NewVersion(strings.TrimPrefix(previousVersion, "v"))
		if err != nil {
			logrus.WithField("previousVersion", previousVersion).WithError(err).Error("Failed to parse git version as semver")
			return "", fmt.Errorf("failed to parse git version as semver: %s", err)
		}
		v.BumpPatch()
		return fmt.Sprintf("v%s", v.String()), nil
	}
}

// determineBranch returns the current checked out branch.
func (r *ReleaseBuilder) determineBranch() string {
	out, err := r.git("rev-parse", "--abbrev-ref", "HEAD")
	if err != nil {
		logrus.WithError(err).Fatal("Error determining branch")
	} else if strings.TrimSpace(out) == "HEAD" {
		logrus.Fatal("Not on a branch, refusing to cut release")
	}
	return strings.TrimSpace(out)
}

// Uses docker to build a tgz archive of the specified container image.
func (r *ReleaseBuilder) archiveContainerImage(out, image string) error {
	_, err := r.runner.Run("docker", []string{"save", "--output", out, image}, nil)
	return err
}

func (r *ReleaseBuilder) git(args ...string) (string, error) {
	return r.runner.Run("git", args, nil)
}

func (r *ReleaseBuilder) gitOrFail(args ...string) {
	_, err := r.runner.Run("git", args, nil)
	if err != nil {
		logrus.WithError(err).Fatal("git command failed")
	}
}

func (r *ReleaseBuilder) makeInDirectory(dir, target string, env ...string) error {
	_, err := r.runner.Run("make", []string{"-C", dir, target}, env)
	return err
}

func (r *ReleaseBuilder) makeInDirectoryWithOutput(dir, target string, env ...string) (string, error) {
	return r.runner.Run("make", []string{"-C", dir, target}, env)
}

func (r *ReleaseBuilder) makeInDirectoryNoOutput(dir, target string, env ...string) error {
	return r.runner.RunNoCapture("make", []string{"-C", dir, target}, env)
}
