git: add checkout strategies

internal/git/checkout.go

@@ -0,0 +1,192 @@
+/*
+Copyright 2020 The Flux CD contributors.
+
+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 git
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/blang/semver"
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing"
+)
+
+type CheckoutStrategy interface {
+	Checkout(ctx context.Context, path string) error
+}
+
+type CheckoutBranch struct {
+	url    string
+	branch string
+}
+
+func (c *CheckoutBranch) Checkout(ctx context.Context, path string) (string, error) {
+	repo, err := git.PlainCloneContext(ctx, path, false, &git.CloneOptions{
+		URL:               c.url,
+		RemoteName:        "origin",
+		ReferenceName:     plumbing.NewBranchReferenceName(c.branch),
+		SingleBranch:      true,
+		NoCheckout:        false,
+		Depth:             1,
+		RecurseSubmodules: 0,
+		Progress:          nil,
+		Tags:              git.NoTags,
+	})
+	if err != nil {
+		return "", fmt.Errorf("git clone error: %w", err)
+	}
+	head, err := repo.Head()
+	if err != nil {
+		return "", fmt.Errorf(" git resolve HEAD error: %w", err)
+	}
+	return fmt.Sprintf("%s/%s", c.branch, head.Hash().String()), nil
+}
+
+type CheckoutTag struct {
+	url string
+	tag string
+}
+
+func (c *CheckoutTag) Checkout(ctx context.Context, path string) (string, error) {
+	repo, err := git.PlainCloneContext(ctx, path, false, &git.CloneOptions{
+		URL:               c.url,
+		RemoteName:        "origin",
+		ReferenceName:     plumbing.NewTagReferenceName(c.tag),
+		SingleBranch:      true,
+		NoCheckout:        false,
+		Depth:             1,
+		RecurseSubmodules: 0,
+		Progress:          nil,
+		Tags:              git.NoTags,
+	})
+	if err != nil {
+		return "", fmt.Errorf("git clone error: %w", err)
+	}
+	head, err := repo.Head()
+	if err != nil {
+		return "", fmt.Errorf(" git resolve HEAD error: %w", err)
+	}
+	return fmt.Sprintf("%s/%s", c.tag, head.Hash().String()), nil
+}
+
+type CheckoutCommit struct {
+	url    string
+	branch string
+	commit string
+}
+
+func (c *CheckoutCommit) Checkout(ctx context.Context, path string) (string, error) {
+	repo, err := git.PlainCloneContext(ctx, path, false, &git.CloneOptions{
+		URL:               c.url,
+		RemoteName:        "origin",
+		ReferenceName:     plumbing.NewBranchReferenceName(c.branch),
+		SingleBranch:      true,
+		NoCheckout:        false,
+		RecurseSubmodules: 0,
+		Progress:          nil,
+		Tags:              git.NoTags,
+	})
+	if err != nil {
+		return "", fmt.Errorf("git clone error: %w", err)
+	}
+	w, err := repo.Worktree()
+	if err != nil {
+		return "", fmt.Errorf("git worktree error: %w", err)
+	}
+	commit, err := repo.CommitObject(plumbing.NewHash(c.commit))
+	if err != nil {
+		return "", fmt.Errorf("git commit not found: %w", err)
+	}
+	err = w.Checkout(&git.CheckoutOptions{
+		Hash:  commit.Hash,
+		Force: true,
+	})
+	if err != nil {
+		return "", fmt.Errorf("git checkout error: %w", err)
+	}
+	return fmt.Sprintf("%s/%s", c.branch, commit.Hash.String()), nil
+}
+
+type CheckoutSemVer struct {
+	url    string
+	semver string
+}
+
+func (c *CheckoutSemVer) Checkout(ctx context.Context, path string) (string, error) {
+	rng, err := semver.ParseRange(c.semver)
+	if err != nil {
+		return "", fmt.Errorf("semver parse range error: %w", err)
+	}
+
+	repo, err := git.PlainCloneContext(ctx, path, false, &git.CloneOptions{
+		URL:               c.url,
+		RemoteName:        "origin",
+		SingleBranch:      true,
+		NoCheckout:        false,
+		Depth:             1,
+		RecurseSubmodules: 0,
+		Progress:          nil,
+		Tags:              git.AllTags,
+	})
+	if err != nil {
+		return "", fmt.Errorf("git clone error: %w", err)
+	}
+
+	repoTags, err := repo.Tags()
+	if err != nil {
+		return "", fmt.Errorf("git list tags error: %w", err)
+	}
+
+	tags := make(map[string]string)
+	_ = repoTags.ForEach(func(t *plumbing.Reference) error {
+		tags[t.Name().Short()] = t.Strings()[1]
+		return nil
+	})
+
+	svTags := make(map[string]string)
+	var svers []semver.Version
+	for tag, _ := range tags {
+		v, _ := semver.ParseTolerant(tag)
+		if rng(v) {
+			svers = append(svers, v)
+			svTags[v.String()] = tag
+		}
+	}
+
+	if len(svers) == 0 {
+		return "", fmt.Errorf("no match found for semver: %s", c.semver)
+	}
+
+	semver.Sort(svers)
+	v := svers[len(svers)-1]
+	t := svTags[v.String()]
+	commit := tags[t]
+
+	w, err := repo.Worktree()
+	if err != nil {
+		return "", fmt.Errorf("git worktree error: %w", err)
+	}
+
+	err = w.Checkout(&git.CheckoutOptions{
+		Hash: plumbing.NewHash(commit),
+	})
+	if err != nil {
+		return "", fmt.Errorf("git checkout error: %w", err)
+	}
+
+	return fmt.Sprintf("%s/%s", t, commit), nil
+}