From ff8ed902ea8321871a9b535585122b23ffcc7372 Mon Sep 17 00:00:00 2001
From: Arsen Musayelyan <arsen@arsenm.dev>
Date: Sat, 28 Jan 2023 20:32:47 -0800
Subject: [PATCH] Add git downloader

---
 internal/dl/git.go | 149 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 149 insertions(+)
 create mode 100644 internal/dl/git.go

diff --git a/internal/dl/git.go b/internal/dl/git.go
new file mode 100644
index 0000000..fa54b3d
--- /dev/null
+++ b/internal/dl/git.go
@@ -0,0 +1,149 @@
+package dl
+
+import (
+	"errors"
+	"net/url"
+	"path"
+	"strconv"
+	"strings"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing"
+)
+
+type GitDownloader struct{}
+
+func (GitDownloader) Name() string {
+	return "git"
+}
+
+func (GitDownloader) Type() Type {
+	return TypeDir
+}
+
+func (GitDownloader) MatchURL(u string) bool {
+	return strings.HasPrefix(u, "git+")
+}
+
+func (GitDownloader) Download(opts Options) (Type, string, error) {
+	u, err := url.Parse(opts.URL)
+	if err != nil {
+		return 0, "", err
+	}
+	u.Scheme = strings.TrimPrefix(u.Scheme, "git+")
+
+	query := u.Query()
+
+	rev := query.Get("~rev")
+	query.Del("~rev")
+
+	depthStr := query.Get("~depth")
+	query.Del("~depth")
+
+	recursive := query.Get("~recursive")
+	query.Del("~recursive")
+
+	u.RawQuery = query.Encode()
+
+	depth := 0
+	if depthStr != "" {
+		depth, err = strconv.Atoi(depthStr)
+		if err != nil {
+			return 0, "", err
+		}
+	}
+
+	co := &git.CloneOptions{
+		URL:               u.String(),
+		Depth:             depth,
+		Progress:          opts.Progress,
+		RecurseSubmodules: git.NoRecurseSubmodules,
+	}
+
+	if recursive == "true" {
+		co.RecurseSubmodules = git.DefaultSubmoduleRecursionDepth
+	}
+
+	r, err := git.PlainClone(opts.Destination, false, co)
+	if err != nil {
+		return 0, "", err
+	}
+
+	if rev != "" {
+		h, err := r.ResolveRevision(plumbing.Revision(rev))
+		if err != nil {
+			return 0, "", err
+		}
+
+		w, err := r.Worktree()
+		if err != nil {
+			return 0, "", err
+		}
+
+		err = w.Checkout(&git.CheckoutOptions{
+			Hash: *h,
+		})
+		if err != nil {
+			return 0, "", err
+		}
+	}
+
+	name := strings.TrimSuffix(path.Base(u.Path), ".git")
+	return TypeDir, name, nil
+}
+
+func (GitDownloader) Update(opts Options) (bool, error) {
+	u, err := url.Parse(opts.URL)
+	if err != nil {
+		return false, err
+	}
+	u.Scheme = strings.TrimPrefix(u.Scheme, "git+")
+
+	query := u.Query()
+	query.Del("~rev")
+
+	depthStr := query.Get("~depth")
+	query.Del("~depth")
+
+	recursive := query.Get("~recursive")
+	query.Del("~recursive")
+
+	u.RawQuery = query.Encode()
+
+	r, err := git.PlainOpen(opts.Destination)
+	if err != nil {
+		return false, err
+	}
+
+	w, err := r.Worktree()
+	if err != nil {
+		return false, err
+	}
+
+	depth := 0
+	if depthStr != "" {
+		depth, err = strconv.Atoi(depthStr)
+		if err != nil {
+			return false, err
+		}
+	}
+
+	po := &git.PullOptions{
+		Depth:             depth,
+		Progress:          opts.Progress,
+		RecurseSubmodules: git.NoRecurseSubmodules,
+	}
+
+	if recursive == "true" {
+		po.RecurseSubmodules = git.DefaultSubmoduleRecursionDepth
+	}
+
+	err = w.Pull(po)
+	if errors.Is(err, git.NoErrAlreadyUpToDate) {
+		return false, nil
+	} else if err != nil {
+		return false, err
+	}
+
+	return true, nil
+}