LMTP: Stub patch application

1 files changed, 76 insertions, 3 deletions

diff --git a/lmtp_handle_patch.go b/lmtp_handle_patch.go
index a3064d1..4e49d55 100644
--- a/lmtp_handle_patch.go
+++ b/lmtp_handle_patch.go
@@ -4,12 +4,85 @@
 package main
 
 import (
-	"log/slog"
+	"bytes"
+	// "crypto/rand"
+	// "fmt"
+	"os"
+	"os/exec"
 
+	"github.com/bluekeyes/go-gitdiff/gitdiff"
 	"github.com/emersion/go-message"
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/object"
 )
 
-func lmtpHandlePatch(groupPath []string, repoName string, email *message.Entity) (err error) {
-	slog.Info("Pretend like I'm handling a patch!")
+func lmtpHandlePatch(session *lmtpSession, groupPath []string, repoName string, email *message.Entity) (err error) {
+	var diffFiles []*gitdiff.File
+	var preamble string
+	if diffFiles, preamble, err = gitdiff.Parse(email.Body); err != nil {
+		return
+	}
+
+	var repo *git.Repository
+	var fsPath string
+	repo, _, _, fsPath, err = openRepo(session.ctx, groupPath, repoName)
+	if err != nil {
+		return
+	}
+
+	var headRef *plumbing.Reference
+	if headRef, err = repo.Head(); err != nil {
+		return
+	}
+
+	var headCommit *object.Commit
+	if headCommit, err = repo.CommitObject(headRef.Hash()); err != nil {
+		return
+	}
+
+	var headTree *object.Tree
+	if headTree, err = headCommit.Tree(); err != nil {
+		return
+	}
+
+	// TODO: Try to not shell out
+
+	for _, diffFile := range diffFiles {
+		var sourceFile *object.File
+		if sourceFile, err = headTree.File(diffFile.OldName); err != nil {
+			return err
+		}
+		var sourceString string
+		if sourceString, err = sourceFile.Contents(); err != nil {
+			return err
+		}
+		hashBuf := bytes.Buffer{}
+		patchedBuf := bytes.Buffer{}
+		sourceBuf := bytes.NewReader(stringToBytes(sourceString))
+		if err = gitdiff.Apply(&patchedBuf, sourceBuf, diffFile); err != nil {
+			return err
+		}
+		proc := exec.CommandContext(session.ctx, "git", "hash-object", "w", "-t", "blob", "--stdin")
+		proc.Env = append(os.Environ(), "GIT_DIR="+fsPath)
+		proc.Stdout = &hashBuf
+		proc.Stdin = &patchedBuf
+		if err = proc.Start(); err != nil {
+			return err
+		}
+		newHash := hashBuf.Bytes()
+		if len(newHash) != 20*2+1 { // TODO: Hardcoded from the size of plumbing.Hash
+			panic("unexpected hash size")
+		}
+		// TODO: Add to tree
+	}
+
+	// contribBranchName := rand.Text()
+
+	// TODO: Store the branch
+
+	// fmt.Println(repo, diffFiles, preamble)
+	_ = preamble
+
 	return nil
 }