1 files changed, 119 insertions, 0 deletions
diff --git a/forged/internal/ipc/git2c/build.go b/forged/internal/ipc/git2c/build.go
new file mode 100644
index 0000000..3d1b7a0
--- /dev/null
+++ b/forged/internal/ipc/git2c/build.go
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
+
+package git2c
+
+import (
+	"encoding/hex"
+	"fmt"
+	"path"
+	"sort"
+	"strings"
+)
+
+func (c *Client) BuildTreeRecursive(repoPath, baseTreeHex string, updates map[string]string) (string, error) {
+	treeCache := make(map[string][]TreeEntryRaw)
+	var walk func(prefix, hexid string) error
+	walk = func(prefix, hexid string) error {
+		ents, err := c.TreeListByOID(repoPath, hexid)
+		if err != nil {
+			return err
+		}
+		treeCache[prefix] = ents
+		for _, e := range ents {
+			if e.Mode == 40000 {
+				sub := path.Join(prefix, e.Name)
+				if err := walk(sub, e.OID); err != nil {
+					return err
+				}
+			}
+		}
+		return nil
+	}
+	if err := walk("", baseTreeHex); err != nil {
+		return "", err
+	}
+
+	for p, blob := range updates {
+		parts := strings.Split(p, "/")
+		dir := strings.Join(parts[:len(parts)-1], "/")
+		name := parts[len(parts)-1]
+		entries := treeCache[dir]
+		found := false
+		for i := range entries {
+			if entries[i].Name == name {
+				if blob == "" {
+					entries = append(entries[:i], entries[i+1:]...)
+				} else {
+					entries[i].Mode = 0o100644
+					entries[i].OID = blob
+				}
+				found = true
+				break
+			}
+		}
+		if !found && blob != "" {
+			entries = append(entries, TreeEntryRaw{Mode: 0o100644, Name: name, OID: blob})
+		}
+		treeCache[dir] = entries
+	}
+
+	built := make(map[string]string)
+	var build func(prefix string) (string, error)
+	build = func(prefix string) (string, error) {
+		entries := treeCache[prefix]
+		for i := range entries {
+			if entries[i].Mode == 0o40000 || entries[i].Mode == 40000 {
+				sub := path.Join(prefix, entries[i].Name)
+				var ok bool
+				var oid string
+				if oid, ok = built[sub]; !ok {
+					var err error
+					oid, err = build(sub)
+					if err != nil {
+						return "", err
+					}
+				}
+				entries[i].Mode = 0o40000
+				entries[i].OID = oid
+			}
+		}
+		sort.Slice(entries, func(i, j int) bool {
+			ni, nj := entries[i].Name, entries[j].Name
+			if ni == nj {
+				return entries[i].Mode != 0o40000 && entries[j].Mode == 0o40000
+			}
+			if strings.HasPrefix(nj, ni) && len(ni) < len(nj) {
+				return entries[i].Mode != 0o40000
+			}
+			if strings.HasPrefix(ni, nj) && len(nj) < len(ni) {
+				return entries[j].Mode == 0o40000
+			}
+			return ni < nj
+		})
+		wr := make([]TreeEntryRaw, 0, len(entries))
+		for _, e := range entries {
+			if e.OID == "" {
+				continue
+			}
+			if e.Mode == 40000 {
+				e.Mode = 0o40000
+			}
+			if _, err := hex.DecodeString(e.OID); err != nil {
+				return "", fmt.Errorf("invalid OID hex for %s/%s: %w", prefix, e.Name, err)
+			}
+			wr = append(wr, TreeEntryRaw{Mode: e.Mode, Name: e.Name, OID: e.OID})
+		}
+		id, err := c.WriteTree(repoPath, wr)
+		if err != nil {
+			return "", err
+		}
+		built[prefix] = id
+		return id, nil
+	}
+	root, err := build("")
+	if err != nil {
+		return "", err
+	}
+	return root, nil
+}