From e15054a4f93fc54806e84aa7036e60168e78e823 Mon Sep 17 00:00:00 2001
From: Runxi Yu
Date: Fri, 6 Mar 2026 08:05:51 +0800
Subject: format/commitgraph: Add initial commit-graph support

---
 format/commitgraph/bloom/contain.go  | 10 +++------
 format/commitgraph/bloom/filter.go   | 21 +++++++++++++++++--
 format/commitgraph/bloom/key.go      | 39 +++++++++++++++++++++++-------------
 format/commitgraph/bloom/settings.go | 21 ++++++++++++++++++-
 4 files changed, 67 insertions(+), 24 deletions(-)

(limited to 'format/commitgraph/bloom')

diff --git a/format/commitgraph/bloom/contain.go b/format/commitgraph/bloom/contain.go
index 4789b321..331b7687 100644
--- a/format/commitgraph/bloom/contain.go
+++ b/format/commitgraph/bloom/contain.go
@@ -5,22 +5,18 @@ package bloom
 // Evaluated against the full path and each of its directory prefixes. A true
 // result indicates a possible match; false means the path definitely did not
 // change.
-func (f *Filter) MightContain(path []byte, settings *Settings) (bool, error) {
-	if f == nil || settings == nil {
-		return false, nil
-	}
-
+func (f *Filter) MightContain(path []byte) (bool, error) {
 	if len(f.Data) == 0 {
 		return false, nil
 	}
 
-	keys, err := keyvec(path, settings)
+	keys, err := keyvec(path, f)
 	if err != nil {
 		return false, err
 	}
 
 	for i := range keys {
-		if filterContainsKey(f, &keys[i], settings) {
+		if filterContainsKey(f, keys[i]) {
 			return true, nil
 		}
 	}
diff --git a/format/commitgraph/bloom/filter.go b/format/commitgraph/bloom/filter.go
index f56e9ba3..7c4aa1b8 100644
--- a/format/commitgraph/bloom/filter.go
+++ b/format/commitgraph/bloom/filter.go
@@ -6,6 +6,23 @@ package bloom
 // parent. Paths are expected to be in Git's slash-separated form and
 // are queried using a path and its prefixes (e.g. "a/b/c", "a/b", "a").
 type Filter struct {
-	Data    []byte
-	Version uint32
+	Data []byte
+
+	HashVersion    uint32
+	NumHashes      uint32
+	BitsPerEntry   uint32
+	MaxChangePaths uint32
+}
+
+// NewFilter constructs one query-ready bloom filter from raw data/settings.
+func NewFilter(data []byte, settings Settings) *Filter {
+	out := &Filter{
+		Data:           data,
+		HashVersion:    settings.HashVersion,
+		NumHashes:      settings.NumHashes,
+		BitsPerEntry:   settings.BitsPerEntry,
+		MaxChangePaths: settings.MaxChangePaths,
+	}
+
+	return out
 }
diff --git a/format/commitgraph/bloom/key.go b/format/commitgraph/bloom/key.go
index 6e49959d..a15df904 100644
--- a/format/commitgraph/bloom/key.go
+++ b/format/commitgraph/bloom/key.go
@@ -1,10 +1,12 @@
 package bloom
 
+import "codeberg.org/lindenii/furgit/internal/intconv"
+
 type key struct {
 	hashes []uint32
 }
 
-func keyvec(path []byte, settings *Settings) ([]key, error) {
+func keyvec(path []byte, filter *Filter) ([]key, error) {
 	if len(path) == 0 {
 		return nil, nil
 	}
@@ -19,7 +21,7 @@ func keyvec(path []byte, settings *Settings) ([]key, error) {
 
 	keys := make([]key, 0, count)
 
-	full, err := keyFill(path, settings)
+	full, err := keyFill(path, filter)
 	if err != nil {
 		return nil, err
 	}
@@ -28,7 +30,7 @@ func keyvec(path []byte, settings *Settings) ([]key, error) {
 
 	for i := len(path) - 1; i >= 0; i-- {
 		if path[i] == '/' {
-			k, err := keyFill(path[:i], settings)
+			k, err := keyFill(path[:i], filter)
 			if err != nil {
 				return nil, err
 			}
@@ -40,7 +42,7 @@ func keyvec(path []byte, settings *Settings) ([]key, error) {
 	return keys, nil
 }
 
-func keyFill(path []byte, settings *Settings) (key, error) {
+func keyFill(path []byte, filter *Filter) (key, error) {
 	const (
 		seed0 = 0x293ae76f
 		seed1 = 0x7e646e2c
@@ -52,7 +54,8 @@ func keyFill(path []byte, settings *Settings) (key, error) {
 		err error
 	)
 
-	if settings.HashVersion == 2 { //nolint:nestif
+	switch filter.HashVersion {
+	case 2:
 		h0, err = murmur3SeededV2(seed0, path)
 		if err != nil {
 			return key{}, err
@@ -62,7 +65,7 @@ func keyFill(path []byte, settings *Settings) (key, error) {
 		if err != nil {
 			return key{}, err
 		}
-	} else {
+	case 1:
 		h0, err = murmur3SeededV1(seed0, path)
 		if err != nil {
 			return key{}, err
@@ -72,21 +75,29 @@ func keyFill(path []byte, settings *Settings) (key, error) {
 		if err != nil {
 			return key{}, err
 		}
+	default:
+		return key{}, ErrInvalid
 	}
 
-	hashes := make([]uint32, settings.NumHashes)
-	for i := range settings.NumHashes {
-		hashes[i] = h0 + i*h1
+	hashCount, err := intconv.Uint32ToInt(filter.NumHashes)
+	if err != nil {
+		return key{}, ErrInvalid
 	}
 
-	return key{hashes: hashes}, nil
-}
+	hashes := make([]uint32, hashCount)
+	for i := range hashCount {
+		iU32, err := intconv.IntToUint32(i)
+		if err != nil {
+			return key{}, ErrInvalid
+		}
 
-func filterContainsKey(filter *Filter, key *key, settings *Settings) bool {
-	if filter == nil || key == nil || settings == nil {
-		return false
+		hashes[i] = h0 + iU32*h1
 	}
 
+	return key{hashes: hashes}, nil
+}
+
+func filterContainsKey(filter *Filter, key key) bool {
 	if len(filter.Data) == 0 {
 		return false
 	}
diff --git a/format/commitgraph/bloom/settings.go b/format/commitgraph/bloom/settings.go
index 5aa122a9..764653bd 100644
--- a/format/commitgraph/bloom/settings.go
+++ b/format/commitgraph/bloom/settings.go
@@ -1,6 +1,10 @@
 package bloom
 
-import "encoding/binary"
+import (
+	"encoding/binary"
+
+	"codeberg.org/lindenii/furgit/internal/intconv"
+)
 
 // Settings describe the changed-paths Bloom filter parameters stored in
 // commit-graph BDAT chunks.
@@ -27,5 +31,20 @@ func ParseSettings(bdat []byte) (*Settings, error) {
 		MaxChangePaths: DefaultMaxChange,
 	}
 
+	switch settings.HashVersion {
+	case 1, 2:
+	default:
+		return nil, ErrInvalid
+	}
+
+	if settings.NumHashes == 0 {
+		return nil, ErrInvalid
+	}
+
+	_, err := intconv.Uint32ToInt(settings.NumHashes)
+	if err != nil {
+		return nil, ErrInvalid
+	}
+
 	return settings, nil
 }
-- 
cgit v1.3.1-10-gc9f91